DEVELOPMENT AND EVALUATION OF OPENLABS AND THE VISIR OPEN ELECTRONICS AND RADIO SIGNAL LABORATORY FOR EDUCATION PURPOSE
Kristian Nilsson
Blekinge Institute of Technology Licentiate Dissertation Series No. 2014:04 Department of Applied Signal Processing
Development and Evaluation of OpenLabs and the VISIR Open Electronics and Radio Signal Laboratory for Education Purpose
Kristian Nilsson
Blekinge Institute Institute of ofTechnology Technology Licentiate doctoral dissertation Blekinge Dissertationseries Series No No2014:03 2014:04
Development and Evaluation of Psychosocial, Socio-Demographic OpenLabs the VISIR Open and Healthand Determinants in Electronics and Radio Signal Information Communication Laboratory for Education Purpose Technology Use of Older-Adult Kristian Nilsson Jessica Berner Doctoral LicentiateDissertation Dissertationinin Applied SignalTechnology Processing Applied Health
Department of Health Department of Applied Signal Processing Blekinge Institute Institute of of Technology Technology Blekinge SWEDEN SWEDEN
2014 Kristian Nilsson Department of Applied Signal Processing Publisher: Blekinge Institute of Technology, SE-371 79 Karlskrona, Sweden Printed by Lenanders Grafiska, Kalmar, 2014 ISBN: 978-91-7295-283-6 ISSN 1650-2140 urn:nbn:se:bth-00592
Abstract For centuries scientists have performed physical experiments in order to understand the phenomena of nature and to create theories and mathematical models. This work covers some of the remotely controlled laboratories, with real physical instruments, experimental objects, etc., created within the VISIR (Virtual Instruments Systems In Reality) Open Lab Platform. This is a platform for opening hands-on laboratories for remote access 24/7 with preserved context. The aim is to create laboratories, where telemanipulators can be used to remotely set up real physical experiments. The students use virtual representations of the hands-on laboratory instruments to collect and measure real physical data. As hands-on laboratories, the VISIR can be used for exploring nature and for training engineering workmanship. Part I and II of this thesis constitute a theoretical and practical approach on how to open up a laboratory for remote access and enabling students to have access to the equipment 24/7. Part I covers a more general solution for enabling remote access to equipment; the suggested solution can be applied to all types of instruments that can be controlled from a PC based system. Part III and IV of this thesis present an encouragement to collaborate within in the eld of remote engineering to utilize the recourses more e ciently. The idea is that universities around the world can share their experiments in a grid laboratory; every university contributes with a small part, but gets access to a wide range of experiments in this grid. Part V of this thesis concerns the modelling and simulation of the remote electronics laboratory with the purpose of estimating the maximum number of simultaneous users without losing the experience of working with a real instrument. The results indicate that one single remote electronics laboratory can handle up to 120 users simultaneously and with 120 users the delay for each user is approximately 2 seconds.
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Preface This licentiate thesis summarizes selected parts of my work within the eld of remote engineering, speci cally in the VISIR (Virtual Instruments Systems in Reality) project. The work has been performed at the Department of Applied Signal Processing at Blekinge Institute of Technology. The thesis consists of ve selected parts: I Remote Access of Computer Controlled Experiments II Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7 III On Objectives of Instructional Laboratories, Individual Assessment, and Use of Collaborative Remote Laboratories IV A Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid V Simulations of the VISIR Open Lab Platform
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Acknowledgements I have many to thank for their support during this work. First I would like to thank Professor Lars Håkansson for giving me the opportunity to start as a Ph. D. student under his guidance and for all the help, support and knowledge that he has given me during these years. Also, I would like to express my sincere gratitude to my research supervisor Ingvar Gustavsson for all his encouragement, help and advices, for being a great source of knowledge, and for the stimulating discussions concerning both work and life in general. I also want to give my sincere gratitude to Johan Zackrisson; without his knowledge and expertise some of this work would have been nearly impossible to carry out, and I would also like to thank him for our sometimes lively discussions during lunches and coee breaks. Finally, I would like to thank all my present and former colleagues at the department for the positive attitude and the open and very friendly atmosphere during coee breaks and lunches. Especially I would like to thank Josef Ström Bartunek, Mikael Swartling and Thomas Sjögren for their good company during lunches, dinners and parties. Karlskrona, April 2014 Kristian
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Publications List The thesis is based on the following publications: I Gustavsson, K Nilsson, J Zackrisson, and L Håkansson. Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7. World Transactions on Engineering and Technology Education, 8(2):5257, 2010. Ingvar Gustavsson, Kristian Nilsson, Johan Zackrisson, Javier Garcia-Zubia, Unai Hernandez-Jayo, Andrew Nafalski, Zorica Nedic, Ozdemir Gol, Jan Machotka, Mats I Pettersson, et al. On objectives of instructional laboratories, individual assessment, and use of collaborative remote laboratories. Learning Technologies, IEEE Transactions on, 2(4):263274, 2009. Ingvar Gustavsson, Johan Zackrisson, Kristian Nilsson, Javier Garcia-Zubia, Lars Håkansson, Ingvar Claesson, and Thomas Lagö. A exible electronics laboratory with local and remote workbenches in a grid. International Journal of Online Engineering, 4(2), 2008. Kristian Nilsson, Johan Zackrisson, and Mats I Pettersson. Remote access of computer controlled experiments. International Journal of Online Engineering, 4(4), 2008. Mikael Swartling, Josef Ström Bartunek, Kristian Nilsson, Ingvar Gustavsson, and Markus Fiedler. Simulations of the visir open lab platform. In
Remote Engineering and Virtual Instrumentation (REV), 2012 9th International Conference on, pages 15. IEEE, 2012.
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Other Publications I Gustavsson, G Alves, R Costa, K Nilsson, J Zackrisson, U Hernandez-Jayo, and J Garcia-Zubia. The visir open lab platform 5.0-an architecture for a federation of remote laboratories.
Remote Eng. & Virtual Instrum.(REV) ,
pages 284288, 2011. Ingvar Gustavsson, Lena Claesson, Kristian Nilsson, Johan Zackrisson, Javier Garcia Zubia, Unai Hernandez Jayo, Lars Håkansson, Josef Ström Bartunek, Thomas L Lagö, Ingvar Claesson, et al. The visir open lab platform.
NI Week, 2009.
Ingvar Gustavsson, Kristian Nilsson, and Thomas Lagö. On physical experiments and individual assessment of laboratory work in engineering education.
In Proceedings of the International Conference on Management of Emergent Digital EcoSystems, page 84. ACM, 2009. Ingvar Gustavsson, Johan Zackrisson, J Ström Bartunek, Kristian Nilsson, Lars Håkansson, Ingvar Claesson, and T Lagö. Telemanipulator for remote wiring of electrical circuits.
Düsseldorf, Germany, 2008.
In
Proceedings of the 2008 REV Conference,
I Khan, D Muthusamy, Wasim Ahmad, Kristian Nilsson, Johan Zackrisson, Ingvar Gustavsson, and L Hakansson. Remotely controlled laboratory setup
Remote Engineering and Virtual Instrumentation (REV), 2012 9th International Conference on , for active noise control and acoustic experiments. In pages 18. IEEE, 2012. Imran Khan, Dinesh Muthusamy, Waqas Ahmad, Benny Sällberg, Kristian Nilsson, Johan Zackrisson, Ingvar Gustavsson, and Lars Håkansson. forming active noise control and acoustic experiments remotely.
tional Journal of Online Engineering (iJOE) , 8(S4):pp65, 2012.
Per-
Interna-
Martin Larsson, Kristian Nilsson, Sven Johansson, Ingvar Claesson, and Lars Håkansson. An active noise control approach for atten-uating noise above
the plane wave region in ducts. In International Congress on Sound and Vibration, ICSV. International Institute of Acoustics and Vibration (IIAV).
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Other Publications
Mohamed Taw k, Elio Sancristobal, Sergio Martin, Rosario Gil, Gabriel Diaz, Antonio Colmenar, Juan Peire, Manuel Castro, Kristian Nilsson, Johan Zackrisson, et al. Virtual instrument systems in reality (visir) for remote wiring and measurement of electronic circuits on breadboard. Learning Technologies, IEEE Transactions on , 6(1):6072, 2013.
Contents Abstract
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Preface
vii
Acknowledgements
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Publications List
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Other Publications
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Contents
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Introduction
1
1
VISIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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2
Open electronics Lab at BTH . . . . . . . . . . . . . . . . . . .
3
3
Expanding the concept . . . . . . . . . . . . . . . . . . . . . . .
5
Bibliography
9 xv
xvi
I
CONTENTS
Remote Access of Computer Controlled Experiments
11
II Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7 19 IIIOn Objectives of Instructional Laboratories, Individual Assessment, and Use of Collaborative Remote Laboratories
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IVA Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid
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V Simulations of the VISIR Open Lab Platform
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Introduction Humans have during their evolution used, for instance, the trial and error method in order to develop new tools, constructions, compounds and other means to enhance their daily life, etc. [5]. For centuries scientists have performed physical experiments to create and to verify theories and mathematical models with the purpose to improve our understanding of the world we live in. Physical experiments are basically the general way to verify and develop our understanding of Mother Nature and her complexity: Archimedes' principle is for instance one well-known example illustrating this. During the last century it has been evident that humans have to live in harmony with nature and that the development of a sustainable relation between humans and nature urges [2]. In the humans' approach towards a sustainable relation with nature, knowledge and understanding of nature is a key factor. Hence, for humans to nd the path to a life in harmony with nature this, will demand that activities concerning physical experiments have to be intensi ed. This concerns for instance both research and education. In education the role of real physical experiments in courses has to be extended in order to, e.g., provide a su cient supply and foundation of engineers and people with university degrees in science with adequate experimentation skills [2]. Furthermore, the designs of new experiments have to be considered to nd answers that lead mankind in a sustainable direction [4, 13, 2]. However, during the last decades the amount of physical experiments, for example in engineering education, has successively been reduced [4]. The number of students per course has increased without a related increase in the funding for sta and laboratory equipment. Consequently, this has imposed a reduction of physical experimentation in engineering education [13]. Reducing the number of laboratory sessions is simple because of the fact that laboratory work in education is rarely evaluated and the cost reduction is generally considerable. The reduction of laboratory sessions in engineering education is alarming and the ABET (Accreditation Board of Engineering and Technology) has pointed out that learning objectives for laboratory work are required to provide a su cient level in engineering education and they have to be continuously evaluated [4, 1]. Thus, to maintain and to restore the level in engineering education the funding of it has to increase and/or new types of 1
2
Introduction
physical laboratories, that have a higher capacity to a lower cost, are required. During the last ten years students have been given extended access to learning resources and increased freedom to organize their studies in a more exible way [6]. This new mobility is pointed out by the Bologna Process as one of their main objectives [11]. Faster and more exible network connections, increased communication speed and accessibility have made this new mobility possible. This has opened doors to so called remote laboratories oering physical experiments operated from a remote location. Remote laboratories have proven to be one way of increasing physical experiments in, e.g., engineering education without imposing signi cant increases on the costs for a university [3, 12]. In the beginning of year 2000, BTH (Blekinge Institute of Technology) founded a remote laboratory project. Today there are ve remote laboratories running around-the-clock at BTH and several more are under development [10, 14]. The fundamental purpose of these laboratories is to provide students with new possibilities to carry out laboratory experiments using real instruments, experiment objects, etc. that replicate the hands-on laboratory but from, e.g., the students' home computers. The students are given total control over instruments similar to the ones they face in the hands-on laboratory at campus and components and instruments are connected by the student in a way that are required, e.g., by a particular experiment.
1
VISIR
BTH started a project in 2006 known as VISIR (Virtual Instruments Systems in Reality) together with National Instruments and Axiom EduTech in Sweden [10]. The International Association of Online Engineering (IAOE) has organized a Special Interest Group for VISIR (SIG VISIR), for people interested in On-line Engineering, especially in opening university laboratories for remote access. The overall goal of the VISIR project is to increase the access to experimental equipment in dierent areas of studies, for example, electronics, sound and vibration or propagation of radio signals, without raising the running cost per student signi cantly for the universities [10]. This is accomplished by sharing online laboratories, created by dierent universities in cooperation. The ultimate goal is to create physical experiments resources that are accessible 24/7 for everyone as a means of inspiring and encouraging people to study engineering and become good professionals.
3
2
Open electronics Lab at BTH
Generalized experiments contain a set of actions and observations performed in a context of solving a particular challenge [7]. The open electronics laboratory provides students with a wide range of actions and observations that can be carried out, as well providing a great exibility for the teacher to construct challenges. Experiments are important not only for acquiring knowledge concerning a physical phenomenon, but are also an important tool for, e.g., verifying mathematical models and to explore their limitations. A typical example of a laboratory setup is the lab workbench in an instructional laboratory for analog electronics at BTH, shown in Figure 1.1. In the instructional electronics
Figure 1.1: Electronics workbench at BTH laboratory at campus a limited number of workbenches, e.g. 8, are available with identical instruments, breadboards, components, etc. Typically, two students are carrying out experiments at each workbench. At the workbench the student wires circuits on a breadboard and uses instruments to measure for example the current in the circuit by connecting a DMM (Digital Multi Meter). The set of experiments possible to perform on a lab workbench for analog elec-
4
Introduction
tronics is mainly limited by the components provided by the instructor. The students, however, are only allowed to be in an instructional laboratory when an instructor is present. In most universities an instructor is given a limited number of hours to spend on each laboratory session, i.e., the scheduled time for the session. Hence, students are rarely given the opportunity to spend any extra time in a laboratory, exceeding the scheduled time for the session, to perform further investigations in the subject in which they are carrying out studies. In the online electronics laboratory, however, the capacity of a workbench is signi cantly greater as compared to an on-campus workbench. For example, at BTH one online electronics laboratory will serve 32 simultaneous students. As shown in Part V of this report, this number can be signi cantly increased without increasing the response time. In the area of analog electronics time sharing may conveniently be used in online electronics laboratories. This will provide experiments identical to the ones available in a hands-on laboratory but in another timescale with circuits having shorter time constants, thus enabling the remote workbenches to serve many students. There are of course dierences between the online electronic workbenches at BTH compared to the traditional on-campus workbenches shown in Fig.1 but basically they oer the same functionality. Students experimenting using the online workbench cannot manipulate the circuit directly by using their hands and ngers; this is instead carried out by utilizing a type of circuit-wiring robot. In the online electronics laboratory, the circuit-wiring robot consists of a relay switching matrix [8, 9]. In the online electronic workbenches, standalone instruments such as the DMM, signal generator, etc. are replaced by plug-in cards in a PXI chassis connected to a host computer in the Equipment Server shown in Figure 1.2. The front panels of the instruments in the online electronics laboratory are freely con gured, for example they can be made from photos of the instruments shown in Figure 1.1 In Figure 1.2, the stack of cards on the top of the PXI chassis is the switching matrix. The switching matrix, the circuitwiring robot, enables online assembling of physical electrical components into circuits and the connection of suitable measurement instruments and devises to the assembled circuit. As shown in Figure 1.3, the matrix contains 4 dierent types of circuit boards. Depending on requirements and the complexity of the experiments in the online electronics laboratory, more cards may for instance be added to the switching matrix allowing greater freedom or more complex circuits. Starting from the top of the switching matrix shown in Fig. 3, the rst circuit board holds the electrical components, the second circuit board handles a two-channel Oscilloscope, the third circuit board handles a DMM and the fourth circuit board handles the power supply and a USB interface for
5
Figure 1.2: Equipment Server communication with the server. A student working in the online electronics laboratory will only be able to see and use a subset of the components installed in the switching matrix, via their web browser, when he or she wires a circuit. The remote laboratory oers support to both inexperienced and experienced students within the area of electronics. First- year students can get more familiar with the instruments and how to measure electrical properties, while more advanced students can, e.g., investigate transient behavior of circuits.
3
Expanding the concept
In parallel with the open electronics laboratory, other online laboratories have been developed and implemented based on the same concepts and goals. In the same way they support real-time measurements using real physical instruments, measurement objects, etc. and are as well accessible 24/7. One of these laboratories is the antenna laboratory described in Part I of the report, where students may investigate the propagation of radio waves shown in Figure 1.4. This laboratory diers from the electronics laboratory regarding the nature of the experiments carried out. The experiments that are performed may take several minutes to complete and therefore time sharing is not an option; in-
6
Introduction
Figure 1.3: Switching Matrix stead several identical experimental setups were installed and are available for the students. This limitation is basically eliminated by having the students register for experiment sessions well in advance of the scheduled time for the experiment sessions. In this way the students are guaranteed access to the laboratory setups. The antenna lab does not provide the students the freedom to change, e.g., the antenna used. This could be made possible by using a switching matrix. Even if there are no time sharing and a x antenna, this laboratory has provided students with access 24/7 to hardware generally only used in a few hands-on sessiond during their time of study. The system suggested in Part I of the licentiate can easily be adapted to handle a wide range of dierent types of laboratory software or hardware. For example, this system could be used to give students access to expensive and licensed software (if the end-user license agreement allows it), without the need of installing it on their personal computer. One of the advantages of the system is the freedom for the user to modify software and operating system. After a completed laboratory session the system will always be returned to a prede ned state, regardless of
7
Figure 1.4: Antenna experiment previous changes.
Bibliography [1]
Martyn Cooper. Remote laboratories in teaching and learningissues impinging on widespread adoption in science and engineering education.
ternational Journal of Online Engineering (iJOE) , [2]
In-
1(1), 2005.
Cli I Davidson, Chris T Hendrickson, H Scott Matthews, Michael W Bridges, David T Allen, Cynthia F Murphy, Braden R Allenby, John C Crittenden, and Sharon Austin. Preparing future engineers for challenges of the 21st century: Sustainable engineering.
[3]
tion,
18(7):698701, 2010.
Ton
de
Jong,
Marcia
C
Linn,
and
Journal of cleaner produc-
Zacharias
C
Zacharia.
Physical
and virtual laboratories in science and engineering education.
Science,
340(6130):305308, 2013. [4]
Lyle D Feisel and Albert J Rosa. The role of the laboratory in undergraduate engineering education.
Journal of Engineering Education ,
94(1):121
130, 2005. [5]
Richard M Felder and Linda K Silverman. in engineering education.
[6]
Learning and teaching styles
Engineering education ,
78(7):674681, 1988.
Denis Gillet, Anh Vu Nguyen Ngoc, and Yassin Rekik. Collaborative webbased experimentation in exible engineering education.
Transactions on, [7]
Education, IEEE
48(4):696704, 2005.
Crissie M Grove, Patricia J Dixon, and Margareta M Pop. Research experiences for teachers: In uences related to expectancy and value of changes to practice in the american classroom.
cation, [8]
Ingvar Gustavsson. How to open a local electronics laboratory for remote access.
[9]
Professional development in edu-
35(2):247260, 2009.
Interactive Computer Aided Blended Learning ICBL2008 ,
2008.
Ingvar Gustavsson, Johan Zackrisson, Henrik Åkesson, Lars Håkansson, Ingvar Claesson, Thomas Lagö, et al.
9
Remote operation and control of
10
BIBLIOGRAPHY traditional laboratory equipment. International Journal of Online Engineering, 2(1):8, 2006.
[10] Ingvar Gustavsson, Johan Zackrisson, Lars Håkansson, Ingvar Claesson, and T Lagö. The visir projectan open source software initiative for distributed online laboratories. In Proceedings of the REV 2007 conference, Porto, Portugal, 2007.
[11] Guenter Heitmann. Challenges of engineering education and curriculum development in the context of the bologna process. European Journal of Engineering Education , 30(4):447458, 2005.
[12] Jing Ma and Jerey V Nickerson. Hands-on, simulated, and remote laboratories:
A comparative literature review.
ACM Computing Surveys
(CSUR), 38(3):7, 2006.
[13] D Magin and S Kanapathipillai. Engineering students' understanding of the role of experimentation. European journal of engineering education , 25(4):351358, 2000. [14] Mohamed Taw k, Elio Sancristobal, Sergio Martin, Rosario Gil, Gabriel Diaz, Antonio Colmenar, Juan Peire, Manuel Castro, Kristian Nilsson, Johan Zackrisson, et al.
Virtual instrument systems in reality (visir)
for remote wiring and measurement of electronic circuits on breadboard. Learning Technologies, IEEE Transactions on , 6(1):6072, 2013.
Part I
Remote Access of Computer Controlled Experiments
Remote Access of Computer Controlled Experiments
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REMOTE ACCESS OF COMPUTER CONTROLLED EXPERIMENTS
Remote Access of Computer Controlled Experiments doi:10.3991/ijoe.v4i4.704
K. Nilsson, J. Zackrisson and M.I. Pettersson Blekinge Institute of Technology/ School of Engineering, Ronneby, Sweden
Abstract—in this paper, we present a way for students to access and operate laboratory equipment, controlled by a laboratory computer via a remote access program. In this way, the solution is not dependent on the specific laboratory equipment, as long as the equipment can be remotely controlled. The system can easily be altered to be used in another laboratory setup. Students are able to make reservations of experiment sessions through a web interface, which is administrated by the system administrator. The solution proposed in this paper is one way to speed up the development of remote accessible laboratories. Most of the proposed solution is based on open source software and the hardware is built on ordinary consumer parts, which makes the proposed remote laboratory architecture cost effective. Index Terms—Remote handling, Student experiments, Training, e-Learning
I. INTRODUCTION The purpose of this work at Blekinge Institute of Technology (BTH) is to provide an effective and efficient environment for experiments. This paper is focusing on antenna equipment and how to remotely control this hardware. The design allows students to perform experiments around the clock, every day. The strength of the system is the access to expensive equipment without the need of a supervisor, continuously monitoring the experiment. This helps meet the demands of more students without increase in staff and funding resources. According to [1] the number of students is increasing compared to the funding dedicated for hands-on experiments. In engineering education, a key-activity to improve the learning process is hands-on experience, gained from laboratory experiments [2]. Students want extended accessibility and free access to learning resources, this demands more flexible laboratories that not only are physical accessibility around the clock. They must also be accessible without the geographical limitation. Today there are many academic institutions offering web-based experiments, so called remote laboratories, which are supporting remote access of physical hardware [3, 4]. The architecture presented in this paper is describing a general solution for how a computer-controlled experiment can be made remote accessible, without the need for special hardware or customized software. The presented architecture is built on simple and robust hardware running standard software. II. GENERAL STRUCTURE The laboratory system is divided in three major parts, Figure 1. The first part is the Web server. The second part
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is the controller. The last part is the computer the students will remote control to perform experiments. Through the laboratory’s web interface, students can allocate resources and mange their experiments. To get access to the laboratory students must first authenticate themselves. This is done through a login webpage where the student enters his/her email address and password. The first time a student want to use the system, the account has to be activated. This activation is generating a password and which is sent to the users email address. When a student is logged-in, he/she can make a reservation. The student can choose which system installation to use. A system installation is a snapshot of hard drive content, also called clone, and consists of an Operating system and all the tools needed for the experiment. The controller is handling and distributing these clones of different operating systems and software. A Power Distribution Unit (PDU) is handling the power distribution to all of the computers. For the cloning system to be able to install a new operating system the remote controlled computer (RCC) have to be rebooted. A PDU that switch the power off and on are the most reliable solution of ensuring that the computer is rebooted.
Figure 1. General view of the core parts in the system.
Control mechanisms make sure that it is safe to give full access of the remote controlled machine to the student. That means that they do not require supervision during their experiment. Users are given full access to the laboratory computer and have the freedom to alter the entire operating system. This is made possible due to the cloning system. When a laboratory session is over, the cloning system will wipe the RCC’s hard disk content and install a new clone for the next experiment.
http://www.i-joe.org
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Part I REMOTE ACCESS OF COMPUTER CONTROLLED EXPERIMENTS
To prevent abuse of the system the only accepted data communication is from the student that booked the laboratory session this security measure is preventing the system from being used for adverse activities. Both the web server and the controller are running on FreeBSD [5], an open source operating system. A. Web Server The web server is handling the web interface, where users can make experiment reservations. In the antenna laboratory this computer are also acting as a firewall and a DNS server. The Web Server is providing the following services: x Firewall (PF) x DNS x DHCP x Web server (Apache) Web application Remote access is vital to the laboratory. At the same time, security measures must be taken to guarantee that the system is not used in adverse ways. A way to provide remote access is to let a firewall give certain IP-addresses access to the laboratory. When a student chooses to begin a laboratory session in the web interface, the address is saved. The IP-address is then used to generate firewalls rules that only allowing data traffic between the user’s computer and the RCC in the laboratory. After the laboratory session is over, access to the laboratory is disabled. This solution requires that the student have the same IP-address for the whole laboratory session. Depending on the demands of the experiments, a system administrator can make exceptions and e.g. grant access from the RCC to different web sites. B. Controller The system used for creating clones is the EXP experiment system [6]. It is provided by EXP innovation and is used under a restricted BTH license. The experiment system EXP is handling all of the clones that can be installed on the RCC. Clone images are raw copies of the content off a hard drive. All of the hardware is built on standard PC parts with this specially built EXP software, which runs on the controller. The controller is acting as a server to all of the RCCs in the network. The cloning system is providing the following functions: x Booting a system on the RCC x Creating of system clones x Installing of system clones x Cleaning hard disks The system administrator creates clones by installing all of the necessary software on the RCC and by using the cloning software to make a complete clone image of its hard drive. The cloning process is providing the necessary tools for experiments without the need of further installations during the laboratory sessions. Because most experiments don’t need to use the whole hard drive a Microsoft Windows XP operating system image can be installed on a 10GB partition and the clone tool can be set to only clone this 10GB area. To compress the size of the
iJOE – Volume 4, Issue 4, November 2008
clone even more the run length encoding (RLE) compression can be used. All of the software, except the cloning system, is released as open source software and can downloaded from http://svn.openlabs.bth.se/trac/openlabsweb C. Remote Controlled Computer The RCC are a built on hardware that are suited for the type of operating system that are demanded by the experimental hardware. In this case are the RCC built on ordinary PC parts. This computer is the only part of the system that is accessed by the student; the controller is transparent for the end user and the web server are only access by the web interface. D. Power Distribution Unit The PDU are distributing power to the computers in the laboratory. The PDU can be controlled via SNMP. When a RCC is cleaned, cloned or reinstalled with a new clone, a reboot of the computer is needed. There are different software solutions for rebooting the computer, but only ways to make sure that the computer is rebooted is to turn the power off and on again. This approach demands that the hardware is supporting power up after power failure. The benefits of a PDU compared to other solutions are that it is independent of hardware manufacturers and are not demanding operating system integration. Unfortunately, it put some extra strain on the RCCs’ hardware as the power is cut without notification. Older hard drives had problems with start-stop (CSS) cycles, which happens when there is a power failure or in our case cut the power to the hard drive without notification. Modern hard drives have different ways to handle power failure. One solution is CSS landing zones, which are specially prepared regions on the platter to where the read head automatically returns in case of a power failure. One other solution is moving the read head away from the platter [11] in case of a power failure. Most of the new hard drives on the market are guaranteeing a start-stop cycle count of 50000 [12, 13] or nearly 3 years (1000 days) of operating at 50 cycles per day. III. SYSTEM MANAGEMENT The solutions presented so far focuses on the general structure of a remote laboratory that can be used with various types of hardware and or software. One of the laboratories adapting this general structure is the antenna laboratory [9]. The antenna laboratory is managed from a web application running in a web browser, where the user can make experiment reservations, deciding when, and what type of experimental environment to use. The administrator can create course occasions for different courses, and the system resources can be distributed among these occasions and shared among different courses. Course occasions are limited in time and the number of users it can handle. This is an estimation of how many reservations that can be expected. For an occasion there can be several teachers assigned and it is up to them to do further management of the occasion. To give access to the system an administrator or teacher has to register the e-mail address for the users. The first time a user wants to access the system, the account has to be activated. This makes the system send an automatically generated password to the users e-mail address. There are
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Remote Access of Computer Controlled Experiments
15
REMOTE ACCESS OF COMPUTER CONTROLLED EXPERIMENTS
three different levels of access to the system, administrator, teacher, and student. Depending on the role, they will be presented with different options.
computer and therefore the maximum numbers of accessible RCCs shown in Figure 3 is one.
A. Administrator The administrator is responsible for the general management of the system; he/she is creating courses and deciding the limitations of recourses for this course. It is the administrator that is creating the different clones that later on can be used in the courses. The system are built in a hierarchy, the administrator are overruling both the teacher and the students settings. B. Teacher The top part of the teacher interface in Figure 2 is showing information about the course occasion. Teachers can make pre-reservation, e.g. for teacher-lead experiments. This type of reservation is given priority over ordinary reservations and do not have the time restrictions ordinary reservations have. The bottom part of the teachers interface Figure 2 is for managing users in the courses occasion. All of the users registered to this occasion are presented with their e-mail address and user type. In the bottommost area e-mail address of new users can be added, this field is accepting multiple inputs as long that there is a new line between every e-mail address. The teacher can perform the following actions:
Figure 3. Overview of the reservation page.
The reservations are made simply by clicking on an available RCC. After a reservation is made, the cloning system needs time to transfer the clone from the controller to the RCC. Depending on size of the clone, variations in cloning time is hard to approximate and therefore a onehour preparation period is added to the reservation system to guarantee that the system have finished. Five minutes before the experiment begins, an e-mail is sent to the student an as reminder. This massage contains all the information needed for the experiment, such as user name, password, and IP-address. IV. ANTENNA LABORATORY In the antenna laboratory, the main part of the software used in web server and controller was developed for the security laboratory at BTH [11]. The security laboratory is focusing on security and the possibility to experiment with dangerous software in a controlled environment. In the antenna laboratory, the focus is to give students remote access to expensive equipment. Figure 4 is illustrating the structure of the antenna laboratory. The antenna laboratory is expanding the general configuration, shown in Figure 1, with one web camera, one camera accessed over the USB and the antenna equipment.
Figure 2. Teacher interface.
x Define the number of computers a student can reserve. x Make a pre-reservation. x Add and remove users from the course. C. Student Students are able to make reservations of laboratory session. It is up to the administrator to decide the maximum duration of one laboratory session and decide which clones that are allowed for the session. Figure 3 shows an overview of the reservation system. The information given is the number of RCC that are available every hour. In the antenna laboratory, there is only one
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Figure 4. Expanded system with more homogenous RCC.
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Part I REMOTE ACCESS OF COMPUTER CONTROLLED EXPERIMENTS
A. Antenna Equipment The equipment used in the laboratory is provided by Lucas-Nuelle Lehr- und Messgeraete GmbH [7]. The company has a wide range of products for antenna laboratories. The one used in this work is the “TAT Antenna Techniques” [8]. This equipment makes it possibly to do experiments in antenna technology fundamentals and is recommended for basic courses in antenna theory. The laboratory equipment is communicating by USB. Without the protocol specification for the USB controlled device, it is almost impossible for third party software to access the hardware. This means we have to depend on the provided software, and that is the reason behind this remote control solution. B. Cameras In the antenna laboratory, there are two cameras. One is used for monitoring and to give visitors of the laboratory home page an overview. This camera is continuously taking pictures of the laboratory equipment and they are shown at the home page [9]. The second camera is used during the experiments in the laboratory. This camera is covering two important areas; one is to provide a feeling of working with real equipment and the other are to give necessary information for the laboratory assignment. The camera that is used by the student is remotely adjustable in vertical and the horizontal level. Depending on the bandwidth of the students Internet connection, the image quality can be adjusted, to allow everyone the same opportunity to perform experiments. C. Preforming a Experiment To remote control the antenna experiment, Microsoft Remote Desktop is used, which is part of the Windows operating system. When the student confirms that he/she is ready to start the experiment session, the firewall settings are updated automatically to allow connections to the RCC. The firewall will then be accepting incoming and outgoing traffic to and from the users IP-address. The student is then allowed to connect to the remote controlled computer. Figure 5 shows the system running a laboratory session. During the session, students can perform all of the tasks that an ordinary laboratory can offer. In the Figure 5 to the right is the software program for the TAT Antenna Techniques [8] and to the left is the remote controlled camera.
V. ADAPTING THE SYSTEM TO NEW APPLICATIONS The system can be adapted to handle different types of laboratory software or hardware, as long as it is controlled by a computer that allows remote control. The requirements (of the laboratory equipment) are that a computer controls it and that the operating system is supporting remote access. The system can for example be used for remote accessing: x Expensive or fragile hardware x Sensitive or expensive software x Sensitive or dangerous hardware One of the advantages of the system is the freedom for the user; one user can control all of the hardware and software resources without worry about the next user. Regardless of what type of changes that has been made in the software, the system always restores the software between every laboratory sessions. The flexibility allows the system to be adapted in various ways. A. Scaling Depending on the needs and demands of the system, more RCC with homogenous hardware can be added. One important thing to consider when expanding the laboratory with more RCC is the cloning time, depending on the LAN configuration and the number of simultaneous cloned computers the cloning time can increase. The system used today is supporting feedback from the RCC when a successful clone is ready but the software handling this feedback is still under construction. That means, a fixed preparation and cleaning time must be used, which have to be estimated by hand. Figure 6 is illustrating a scaled version of the antenna laboratory.
Figure 6. Expanded system with more homogenous RCC.
Figure 5. Running laboratory session, to the right is the software program for the tat antenna techniques and to the left is the remote controlled camera.
iJOE – Volume 4, Issue 4, November 2008
B. Adapting to a Specific Problem On BTH the EXP system are been used to supply on campus laboratories with on demand reinstallation of the entire operating system. Different laboratory sessions demand different software and sometimes even different operating systems. Instead of having multiple operating systems installed on the local computer, the teacher can prepare a clone in advance. This clone is then installed on the local computers. By using this solution the teacher only needs to maintain one copy of the software and
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REMOTE ACCESS OF COMPUTER CONTROLLED EXPERIMENTS
students don’t have to worry about system configuration, all of the computers are having the same configuration when the laboratory session are starting. VI. CONCLUSION AND FURTHER WORK In this paper, a general computer based structure is presented that can be applied to various computer based experiments. The proposed solution has the potential to be adapted to a wide range of laboratory experiments The laboratory could also be used to give students access to expensive and licensed software (if the end user license agreement allows it), without need to install it on their home computers. The solution of the antenna laboratory is focusing on the access of the computer through for example remote desktop rather than focusing on the interface controlling the hardware. This approach makes detailed knowledge of the communication between hardware and the computer unnecessary. The solution is a fast and simple way of constructing a remote accessed laboratory. The goal is to offer access to experimental equipment around the clock and the experience of a genuine laboratory. Adapting this architecture will help the universities to increase remote experiment possibilities, without increasing running cost per student. BTH has developed software for online laboratory that uses the same equipment as a traditional laboratory. In the antenna laboratory the difference between a traditional laboratory and the online laboratory are the ability to change antennas in the laboratory equipment, this limitation are going to be further investigated. REFERENCES [1]
[2]
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Magin, D, and Kanapathipillai, S, “Engineering Students´Understanding of the Role of Experimentation”, European Journal of Engineering Education, Vol. 25, no. 4, 2000, pp. 351-358 (doi:10.1080/03043790050200395) Ursulet, S and Gillet,D, “Introducing Flexibility in Traditional Engineering Education by Providing Dedicated On-line
[3]
[4]
[5] [6] [7] [8] [9] [10]
[11] [12] [13]
Experimentation and Tutoring resources”, the International Conference on Engineering Education, Manchester, UK, August 18 – 21, 2002 Nedic, Z and Machotka, J, “Remote Laboratory Net-Lab for Effective Teaching of 1st Year Engineering Students”, Proceedings of the REV 2007 Conference, Porto, Portugal. June 25-27, 2007 Scapolla, A, Bagnasco, A, Ponta, D, and Parodi, G, “A Modular and Extensible Remote Electronic Laboratory”, International Journal of Online Engineering, Vol. 1, No. 1, 2005 http://www.freebsd.org/ Mellstrand, P, “Informed System Protection”, Dissertation, 2007, pp. 163-178 http://www.lucas-nuelle.de http://www.lucas-nuelle.de/299/Products/Training_Systems/Infor mation_and_Communication_Technology/tan.htm http://antenna.openlabs.bth.se/ Zackrisson, J and Svahnberg,C,” OpenLabs Security Laboratory The Online Security Experiment Platform” International Journal of Online Engineering, Vol. 4, 2008 Patricia Kim and Mike Suk, “Ramp Load/Unload Technology in Hard Disk Drives” whitepaper, 2007. Maxtor Corporation, “Maxtor DiamondMax 10” specification, 2006. Hitachi Global Storage Technologies, “Hitachi Deskstar 7K1000” specification, 2007.
AUTHORS K. Nilsson is with Blekinge Institute of Technology, Ronneby, Sweden (e-mail: kristian.nilsson@ bth.se). J. Zackrisson is with Blekinge Institute of Technology, Ronneby, Sweden (e-mail: johan.zackrisson@ bth.se). M.I. Pettersson is with Blekinge Institute of Technology, Ronneby, Sweden (e-mail: mats.pettersson@ bth.se). The VISIR project is supported by VINNOVA (Swedish Governmental Agency for Innovation Systems). Manuscript received 24 October 2008. Published as submitted by the authors.
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Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7
Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7 21 1st WIETE Annual Conference on Engineering and Technology Education Pattaya, Thailand, 22-25 February 2010
¤ 2010 WIETE
Open your laboratories for remote access to offer experimenting for students on-campus or off-campus 24/7 I. Gustavsson, K. Nilsson, J. Zackrisson & L. Håkansson Blekinge Institute of Technology Ronneby, Sweden
ABSTRACT: Physical experiments are indispensable because they offer the only possibility of seeing differences between mathematical models of nature and nature itself. It is possible to increase the capacity of instructional laboratories without raising the cost per student significantly by opening them for remote access and lab work 24/7. In this paper an on-line workbench mimicking a hands-on workbench in a laboratory for electrical experiments is presented. Here mimicking means that students on their computer screen are able to recognise the instruments and other equipment that most of them previously have used in a hands-on laboratory. In the on-line workbench, mouse-cursor-on procedures supplements hands-on ones. At the end of 2006, the Department of Electrical Engineering (AET) at Blekinge Institute of Technology (BTH) in Sweden started a project known as Virtual Instrument Systems in Reality (VISIR) to disseminate the lab concept now denoted the VISIR Open Lab Platform. The software representing 20 person-years of work is published as open source. So far, three other universities have implemented replicas of the on-line workbench at BTH.
INTRODUCTION Only recently has it become evident that mankind must live in symbiosis with nature and focus on its sustainability. Thus, mankind has to adapt to, and meet the demands of, nature, i.e. improve present technologies, develop new technologies, etc. Here, information extracted from measurements of nature’s response to applied technologies is crucial. This, in turn, requires that people are able to make relevant and accurate measurements on nature, as well as making appropriate analyses that provide estimates of relevant quantities of the measured data. Thus, the demand for engineers with documented laboratory experience should increase [1]. This demand is very much in line with the Bologna Process, where universities are required to declare the developed skills of graduate engineers, and the aims and learning outcomes for each course. Still, a substantial rise in base funding resources is unlikely to happen. Furthermore, students nowadays want extended accessibility to learning resources and an increased freedom in organising their own learning activities, which is also one of the main objectives of the Bologna Process. From a technological perspective, such flexible education corresponds to an adequate usage of information, communication devices and infrastructures, especially the Internet [2]. AET started a remote laboratory project as a feasibility study in 1999. The vision was to create an on-line replica of a traditional hands-on laboratory workbench for electrical experiments in order to provide free access to the laboratory for the students. Figure 1 shows a hands-on workbench in a laboratory for electrical experiments at BTH. The small components (an operational amplifier and 8 resistors) in the lower left corner of Figure 1 at the arrow are the set of components provided by the instructor to be used in a laboratory session. An on-line workbench can supplement such workbenches, enabling students to perform physical electrical experiments 24/7 within limits set by the teacher, using a Web browser only. The on-line workbench will be presented in the next section. Today, many academic institutions offer a variety of Web-based experimentation environments, so-called remote laboratories that support remotely operated physical experiments [3-5]. These are new tools enabling universities to provide students with free experimentation resources without a substantial increase in cost per student. At the end of 2006, AET started a project known as Virtual Instrument Systems in Reality (VISIR) together with National Instruments in USA and Axiom EduTech in Sweden, to disseminate the on-line workbench concept created at BTH using open source technologies in collaboration with other universities and organisations. The VISIR project will be presented in a later section. THE VISIR ON-LINE WORKBENCH MIMICS A TRADITIONAL ONE Most instruments in a laboratory for electrical experiments have a remote control option but the solderless breadboard has not. Remote wiring of circuits requires a wiring manipulator that it is possible to control remotely. A switching 52
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matrix equipped with controllable switches, i.e. electro-mechanical relays, can serve as such a device. Figure 2 shows an on-line workbench at BTH and replicas of this workbench are on-line at three other universities outside Sweden. The desktop instruments are replaced by PXI instruments. PXI (PCI eXtensions for Instrumentation) is an international standard for instrumentation. PXI instruments are PC-controlled plug-in boards with a tiny front panel fitted with connectors only. Usually, the control knobs and buttons of these instruments are displayed on the monitor of the controller of the PXI system. An example of such a virtual front panel is shown in Figure 3. The chassis and the instruments in Figure 2 were manufactured by National Instruments. It is possible to combine a virtual front panel representing a particular instrument from one manufacturer with the corresponding hardware from another, as long as the performance of the hardware matches that of the displayed instrument.
Figure 1: A workbench for electrical experiments in a laboratory at BTH. Most universities around the world have hands-on workbenches similar to the one in Figure 1. It is a kind of de facto standard. However, instrument brands and models vary. An on-line workbench should provide a number of, for example, oscilloscope models to allow students or the teacher to select the model they want. In fact, the laboratory platform offers a virtual instrument shelf (Figure 4). In the upper part of Figure 4 all instruments available are displayed and the lower part shows the instruments currently selected. Currently, the soft panels belonging to the PXI instruments and to the instruments of the workbenches at the BTH laboratories are available on the shelf. The client software package is modular and it is recommended that every university creates virtual front panels representing the instruments they have in their hands-on laboratories, to preserve the student’s context.
Installed components
Figure 2: The online workbench at BTH. 53
Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7 23 The switching matrix for remote wiring of electrical circuits is shown at the upper left side of Figure 2. It is the card stack on the top of the PXI chassis. The relays are arranged in a three-dimensional pattern together with instrument connectors and component sockets. Sets of components for a number of laboratory sessions are installed in component sockets at the edge of some of the boards of the switching matrix [6]. The PC to the right in the figure controls the workbench.
Figure 3: Virtual front panel of an oscilloscope. STUDENTS WIRE DESIRED CIRCUITS USING A VIRTUAL BREADBOARD A virtual breadboard shown in Figure 5 is used as a virtual front panel of the switching matrix. The breadboard is a photograph of an ordinary physical solderless one. Thus, the students control the matrix hardware by wiring on the virtual breadboard using the mouse. A short video demonstration can be accessed at the following site on the Internet: http://openlabs.bth.se/static/video/Opamp.html A software module called Virtual Instructor checks that every circuit is safe before it is activated, i.e. that neither a component nor an instrument can be damaged. The laboratory staff creates the rules for the Virtual Instructor when configuring the matrix. Thus, it is up to the laboratory staff to make sure that no hazardous circuit can be created physically.
Figure 4: Virtual instrument shelf.
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Figure 5: Virtual breadboard view. MANY REMOTE STUDENTS CAN PERFORM PHYSICAL EXPERIMENTS SIMULTANEOUSLY USING MODEM SPEED INTERNET CONNECTIONS By selecting appropriate values of the components controlling the time constants, it is possible to study a certain phenomenon at different timescales. This feature of electronics is used in the on-line workbench to allow simultaneous access for many students by time-sharing. In this way, the workbench can emulate a whole hands-on laboratory. Still, the students can use all the time they need to wire their circuit and set up the instruments because they do it in their local computer. The desired circuit and the instrument set-up are sent to the server only when they press the Perform Experiment button. Then, the client software sends a message containing a description of the desired circuit and the instrument settings to the workbench (server). If the workbench is not occupied, the experiment procedure is performed, and the result or an error message is returned to the requesting client computer. Otherwise, the request is queued and is executed in proper order. The current time-slice period is 0.1 second. The teachers who design the experiments to be performed in a laboratory session are instructed to select the values of the components so that an experiment lasts less than this period. Time-sharing means that you can only get a single acquisition from the oscilloscope when you press the Perform Experiments button. The Run/Stop button on the Agilent oscilloscope is red. However, if the administrator allows run mode, the Run/Stop button will be green when pressed. Then, run mode of the oscilloscope will be emulated and repetitive acquisitions ensue without the need to press the Perform Experiments button repetitively. To stop run mode the Run/Stop button should be pressed again. The reason why the administrator may not allow run mode is that the response time will be longer for other users who are on-line. Two types of error, which are special for the online version of the laboratory, are reported: x x
The Virtual Instructor finds the desired circuit hazardous. The desired circuit may be safe but the Virtual Instructor has not been instructed to allow it.
The messages sent to and from a client machine is short. A message containing two oscilloscope traces is two kB. All other messages are shorter. The client software module is approximately 2.5 MB but it is downloaded only once. Thus, a modem connection is sufficient. THE ON-LINE WORKBENCH IS USED IN REGULAR EDUCATION The on-line workbench is used in three ways at BTH: x x
In supervised laboratory classes in the local laboratory where students can select if they want to perform the experiments locally or remotely. However, in the first laboratory class, it is compulsory to do the wiring on the real breadboard. Fortunately, most of the students prefer the hands-on one. In supervised laboratory classes for distance-learning courses, where the students are scattered all over the country. Remote desktop software and MS Messenger has been used to communicate between the students themselves and between the students and the instructor. More advanced means of communication will be adopted. In interviews, most of the distant students say they appreciate very much the possibility of participating from home in the supervised laboratory classes. They do not miss the hands-on version because they have experience from their work 55
Open your laboratories for remote access to oer experimenting for students on-campus or o-campus 24/7 25
x
of electronic instruments and components. Home experimentation could be a method for distant students without laboratory experience to acquire introductory hands-on experience and become familiar with electronic components and wiring, etc [7][8]. However, affordable devices such as an inexpensive multi-meter and/or a soundcard-based oscilloscope are only adequate for elementary experiments. Students can prepare supervised laboratory classes and perform the experiments at home, knowing that the equipment in the hands-on laboratory looks and behaves in a similar fashion. They can also repeat experiments afterwards! Inexperienced or less-confident students requiring more time, appreciate these possibilities. A student wanting, for example, to master the oscilloscope, can practise in the privacy of his/her own home without anyone watching.
THE VISIR PROJECT The VISIR project, which started at the end of 2006, is about disseminating the on-line workbench concept now called the VISIR Open Laboratory Platform [9]. Thus, VISIR does not provide prepared on-line experiments but offers a software distribution released under a GNU GPL licence and documentation, which can be used to implement on-line workbenches [10]. The aim of the VISIR project is establishing a VISIR Community of collaborating universities/organisations, further developing the laboratory platform and sharing laboratory resources and course material. The International Association of Online Engineering (IAOE) has organised a Special Interest Group for VISIR (SIG VISIR), for people interested in On-line Engineering, especially in opening university laboratories for remote access 24/7. The goal of the VISIR Community is to develop tools and methods, enabling universities to offer access to laboratory workbenches without raising the running costs per student. A side effect could be that many more people become interested in engineering education, if access is offered to the public when the equipment is not used in regular education. Instrument I/O is a well-studied domain with established industrial standards. Most commercial products follow the Virtual Instrument System Architecture (VISA) or the Interchangeable Virtual Instrument (IVI) standards. The IVI foundation creates instrument class specifications. There are currently eight classes, defined as DC power supply, Digital multi-meter (DMM), Function generator, Oscilloscope, Power meter, RF signal generator, Spectrum analyser, and Switch. Within each class, a base capability group and multiple extension capability groups are defined. Base capabilities are the functions of an instrument class common to most of the instruments available in the class. For an oscilloscope, for example, this means edge triggering only. Other triggering methods are defined as extension capabilities. The goal of the IVI Foundation is to support 95% of the instruments in a particular class. It is not necessary to use IVI drivers, but to enable interchangeability between workbenches, VISIR recommends functions and attributes defined by the IVI Foundation be used to describe the capabilities of the laboratory hardware. In this way, it should be possible to create a standardised approach which is easy to adopt (Figure 6). The universities can use a variety of instrument platforms. Currently, VISIR supports PXI.
Agilent panels
GPIB XML based protocols Student selctor
Tektronix panels
IVI compliant functions
PXI University selector
NI Soft panels
LXI
Figure 6: Virtual front panel and hardware platform selections. CONCLUSIONS A sustainable society needs engineers who are familiar with experimenting and laboratory work. Open instructional laboratories providing remote access and preserved context for students, not only offer physical experimentation 24/7 but also possibilities to practise laboratory work, albeit hands-on procedures are replaced by mouse-pointer-on ones. The platform can be used not only at university level but also in vocational education and life-long learning. It should be possible to access a VISIR on-line workbench from rural areas at modem speed connections only. The ultimate goal of the research on remote laboratories at BTH is ubiquitous physical experimental resources accessible 24/7 for students and for everyone as a means of inspiring and encouraging children, young people and others to study engineering or to be used as a means of life-long learning. 56
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REFERENCES 1.
Gustavsson, I., Nilsson, K., Zackrisson, J., Garcia-Zubia, J., Hernandez-Jayo, U., Nafalski, A., Nedic, Z., Göl, Ö., Machotka, J., Pettersson, M.I., Lagö, T. and Håkansson, L., On objectives of instructional laboratories, individual assessment, and use of collaborative remote laboratories. IEEE Transactions on Learning Technologies (2009) (accepted for publication, pre-published in IEEEXplore). 2. Gillet, D., Ngoc, A.V.N. and Rekik Y., Collaborative Web-based experimentation in flexible engineering education. IEEE Transactions on Educ., 48, 4, 696-704 (2005). 3. Nedic, Z and J. Machotka, J., Remote laboratory NetLab for effective teaching of 1st year engineering students. Proc. REV 2007 Conference, Porto, Portugal (2007). 4. Scapolla, A.M., Bagnasco, A., Ponta, D. and Parodi, G., A modular and extensible remote electronic laboratory. Inter. J. of Online Engng., 1, 1 (2005). 5. Garcia-Zubia, J., López-de-Ipiña, D., Hernández, U., Orduña, P. and Trueba, I., WebLab-GPIB at the University of Deusto. Proc. REV 2007 Conference, Porto, Portugal (2007). 6. Gustavsson, I., Zackrisson, J., Ström Bartunek, J., Nilsson, K., Håkansson, L., Claesson, I. and Lagö, T., Telemanipulator for remote wiring of electrical circuits. Proc. REV 2008 Conference, Düsseldorf, Germany (2008). 7. Long, J.M., Florance, J.R. and Joordens, M., The use of home experimentation kits for distance students in firstyear undergraduate electronics. Proc. 2004 ASEE Annual Conf., Salt Lake City, USA (2004). 8. Bhunia, C., Giri, S., Kar, S., Haldar, S. and Purkait, P., A low-cost PC-based virtual oscilloscope. IEEE Transactions on Educ., 47, 2, 295-299 (2004). 9. Gustavsson, I., Zackrisson, J., Håkansson, L., Claesson, I., and Lagö, T., The VISIR project – an open source software initiative for distributed online laboratories. Proc. REV 2007 Conference, Porto, Portugal (2007). 10. Gustavsson, I., Zackrisson, J. and Håkansson, L., An overview of the VISIR open source software distribution 2007. Proc. REV 2007 Conference, Porto, Portugal (2007).
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On Objectives of Instructional Laboratories, Individual Assessment, and Use of Collaborative Remote Laboratories
On Objectives of Instructional Laboratories, Individual Assessment, and Use of Collaborative Remote Laboratories 29 IEEE TRANSACTIONS ON LEARNING TECHNOLOGIES,
VOL. 2,
NO. 4,
OCTOBER-DECEMBER 2009
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On Objectives of Instructional Laboratories, Individual Assessment, and Use of Collaborative Remote Laboratories Ingvar Gustavsson, Member, IEEE, Kristian Nilsson, Johan Zackrisson, Javier Garcia-Zubia, Member, IEEE, Unai Hernandez-Jayo, ¨ zdemir Go¨l, Jan Machotka, Andrew Nafalski, Senior Member, IEEE, Zorica Nedic, O Mats I. Pettersson, Member, IEEE, Thomas Lago¨, and Lars Ha˚kansson Abstract—Three key issues should be addressed to enable universities to deliver engineers who have a solid documented laboratory experience enabling them to design goods and services complying with the requirements of a sustainable society. First, introduce learning objectives of engineering instructional laboratories in courses including laboratory components. Second, implement individual student assessment. Third, introduce free access to online experimental resources as a supplement to the equipment in traditional laboratories. Blekinge Institute of Technology (BTH) in Sweden and the University of South Australia (UniSA) have created online laboratory workbenches for electrical experiments that mimic traditional ones by combining virtual and physical reality. Online workbenches not only supplement traditional ones, but they can also be used for low-cost individual assessment. BTH has started a project disseminating the BTH workbench concept, The Virtual Instrument Systems in Reality (VISIR) Open Laboratory Platform, and invites other universities to set up replicas and participate in further development and standardization. Further, online workbenches offer additional learning possibilities. UniSA has started a project where students located in different countries can perform experiments together as a way to enhance the participants’ intercultural competence. This paper discusses online laboratory workbenches and their role in an engineering education appropriate for a sustainable society. Index Terms—Engineering education, laboratories, learning objectives, online learning, remote laboratories, assessment.
Ç 1
INTRODUCTION
W
HILE there seems to be a general agreement that laboratory classes are necessary in engineering education, little has been said about what they are expected to accomplish. If you don’t know where to go, you won’t know which road to take and you won’t know if you have arrived. This truism, when applied to education suggests that clear learning objectives and assessment are essential in designing an effective learning system. However, laboratory instruction has not received a great deal of attention during the last decades of the last century [1], [2]. At the same time, the amount of hands-on laboratory work in engineering education has bit by bit been reduced. The prime cause is clearly due to the task of handling the dramatically increased number of students, while staff and funding
. I. Gustavsson, L. Ha˚kansson, K. Nilsson, M.I. Pettersson, and J. Zackrisson are with ING-AET, Blekinge Institute of Technology, SE372 25 Ronneby, Sweden. E-mail: {ingvar.gustavsson, lars.hakansson, kristian.nilsson, mats.pettersson, johan.zackrisson}@bth.se. . J. Garcia-Zubia and U. Hernandez-Jayo are with the Faculty of Engineering, University of Deusto, Apdo 1, 48080 Bilbao, Spain. E-mail: {zubia, uhernand}@eside.deusto.es. . A. Nafalski, Z. Nedic, J. Machotka, O¨. Go¨l, and T. Lago¨ are with the School of Electrical and Information Engineering, University of South Australia, Mawson Lakes Adelaide, South Australia 5095, Australia. E-mail: {nafalski, zorica.nedic, jan.machotka, ozdemir.gol, thomas.lago}@unisa.edu.au. Manuscript received 31 Mar. 2009; revised 18 June 2009; accepted 6 Oct. 2009; published online 14 Oct. 2009. For information on obtaining reprints of this article, please send e-mail to:
[email protected], and reference IEEECS Log Number TLTSI-2009-03-0049. Digital Object Identifier no. 10.1109/TLT.2009.42. 1939-1382/09/$25.00 ß 2009 IEEE
resources have not improved [3]. A second cause is the digital evolution. Simulators which are based on mathematical models have evolved and simulations have to a large extent replaced experiments in engineering education. Simulators and physical experiments will be compared in the next section. A third reason is the fact that experiments take time, are messy, and will delay experiment-oriented teachers’ academic career [4]. Reducing the number of laboratory classes in engineering education has been easy because laboratory work is seldom evaluated, and the cost reduction obtained is often considerable. Only recently has it become evident that mankind must live in symbiosis with nature and focus on its sustainability and understanding. Thus, mankind has to adapt to and meet the demands of nature, for instance, improve present technologies, develop new technologies, etc. Here, information extracted from measurements of nature’s response to applied technologies is crucial. This in turn require that we are able to make relevant and accurate measurements on nature as well as making appropriate analysis that provides estimates of relevant quantities of the measured data. Thus, the demand for engineers with documented laboratory experience should increase. This demand is very much in line with the Bologna process where universities are required to declare developed skills of graduated engineers and aim and learning outcome for each course. Still, a substantial rise in base funding resources is unlikely to happen. Furthermore, students nowadays want extended accessibility to learning resources and an increased freedom Published by the IEEE CS & ES
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IEEE TRANSACTIONS ON LEARNING TECHNOLOGIES,
to organize their own learning activities, which is also one of the main objectives of the Bologna Process. From a technological perspective, such flexible education corresponds to an adequate usage of information, communication devices, and infrastructures, especially the Internet [5]. Today, many academic institutions offer a variety of web-based experimentation environments, so called remote laboratories (RLs), that support remotely operated physical experiments [6], [7], [8]. These are new tools enabling universities to provide students with free experimentation resources without a substantial increase in cost per student. Examples from BTH will be described in Section 3. In Section 4, learning objectives and individual assessment will be discussed. At the end of 2006, the Department of Signal Processing (ASB) at BTH started a project known as Virtual Instrument Systems in Reality (VISIR) together with National Instruments in USA and Axiom EduTech in Sweden to disseminate the online workbench concept created at BTH using open source technologies in collaboration with other universities and organizations. Carinthia University of Applied Sciences and FH Campus Wien University of Applied Sciences both in Austria and University of Deusto in Spain have already implemented VISIR laboratories for electrical experiments. The VISIR project will be presented in Section 5. Remote laboratories and online workbenches not only supplement traditional laboratories but offer new learning possibilities as is discussed in Section 6.
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PHYSICAL EXPERIMENTS AND SIMULATIONS
Our knowledge of nature is based on observations and/or existing models which can range from simple to advanced. Simple models are easy to learn and will do in undergraduate education while advanced models are more accurate but are also complicated. Constantly improved measurement technology enable experimenters to make better and better observations of nature and see new phenomena. Then the models can be updated. Penetrating deeper and deeper into nature requires more and more sophisticated means and the models will be more complicated as well. There will be a gap between the best models and nature at least in the foreseeable future. For centuries, scientists have performed physical experiments in order to create mathematical models and theories describing phenomena of nature. Professional engineers have these models and theories in their mind and use simulators to design prototypes. However, they perform experiments too for two reasons. First, in the design process they often “ask” nature when they suspect that certain aspects of the models to be used may not be accurate enough. The second reason is to determine if a prototype meets the specification and performs as intended in the environment where the product is to be used. When students, especially undergraduates, perform experiments, it is not typically to extract some data necessary for a design, to evaluate a new device, or to discover a new addition to our knowledge of nature. Each of these functions involves a complex mental process—something that is not expected and available. Students, on the other hand, perform experiments to learn laboratory workmanship and to see that the models are useful descriptions of nature even if
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they are not perfect and that there is more exciting work to do to update them. Laboratory workmanship includes procedures, methods, and other things required to read a useful answer from nature. Will it be possible for a student working remotely to see if a result emanates from a physical experiment or a simulation? A student—at least an undergraduate one— will not be able to realize if an outcome is, for example, the result of a low frequency experiment performed on, an electrical circuit comprising passive components or a corresponding simulation. On the other hand, if the circuit is replaced by, for example, a mechanical structure and appropriate instrumentation even a novice should be able to see the difference. Students working in an online configuration are entitled to know whether they are operating in the mathematical world or in the real one and should be informed how the remote equipment works if they are working in the physical domain. Hand calculations and simulations are the best tools to learn theories and mathematical models because no noise or other imperfections not included in the model will hide the expected result. However, physical experiments are indispensable because they offer the only possibility to see the relevance of models and the differences between results of calculations based on models and results of observations of nature [9], [10]. Thus, physical experiments can do more than simulations and there should be learning objectives for the practical part of a course as well as for the theoretical part and both should be assessed individually.
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LABORATORIES AT BTH
OPENED FOR FREE ACCESS
Most remote laboratories provide prepared experiments. In some cases the students are allowed to do some rearrangements, but in other laboratories they are only allowed to set input parameters before they start an experiment. In such laboratories, the students focus on performing the actual physical experiments and acquiring the physical data. In Section 3.1, one such application will be presented that demonstrates a certain physical phenomenon. On the other hand, the student should also be able to specify appropriate equipment and procedures as well as implement these procedures. Would it be possible to include the experiment preparations? Yes, in Section 3.2, the online laboratory workbench for electrical experiments created at ASB will be described. It mimics a traditional workbench found in most universities around the world. The online workbench is equipped with a unique virtual interface enabling students to recognize the desktop instruments and the breadboard they have already used in the local laboratory on their own computer screen at home. Thus, mouse-pointer-on experiments can complement hands-on ones by combining virtual and physical reality. This online workbench concept can be transferred to other subject fields, for example, the mechanical. ASB has designed a workbench for mechanical vibration experiments where the electrical circuit is replaced by a mechanical structure. In the mechanical vibration area, the simulators are still less useful and more experiments are
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Fig. 1. Antenna laboratory—remote desktop view.
indispensable. The equipment is so expensive that the average university can only afford one or two workbenches. The online workbench for vibration experiments is presented in Section 3.3. Grid technologies could be used to increase laboratory capacity. Online workbenches located at various universities could form a grid laboratory. Such an approach will be discussed in Section 3.4.
3.1 A Laboratory Using Remote Desktop BTH delivers an antenna theory course with a laboratory component. Unfortunately, the capacity of the laboratory is not sufficient for the high number of students in the course (120 students enrolled in one course 2008). Only one laboratory setup is available and not more than two or three students can use the laboratory equipment at the same time. However, the setup is computer controlled and is possible to access remotely using remote desktop software. A time reservation system is provided and the computer software is restored to a known state before each class starts. The students do not need to do any preparations of the setup. They can concentrate on the interactive online laboratory user guide. In the guide, they learn how to use the equipment and basic antenna theory principles. Attached to the online guide, there are interactive test questions. In the end, the student can perform measurements and draw the radiation diagram for the antenna element provided [11]. The only manual intervention required is an exchange of antenna elements which is made by the teacher on a regular basis during the course. The final supervised hands-on laboratory classes can be more effective because the students learn how to perform the experiments at home. The student’s screen on a remote PC is shown in Fig. 1. A camera window has been added to show a picture of the setup. Online access has been offered the last year only and one course evaluation is available. Generally, the course receives good marks from the students and this year the course moments were graded between four and five, in average, on a five graded scale. However, the online antenna laboratory exercises were only graded 3.4 and there are probably mainly two reasons. First, the course evaluation was made before the final hands-on classes. Among the comments, the students wrote that they
Fig. 2. Workbench in a local laboratory for electrical experiments at BTH.
preferred hands-on classes. Second, it was the first time the online antenna setup was tested in a regular course with many students. Next year, the equipment will be tripled and the login procedure will be improved.
3.2 Online Workbench for Electrical Experiments ASB started a remote laboratory project as a feasibility study in 1999. The vision was creating an online replica of a traditional laboratory workbench for electrical experiments in order to provide free access to the laboratory for the students. Such a workbench comprising power supplies, a function generator, an oscilloscope, a multimeter, and a solderless breadboard is shown in Fig. 2. The first workbench for electrical experiments using General Purpose Interface Bus (GPIB) instruments and switch modules for circuit wiring was put online the year after. It was a server/ client application. LabVIEW style virtual front panels were displayed on the student’s client PC. In 2003, version 3 of the workbench was created. The major improvement was a relay switching matrix replacing the switch modules for creation of the students’ desired circuits and a virtual breadboard. The new matrix was a compact card stack in three dimensions reducing the length of the wires in order to increase the bandwidth of the wired circuits. A virtual breadboard was created to be a “virtual front panel” for the matrix. Every circuit the student wired on the virtual breadboard was then created in the matrix. A virtual instructor was introduced to prevent students from creating circuits which could damage the equipment [12]. The current version of the online workbench for electrical experiments is 4 [13], [14]. This version is a major upgrade of the software and the switching matrix layout is somewhat reorganized to make it more flexible but the functionality of the workbench is the same. A set of components provided for a certain laboratory class is displayed in a component box at the top of the virtual breadboard. In Fig. 3, most of the components have already been moved to the breadboard and a circuit wired.
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Fig. 3. Virtual breadboard.
The wire holes at the sides of the virtual breadboard connects to the instruments mimicking the box carrying the detachable breadboard in Fig. 2 but the BNC sockets and the instrument cables are omitted in Fig. 3. The virtual circuit that an experimenter wires on the breadboard, using the mouse, is transformed into a net list similar to PSPICE net lists. Then, the virtual instructor compares the net list with a number of so called maxlists, which define all circuits permitted and define the maximum output voltages allowed from the sources. The teachers create these rules for the virtual instructor. If an instrument or some component in the switching matrix happens to be damaged a teacher is to blame and not the student who caused the damage. If the net list passes the check, a CreateCircuit command is sent to the switching matrix. If the desired circuit is not permitted or not possible to create an error message is returned. The online workbench at BTH is used in three ways: .
.
.
In supervised laboratory classes in the local laboratory where students can select if they want to perform the experiments locally or remotely. However, in the first laboratory class, it is compulsory to do the wiring on the real breadboard. Fortunately, most of them prefer the hands-on one. In supervised laboratory classes for distance learning courses, where the students are scattered all over the country. Remote desktop software and MS Messenger has been used to communicate between the students themselves and between the students and the instructor. More advanced means of communication will be adopted. In interviews most of the distant students say that they appreciate the possibility to participate in the supervised laboratory classes from home very much. They do not miss the hands-on version because they have experience of electronic instruments and components from their work. Home experimentation could be a method for distant students without laboratory experience to acquire introductory hands-on experience and become familiar with electronic components and wiring, etc. [15], [16]. However, affordable devices such as a cheap multimeter and/or a sound-card-based oscilloscope are only adequate for elementary experiments. Students can prepare supervised laboratory classes and perform the experiments at home, knowing that
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the equipment in the traditional laboratory looks and behaves in a similar fashion. They can also repeat experiments afterwards! Inexperienced or less confident students requiring more time, appreciate these possibilities. A student wanting, for example, to master the oscilloscope, can practice in the privacy of his/her own home. It is possible to perform the same electrical experiment for different time scales by selecting the values of the components controlling the time constants properly. This “feature” is used in the online workbench for electrical experiments to allow simultaneous access by time sharing. The students send their instrument settings and a description of the desired circuit to the workbench that creates the circuit and performs the measurements in a fraction of a second. A single workbench can then replace a whole laboratory with many workbenches. The maximum duration of a single experiment, i.e., circuit creation and measurement procedure is currently set to 0.1 second to get a reasonable response time even with a large number of experimenters. Thus, the experiments are set up locally in each client computer. Only by pressing a Perform Experiment button shown in Fig. 3 the experimenter sends a message containing a description of the desired circuit and the instrument settings to the workbench (server). If the workbench is not occupied, the experiment procedure is performed in a predefined order, and the result or an error message is returned to the requesting client computer. Otherwise, the request is queued.
3.3
Online Workbench for Mechanical Vibration Experiments
ASB has created an online workbench for vibration experiments using the same concept to see if the concept can be used in the mechanical subject field. The first prototype comprised a signal analyzer replacing the oscilloscope, an electrodynamic shaker and a shaker amplifier replacing the function generator, a number of accelerometers, an impedance head and a mechanical structure—a clamped boring bar (tooling structure for internal turning) replacing the circuit and the breadboard. The first workbench for vibration experiments was put online in 2005. LabVIEW style virtual front panels were displayed on the student’s client PC [17]. Compared to electrical experiments the time frame required for vibration experiments in the mechanical domain is generally substantially longer and simultaneous access of one experimental setup by time sharing is not an alternative. Currently, the online version 1 workbench for vibration experiments at BTH is used in courses at BTH and is much appreciated by the students. To increase the capacity and flexibility of the workbench for vibration experiments, work on developing version 2 started in 2007. The new workbench for sound and vibration experiments will have large capacity, enabling remote parallel single-channel, and SISO measurements to more advanced MIMO (22 inputs and four outputs) analysis and measurements of sound and vibration. The version 2 workbench is shown in Fig. 4.
3.4 Grid Laboratory It is true that the workbench for electrical experiments at BTH can be used by many students performing different
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Fig. 4. Workbench for sound and vibration experiments
experiments simultaneously but the time sharing scheme imposes restrictions. When the experimenter has pressed the Perform Experiment button, she can only wait for the result. Thus, if it is desirable that online students in a laboratory class should be able to control the measurement process details then time sharing is no option but each client computer must be connected to a workbench of its own. Grid computing has emerged as a way to harness and take advantage of computing resources across geographies and organizations. A suitable number of online workbenches located at a number of universities could be organized as a grid laboratory allowing online laboratory classes using appropriate teleconferencing tools [18]. In a laboratory class, more workbenches in the laboratory allow more students per instructor. If there are enough workbenches, the number of students could match the capacity of an instructor minimizing the number of teaching hours. An advanced booking system is required to find the right number of free workbenches for a certain laboratory class especially if the workbenches are not identical.
4
LEARNING OBJECTIVES FOR LABORATORY WORK AND INDIVIDUAL ASSESSMENT
The first author (Ingvar Gustavsson) was an undergraduate student in electrical engineering at the Royal Institute of Technology (KTH) in Stockholm in the mid 1960s. He took courses in measurement and instrumentation technologies where the dominating part was supervised laboratory classes. Nobody talked about learning objectives, but each
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laboratory class covered a certain aspect of the subject. The courses ended with both written and practical exams. The practical exams took place in the laboratory where there were eight workbenches without equipment. When the student at one of the workbenches had considered the assignment, she had to list equipment needed and its performance. Then, a laboratory instructor brought it from the storeroom. If you, for example, ordered just an oscilloscope then the instructor most certainly would bring an oscilloscope from the department museum. Finally, the student discussed her results obtained with the professor who was also present. This examination form engaging a professor and an instructor for only eight students was expensive. It was abandoned because of reduced course funding. Then, KTH lost its capability to deliver masters of electrical engineering with documented laboratory experience. In circuit analysis courses at BTH the students must analyze every circuit in the laboratory instruction manuals using both hand calculation and simulation before supervised laboratory classes. If the results emanating from the two methods are identical the students have reasons to believe that their calculations are correct. The final step is to perform the corresponding experiment using the online workbench or a traditional one. If the result still is the same, students have reason to believe that the theory works in real life. Unfortunately, some students do not spend so much effort on the practical part. They concentrate on the written exam and rely on a colleague who knows how to perform the compulsory practical part. In the last laboratory class, the students are supposed to identify a circuit comprising three passive components in a “black box.” It would be interesting to move the written exam to a room where the examinees could access the online workbench and exchange one of the theoretical problems for a practical problem, for example, identifying the circuit in the black box with other components than during the laboratory class. Would such a change make students more interested in the practical part? The first author still remembers that the practical assessment to come encouraged him to take the laboratory classes extra seriously. In the mid 1960s, the laboratory classes were the only possibility to access the expensive equipment. If students of today are granted free access without health and safety risks and individual assessment is introduced, they are supposed to do more on their own and learn more from nature. The lack of learning objectives for laboratory work became clear to Accreditation Board for Engineering and Technology (ABET) in the US when distant education programs began inquiring about accreditation. As a result of ABET activities 13 learning objectives were defined [1], [19]. A way to implement at least some of these learning objectives might be a course on measurements technology providing laboratory classes covering physical principles used for sensing and general measurement procedures similar to the courses in the 1960s where the students perform much of the laboratory work at home using an online workbench and other online resources. Then, the supervised laboratory classes could deal with the essence of the subject and be lead by a professor. The written exam could contain both theoretical and practical problems. Three steps are proposed:
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1.
2. 3.
5
An introductory course similar to the circuit analysis course presented in the preceding paragraph where the students can learn to be familiar with common models in the electrical subject field and practice measurements of electrical quantities. The students should also learn that these models can be used in other subject fields too. For example, a capacitor in the electrical subject field corresponds to a spring in the mechanical one. The course mentioned earlier in the paragraph would be the main general measurement technology course. The laboratory components of the courses of the student’s major field, for example, mechanical vibration technologies would be the last step.
COOPERATION IN THE VISIR PROJECT
The VISIR project which was started at the end of 2006 is about disseminating the online workbench concept now called the VISIR Open Laboratory Platform [20]. Thus, VISIR does not provide prepared online experiments but offers a software distribution released under a GNU GPL license and documentation, which can be used to implement online workbenches [21]. Students can use such workbenches to perform experiments within limits set by the teacher in the same way as in the local laboratory. The aim of the VISIR project is establishing a VISIR Community of collaborating universities/organizations further developing the laboratory platform and sharing laboratory resources and course material. The International Association of Online Engineering (IAOE) has organized a Special Interest Group for VISIR (SIG VISIR) for people who are interested in Online Engineering especially in opening university laboratories for remote access 24/7 [22]. The goal of the VISIR Community would be tools and methods enabling universities to offer access to laboratory workbenches without raising the running costs per student. A side effect could be that much more people will be interested in engineering education if access is offered for the public when the equipment is not used in regular education. The ultimate goal of our research at BTH is ubiquitous physical experimental resources accessible 24/7 for students and for everyone as a means of inspiring and encouraging children, young people, and others to study engineering or to be used as a means of life-long learning. In Section 5.1, University of Deusto will be presenting how they are implementing the VISIR Open Lab Platform. FH Campus Wien has implemented a VISIR online workbench for electrical experiments too. They use it in regular education. Section 5.2 discusses laboratory workbench standardization.
5.1 VISIR at University of Deusto in Spain The Faculty of Engineering of the University of Deusto has a remote laboratory (http://weblab.deusto.es) since 2005 offering remote experimentation with VHDL, CPLD, FPGA, microcontrollers (PIC), and GPIB. WebLab-DEUSTO has been designed using a web 2.0 approach and it is used in different subjects and degrees by 100 students per year [23]. In 2007, the VISIR (http://weblab-visir.deusto.es/ electronics) was deployed at the University of Deusto and it began to be used in test by some students and teachers. The
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Fig. 5. A typical practical session with VISIR in the U. Deusto.
results were good and the Faculty decided to deploy the VISIR in the regular teaching. During the year 2008-2009, it has been used in two different degrees: Informatics Engineering, Electronics and Control Engineering in the subject Digital Electronics. The subject is assigned to the first year in the two degrees; for Electronics and Control Engineering it is in the first semester and for Informatics Engineering it is in the second. VISIR is used to experiment with the basics of analog electronics and its instrumentation in three practical sessions: .
Assemble and measure of serial/parallel resistors. The students can only use 1K and 10K resistors in different positions. . Ohm Law. The students assemble a circuit, for example, a voltage divider, and they measure the resistors, voltage, and current with the digital multimeter (DMM). . Analysis and use of diodes and capacitors. The students complete different experiences. At the beginning, they practice using the digital multimeter and analyzing what happens with the diode and its polarization. After this, they see what happens when a sine wave is input through a diode (rectification). Finally, they add different capacitors to see their effects (filter). To complete these parts, they use the function generator and the oscilloscope. A typical practical session in the University of Deusto has four steps (Fig. 5): configure the circuit, configure the instruments (function generator, DMM, scope, ...), run the experiment, and analyze the results. If the student makes something dangerous, the VISIR shows a warning message. Fig. 6 shows a dangerous circuit (short circuit) and the harmful message. But if the student makes something wrong, i.e., the function generator is off, the components are not well connected, etc., the VISIR will not help him with a message, the student will have to analyze the results to find the error. The VISIR runs the experiments as in a classical laboratory; the VISIR will not make anything for the student. After the three sessions, a survey has been passed to the students to know their opinion about the VISIR-DEUSTO. The questionnaire has 18 items and it is based in the original designed for WebLab-DEUSTO [24] and in the works of Corter et al. [25] and Lang et al. [26]. The questionnaire covers four characteristics of a remote lab: B1. Usefulness (Q1, Q3, Q9, Q11, Q17, Q12), B2. Sense of Reality/ Immersion (Q2, Q6, Q10), B3. Usability (Q4, Q5, Q7, Q8),
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Fig. 6. A short circuit and the harmful message.
and B4. Quality of the service (Q13, Q14, Q16, Q18). Q15 is an internal question without interest out of the Faculty. The data in the next table are in the range of 1-5. 1 is “I totally disagree” and 5 “I totally agree.” In the regular teaching, VISIR-DEUSTO (Fig. 7) is used by the teacher to explain the basis of analog electronics in the classroom, and it is used by the students to prepare the practice before going to the classical (hands-on) laboratory. The goals are to reinforce the concepts learned in the classical laboratory and to practice without time restrictions and “without eyes in the nape of the neck.” VISIR-DEUSTO is not used as a substitute of the classical laboratory; it is a complement of it. Some conclusions can be remarked: 1.
2.
3.
4.
5.
VISIR is accepted by the students as a good learning tool, so it can be integrated in other subjects and degrees. The results are very similar for the two semesters. The opinion of the students is similar in the two semesters for two questions: B1. Is the VISIRDEUSTO useful? and B4. Is the VISIR-DEUSTO a good service? This situation is logical because the VISIR-DEUSTO is the same in the two semesters. The opinion of the students of the second semester about B2 and B3 is better than the opinion of the students of the first semester. Really, VISIR-DEUSTO is the same in the two semesters, but in the second semester a special effort was made for creating a better manual and materials and for explaining better what the VISIR is: architecture, design, researchers, etc. If the students know the tool they will “trust” it. Following to the recommendations of Corter et al. [25], it is very important to improve the sense of reality in the students when they use any remote lab. This is especially important in VISIR because it is real, but it seems to be a simulator. The marks in B2 are higher in the second semester, and the students of the second semester have a better opinion of VISIR than the students of the first semester. These results are in line with Garcia-Zubia et al. [24]. In the two semesters, the students order the blocks in the same way: B1-B4-B3-B2.
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Fig. 7. VISIR-DEUSTO.
Future work in VISIR-DEUSTO: 1. 2. 3.
To give more potential to VISIR by integrating more component boards to allow the students/teachers to assemble more experiments and more complex. To design a new module to allow the students/ teachers to assemble and to analyze digital circuits. In Table 1, it can be seen that the students think that VISIR is more useful than usable, that is, the students cannot exploit all the potential of VISIR because its usability is not high. A special effort must be done to improve the usability of VISIR-DEUSTO: better manuals, better examples, better use of the potential of VISIR, etc.
5.2 Laboratory Workbench Standardization Most universities around the world have workbenches similar to the one in Fig. 2. It is a kind of de facto standard. However, instrument brands and models vary. The online workbench should provide a number of, for example, oscilloscope models to allow the students or the teacher to select the model they want. In fact, the laboratory platform offers a virtual instrument shelf, Fig. 8. In the upper part of the figure, all instruments available are displayed and the lower part shows the instruments currently selected. So far, there are only two models of each instrument available. In fact, in the platform it is possible to combine a virtual front panel representing a particular instrument from one manufacturer with the corresponding hardware from another, as long as the performance of the hardware matches that of the displayed instrument. The VISIR client software package is modular, and it is recommended that every university creates virtual front panels representing the instruments they have in their local laboratories to preserve the student’s context. Instrument I/O is a well-studied domain with established industrial standards. Most commercial products follow the Virtual Instrument System Architecture (VISA) or the Interchangeable Virtual Instrument (IVI) standards [20]. The IVI foundation creates instrument class specifications. There are currently eight classes, defined as DC power supply, DMM, Function generator, Oscilloscope, Power meter, RF signal generator, Spectrum analyzer, and Switch. Within each class, a base capability group and multiple extension capability groups are defined. Base capabilities are the functions of an instrument class that
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TABLE 1 Results of the Questionnaire for VISIR-DEUSTO in 2008-2009
are common to most of the instruments available in the class. For an oscilloscope, for example, this means edge triggering only. Other triggering methods are defined as extension capabilities. The goal of the IVI Foundation is to support 95 percent of the instruments in a particular class. It is not necessary to use IVI drivers, but to enable interchangeability between workbenches VISIR recommends functions and attributes defined by the IVI Foundation to be used to describe the capabilities of the laboratory hardware. In this way it should be possible to create a standardized approach which is easy to adopt, Fig. 9. The universities can use a variety of instrument platforms. Currently, VISIR supports PCI eXtensions for Instrumentation (PXI).
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COLLABORATIVE REMOTE LABORATORIES
Online laboratories are not only supplementing traditional laboratories without remote access, but they also add new learning dimensions. For example, students located in different countries around the world can perform experiments together. It could be a way to enhance the
participants’ intercultural competence and their international perspective. The international project recently awarded by the Australian Learning and Teaching Council (AU$220.000 over 2008-2010), administered by the University of South Australia (UniSA) aims to develop, implement, evaluate, and disseminate best practice in international online collaboration in RLs. The initial platform will be the remote laboratory at UniSA—NetLab [6], because it is one of a very few RLs that support collaborative work. However, the use of other collaborative RLs will be encouraged and the development of future RLs as collaborative working environment will be promoted. The main outcome of this project is a framework to utilize RLs as enabling medium for creating student international perspective through the development of international collaboration and intercultural communication skills. The project partners include Blekinge Institute of Technology, Sweden, the University of Porto, Portugal, and the University of Technology Sydney, Australia. Students from all four participating institutions as well as students from UniSA transnational programs in Singapore and Sri Lanka will be involved in the project.
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Fig. 8. Virtual instrument shelf.
NetLab is an RL specialized for experiments in electrical circuits and systems and can be accessed from http:// netlab.unisa.edu.au. It has a specially designed GUI that uses photographic images of laboratory instruments with animated controls and displays. This enables students to control the instruments in the same way as if they were working in the real laboratory. The NetLab GUI is shown in Fig. 10 and includes a digital storage oscilloscope, a function generator, a multimeter, the Circuit Builder (to connect remote devices and components), an image from a web camera, and communication and status windows. The system allows for collaboration in teams of two to three students, either domestically or internationally. This is enabled by a unique booking system that displays student’s local geographical time for bookings. To prevent excessive
booking, a lecturer (administrator) can set a limit on a number of hours per week that each student can book, currently 3 hours. The booking system can become quite busy as illustrated by Fig. 11 when students try to catch up with the assignment deadline. Technically, the NetLab system may cope with student teams larger than 3. However, all concurrent users have full control over the system and the experience dictates the limit of 3 due to excessive multiple system’s reconfiguration attempts by large teams [27]. The framework has been initially developed and implemented for two UniSA undergraduate courses: Electrical
Fig. 9. Virtual front panel and hardware platform selections.
Fig. 10. Graphical User Interface (GUI) of NetLab.
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and offer free access to experimental equipment complementing the traditional laboratory. Online workbenches can be used to recreate the context of the hands-on laboratory, albeit hands-on is replaced by mouse-pointer-on. Even though much remains to be done concerning these new tools, the workbenches are ready for exploration by pedagogical experts and engineering educators in an interdisciplinary research combining these tools with learning objectives and individual assessment. Such research that crosses borders is difficult but is important to take on for a sustainable development of our society. Furthermore, it is likely to be rewarding for both pedagogic experts and experiment-oriented teachers. Remote laboratories and online workbenches could also be used for development of other skills than just technical. For example, the current job market for engineers is global and new capabilities such as intercultural competence are sought after. Fig. 11. NetLab booking system interface.
Circuit Theory (second year course) and Signals and Systems (third year course) and the corresponding courses at partner institutions but it will be later expanded to include more courses. An assessment component will be introduced for these courses to assess the effectiveness of student participation and learned skills. RLs will not be used for assessment; rather students will be submitting reports on assessment tasks which will be marked to form a component of the summative assessment. After evaluation of pilot trials with small numbers of students, the framework will be implemented for whole classes and evaluated. The work will be documented and disseminated nationally and internationally in the form of guidelines for best practice accompanied by case studies that can be used by students and teaching staff. The collaborative remote laboratory developments in Australia have been further boosted by the Diversity and Structural Adjustment Fund of the Australian Governments Department of Education, Employment and Workplace Relations. UniSA is a partner institution in a project coordinated by the University Technology Sydney. The project on “National Support for Laboratory Sharing” has attracted some AU$2.12mln of the Diversity Fund from the Australian Government. Together with the partner institutions’ contributions, the total funding amounts to nearly AU$3.9mln. The project incorporates explicit collaboration between five Australian Universities, expandable nationally and internationally. It is envisaged to involve at least 10,000 students within 3 years of the project duration, from Australian universities, Tertiary and Vocational Education institutions, and from High Schools. After the identification of existing shared remote laboratories, the development of crossinstitutional collaboration will result in large cost reduction, sharing of expertise, improved laboratory quality, and a greater access to a large range of quality laboratories.
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CONCLUSIONS
A sustainable society needs engineers who are familiar with experimenting and laboratory work. Remote laboratories and online workbenches can supplement traditional ones
ACKNOWLEDGMENTS BTH has fully realized the importance of laboratory education and supported the research since the start in 1999. Grants have been received from the Swedish Agency for Distance Education, the Savings Bank Foundation Kronan, the Knowledge Foundation (KKS), and Swedish Governmental Agency for Innovation Systems (VINNOVA). Equipment grants from National Instruments are also gratefully acknowledged. Support for this publication has been provided by the Australian Learning and Teaching Council Ltd., an initiative of the Australian Government, Department of Education, Employment and Workplace Relations. The views expressed in this publication do not necessarily reflect the views of the Australian Learning and Teaching Council.
REFERENCES [1]
L.D. Feisel and A.J. Rosa, “The Role of the Laboratory in Undergraduate Engineering Education,” J. Eng. Education, vol. 94, pp. 121-130, Jan. 2005. [2] H. Hult, “Laborationen—Myt Och Verklighet,” CUP:s rapportserie Nr. 6, NyIng-projektet, Linko¨ping Univ., 2000 (in Swedish). [3] D. Magin and S. Kanapathipillai, “Engineering Students’ Understanding of the Role of Experimentation,” European J. Eng. Education, vol. 25, no. 4, pp. 351-358, 2000. [4] “New Directions in Laboratory Instruction for Engineering Students,” Report of the Commission of Engineering Education J. Eng. Education, vol. 58, pp. 191-195, Nov. 1967. [5] D. Gillet, A.V.N. Ngoc, and Y. Rekik, “Collaborative Web-Based Experimentation in Flexible Engineering Education,” IEEE Trans. Education, vol. 48, no. 4, pp. 696-704, Nov. 2005. [6] Z. Nedic and J. Machotka, “Remote Laboratory NetLab for Effective Teaching of First Year Engineering Students,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’07), June 2007. [7] A.M. Scapolla, A. Bagnasco, D. Ponta, and G. Parodi, “A Modular and Extensible Remote Electronic Laboratory,” Int’l J. Online Eng., vol. 1, no. 1, 2005. [8] J. Garcia-Zubia et al., “WebLab-GPIB at the University of Deusto,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’07), June 2007. [9] Z. Nedic, J. Machotka, and A. Nafalski, “Remote Laboratories Versus Virtual and Real Laboratories,” Proc. 33rd ASEE/IEEE Frontiers in Education Conf., Nov. 2003. [10] J. Ma and J.V. Nickerson, “Hands-On, Simulated, and Remote Laboratories: A Comparative Literature Review,” ACM Computing Surveys, vol. 38, 2006.
On Objectives of Instructional Laboratories, Individual Assessment, and Use of Collaborative Remote Laboratories 39 GUSTAVSSON ET AL.: ON OBJECTIVES OF INSTRUCTIONAL LABORATORIES, INDIVIDUAL ASSESSMENT, AND USE OF COLLABORATIVE...
[11] K. Nilsson, J. Zackrisson, and M. Pettersson, “Remote Access of Computer Controlled Experiments,” Int’l J. Online Eng., vol. 4, no. 4, 2008. [12] I. Gustavsson, “A Traditional Electronics Laboratory with Internet Access,” Proc. Int’l Conf. Networked e-Learning for European Univ., Nov. 2003. [13] I. Gustavsson et al., “A Flexible Electronics Laboratory with Local and Remote Workbenches in a Grid,” Int’l J. Online Eng., vol. 4, no. 2, 2008. [14] I. Gustavsson et al., “Telemanipulator for Remote Wiring of Electrical Circuits,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’08), June 2008. [15] J.M. Long, J.R. Florance, and M. Joordens, “The Use of Home Experimentation Kits for Distance Students in First-Year Undergraduate Electronics,” Proc. 2004 ASEE Ann. Conf., June 2004. [16] C. Bhunia et al., “A Low-Cost PC-Based Virtual Oscilloscope,” IEEE Trans. Education, vol. 47, no. 2, pp. 295-299, May 2004. [17] H. Akesson, L. Ha˚kansson, I. Gustavsson, J. Zackrisson, I. Claesson, and T. Lago¨, “Vibration Analysis of Mechanical Structures over the Internet Integrated into Engineering Education,” Proc. Am. Soc. for Eng. Education Ann. Conf., June 2006. [18] C. Schmid, “Grid Supported Virtual Laboratories with Collaboration in Engineering Education,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’08), June 2008. [19] D. Lowe, S. Murray, E. Lindsay, D. Liu, and C. Bright, “Reflecting Professional Reality in Remote Laboratory Experiences,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’08), June 2008. [20] I. Gustavsson et al., “The VISIR Project—An Open Source Software Initiative for Distributed Online Laboratories,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’07), June 2007. [21] J. Zackrisson, I. Gustavsson, and L. Ha˚kansson, “An Overview of the VISIR Open Source Software Distribution 2007,” Proc. Int’l Conf. Remote Eng. and Virtual Instrumentation (REV ’07), June 2007. [22] http://www.online-engineering.org/sig.htm, 2009. [23] J. Garcia-Zubia et al., Advances on Remote Labs and e-Learning Experiences, L. Gomes and J. Garcia-Zubia, eds., pp. 131-149. Univ. of Deusto, 2007. [24] J. Garcia-Zubia et al., “Acceptance, Usability and Usefulness of WebLab-DEUSTO from the Students Point of View,” Proc. Third Int’l Conf. Digital Information Management (ICDIM ’08), 2008. [25] E. Corter et al., “Constructing Reality: A Study of Remote, HandsOn, and Simulated Laboratories,” ACM Trans. Computer-Human Interaction, vol. 14, no. 2, 2007. [26] D. Lang et al., “Pedagogical Evaluation of Remote Laboratories in eMerge Project,” European J. Eng. Education, vol. 32, no. 1, pp. 5772, 2007. [27] Z. Nedic, J. Machotka, and A. Nafalski, “Remote Laboratory NetLab for Effective Interaction with Real Equipment Over the Internet,” Proc. IEEE Conf. Human Systems Interaction (HSI ’08), pp. 846-851, May 2008. Ingvar Gustavsson received the MSEE and Dr Sc degrees from the Royal Institute of Technology (KTH), Stockholm, in 1967 and 1974, respectively. After completing his military service in 1968, he worked as a development engineer at Jungner Instrument AB in Stockholm. In 1970, he joined the computer vision project SYDAT at the Instrumentation Laboratory, KTH. In 1982, he was appointed the head of the Instrumentation Laboratory. Together with another research scientist, he founded a private company providing automatic inspection systems for industrial customers in 1983. In 1994, he returned to the academic world to take up his current position as an associate professor of electronics and measurement technology at Blekinge Institute of Technology (BTH), Sweden. His research interests are in the areas of instrumentation, remote labs, industrial electronics, and distance learning. He is a cochair of the scientific advisory board of the International Association of Online Engineering (IAOE) and is a member of the editorial board of the International Journal of Online Engineering. He is a member of the IEEE.
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Kristian Nilsson received the MSEE degree from Blekinge Institute of Technology, Ronneby, Sweden, in 2007, where he is currently working with the VISIR Open Laboratory Platform. His research interests are in distance learning, remote labs, electronics, and signal processing.
Johan Zackrisson has been working as a research engineer in the Department of Signal Processing at the Blekinge Institute of Technology since 2003. He has been involved in developing remote laboratories in the fields of electronics, vibration analysis, antenna theory, and security and is now the manager of the laboratories.
Javier Garcia-Zubia received the PhD degree in computer engineering and is a teacher at the Faculty of Engineering of the University of Deusto, Spain. He is also the director of the Computer Architecture, Electronics, and Control Department. His research focus is remote experimentation: design, deployment, and evaluation. He is responsible for the WebLabDEUSTO. He is a member of the IEEE.
Unai Hernandez-Jayo is a telecommunication engineer and a professor in the Faculty of Engineering at the University of Deusto, Spain. His research interest is focused on remote experimentation. He develops his work at the WebLab-Deusto research team, and he is in charge of the deployment of the VISIR project at Deusto University.
Andrew Nafalski received the MEng (1972), PhD (1968), and DSc (1979) degrees from the Warsaw University of Technology, Poland. His career includes assignments in academic and research institutions in Poland, Austria, Wales, Germany, France, Japan, USA, Canada, and Australia. He is a chartered professional engineer and a fellow of the Institution of Engineers, Australia, fellow of the Institution of Engineering and Technology (UK), a senior member of the IEEE, and an honorary member of the Golden Key International Honor Society. He is currently a professor of electrical engineering at the University of South Australia (UniSA) in Adelaide. His major research interests are related to electromagnetic devices, magnetic materials, and technologies, as well as innovative methods in engineering education. He has published more than 300 scholarly works in the above fields. He has received numerous national and international awards for excellence in research, teaching, engineering education, and community service.
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IEEE TRANSACTIONS ON LEARNING TECHNOLOGIES,
Zorica Nedic received the MESc degree in electrical engineering, specializing in electronics, from the University of Belgrade, former Yugoslavia. She received the ME degree in electrical engineering (control) in 1997 from the University of South Australia (UniSA), Adelaide, Australia. She worked for six years as a design engineer at the Institute Mihajlo Pupin in Belgrade. Since 1991, she has been working as a lecturer in electrical engineering at UniSA. She is currently studying for the PhD degree at UniSA in the field of modeling biological vision.
¨ zdemir Go¨l received the MESc, ME, and PhD O degrees in electrical engineering. He has had extensive experience as an engineering educator in addition to his substantial industrial experience. His academic career has included teaching and research in electrical engineering at universities in Turkey, Australia, France, Belgium, Switzerland, Finland, and Greece. He is currently an associate professor at the University of South Australia. His research interests have been focused on electrical machines and drives, and include modeling and simulation of electrical machines using numerical methods, design optimization of electromagnetic devices, and condition monitoring of electrical machines. He is the recipient of several national and international awards for excellence in research, teaching, engineering education, and community service. He is the author and coauthor of some 300 publications.
Jan Machotka received the Dipl Ing degree from Czech Technical University in Prague. After spending 10 years in industry, he has joined the University of South Australia. Currently, he is a transnational program director at the School of Electrical and Information Engineering, UniSA. He is a project leader of the remote laboratory NetLab. His main research interest is in remote engineering and innovations in engineering education.
VOL. 2,
NO. 4,
OCTOBER-DECEMBER 2009
Mats I. Pettersson received the MSc degree in engineering physics in 1993, the Lic Eng degree in radio and space science in 1995, and the PhD degree in signal processing in 2000 from Chalmers University of Technology, Gothenburg, Sweden. From 1993 to 1995, he was employed as a PhD student in the Department of Radio and Space Science working with radar measurements, modeling, electromagnetic scattering, and image processing. For two years, 19961997, he worked at Ericsson Mobile Communication in Lund, and from 1998 to 2007, he was employed at the Swedish Defence Research Agency (FOI) in Linko¨ping. At FOI, he has been developing Ultra Wide Band (UWB) low frequency SAR systems both as a researcher and as a research manager. In the scientific field, he focused on array signal processing and especially Synthetic Aperture Radar (SAR) processing in combination with Space Time Adaptive Processing (STAP). From December 2004, he has been employed at the Department of Signal Processing at Blekinge Institute of Technology. His scientific work is related to radar and sonar signal processing. He is a member of the IEEE. Thomas Lago¨ is an adjunct professor at Virginia Polytechnic Institute and State University (Virginia Tech) in mechanical engineering, and at the University of Arkansas in civil engineering. Previous adjunct professorships include Brigham Young University, in physics, and the World Capital University, in electronics. His research is focused on applied active noise and vibration control plus embedded electronics, and he holds more than 25 patents and has published more than 200 scientific papers. His industrial background includes executive positions in, e.g., Hewlett Packard as the European product line manager and other international president and CEO positions. Currently, he is the chairman of the Board for Acticut International AB (publ), cofounder, and one of the main owners. Lars Ha˚kansson received the MSc degree in signal and telecommunication theory from Lund University of Technology, Sweden, and the PhD degree in mechanical engineering from Lund University of Technology, Sweden, in 1989 and 1999, respectively. He was appointed as a senior lecturer in electrical engineering in 1999 and as an associate professor in electrical engineering with an emphasis on active noise and vibration control in 2005 at the Blekinge Institute of Technology. His current research interests are in noise and vibration control, adaptive signal processing, automatic control, and signal and vibration analysis.
Part IV
A Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid
A Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid
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A Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid Ingvar Gustavsson Blekinge Institute of Technology Department of Signal Processing SE-372 25 Ronneby, Sweden
[email protected]
Johan Zackrisson Blekinge Institute of Technology Department of Signal Processing SE-372 25 Ronneby, Sweden
[email protected]
Kristian Nilsson Blekinge Institute of Technology Department of Signal Processing SE-372 25 Ronneby, Sweden
[email protected]
Javier Garcia-Zubia University of Deusto Faculty of Engineering Apdo. 1, 48080 Bilbao, Spain
[email protected]
Lars Håkansson Blekinge Institute of Technology Department of Signal Processing SE-372 25 Ronneby, Sweden
[email protected]
Ingvar Claesson Blekinge Institute of Technology Department of Signal Processing SE-372 25 Ronneby, Sweden
[email protected]
Thomas Lagö Acticut AB Gjuterivägen 7 SE-311 32 Falkenberg, Sweden
[email protected] Abstract The Signal Processing Department (ASB) at Blekinge Institute of Technology (BTH) has created two online lab workbenches, one for electrical experiments and one for mechanical vibration experiments, mimicking and supplementing workbenches in traditional laboratories. Since some years, the workbenches are used concurrently with on-site ones in regular supervised lab sessions. The students are also free to use them on their own around the clock e.g. for preparation. The electronic workbench can be used simultaneously by many students. The aim of a project known as VISIR (Virtual Systems in Reality) founded by ASB at the end of 2006, is disseminating the online lab workbenches using open source technologies. The goal is to create a template for a grid laboratory where the nodes are workbenches for electrical experiments, located at different universities. This paper focuses on standards, pedagogical aspects, and measurement procedure requirements.
1
Introduction
During centuries scientists have performed physical experiments in order to verify and test theories and create proper mathematical models, describing reality well enough. Such experiments are the only way to “communicate” with nature and to learn its principles, often quite revealing. Only recently, it has been evident that mankind must live in symbiosis with nature and focus on sustainability and understanding. Thus, the demand for experimenters will increase. However, during recent decades the amount of hands-on laboratory work, for example, in engineering education has been reduced. The prime cause is clearly the task of handling the greatly increased student numbers, while staff and funding resources have scarcely changed [1]. Reducing the number of lab sessions is easy because laboratory work is seldom evaluated and the cost reduction obtained is often considerable. However, for example, ABET (Accreditation Board for Engi-
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neering and Technology) in USA has pointed out that learning objectives for laboratory work must exist and be evaluated [2, 3]. Thus, the amount of handson laboratory work in a course must be correlated to the learning objectives of the course. Unfortunately, a substantial rise of base funding resources is not probable. It is, of course, also fundamental for students to understand theories and mathematical models. Often appropriate and low cost tools are hand calculations and simulations. The use of computer simulations has increased very much in engineering education in the last decades. However, to properly assess differences between mathematical models and real world, experiments are indispensable [4, 5]. On the other hand traditional laboratories have limited accessibility and high running costs. Nowadays, students want an extended accessibility to learning resources and increased freedom to organize their learning activities which is also one of the main objectives of the Bologna Process. From a technological perspective, such flexible education corresponds to an adequate exploitation of information, communication devices and infrastructures, especially the Internet. Today, many academic institutions offer a variety of web-based experimentation environments so called remote laboratories that support remotely operated physical experiments [6-9]. This is one way to compensate for the reduction of lab sessions with face-to-face supervision. The remote or online laboratories around the world are used in a variety of disciplines. However, the wide range of user interfaces is a problem for students and teachers. Efforts are being made to handle the situation. The iLabs project at Massachusetts Institute of Technology in USA, for example, has developed a suite of software tools that facilitates online complex laboratory experiments, and provides the infrastructure for user management [10]. A somewhat different approach would be to create a grid laboratory where the nodes are online lab workbenches distributed among a number of universities or other organizations. In such a laboratory intended for the same type of experiments it would be possible to organize supervised lab sessions with as many students or student teams working concurrently as are optimal for one instructor. Such supervised lab sessions could, for example, take place in a traditional laboratory where some students could use the local lab workbenches and others could perform the experiments remotely on distant grid nodes. Then it should be possible for each university to offer more time in the laboratory for its students. In 1999, ASB started a remote laboratory project. Today ASB has two online lab workbenches, one for electrical experiments and one for mechanical vibration experiments, based on the BTH Open Laboratory concept [11]. The concept is about providing
new possibilities for students to do laboratory work and become experimenters by adding online lab workbenches to traditional instructional laboratories to make them more accessible for students, whether they are on campus or mainly off campus. These workbenches are equipped with a unique interface enabling students to recognize on their own computer screen the instruments and other equipment most of them have previously used in the local laboratory. At the end of 2006, ASB started the VISIR project together with National Instruments in USA and Axiom EduTech in Sweden, to disseminate the online laboratories at BTH using open source technologies. Axiom EduTech is a supplier of education, technical software, and engineering services for noise and vibration analysis. The project is financially supported by BTH and by VINNOVA (Swedish Governmental Agency for Innovation Systems). What type of instructional laboratory would be feasible for creating a template for a grid laboratory? There are reasons for starting with a grid laboratory for electrical experiments: x
There are instructional electronics laboratories at most universities around the world containing the same equipment, (oscilloscopes, waveform generators, multi-meters, power supplies, and solderless breadboards) although models and manufacturers may vary. Such laboratories are already in a way a de facto standard.
x
There are standards defining the functionality for instruments common in an electronics laboratory. The IVI Foundation is a group of end user companies, system integrators, and instrument vendors, working together defining standard instrument programming interfaces [12].
x
Today BTH has an online electronics laboratory running in regular education where the software produced is released as open source [13].
Then this template can be used for designing grid laboratories for other areas. ASB has identified a laboratory for mechanical vibration experiments as an appropriate candidate because those lab workbenches are very expensive and the mathematical models are not accurate enough even for introductory courses.
2
The Open Electronics Lab at BTH
An experiment is a set of actions and observations, performed in the context of solving a particular problem. Experiments are cornerstones in the empirical approach to acquire a deeper knowledge of the physical world but also an important approach to verify that a model is accurate enough. The experimenter sets up and operates the experiment with his or her hands and/or with actuators. As an example, a lab
A Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid workbench in an instructional laboratory for lowfrequency analog electronics at BTH is shown in Fig. 1. The student wires a test circuit on the breadboard with the fingers and uses instruments to measure what s/he cannot perceive directly with the human senses as, for example, the electrical current. The experiments possible to perform in this environment are mainly limited by the set of components provided by the instructor.
Figure 1: Workbench in a local electronics laboratory at BTH
In instructional laboratories at most universities, there are a number of lab workbenches where the same number of students or usually pair of students performs experiments supervised by an instructor. The students are permitted to be in the laboratories only during lab sessions when an instructor is present. The number of lab workbenches in a laboratory is usually selected, considering how many students an instructor can supervise if a workbench is not too expensive. Typically, electronics instructional laboratories are equipped with eight identical workbenches. Fewer lab workbenches mean more teaching hours per course but less investment. It is a pedagogical advantage if the lab workbenches are identical because the students can then perform the same experiments in each session and in the correct order required by the syllabus. On the other hand, it implies larger investments i.e. more duplicates of each instrument [9]. In electronics, it is possible to perform the same experiment in different time scales by selecting the electrical size of the components. This “feature” is used in the online electronics laboratory at BTH containing only one workbench to allow simultaneous access by time sharing. A single workbench can replace a whole laboratory with many workbenches. The maximum duration of a single experiment i.e.
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circuit creation and measurement procedure is currently set to 0.1 second to get a reasonable response time even with a large number of experimenters. The experiments are set up locally in each client computer. Only by pressing a Perform Experiment button the experimenter sends a message containing a description of the desired circuit and the instrument settings to the workbench (server). If the workbench is not occupied, the experiment procedure is performed in a predefined order, and the result or an error message is returned to the requesting client computer. Otherwise, the request is queued. The online lab workbench at BTH is different versus the traditional one in Fig.1. It is, of course, not possible for students to manipulate the components and wire a desired circuit on the breadboard with their fingers remotely. A type of circuit-wiring robot e.g. a relay switching matrix must be used. The instruments are plug-in boards installed in the PXI chassis connected to the host computer as shown in Fig. 2. This chassis and its contents are manufactured by National Instruments. The corresponding virtual front panels are photographs of the front panels of the instruments in Fig. 1. As an example, a screen dump displaying the multi-meter is shown in Fig. 3. The card stack on the top of the PXI chassis in Fig. 2 is the switching matrix. A subset of the components a teacher or the laboratory staff has installed in the matrix is displayed on the client computer screen adjacent to a virtual breadboard where the student wires the desired circuit to control the matrix. It is possible to assemble a circuit with up to 16 nodes by engaging a number of relays in the matrix. Apart from a controller board the card stack contains two types of board: one with component sockets and one for connecting instruments. The nodes passing all boards can be connected to sources, instruments, and/or components installed in the sockets via relay switches. The online electronics laboratory at BTH is used in three ways: x
In supervised lab sessions in the local laboratory where the students can select if they want to perform the experiments locally or remotely. However, in the first lab session it is mandatory to do the wiring on the real breadboard.
x
In supervised lab sessions in distance learning courses where the students are scattered all over the country. Various communication methods are used to communicate between the students themselves and between the students and the instructor.
x
Students can prepare supervised lab sessions and perform the experiments at home knowing that the equipment in the traditional laboratory look the same and behave in the same way. They can also repeat experiments afterwards. Especially inexperienced or less confident students requiring more time appreciate these
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possibilities. A student wanting, for example, to master the oscilloscope can practice at home without anybody watching.
Figure 2: Equipment Server
cess Sumaya University for Technology in Jordan, Carinthia University of Applied Sciences in Austria, Gunadarma University in Indonesia, UNINOVA (Institute for the Development of New Technologies) in Portugal, and ISEP (Instituto Superior de Engenahria do Porto) in Portugal. The first two universities have already implemented online workbenches using the currently released software. BTH will act as a hub for the development and maintain a server from which the current version of the software can be downloaded. The overall goal of the VISIR project is aimed at increasing the access to experimental equipment in many areas for students, without raising the running cost per student significantly for the universities. The means are shared online laboratories created by universities in cooperation and supported by instrument vendors. Sharing of laboratories may lead to sharing of course material. The ultimate goal of our research at BTH is ubiquitous physical experimental resources, accessible 24/7 for everyone, gender neutral, as a means of inspiring and encouraging children, young people and others to study engineering and become good professionals or to be used as a means of life-long learning.
4
Figure 3: Screen dump showing the multimeter
So far the research has been focused on recreating as accurately as possible the laboratory experience for the remotely based learner. Remote desktop software and MS Messenger has been used for communication. More advanced communication means will be adopted [14].
3
The VISIR project
The aim of the VISIR project is to form a group of cooperating universities and other organizations, a VISIR Consortium, creating/modifying software modules for online laboratories using open source technologies and setting up online lab workbenches [15]. A number of such scattered lab workbenches may be nodes in a grid laboratory. The VISIR Initiative is not confined to electronics laboratories but the VISIR project has started with lab workbenches for electrical experiments, since that is an easy and straightforward application to demonstrate the powerful concept. So far, the following universities are participating or are interested in participating in the project FH Campus Wien in Austria, University of Deusto in Spain, University of Genoa in Italy, Prin-
A grid laboratory for electrical experiments
Grid computing has emerged as a way to harness and take advantage of computing resources across geographies and organizations. Grid architecture for an electronics laboratory similar to the BTH one has been published [16, 17]. In this grid-based laboratory a measurement workflows execution service takes care of executing the measures according to the rules and sequence described in a measurement workflow repository. It invokes instrument services and manages multi-user concurrent sessions on the same physical test bench. The composition of measurement workflows is in charge to teachers, who provide the description of the measurement process in terms of, for example, instruments activation process. Sharing one lab workbench is the same approach as in the current online laboratory at BTH. On the other hand knowing how to handle the measurement process is an important part of lab assignments. To display a transient on the oscilloscope, for example, the oscilloscope must first be armed and then the transient is started. Each student or student team in front of a client computer should have a workbench at their own disposal for exclusive access as in the local laboratory. Then the Perform Experiment button is no longer required. It should be possible to organize a grid laboratory distributed among universities around the world. The workbenches should be the proper grid nodes. Smaller nodes are not feasible because the instru-
A Flexible Instructional Electronics Laboratory with Local and Remote Lab Workbenches in a Grid ments and the circuit under test must be located close together. The instruments and the circuit creation manipulator would be device services accessible by the lab clients via virtual front panels or a virtual breadboard, Fig. 4, 5. Web services prescribe XMLbased messages conveyed by Internet protocols such as SOAP. However, real time performance requires protocols without significant latencies and overhead. For example, the oscilloscope display should be updated at least every second.
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Spectrum analyzer, and Switch. Within each class a base capability group and multiple extension capability groups are defined. Base capabilities are the functions of an instrument class that are common to most of the instruments available in the class. For an oscilloscope, for example, this means edge triggering only. Other triggering methods are defined as extension capabilities. For example, the functions supported by the VISIR oscilloscope are listed in Table 1. The goal of the IVI Foundation is to support 95% of the instruments in a particular class. Table 1: The VISIR oscilloscope capabilities Group Name
Base Capabilities of the IviScope specification. This group includes the capability to acquire waveforms using edge triggering.
IviScopeWaveformMeas
Extension: IviScope with the ability to calculate waveform measurements, such as rise time or frequency.
Figure 4: Oscilloscope service Lab client computer
Grid node
IviScopeTrigger Extension: IviScope with the Modifier
ability to modify the behavior of the triggering subsystem in the absence of a expected trigger.
Internet
Manipulator Control routine
Lab client routine
Virtual Breadboard
Description
IviScopeBase
Relay Switching Matrix
Figure 4: Wiring service It is possible to combine a virtual front panel representing a particular instrument from one manufacturer with the corresponding hardware from another as long as the performance of the hardware matches that of the depicted instrument. The VISIR client software package is modular and it is recommended that every university creates virtual front panels representing the instruments they have in their local laboratories to preserve the student’s context. Instrument I/O is a well-studied domain with established industrial standards. Most commercial products follow the Virtual Instrument System Architecture (VISA) or the Interchangeable Virtual Instrument (IVI) standards [18]. The IVI foundation creates instrument class specifications. There are currently eight classes, defined as DC power supply, Digital multi-meter (DMM), Function generator, Oscilloscope, Power meter, RF signal generator,
IviScopeAutoSetup
Extension: IviScope with the automatic configuration ability. It is not necessary to use IVI drivers but to enable interchangeability between grid nodes VISIR recommends functions and attributes defined by the IVI Foundation to be used to describe the capabilities of the lab hardware. In this way it should be possible to create a standardized approach which is easy to adopt.
5
Conclusions and future work
BTH is disseminating software for an online workbench comprising the same equipment as a workbench in a traditional instructional electronics laboratory. Two universities have already implemented such workbenches using the VISIR software. A number of students can perform experiments on each of these online workbenches simultaneously by time sharing. However, each remote student or student team should have a workbench at their own disposal to be able to control each step of the measurement process. A way to reach this ideal situation would be increasing the number of online workbenches and organize them in a grid. Further research seems to be required to get real time performance comparable
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with that of the local workbench when a web service approach is to be adopted. The goal is to offer free access to experimental equipment for students and a lab experience that is as genuine as possible despite the lack of direct contact with the actual lab hardware. The universities will also be able to produce experimenters without increased running cost per student.
References [1] D. Magin and S. Kanapathipillai, “Engineering Students’ Understanding of the Role of Experimentation”, European Journal of Engineering Education, 2000, Vol. 25, no. 4, pp. 351-358 [2] L. D. Feisel and A. J. Rosa, “The Role of the Laboratory in Undergraduate Engineering Education”, Journal of Engineering Education, January 2005, pp 121130. [3] Cooper, M., “Remote laboratories in teaching and learning – issues impinging on widespread adoption in science and engineering education”, International Journal of Online Engineering, Vol. 1 No. 1, 2005. [4] Nedic, Z., Machotka, J., and Nafalski, A., “Remote Laboratories Versus Virtual and Real Laboratories”, Proceedings of the 33rd ASEE/IEEE Frontiers in Education Conference, Bolder, USA, November 5 – 8, 2003. [5] J. Ma, and J. V. Nickerson, "Hands-on, simulated, and remote laboratories: A comparative literature review", ACM Computing Surveys, 2006. [6] D. Gillet, A. V. N. Ngoc, and Y. Rekik, “Collaborative Web-Based Experimentation in Flexible Engineering Education”, IEEE Transactions on Education, Vol. 48, No. 4, November 2005 . [7] Z. Nedic and J. Machotka, “Remote Laboratory NetLab for Effective Teaching of 1st Year Engineering Students”, Proceedings of the REV 2007 Conference, Porto, Portugal, June 25 – 27, 2007. [8] A. M. Scapolla, A. Bagnasco, D. Ponta, and G. Parodi, “A Modular and Extensible Remote Electronic Laboratory”, International Journal of Online Engineering, Vol. 1 No. 1, 2005. [9] J. Garcia-Zubia et al., ”WebLab-GPIB at the University of Deusto”, Proceedings of the REV 2007 Conference, Porto, Portugal, June 25 – 27, 2007. [10] iLabs: Internet access to real labs - anywhere, anytime, http://icampus.mit.edu/iLabs/, 2007-07-20. [11] L. Gomes and J. Garcia-Zubia (eds), Chapter 11 in Advances on remote laboratories and e-learning experiences, University of Deusto, Bilbao, Spain, 2007, pp. 247 – 267, ISBN 978-84-9830-077-2. [12] http://www.ivifoundation.org/, 2007-12-15. [13] I. Gustavsson et al., “An Instructional Electronics Laboratory Opened for Remote Operation and Control", Proceedings of the ICEE 2006 Conference, San Juan, Puerto Rico, July 23 - 28, 2006.
[14] MJ. Callaghan, J. Harkin, TM. McGinnity and LP. Maguire, “Paradigms in Remote Experimentation”, International Journal of Online Engineering, Vol. 3 No. 4, 2007. [15] I. Gustavsson et al., “The VISIR project – an Open Source Software Initiative for Distributed Online Laboratories”, Proceedings of the REV 2007 Conference, Porto, Portugal, June 25 – 27, 2007. [16] A. Bagnasco, A. Poggi, A. M. Scapolla, “A Gridbased Architecture for the Composition and the Execution of Remote Interactive Measurements, ”2nd IEEE International Conference on e-Science and Grid Computing, Amsterdam, the Netherlands, Dec. 2006. [17] A. Bagnasco, A. Poggi, A. M. Scapolla, “Computational GRIDSs and Online Laboratories”, 1st International ELeGI Conference on Advanced Technology for Enhanced Learning, 2005. [18] Y. Yan, Y. Liang, X. Du, H. Saliah-Hassane, and A. Ghorbani, ”Putting Labs Online with Web Services”, IT Pro, MarchApril 2006, Published by the IEEE Computer Society.
Part V Simulations of the VISIR Open Lab Platform
Simulations of the VISIR Open Lab Platform
51
Simulations of the VISIR Open Lab Platform Mikael Swartling∗ , Josef Str¨om Bart˚unˇek∗ , Kristian Nilsson∗ , Ingvar Gustavsson∗ and Markus Fiedler† ∗ Department
of Electrical Engineering of Computing Blekinge Institute of Technology, SE-371 79 Karlskrona, Sweden † Department
Abstract—This paper presents a queue simulation of a remote laboratory based on the VISIR Open Lab Platform designed at Blekinge Institute of Technology. A model of this VISIR laboratory and statistical distributions of how users interact with the system based on real log files are presented. The system is then simulated in order to determine how many concurrent students that can be allowed to use the laboratory while at the same time keeping a low response time to ensure the quality of the service. The results show, in a worst case setup with approximately 300 ms response time per experiment, that roughly 100 concurrent users is an upper limit to ensure an average response time below 2 s. The results also show that raising the limit of the desired experiment response time does not necessarily increase the number allowed concurrent users significantly once the system is saturated. However, improving the experiment response time can significantly increase the number of users that can simultaneously be connected. Index Terms—VISIR, Simulation, Quality of Experience
I. Introduction Instructional laboratories for electrical experiments are widely used in the educational system because both majors and non-majors in electrical engineering perform electrical experiments. Most universities around the world providing engineering education also have such laboratories and they often look the same; they are a kind of de facto standard well-known among teachers and students. Such laboratories contain a number of identical workbenches consists of at least a DC power supply, a function generator, a digital multi-meter (DMM), an oscilloscope and a breadboard. The VISIR Open Lab Platform designed at the Department of Electrical Engineering at Blekinge Institute of Technology (BTH) in Sweden is an architecture to provide remote access to instructional laboratories [1], [2]. In VISIR laboratories, students perform physical experiments and laboratory work remotely over the Internet. The remote laboratory project started as a feasibility study in 1999 in order to provide more opportunities for students to conduct electrical experiments. Traditional circuit theory experiments have been conducted over the Internet using an online workbench at BTH from different locations simultaneously [3], [4]. VISIR laboratoriees each containing one online workbench have been set up at a number of universities worldwide [5]–[7] and the development of a grid laboratory that will use the resources more efficiently is in progress [8]. Opening a hands-on laboratory for remote access means providing a computer-mediated laboratory [9]. The student connecting to a VISIR laboratory remotely wires the circuit
and connects instruments on a virtual breadboard displayed on the computer screen. A relay switching matrix then connects the physical components and instruments [10]. The VISIR Open Lab Platform specifies a few distinct parts. A measurement server executes requests from an experiment client. An equipment server that hosts and controls the instruments and the switching matrix. Finally, an experiment client written in Adobe Flash is embedded in an HTML page served by the web interface. A web interface handles administration, user admission and resource scheduling. A simplified schematic view of the platform is shown in figure 1. In figure 1, the users interact with the public interface and experiment requests are submitted to the measurement and the equipment servers via the internal interface. Only a single experiment can be performed by the measurement and the equipment servers at any given time. Multiple submitted experiment requests must therefore be queued and handled sequentially. The public interface is currently limited to 16 concurrent users experimenting to ensure that the response time for a submitted experiment is low so that a sufficient quality of experience is ensured. Figure 2 shows a typical matrix used in a VISIR laboratory at BTH and is the target of the simulations performed in this paper. The figure shows, from the bottom, a source board, two instrument boards and a component board stacked [10]. Additional instrument and component boards can be stacked as required by particular experiments or setups. The current desired goal with this VISIR laboratory is that a submitted experiment request shall be performed and that the result shall be returned and presented to the user within two seconds. All the simulations performed in this paper will therefore be compared against this desired two-second limit. II. Goal of the Simulations The goal of this paper is to present and evaluate a model of the response times the users experience by simulating the activity and to examine how the number of connected users affects the response time. The simulations are performed to determine if the current limit of 16 concurrent users can be raised and at what point the quality of service (as determined by the two-second response time) can be compromised. III. Simulation Model and Parameters A. Simulation Model The queue system model consists of a fixed number of independent users submitting experiments and a single server
978-1-4673-2542-4/12/$31.00 ©2012 IEEE
User
User
User
Internet Public interface Web interface
Internal interface Measurement and equipment servers
handling the experiments. If the server is busy performing an experiment, then new submissions are placed in a queue and served on a first-come first-serve basis. The goal is to analyze how the submission queue behaves to allow as many concurrent users as possible while at the same time having a short submission queue time. In the particular setup being analyzed, the response time for an experiment (from when the experiment is submitted to when the result is presented to the user) is required by choice to be less than two seconds to ensure the quality of the experience for the users. The arrival of experiments from the connected users is a closed system where a limited number of users submit new experiments. A user cannot submit a new experiment until the previous experiment has been finished and the result has been presented. The submission queue is thus strictly limited to one less than the total number of user in the system. Therefore, there is a guaranteed upper limit on the experiment service time: Ts ≤ N · Te.
Signal analyzer
Switching matrix
DMM Function generator Oscilloscope Power supply
Fig. 1.
A simplified schematic view of the VISIR Open Lab Platform.
(1)
Here, T s is the total time to service an experiment including queue time, T e is the experiment time which is the time to perform a single experiment and N is the number of connected users. The experiment time T e is typically not constant but depends on what experiment a user is performing. Given the two-second upper limit on the service time T s , the number of users N can, therefore, not be calculated directly other than ensuring that the maximum desired service time in the worst case does not exceed the desired limit. Parameters that have to be identified for the simulations are: • the experiment arrival distribution to represent the rate at which a user submits new experiments, • the number of concurrent users to see how the system handles an increasing number of users, and • the experiment time to represent the time taken to perform a submitted experiment. The only parameter that has to be estimated is the experiment arrival distribution. The number of concurrent users is a controlled parameter for each simulation in order to determine a saturation point for the system and the experiment time is taken from timing diagrams and data sheets for the system components. Log files from real experiment servers are used to estimate the experiment arrival distribution. B. Experiment Arrival Distribution
Fig. 2. A switching matrix consisting of (from the bottom) a source board, two instrument boards and a component board stacked.
When parsing the log files containing activities from multiple users, the individual users must be identified and separated to determine how a single user behaves on average so that the number of users and the behavior of the users can be controlled individually in the simulations. Assume that tu (n) is the time at which the user u submitted the experiment n and that Δtu (n) = tu (n + 1) − tu (n) is the time between experiment n and n + 1 for the user u. Thus, Δtu (n) is a sample of the stochastic process that is the experiment arrival distribution. Furthermore, the set P contains all sample point pairs {u, n}.
Simulations of the VISIR Open Lab Platform
53 TABLE I The times in milliseconds for configuring the equipment and for measuring an experiment.
Probability density
100 Measured distribution Log-normal distribution
10−1
General overhead Matrix switch (per layer) Power supply +6 V Power supply ±20 V Function generator DMM, auto range DC DMM, auto range AC DMM, auto range resistance Oscilloscope Measurement
10−2 10−3 10−4
T w [ms]
Unit
0
100
200
300
400
500
10 0.08 25 56 1 5 250 50 5—50 10
Measurement time, T m , models the time taken to perform the actual experiment. For example, the time for the circuit to stabilize and the time to perform a measurement using some of the attached equipments. • Cool-down time, T c , models the time to shut down the experiment. For example, the time to read back and present the results of the experiment to the user. The experiment time is then •
Fig. 3. The experiment arrival times modeled as a log-normal distribution with μ = 33 s and σ = 65 s.
The mean μ and variance σ2 of the experiment arrival times are then estimated as 1 μ= Δtu (n) (2) |P| {u,n} 1 (Δtu (n) − μ)2 . σ2 = (3) |P| − 1 {u,n} By matching usage patterns for various distributions and empirically studying the actual distribution of the available data, the experiment arrival times are assumed to be lognormally distributed. Given the mean and the variance of the distribution, the parameters μLN and σ2LN for the log-normal distribution is calculated as [11]
and the modeled experiment arrival time is Δt(n) ∼ exp N(μLN , σ2LN ) .
T c [ms]
600
Experiment arrival time [s]
μ2 μLN = log σ2 + μ2 2 σ 2 σLN = log 2 + 1 μ
T m [ms]
10 0.08 1 1 1
(4) (5)
(6)
The parameters μLN and σLN are the mean and variance of the normal distribution used to generate the log-normal distribution. Figure 3 shows the probability density function of the measured experiment arrival times and the corresponding estimated log-normal distribution. C. Experiment Time The experiment time is the time taken to perform a single submitted experiment, to present the result to the user and to initiate the next experiment in the service queue. However, to derive the service time, the service time is split into three parts: • Warm-up time, T w , models the time to start up an experiment. For example, the time to configure the voltage or signal generator, multi-meter, oscilloscope or spectrum analyzer, and switch relays in the component matrix.
Te = Tw + Tm + Tc.
(7)
The warm-up, the measurement and the cool-down times are determined from data sheets, by timing the circuits and from fixed times to have the circuit stabilize itself for a reliable measurement. The times for the different units to perform an experiment are shown in table I and table II lists the actual instruments used for the physical experiments in this particular setup. The warm-up and cool-down times are obtained from the data sheets for the equipments used in the experiment setup. The warm-up time is to set up the power supply and to switch the component matrix. The measurement time is a fixed time of 10 ms to stabilize the circuit and an additional measurement time depending on the equipments and the configuration used for the measurement. The cool-down time is to let the power supply shut down and to reset the component matrix. The component matrix typically consists of 8 to 12 layers. Not all combinations of equipments and measurements are relevant to the analysis. For example, the function generator, oscilloscope and AC auto-ranging are not always relevant for DC circuits, the DC power supply is not always relevant for AC circuits, and neither the power supply nor the function generator are relevant for resistance circuits. The analysis will focus on the worst case configuration, which means an AC circuit, to ensure that the simulations represent the behavior under maximum queue times. IV. Simulation and Results The main goal is to ensure that the users are served rapidly when performing an experiment. In the worst case, the maximum number of concurrent users becomes Td (8) Nmax = Te
54
Part V
TABLE II Instruments used for the different units of the physical component matrix. Unit
Instrument
Power supply Function generator Digital multi-meter Oscilloscope
NI-PxI-4110 NI-PxI-5402 NI-PxI-4060 NI-PxI-5112
concurrent users can be greatly increased if the demand for a desired limit is relaxed to allow, on average, a service time below the desired limit; from approximately 10 users for the theoretical limit to around 100 users for the average wait time. Even if the maximum wait time for any single user is considered, 30 to 40 concurrent users may be allowed. When the simulated system reaches a breaking point at around 100 users for the average case, the wait time increases at a rate similar to the theoretical limit. An additional observation is that raising the desired service time limit T d does not significantly change the number of allowed users after the breaking point around 100 users. As seen from figure 4, the limit in the average case is approximately 110 users. However, doubling the limit to T d = 4 s only increases the number of allowed users to approximately 120.
where T d is the desired maximum service time. The worst case is when all Nmax users submit an experiment at the same time: the last user in the queue is still guaranteed to be served within T d . Instead of enforcing a worst case limit, simulations are performed to determine a limit on the number of users that still provides a low service time to some probability. The simulations are performed using the user model, the equipment model and their parameters described in the previous section. A worst case setup is assumed: an AC circuit with DMM autoranging. The set times are therefore T w = 11 ms, T m = 260 ms and T c = 11 ms. Thus, the experiment response time is T e = 282 ms. The simulations are performed with 10 000 000 experiments per batch, corresponding to approximately 40 days of continuous load from 100 concurrent users according to the estimated distribution. Furthermore, the results are the average of 10 batches. The confidence intervals for the estimated values are very small due to the large number of experiments being simulated. The primary goal of the simulations is not to estimate precise values, but to determine general trends to assist in determining a limit on how many users that can be connected and perform experiments at the same time. For this reason, confidence intervals have been omitted since even a high confidence interval is not large enough to significantly affect any decision on limiting the number of users.
Figure 5 shows the estimated probability that a submitted experiment is queued. As the number of concurrent users increases, the chance of a submitted experiment being queued is increased. The figure shows the estimation of the probability that an experiment is not queued at all, is queued for shorter than the desired limit and is queued for longer than the the desired limit. The time an experiment is waiting in the queue is T q . Before the system starts to saturate around 100 users, the chance that an experiment is queued increases linearly. These queued submissions are, however, queued for a time less than the desired limit and are thus not a problem for the quality of the service. Beyond the saturation point, the probability of being queued for longer than the desired limit increase dramatically. Even though nearly half of the experiments are queued with 50 to 60 concurrent users, almost none of them are queued longer than the desired limit.
A. Simulation: Wait Times
C. Simulation: Improved Experiment Response Time
Figure 4 shows the result from the simulation of the time a user has to wait for an experiment to complete. As the number of concurrent users increases, the wait time also increases since there will also be an increasing number of queued experiment requests that have to be served. The figure shows three graphs: the average wait time per user, the maximum wait time for any user encountered during the simulation and the limit of the maximum possible wait time a user can theoretically experience. The figure also shows the desired upper limit of the response time for reference which is T d = 2 s. The maximum wait time during a simulation depends on how long the simulation is performed and it will increase towards the theoretical limit as the simulation time approaches infinity. The limit of the maximum possible wait time occurs if all users submit an experiment at the same time and is simply evaluated as T max = N · T e . To guarantee a service time below T d , the maximum number of users can be calculated from (8). The maximum number of users can also be observed from figure 4 where the graph for T max intersects the desired upper limit. The number of
The previously presented simulations were performed with a worst case setup. It was there shown that the number of allowed users cannot be significantly improved by allowing a slightly longer desired maximum response time. Figure 6 shows the average wait time per user for different experiment times. The figure shows that the average wait time can be significantly decreased when the experiment time is improved. This corresponds to performing experiments using equipments with a lower response time, for example due performing other types of measurements (DC vs. AC measurements), or simply due to better performing instruments. Likewise, increasing the experiment time increases the average wait time.
B. Simulation: Queued Users
V. Conclusions The VISIR Open Lab Platform was analyzed and simulated to determine how the response times behave when different number of users interact with it. The goal was to determine how many users can be allowed to log in and experiment at the same time while at the same time ensuring a low service time. From a model of the queuing system, distributions
Simulations of the VISIR Open Lab Platform
55
20 Average Maximum T max Td
Wait time [s]
15 10 5 0
0
20
40
80 100 60 Number of users
120
140
Fig. 4. The estimated wait times for a submitted experiment when the number of users increases.
References
Estimated probability
1 Tq = 0 0 < Tq < Td Tq ≥ Td
0.8 0.6 0.4 0.2 0
0
20
40
60
80
100
120
140
Number of users Fig. 5. The estimated probability that a submitted experiment is queued when the number of users increases.
Te Te Te Te Te
Wait time [s]
4
= 0.5 s = 0.4 s = 0.3 s = 0.2 s = 0.1 s
2
0
and parameters of how users perform experiments and the behavior of the physical equipment it can be seen that even with around 100 users the response time is still acceptable on average. Occasional wait times above the desired twosecond limit may be allowed to be able to increase the number of concurrent users. The simulations were performed with a worst case setup. It was, furthermore, shown that improving the experiment time can significantly improve the performance of the system, which in turn allows for more users. Considering the number of students of the classes performing the experiments during a course, this limit may not be a practical problem. All students may, of course, not be connected at the same time during a course. However, the planning of the course may naturally force the students to perform the experiments on given times during the course. The number of concurrent users was not so much of a practical problem with respect to response times. Simulations of the system show that the limit on the number of concurrent users can be greatly increased and still provide a low service time.
0
20
40
80 100 60 Number of users
120
140
Fig. 6. The estimated wait times for a submitted experiment for different experiment times when the number of users increases.
[1] J. Zackrisson, I. Gustavsson, and L. Håkansson, “An overview of the VISIR open source software distribution 2007,” in Proceedings of the 2007 REV Conference, Jun. 2007. [2] [Online]. Available: http://openlabs.bth.se/ [3] I. Gustavsson, “A remote access laboratory for electrical circuit experiments,” International Journal of Engineering Education, vol. 19, 2003. [4] I. Gustavsson, J. Zackrisson, L. Håkansson, I. Claesson, and T. Lag¨o, “The VISIR project—an open source software initiative for distributed online laboratories,” in Proceedings of the 2007 REV Conference, Jun. 2007. [5] J. Garcia-Zubia, I. Gustavsson, U. Hernandez-Jayo, P. Orduna, I. Angulo, L. Rodriguez, and D. L. de Ipina, “Using VISIR: Experiments, subjects and students,” International Journal of Online Engineering, vol. 7, no. S2, pp. 11–14, 2011. [6] D. G. Zutin, “A VISIR lab server for the iLab shared architecture,” International Journal of Online Engineering, vol. 7, no. S1, pp. 14–17, 2011. [7] G. Alves, M. Marques, C. Viegas, M. Costa Lobo, R. Barral, R. Couto, F. Jacob, C. Ramos, G. Vilao, D. Covita, J. Alves, P. Guimaraes, and I. Gustavsson, “Using VISIR in a large undergraduate course: Preliminary assessment results,” in IEEE Global Engineering Education Conference, 2011, pp. 1125–1132. [8] I. Gustavsson, J. Zackrisson, K. Nilsson, J. Garcia-Zubia, L. Håkansson, I. Claesson, and T. Lag¨o, “A flexible instructional electronics laboratory with local and remote lab workbenches in a grid,” International Journal of Online Engineering, vol. 4, no. 2, 2008. [9] L. Gomes and J. Garcia-Zubia, Eds., Advances on Remote Laboratories and e-Learning Experiences. University of Deusto, Bilbao, Spain, 2007. [10] I. Gustavsson, J. Zackrisson, J. S. Bart˚unˇek, K. Nilsson, L. Håkansson, I. Claesson, and T. Lag¨o, “Telemanipulator for remote wiring of electrical circuits,” in Proceedings of the 2008 REV Conference, Jun. 2008. [11] A. M. Law, Simulation Modeling and Analysis, 4th ed. McGraw-Hill, 2007.
ABSTRACT For centuries scientists have preformed physical experiments in order to understand the phenomena of nature and to create theories and mathematical models. This work covers some of the remotely controlled laboratories, with real physical instruments, experimental objects, etc., created within the VISIR (Virtual Instruments Systems In Reality) Open Lab Platform. This is a platform for opening hands-on laboratories for remote access 24/7 with preserved context. The aim is to create laboratories where telemanipulators can be used to remotely set up real physical experiments and where the students use virtual representations of the hands-on laboratory instruments to collect and measure real physical data. As hands-on laboratories, the VISIR can be used for exploring nature and for training engineering workmanship.
Part III and IV of this thesis present an encouragement to collaborate within in the field of remote engineering to utilize the recourses more efficiently. The idea is that universities around the world can share their experiments in a grid laboratory; every university contributes with a small part, but gets access to a wide range of experiments in this grid. Part V of this thesis concerns the modelling and simulation of the remote electronics laboratory with the purpose of estimating the maximum number of simultaneous users without losing the experience of working with a real instrument.The results indicate that one single remote electronics laboratory can handle up to 120 users simultaneously and with 120 users the delay for each user is approximately 2 seconds.
Part I and II of this thesis constitute a theoretical and practical approach on how to open up a laboratory for remote access and enabling students to have access to the equipment 24/7. Part I covers a more general solution for enabling remote access to equipment; the suggested solution can be applied to all types of instruments that can be controlled from a PC based system.
2014:04
ISSN 1650-2140 ISBN: 978-91-7295-283-6