Automatic Control Theory
Teacher,Xiong Rui (熊 蕊 ）
x_ruihg@ mail.hust.edu.cn
College of Electrical and Electronic Engineering,
HUST
Teaching hours,60 hours
Experiment hours,4 hours
Total,64 hours ( 4 credits )
Text Book:
Morris Driels,Linear Control Systems
Engineering (线性控制系统工程）,北京：
清华大学出版社,2000年 12月
Other Reference Teaching Books:
Richard C,Dorf,Robert H,Bishop,Modern
Control Systems （ Ninth Edition)（现代控制系统 第九版）,北京：科学出版社，
2002年 3月
Module 1
Introduction to Feedback Control
(4 hours)
1.1 Introduction to Automatic Control
Automatic Control Systems permeate life in all
advanced societies today,Technological develop-
ments have made it possible to
travel to the moon;
explore outer space,And
the successful operation of space vehicle;
the space shuttle; space station;
robot;
industry Control,such as the control of
temperature,pressure,fluid,lever,and so on.
The Utah/MIT Dextrous Robotic Hand
1.2 Introduction to Feedback Control
----Feedback control systems are at work all around us!
Example 1,A water temperature control system
Fig.1.1
Water temperature control system with a
automatic method
The block diagram of the water
temperature automatic control system
The block diagram of a generalized feedback
control system
Compare manual control method with automatic
control method-----
Brain ---- Thermostat
(Reference input or desired output)
Nervous system
(Differencing junction)
Hand ---- Amplifier,
Motor and Wheel drivers
Skin sensor ---- Temperature sensor
Mixer Valve ---- Mixer Valve
The principle of automatic control is ---
Measure the error,and
correct the error.
Compare with a
open-loop control
system:
The error of open-
loop system can
not be corrected
T
Plant
θ Mixer Valve
ColdHot
Open-loop control system
1.3 Some Definitions
(are based on the standards of IEEE,and used in this course)
Reference input (Desired output) – The reference
signal produced by the reference selector,It is the
actual signal input to control system.
Disturbance input – A disturbance input signal to the
system that has an unwanted effect on the system
output.
Output (controlled variable ) – The quantity that
must be maintained at a prescribed value,i.e.,it must
follow the command input without responding to
disturbance.
Open-loop control system – A system in which the
output has no effect upon the input signal.
Feedback element – The unit provides the
measurement value for feeding back the output quantity,
or a function of the output,in order to compare it with
the reference.
Actuating signal (error signal) – The signal that is the
difference between the reference input and the feedback
signal,It is the input to the control unit that causes the
output to have the desired value.
Closed-loop control system – A system in which the
output has an effect upon the input quantity in such a
manner as to maintain the desired output value.That is,
a system that uses a measurement of the output and
compares it with the desired output.
Negative feedback – The output signal is fed back so
that it subtracts from the input signal.
Sample Problems,
SP1,James Watt’s Flyball Governor (1769)
1.4 How to Control?
--,Control” is the design and analysis of
sensors,actuators,and computational systems
(analog or digital) to modify the behavior of
physical systems.
For each problem we should try to answer
these questions:
What is (are) the system input(s)?
What is (are) the system output(s)?
What is the feedback path?
Typical steps:
selection of actuators and sensors
development of a dynamic model of
the system to be controlled
design of control systems based on
the sound fundamental principles
implementation of the controller
using analog or digital electronics
SP2,Closed-loop
Position Control
System
1.5 The Comparison between the open-loop
control system and the closed-loop control system
SP3,Open-loop Speed Control System
SP4,Closed-loop Speed Control System
1.5.1 About open-loop control system
The advantages,
Much simple and less expansive to construct;
Easy to have good stability;
The main disadvantage,
Require detailed knowledge of each component
in order to determine the input value for a
required output,
1.5.2 About closed-loop control system
The advantages,
Have higher accuracy;
Not require detailed knowledge of each component
or accurate model of the individual component;
The ability to recover from external,unwanted
disturbances,(See P5,Fig.1.7)
The main disadvantages,
Complex and expensive to construct;
Quite easy to become unstable.
1.5.3 Combine open-loop control with closed-
loop control – Mulriple control system
SP5.
Speed
mulriple
control
system:
1.6 Instructional objectives:
At the end of this lecture students should
be able to
(P6,This concludes the … …)
analyze a physical feedback control system
so as to draw a block diagram
representation of it;
identify elements in control system,such
as ……
SP6,A level control system
电位器期望水位高度
(电位器的中点位置 )
位置量到电压量转换控制电压信号浮子和杠杆实际水位显示电动机 减速器机械转动信号水池进水量控制阀 水池水池出水量 (扰动 )
实际水位高度
C
SP7,A temperature control system—Plot its
control block-diagram
恒定电压电位器减速器调压器
SP8,Two voltage control systems — Are they
closed-loop control systems? And which has error when load varies?
FigSP8 A Voltage Control
System
L O
A
D
L O
A
D
The system in Fig,P1 shows an operator attempting to maintain the
speed of a conveyor carrying manufactured parts through a spray
booth,When more boxes are placed on the conveyor,it slows down,
while fewer boxes allow it to speed up,(ⅰ ) Draw a block diagram of
the system indicating the principal elements,(ⅱ ) Redesign an
automatic control system without any operator.
Problem
Teacher,Xiong Rui (熊 蕊 ）
x_ruihg@ mail.hust.edu.cn
College of Electrical and Electronic Engineering,
HUST
Teaching hours,60 hours
Experiment hours,4 hours
Total,64 hours ( 4 credits )
Text Book:
Morris Driels,Linear Control Systems
Engineering (线性控制系统工程）,北京：
清华大学出版社,2000年 12月
Other Reference Teaching Books:
Richard C,Dorf,Robert H,Bishop,Modern
Control Systems （ Ninth Edition)（现代控制系统 第九版）,北京：科学出版社，
2002年 3月
Module 1
Introduction to Feedback Control
(4 hours)
1.1 Introduction to Automatic Control
Automatic Control Systems permeate life in all
advanced societies today,Technological develop-
ments have made it possible to
travel to the moon;
explore outer space,And
the successful operation of space vehicle;
the space shuttle; space station;
robot;
industry Control,such as the control of
temperature,pressure,fluid,lever,and so on.
The Utah/MIT Dextrous Robotic Hand
1.2 Introduction to Feedback Control
----Feedback control systems are at work all around us!
Example 1,A water temperature control system
Fig.1.1
Water temperature control system with a
automatic method
The block diagram of the water
temperature automatic control system
The block diagram of a generalized feedback
control system
Compare manual control method with automatic
control method-----
Brain ---- Thermostat
(Reference input or desired output)
Nervous system
(Differencing junction)
Hand ---- Amplifier,
Motor and Wheel drivers
Skin sensor ---- Temperature sensor
Mixer Valve ---- Mixer Valve
The principle of automatic control is ---
Measure the error,and
correct the error.
Compare with a
open-loop control
system:
The error of open-
loop system can
not be corrected
T
Plant
θ Mixer Valve
ColdHot
Open-loop control system
1.3 Some Definitions
(are based on the standards of IEEE,and used in this course)
Reference input (Desired output) – The reference
signal produced by the reference selector,It is the
actual signal input to control system.
Disturbance input – A disturbance input signal to the
system that has an unwanted effect on the system
output.
Output (controlled variable ) – The quantity that
must be maintained at a prescribed value,i.e.,it must
follow the command input without responding to
disturbance.
Open-loop control system – A system in which the
output has no effect upon the input signal.
Feedback element – The unit provides the
measurement value for feeding back the output quantity,
or a function of the output,in order to compare it with
the reference.
Actuating signal (error signal) – The signal that is the
difference between the reference input and the feedback
signal,It is the input to the control unit that causes the
output to have the desired value.
Closed-loop control system – A system in which the
output has an effect upon the input quantity in such a
manner as to maintain the desired output value.That is,
a system that uses a measurement of the output and
compares it with the desired output.
Negative feedback – The output signal is fed back so
that it subtracts from the input signal.
Sample Problems,
SP1,James Watt’s Flyball Governor (1769)
1.4 How to Control?
--,Control” is the design and analysis of
sensors,actuators,and computational systems
(analog or digital) to modify the behavior of
physical systems.
For each problem we should try to answer
these questions:
What is (are) the system input(s)?
What is (are) the system output(s)?
What is the feedback path?
Typical steps:
selection of actuators and sensors
development of a dynamic model of
the system to be controlled
design of control systems based on
the sound fundamental principles
implementation of the controller
using analog or digital electronics
SP2,Closed-loop
Position Control
System
1.5 The Comparison between the open-loop
control system and the closed-loop control system
SP3,Open-loop Speed Control System
SP4,Closed-loop Speed Control System
1.5.1 About open-loop control system
The advantages,
Much simple and less expansive to construct;
Easy to have good stability;
The main disadvantage,
Require detailed knowledge of each component
in order to determine the input value for a
required output,
1.5.2 About closed-loop control system
The advantages,
Have higher accuracy;
Not require detailed knowledge of each component
or accurate model of the individual component;
The ability to recover from external,unwanted
disturbances,(See P5,Fig.1.7)
The main disadvantages,
Complex and expensive to construct;
Quite easy to become unstable.
1.5.3 Combine open-loop control with closed-
loop control – Mulriple control system
SP5.
Speed
mulriple
control
system:
1.6 Instructional objectives:
At the end of this lecture students should
be able to
(P6,This concludes the … …)
analyze a physical feedback control system
so as to draw a block diagram
representation of it;
identify elements in control system,such
as ……
SP6,A level control system
电位器期望水位高度
(电位器的中点位置 )
位置量到电压量转换控制电压信号浮子和杠杆实际水位显示电动机 减速器机械转动信号水池进水量控制阀 水池水池出水量 (扰动 )
实际水位高度
C
SP7,A temperature control system—Plot its
control block-diagram
恒定电压电位器减速器调压器
SP8,Two voltage control systems — Are they
closed-loop control systems? And which has error when load varies?
FigSP8 A Voltage Control
System
L O
A
D
L O
A
D
The system in Fig,P1 shows an operator attempting to maintain the
speed of a conveyor carrying manufactured parts through a spray
booth,When more boxes are placed on the conveyor,it slows down,
while fewer boxes allow it to speed up,(ⅰ ) Draw a block diagram of
the system indicating the principal elements,(ⅱ ) Redesign an
automatic control system without any operator.
Problem
