Idea Transcript
Lecture #1
Control Systems Introduction to Control Systems
Assoc. Prof. Haluk Görgün 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
1
0123152 Control Systems Room and Hours: A153,Tue 4-7Pm Office Hours: Mon., 3-4pm, A101 TA’s: Res.Ass. Yavuz Eren, Res.Ass. Ozgur Aktekin, A113 Text Book: Control System Engineering, Norman S. Nise, Fourth Edition, John Willey and Sons, ISBN 0-471-44577-0 Class Material: Automatic Control Systems, Benjamin Kuo, Eighth Edition, Prentice-Hall. Feedback and Control Systems, J.J. DiStefano, III, A.R. Stubberud, I.J. Williams, Schaum’s Outline Series. Modern Control Engineering, K. Ogata, Fourth Edition, 2001, Prentice Hall 19 February 2013 Otomatik Kontrol Doç.Dr. Haluk Görgün
2
Course Brief Description: The objective of this course is to introduce theoretical and practical background of control systems. To design a controller for a system good knowledge of linear autonomous systems is required. This course will present student the basis of linear dynamic systems, modeling and control principles. Besides, it is aimed to deliver the details of the first and the second order systems, transient and steady state responses, performance criteria, stability analysis and steady state errors.
Grading: Midterm 1: 30%, Midterm2: 30%, Final: 40% Midterm Date: Be announced by Electrical Engineering Department and usually in 8th week. Final Date: In Final’s week( o be announced in Dept’s webpage) 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
3
WEEK$ 1$ 2$ 3$ 4$ 5$ 6$ 7$ 8$ 9$ 10$ 11$ 12$ 13$ 14$ 15$
DATE$ 11.02$ 18.02$ 25.02$ 04.03$ 11.03$ 18.03$ 25.03$ 01.04$ 08.04$ 15.04$ 22.04$ 29.04$ 06.05$ 13.05$ 20.05$
19 February 2013
CLASS$TOPIC$ Introduction*to*Control*Systems* Laplace*Transformation* Block*Diagrams*and*Signal*Flow*Diagrams* Modeling*of*Physical*Systems* Gears*and*DC*Motors** st 1 *Order*Systems*and*Performance*Criteria* 2nd*Order*Systems*and*Performance*Criteria* Midterm$(*To*be*announced*in*Dept’s*webpagei*it*is*tentative)$ Under*damped*2nd*Order*Systems** Stability* InputJOutput*Stability* Introduction*to*Modern*Control*Theory* Midterm$(*To*be*announced*in*Dept’s*webpagei*it*is*tentative)* Introduction*to*Modern*Control*Theory* Root*Locus** Otomatik Kontrol Doç.Dr. Haluk Görgün
4
Brief History of Controls • James Watt’s centrifugal governor – 18th century • J. C. Maxwell formulated math. model for the governor stability • 1922: Minorsky: Automatic control of steering ships; stability with diff. eqn. • 1927: H. S. Black, idea of negative feedback op-amps • 1932: Nyquist: Stability of closed-loop systems from open-loop response • 1934: Hazen: Servomechanism, position control, tracking • 1940-1950: Bode: Frequency response methods; ZieglerNichols: PID tuning; Evans: Root-locus methods • 1960: Modern control theory, MIMO • 1960-1980: Optimal control of deterministic/stochastic; adaptive/learning control • 1980-1990: Robust control and more advanced topics 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
5
Some Definitions – 1 • Controlled Variable: The quantity or the condition that is measured* and controlled – Temperature of the room – Speed of a car – Orientation of a space vehicle • Control Signal (Manipulated Variable): The quantity or the condition that is “varied” by the controller so as to affect the value of the controlled variable – Burn more fuel or force cooled the air – Accelerate or break – Exchange momentum or burn fuel
19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
6
Some Definitions – 2 • Control: Measuring the value of the controlled variable and applying the control signal to the system to command, direct, or regulate the deviation of measured value from desired value – – – –
Do this within prescribed limits How good à Performance How to measure: SENSORS How to act upon: ACTUATORS
7 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Some Definitions – 3 • Plant: A piece of equipment functioning together to perform a particular operation • Process: A progressively continuing operation marked by a series of gradual changes that lead towards a particular result • Systems: A combination of components that act together to perform a certain objective • Disturbances: Signals that tend to adversely affect the vale of the output of a system 8 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Some Definitions – 4 • Feedback Control: An operation that in the presence of disturbances tends to reduce the difference between the output and reference/desired input • Input: Stimulus, excitation, or command applied to a control system typically from an external energy source, usually in order to produce a specified response from the control system • Output: Actual response obtained from a control system – Usually the controlled variable is the output of the system 9 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Open vs. Closed Loop
• Disadvantages of OL • Advantages of OL – Disturbances cannot be – Simple construction compensated for – Less expensive, no sensor – Recalibration necessary – No major stability problem to get expected output – Convenient when output – Cannot be used often not easy to measure times! à Unstable systems 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
10
General Closed Loop
Implementation • Analog/Digital
11 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Design and Compensation of Control Systems • Components in control systems – Electronic – Mechanical – Pneumatic – Hydraulic • The choice for the types depends on the nature of the controlled system – Flammable fluid à pneumatic – Electronics used: • Simplicity of transmission, increased accuracy, increased reliability, ease of compensation, etc. – Mechatronics 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
12
Outputs:Speed, Direction Inputs: Gas Pedal, Steering Wheel Input
19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
System
Output
13
Performance Specifications • Controllers perform specific tasks in which we want response of the controlled system to be at a desired value – Elevator: Go to 4th floor
• Requirements à performance specifications – Elevator: How fast? How smooth? – Requirements can be against each other! à TRADE-OFF!
• Types of control system performance specifications – Transient Response Requirements • Maximum overshoot, settling time, etc.
– Steady-State Response Requirements • Steady-state error in following a given input signal
– Frequency Response Requirements • Stability requirements
• The specifications must be given before the design process! 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
14
Performance Specs (Cont’d) • Performance Specifications – Accuracy – Relative stability – Speed of response • Requirements can be against each other! – TRADE-OFF! • Engineering judgment must be used NOT to make the system expensive than necessary 15 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Design Procedures • Adjusting the gain is the fist step – However, often this will not be enough – The system dynamics must be modified – This process is called “compensation” and the device that perform this action is the “compensator” • Obtain mathematical model of system and controllers • Test against given performance specifications • You may not get the desired results in first trial: – Neglected effects: nonlinearity, distributed parameters – You need to make necessary adjustments and try again – Use computer tools: MATLAB/Simulink 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
16
Washing Machine • Although there are expensive models, it is very hard to measure cleanliness of cloths – An open-loop system based on length of time for washing machines more convenient – Sensors to measure cleanliness à expensive
17 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Automatic Toaster • These are usually open-loop systems with certain types of timers (mostly analog) • If you make a closed-loop toaster, it will be expensive – What to measure? • Darkness • Surface temperature 18 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Human Body • Human body is full of automatic control concepts: closed-loop – Pancreas regulates blood sugar level – When climbing mountains the adrenalin level is regulated with increased heart beat to provide more oxygen – Perspiration system – Auto-balanced walking 19 – Reflexes and more 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Elevator
20 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Room Temperature Control
21 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Airplane Control
22 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Speed Control of a Rotating Disk (Open-Loop)
How to make this a closed-loop
23 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
Speed Control of a Rotating Disk (Close-Loop)
24 19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
25
19 February 2013
Otomatik Kontrol Doç.Dr. Haluk Görgün
26
Assignment Study MATLAB Tutorials • http://www.me.metu.edu.tr/courses/ me304/Matlab_2004.pdf • http://www.indiana.edu/~statmath/math/ matlab/gettingstarted/index.html • http://www.engin.umich.edu/class/ctms/ • http://www.me.metu.edu.tr/courses/ me304/Matlab_Tutorial.pdf
27