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Lecture 1b ContinueBy Oladokun Sulaiman
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1.11 Recap:
Contribution of control system to modern
society
Control system Types of control system
Example of control system
Case study : Antenna position control
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History
Steam Pressure ( Denis Papin, 1681) : Safety valve Speed Control
( James Watt) : fly-ball speed governor Stability, Stabilization (
Feedback control )
Edward John Routh(1874) : Stability criterion to
fifth-ordersystemsLyapunov(1892) : Stability Criterion to nonlinear
systems
Twentieth-Centry DevelopmentsNicholas Minorsky : PID
ControllerH.W. Bode and H. Nyquist at Bell Lab (1930`s)Walter R.
Evans(1948) : root locus
Contemporary Applications
Optimal Control : Apollo
Digital Control : Digital computerAdaptive ControlIntelligent
Control
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fig_01_01
fig_01_01
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fig_01_06
fig_01_06
Response of close loop control system
close loop control system
Open loop control system
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fig_01_12
fig_01_12Typical DC closed loop control system
Typical AC closed loop control system
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fig_01_14Sample data control system
Digital autopilot system for guided missile
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Figure
Elevator input and output
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Application
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fig_01_04 Solar power water
extraction system Sun tracking control system
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fig_
01
_08
fig_01_08CASE STUDY: ANTENA POSITION CONTROL SYSTEM
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fi
g
_0
1_
09
fig_01_09
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fig
_0
1_
09a
fig_01_09a
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fig_01_10
fig_01_10
Ref: Norman Nise, Also check :PAGE 160-161 INSTRUMENTATION
AND CONTROL BY D. C. RAMSAY
Response of a position control system showing effect of high and
low
controller gain on the output response
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1.12 Roles of control engineer
Identify components actuator, controller,
sensor
Controller output as desired output
Model mathematic for controlled system
Block diagram
Analysis time response, frequency response,
stability Simulation
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1.13 Analyzing control system
The analysis of control system is requiredto determine its
performance
Examination is done in:
Time domain : for simple system
frequency domain: complex system :mostly sinusoidal input where
tedious
mathematic is avoided. Frequencyresponse result is checked
byexperimental and graphical analysis
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fig_02_01
fig_02_01
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Control system design objective
Production of desired transient respons: to reduce
influence on human confort and pateience,
mechanical stress, speed of system Reducing steady state errors:
to determine
accuracy of how closely the output matches the
desired response
Achieving stability:to produce proper steady and
transient state response
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Steps for design of control system
Determine physical system and specificationfrom requirement
Draw functional block diagram Represent the physical system as a
schematic Use schematic to obtain mathematical model
such as block diagram Reduce the block diagram Analyse and
design the system to meet
specified requirement and specification hatinclude stability,
transient response and steadystate performance
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fig_01_11
fig_01_11Control System Design Process
Table (p 19) : test waveform
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Table (p.19) : test waveform
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0 t1 t2t3
t4Time, second
50
100
Force,N
0 t1 t2 t3t4
Time, second
50
100
Force,N
0 t1 t2 t3t4
Time, second
50
100
Force,
N
0 t1
t2 t3
Time, second
50
100
Force,N
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Step Input Response
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Ramp Input Response
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Time Constant
It is defined as time taken by a control
plant to achieve output response
equal to 63% of its desired value.
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Control System Response
Time response
Frequency response
Steady state response Transient response
Undershoot
Overshoot Settling time
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Control system stability
Damping factor
Damping ratio
Rouths stability criteria Nyquist stability criteria
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QUESTIONS
What is a control system? How are control systems classified?
What provides information to the controller? What is the term
transmitter commonly used to describe? What does the behaviour and
performance of a control system
depend on? What is a control system called if its action is
dependent upon the
output? What is excessive corrective action called? What is the
difference between the input and output signals called? What are
the three common essential elements of a control system? What are
the three components of a transducer? What is the set point
values?
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QUESTIONS
What are the two major factors that haveinfluenced the
development of marine automaticcontrols?
What are the 12 main parameters monitored at
sea? What does the UMS class notation mean? What does the CCS
class notation mean? What are the five different control media?
What is the process of long distance controlsignal transmission
called?
What is the modern definition of a transducer?
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Conclusion
Introduction to control and control system
Elements of control system
Application of control system Example of control system
Case study of control system
Block diagram and schematic of controlsystem
