1. Overview of Control System
DAE32103
9/24/2013
Chapter 1
Overview of Control System
Muhammad Faizal bin Ismail
Dept. of Electrical Engineering
PPD, UTHM
Lecture Notes by M. Faizal PPD UTHM

2. Outline Outline: 1.1 Objective 1.2 Introduction
1.3 Control System Concept
1.4 Control System Classification
1.5 Control System Design

3. 1.1 Objective After completing this chapter, student will be able to :
Define the basic features and configurations of control systems
Describe the open/closed-loop control system
Learn control system applications
Describe a general process for designing a control system

4. 2. Control System Concept
What is Control System?
A system that provides an output or response for a given input
Can you give an example?

5. 2. Control System Concept

6. 2.1 What is System?
Definition: A combination of components or subsystems that act together and perform a certain objectives.
Systems interact with their environment across a separating boundary.
The interaction is defined in terms of variables.
System inputs
System outputs
Environmental disturbance

7. 2.2 Control System Component
Definition:
An interconnection of
COMPONENTS
forming a system
configuration
that will provide
a desired system response
Electrical
Hydraulic Pneumatic
Mechanical
Mathematical Model
Block Diagram

8. 2.3 General Block Diagram of Control System

9. 2.4 Terms of block diagram Input: desired response
Output: actual response
Controlled variable: The quantity or condition that is measured and controlled (normally in the output)
Manipulated Variable: The quantity or condition that is varied by the controller to adjust the controlled variable.
Disturbance: Signal that affect the value of the output.
Controller: Measuring the controlled variable and applying the manipulated variable to correct deviation of the measured value (output) from a desired value (input).
Summing Junction/Point: to represent addition / subtraction of signals:
Incoming signal lines either a “+” (addition) or “-” (subtraction) sign.
Output signal is shown with an outgoing arrow.

10. OPEN LOOP and CLOSED-LOOP
3. Type of Control System
The control system can be described into two configuration:
OPEN LOOP and CLOSED-LOOP

11. Open loop system Power Supply +V Input signal AMPLIFIER 0V -V Back
Output response O
AMPLIFIER
Power Supply
High power +V -V 0V
Input signal
Low power
GEARS
MOTOR
Back

12. Closed-loop system

13. Advantage and Disadvantage of Open Loop System
Advantages
Disadvantages
Stability not a major problem
Cheaper than closed loop system
Can be used even if output cannot be measured
Easier to maintain
Changes in system or disturbance cause errors
No longer accurate when the system is disturb. Needs calibration to maintain accuracy (Periodic calibration is required)
Low bandwidth – slow response

14. Advantage and Disadvantage of Closed Loop System
Advantages
Disadvantages
Reduced sensitivity to disturbances inputs and parameter changes.
Can stabilize an open-loop unstable plant.
Can change system dynamics speed of response, accuracy, reduce effects of nonlinearities
Highly accurate due to corrective actions
High bandwidth – fast response
More complex (Increased complexity and cost)
Risk of instability (stability is major problem)

15. Feedback and its effect
Feedback system is a system that maintains a relationship between the output and some reference input by comparing them and using the difference as a means of control.
Feedback is used to reduce the error between reference and the system output.
The feedback has effects on performance characteristics as
Stability
overall gain
noise (external disturbance).

16. Feedback and its effect (cont)
Response of a position control system showing effect of high and low controller gain on the output response

17. 4. Control System Classification
Single input single output (SISO)
Multiple input multiple output (MIMO)
Linear
Non-linear
Time-variant
Time-invariant
Analog
Digital
Process Control
Sequential Control

18. 5. Control System Design
6 Steps

19. Summary of today’s lesson?
You have learn:
The definition of control system.
The components of control system.
Block diagram.
Type of control system.
How to design a control system.

20. Activity # 1 (1 hour) Form a group of 5 persons.
Select one sector from the list on the next slide.
According to the design steps, describe the system operation.
You are not designing the system but you are doing ‘reverse engineering’.
Explain you work in 10 minutes presentation on the next class.
A tutorial class next Friday is for a discussion for this activity.
This activity carries 5% of your total marks.