1. CONTROL SYSTEM
AN INTRODUCTION

2. Contents 1. An Motion Control System 2. Purpose of Closed-Loop Control
3. Servo and Regulation Systems
4. Controller
5. How to Identify System
6. Summary

3. 1. An Motion System

4. Plant: Input-output relationship (transfer function) may vary uncertainties (including time-varying) and Disturbances
Nominal Model G(s)=5/(s+1)
Actual Model G(s)=5.9/(s+1.3)
Sensor: output may be digital or analog. Its input: real “speed”, its output: “readable data” of speed
Actuator: Its input: “readable data” of the voltage of the power source.
Its output: voltage, with needed current

5. Decision Making: Controller
Analog Controller
Digital Controller

6. 2. Purposes
Open-loop: speed varies with the motor and load for a given drive voltage
Closed-loop: Compensates for the influence of the variations in the motor and the load (uncertainties and disturbances) on the speed.

7. 3. Types of Systems
Servo Systems: the desired speed (set-point) changes fast. Major requirement: to follow the changing “set-point” at an acceptable speed and accuracy.
Regulation Systems: the desired speed does not changes very fast. It may be constant. Major concern: substantial uncertainties/disturbances and high accuracy.

8. 4. Controller
What does a controller do? Decides how to respond to the observed difference between the measured speed and the desired speed set-point.
How should the controller respond? Primarily based on the model, which describes the relationship between the input (voltage) and the output(speed) Robust Control: also largely based on the uncertainties
An important Step in System Design: Find the model (system identification)
Design: compromise between the uncertainties /disturbance and the response speed.

9. 5. How to Identify the System
Analyze the input-output data pairs to fit the parameters in the used model (structure)
How to analyze and how to generate the data pairs for analysis:
System Identification

10. 6. Summary This class: Part One: Identification
Part Two: Control Design Based on Model
Part Three: Discrete Control
Project 1: Parts One and Two
Project 2: Part Three

11. SYSTEM IDENTIFICATION
INTRODUCTION
Dr. YuMing Zhang
College of Engineering
University of Kentucky

12. Contents 1. System 2. System Identification 3. Importance
4. Why Specific Techniques?
5. Example
6. Summary

13. 1. System
System: an object in which variables of different kinds interact and produce observable signals
Control engineers’ views:
Process producing outputs from inputs
Outputs:
Inputs: manipulated to change the outputs
Disturbances:

14. 2. System Identification
End products: empirical models of systems
Model: description of relationship among related variables
Theoretical Models: from first principles
Empirical models:
Observations of system variables
==>Relationship among variables
==> Models linking the variables

15. 3. Importance
Control algorithms & system dynamics
First principles

16. 4. Why Specific Techniques?

19. 5. Example

21. 6. Summary Data Generation (Experiment Design)
Model Structure Determination
Parameters Estimation
Model Validation