1. Chapter 1. Introduction to Control System
The best and most beautiful things in the world cannot be seen or even touched - they must be felt with the heart.
Pusan National University
Intelligent Robot Laboratory

2. Table of Contents Introduction System Configurations
Analysis and Design Objectives
Design Process
Computer-aided Design

3. Introduction Control System definition
A control system consists of subsystems and processes assembled for the purpose of obtaining a desired output with a desired performance.
A control system produces the output for a given input or response to stimulation.
Figure 1.1 Simplified description of a control system

4. Introduction Two major measures of performance Transient response
Steady – state error
Figure 1.2 Elevator response

5. Introduction Advantages of control system Power amplification
Remote control
Convenience of input form
Compensation for disturbances

6. System Configuration Open – loop system
Open-loop system cannot compensate for any disturbances that add to the controller’s driving signal.
Mechanical systems are consisting of a mass, spring, and damper.
Figure 1.6 Block diagrams of control systems : a. open loop system

7. System Configuration Closed-loop System
Closed-loop systems have the obvious advantages of greater accuracy than open-loop systems.
The systems are less sensitive to noise and disturbances.
Transient response and steady state error can be controlled more conveniently.
Complex and expensive
Figure 1.6 Block diagrams of control systems :b. closed loop system

8. System Configuration Computer – controlled systems
In many modern system, the controller is a digital computer.
Many loops can be controlled or compensated by the same computer through time sharing.
Any adjustments of the compensator parameters required to yield desired response can be made by changes in software.

9. Analysis and Design Objectives
Analysis is the process by which a system’s performance is determined.
Design is the process by which a system’s performance is created and changed.
Three major objectives of systems analysis and design
Producing the desired transient response
Reducing steady-state error
Achieving stability

10. Analysis and Design Objectives
Transient response
Affects the speed of the entire system
Too fast a transient response could cause permanent physical damage
Steady – state response
Resembles the input
Accuracy is very important

11. Analysis and Design Objectives
Stability
Total response = Natural response + Forced response
Natural response describes the way the system dissipates or acquires energy.
It is dependent only on the system.
Forced response is dependent on the inputs.
For a control system to be useful
Natural response must eventually approach zero, thus leaving only the forced response.
Other Considerations
Factors affecting hardware selection
Finances
Robust design

12. The Design Process Control system design process Step 1 Step2 Step3
Determine a physical system and specifications from the requirements.
Step 1
Draw a functional block diagram.
Step2
Transform the physical system into a schematic diagram.
Step3
Use the schematic diagram to obtain a block diagram, signal-flow diagram, or state-space representation.
Step4
If multiple blocks, reduce the block diagram to a single block or closed-loop system.
Step5
Analyze, design, and test to see that requirements and specifications are met.
Step6

13. The Design Process
Step 1: Transform requirements into a physical System
Transforming the requirements into a physical system
Step 2: Draw a functional block diagram
The designer now translates a qualitative description of the system into a functional block diagram that describes the component parts of the system.
(a)
(b)
Figure 1.9 Antenna azimuth position control systems : a. system concept; b. detailed layout

14. The Design Process Step 3: Create a schematic
Transforms the physical system into a schematic diagram.
Checks the assumptions made about the physical system through analysis and computer simulations.
(c)
Figure 1.9 Antenna azimuth position control systems : c. schematic

15. The Design Process
Step 4: Develop a mathematical model (Block diagram)
Uses physical laws and Newton’s law, along with simplifying assumption, to model the system mathematically.
(d)
Figure 1.9 Antenna azimuth position control systems : d. functional block diagram

16. The Design Process Step 5: Reduce the block diagram
Reduce this large system’s block diagram to a single block
(c)
Figure Equivalent block diagram for the antenna azimuth position control system

17. The Design Process Step 6: Analyze and Design
Analyzes the system to see if the response specifications and performance requirements can be met by simple adjustments of system parameters.
Test input signals are used, both analytically and during testing, to verify the design.
TABLE 1.1 Test waveforms used in control systems

18. Computer – aided Design
The use of computers as a computational tool
At desktop computers, perform analysis, design, and simulation with one program.
Simulate a design rapidly, easily make changes and immediately test a new design.
MATLAB

19. Intelligent Robotics LaboratoryH A N K Y O U
TEL:
Intelligent Robotics Laboratory