Jakub Możaryn
Institute of Automatic Control and Robotics, Department of Mechatronics, WUT
Warszawa, 2016
Control System
Control System is an interconnection of components forming a system configuration that shall provide a desired system response (behaviour).
Open-loop control system
Examples:
Toaster
Cofee vending machine
Signals yr(t) - desired output response
u(t) - control signal x (t) - input signal y (t) - output signal
Closed-loop control system
Examples:
Temperature control in greenhouse
Water level control in a tank Automatic pilot
Signals u(t) - control signal x (t) - input signal y (t) - output signal yr(t) - desired output response
ym(t) - measured output e(t) = yr(t) − ym(t) - error signal
Closed-loop feedback control system
Control system that tends to maintain a prescribed relationship of one system variable to another by comparing functions of these variables and using the difference as a means of control
error signal e(t) is amplified
controller causes the actuator to modulate the process in order to reduce the error e(t)
Feedback concept
A closed-loop control system uses a measurement of the output and feedback of this signal to compare it with the desired output (reference or command).
Closed-loop control system
Elements
C - controller, A - actuator, O - process/object, S - sensor Main Path indicates always an essential input value of the system and output value. This path typically illustrates the main flow of material or energy in the system.
Feedback Path is used to transmit information. Energy requirements of this path is usually small, and can be ommited.
Closed-loop control system - disturbances and noise
Advantages of the closed-loop control system over open-loop control system
rejects external disturbances d (t),
improves measurement noise n(t) attenuation.
Closed-loop control system - simplified scheme
Multi-loop Feedback Control System
Single Input Single Output - SISO system
Multiple Input Multiple Output - MIMO system
Lecture 1.1 - Basic concepts / Control System Design
Jakub Możaryn
Institute of Automatic Control and Robotics, Department of Mechatronics, WUT
Warszawa, 2016
