Chap1 Intro to Control System
41
BEKC 3533 | INTRODUCTION TO CONTROL SYSTEM CHAPTER 1 Introduction to Control System 1 DR CHONG 1516-1 Dr. Chong Shin Horng Control, Instrumentation & Automation Faculty of Electrical Engineering
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This is about the intro to control system, which included the history of control system, basic control system and its configurations.
Transcript of Chap1 Intro to Control System
DR CHONG 1516-1 1
BEKC 3533 | INTRODUCTION TO CONTROL SYSTEM
CHAPTER 1Introduction to Control System
Dr. Chong Shin HorngControl, Instrumentation & Automation Faculty of Electrical Engineering
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CONTENT
History of control systems
Control system basic
Control system configuration
The control problem
1.1
1.2
1.3
1.4
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1.1History of Control System
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History of Control System
Early• Simple, primitive
20th Century • Extensive use of
sensors
Contemporary • Widespread
applications
300 BC 1900’s 2000’s
Water clock (300 BC) Steam pressure &
temperature control systems (1680s)
Speed control (1745) Stability theories
Routh-Hurwitz (1877)
Lyapunov (1892)
Automatic ship steering (1922)
PID controller (1920s) Feedback control
system technique (1930s)
Root locus, Bode, Nyquist (1948)
Navigation Entertainment Smart homes Military Space applications Chemical process
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History: 300BC – water clock
One of the earliest control system - water clock Is a time-measuring instruments – time was measured by measuring the water
dropping at a constant rate from a reservoir through an orifice.
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History: 300BC – temperature regulator Cornelis Drebbel (1572 – 1633), a Dutch
mechanic and chemist. Invented a temperature regulator to maintain
a constant temperature in a chamber, which is though to be used both in chicken incubators and in a general furnace for his chemical experimentation.
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History: 300BC – Steam pressure control
In 1681, Denis Papin introduced the steam pressure control system (where he invented the safety valve)
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History: 20th century applications
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History: 20th century applications
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Review Question (Lecture 1)
Problem 1
Describe how a water clock function. An appropriate diagram is required to assist the description.
Problem 2
List out more histories of control system in 300 B.C.
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1.2Control System Basic
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Control System Basics
General Control System Block Diagram
Controller Plant
Input signal
Subsystem 1 Subsystem 2 ProcessOutput signal
Control System
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Control System Basics
Control Systems – an interconnection of components forming a system configuration that will provide a desired system response.
Provides an output or response for a given input or stimulus
Input; stimulus
Desired response
Output; response
Actual response
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Control System Basics
Primary aim: To regulate certain variables about constant values even when
there are disturbances To force some parameter to vary in a specific manner.
Control methods: control control
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Control System Basics
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Control System Basics
• For• e.g. in moving the radar antenna position to certain angle,
small input power is amplified to produce high output torque
1• For• e.g. in controlling the movements of robots working
in contaminated areas where human presence should be avoided.
2• For• e.g. in a temperature control system, the turn of a
knob corresponds to certain desired room temperature 3
• For• e.g. to maintain antenna position in the presence
of strong wind 4
4 main control purposes
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1.3Control system
configuration
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Control System Configuration
Open-loop system
Controller
Desired output response Output
Actuator Process
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Control System Configuration
Closed-loop system
Controller
Desired output response Output
Actuator Process
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Control System Configuration
Open-loop system
Closed-loop system
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Control System Configuration Example of open-loop system:
- Automatic washing machines,
Does not have a loop
Open-loop system
Actual / current condition is taken as a data to calculate the necessary corrective action needed.
Corrective action is needed to maintain the desired value.
Positive / negative feedback
Closed-loop system
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Control System Configuration
Open-loop system
Simple construction Ease of maintenance No stability problem No
Advantages Disadvantages
Disturbances cause errors Changes in calibration
cause errors Output
Rec
Example of open-loop system:
- Automatic washing machines,
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Control System Configuration
Closed-loop system
High accuracy Not sensitive on
disturbance Controllable steady-state
error
Advantages Disadvantages
More complex More Possibility of needed Need for output
measurement
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Control System Configuration
Driver
Desired course of travel
Actual course of travelSteering
mechanism
Automobile
Measurement, visual and tactile
Controller Actuator Process
Measurement output Feedback
Sensor
Error+_
Example of control system
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Control System Configuration
An automatic iron regulates the temperature of iron in such as way that the temperature for a specific cloth remains in a specified range.
Example of closed-loop system: Automatic electric irons
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Control System Configuration
Example of closed-loop system : Human moves on desired road
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Control System Configuration
Example of closed-loop system : Sun seeker solar system
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1.4The control problem
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The Control Problem
Generally, a controller / compensator, is required to filter an error signal in order that certain control criteria, or specifications, be satisfied.
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The Control Problem The control criteria may involve, but not be limited to:
1. Disturbance rejection
2. Steady-state errors
3. Transient response characteristics
4. Sensitivity to parameter changes in the plant
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Controller Design Process
STEP 1• Determine a
physical system and specifications from the requirements.
STEP 2• Draw
functional block diagram
STEP 3• Transform
the physical system into a schematic
STEP 4• Develop
mathematical model (block diagram)
STEP 5• Reduce
block diagram
STEP 6• Analyze and
design (to meet the requirements & specification)
CHAPTER 1 CHAPTER 2 CHAPTER 3, 4, 5
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Three major objectives in analysis and design objectives:
1 Producing the desired transient response
2 Reducing
3 Achieving
Controller Design Process
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Controller Design Process Solving in control problem generally involves
1. Choosing sensors to measure the plant output
2. Choosing actuators to drive the plant
3. Developing the plant, actuator, and sensor equations (models)
4. Designing the controller based on the models developed and the control criteria
5. Evaluating the design analytically, by simulation, and finally, by testing the physical system
6. If the physical tests are unsatisfactory, iterating these steps
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Q1 Can you give one example of a control system ?
Q2 List down the differences between the open-loop and closed-loop system.
Review Questions 1-1
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Closed-loop System Open-loop System
Q2 List down the differences between the open-loop and closed-loop system.
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Review Questions 1-2
A temperature control system operates by sensing the difference between the thermostat setting and the actual temperature and then opening a fuel valve an amount proportional to this difference. Draw a functional closed-loop block diagram (feedback system) and identifying the input and output transducers, the controller, and the plant. Further, identify the input and output signals of all subsystems previously described.
Answer Review Question 1-2
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Review Questions 1-3
An aircraft’s attitude varies in roll, pitch, and yaw as defined in Fig. T1-1. Draw a functional block diagram for a closed-loop system that stabilizes the roll as follows: The system measures the actual roll angle with a gyro and compares the actual roll angle with the desired roll angle. The ailerons respond to the roll angle error by undergoing an angular deflection. The aircraft responds to this angular deflection, producing a roll angle rate. Identify the input and output transducers, the controller, and the plant. Further, identify the nature of each signal.
Fig. T1-1: Aircraft attitude defined
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Answer Review Question 1-3
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Review Questions 1-4
A dynamometer is a device used to measure torque and speed and to vary the load on rotating devices. The dynamometer operates as follows to control the amount of torque: A hydraulic actuator attached to the axle presses a tire against a rotating flywheel. The greater the displacement of the actuator, the more force that is applied to the rotating flywheel. A strain gage load cell senses the forces. The displacement of the actuator is controlled by an electrically operated valve whose displacement regulates fluid flowing into the actuator. Draw a functional block diagram of a closed-loop system that uses the described dynamometer to regulate the force against the tire during testing. Show all signals and systems. Include amplifiers that power the valve, the actuator and load, and the tire
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Answer Review Question 1-4
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Summary & Exercises
Today topic 1.2 Control System Basic 1.3 Control System Configuration 1.4 The Control Problem Review Questions
Next Chapter 2 (2.1.1, 2.1.2)
Exercise Tutorial 0 & Tutorial 1
