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UWE Bristol
Control Systems EngineeringUFMEUY-20-3Aerospace Systems, Avionics and Control
UFMFB7-30-2
ControlUFMFV7-15-2
Lecture 1: Introduction to Control
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Teaching
Course structure:
1 hour lecture + 2 hour tutorial per week
Two modules, co-taught (assessments are different)
14 weeks control 6 weeks sensors and actuators
Delivered by Ben, Neil and Sabir
Tutorials: 1stSemester: Classroom examples/problems
Tutorial Sheets on Blackboard (and solutions)
2ndSemester: Laboratory (Simulink, DC motor control
+ sensors and actuators)
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Assessment
1 courseworklaboratory report (40%)
Group report
Exam after Easter Break (60%)
Reading list:
The Art of Control Engineering, Ken Dutton, Steve
Thompson, Bill Barraclough
Control Engineering, W. Bolton
Control Systems Engineering, N.S. Nise
Aircraft Control and Simulation, B.L. Stevens & F.L.
Lewis
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Todays Lecture
Introduction to Control
Examples
Control Basics Open- and Closed-loop control
Control System Design Steps
Example Models
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Introduction to Control
What is a control system?
Common example in the human body:
temperature control
Body
Action
External temperature
Sun, Illness, etc.
Body temperature
Sweat/shiver
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Introduction to Control
Applications in:
Physiology
Economics
Many fields of engineering:
Hydraulics
Electronics
Mechanics Etc.
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Simple Examples
Car speed
Room fan
Throttle EngineDesired speed Actual speed
Vehicle
Actual coolingSwitch Wall fanDesired
cooling
Electrical
power
System or Plant
Controller
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Examples
Control systems are required in complex
machines, devices
Aircraft control systems
Anti-lock braking systems
Manufacturing processes
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Examples
Inverted Pendulum
Demo
Videos
http://tinyurl.com/uwetriple
http://tinyurl.com/uweballrobot
http://tinyurl.com/uwebigdog
http://tinyurl.com/uwekestrel
http://tinyurl.com/uwetriplehttp://tinyurl.com/uweballrobothttp://tinyurl.com/uwebigdoghttp://tinyurl.com/uwekestrelhttp://tinyurl.com/uwekestrelhttp://tinyurl.com/uwebigdoghttp://tinyurl.com/uweballrobothttp://tinyurl.com/uwetriple -
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Open and Closed Loop Control
Open Loop
Turntable example
DC Amplifier
Battery
Speed
settingDC motor
Speed
Turntable
Amplifier DC motor Turntable
Control Device Actuator Process
Desired speed
(voltage)
Actual speed
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Closed Loop
Open and Closed Loop Control
DC Amplifier
Battery
Speed
settingDC motor
Speed
Turntable
+
Tachometer
Amplifier DC motor Turntable
Control Device Actuator ProcessDesired speed
(voltage) Actual speed+
Tachometer
Sensor
Error
Measured speed
(voltage)
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Open and Closed Loop Control
Cruise control example
Closed loop
Output compared to the input
Error is used to drive the system
Throttle EngineDesiredspeed
Actual
speed
Speed sensor
Error
Feedback
+
Vehicle
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Open and Closed Loop Control
Oven example
Closed loop
Output compared to the input
Error is used to drive the system
SwitchHeating
elementDesired
temperature
Actualtemperature
Temperature
sensor
Error
Feedback
+
Electrical
power
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Open and Closed Loop Control
Components in a Closed Loop System
Normally depicted in a block diagram
Plantprovides the system output
Controllertakes the control input and provides a control output
Sensortakes the output and feeds it to the subtractor(or comparator)
that compares the demand (the setpoint value) with the output of the
sensor to produce an error
All connected by arrows, which represent signals
Controller Plantdemandoutput
Sensor
error
feedback
+
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Control System Design
Understand the general schemes that can
be used to control a system.
Understand the system youre trying to
control. You need topredict how a system
behavesmathematical techniques that
involve differential equation solution
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Control System Design Steps
1. System analysisestablish requirements (talk
to users)
2. Formal specification of required system
performance3. System modellingsystem must be accurately
modelled before controller design can
commence. Usually a differential equation
(some quantity that changes w.r.t. time)
4. Control algorithm developmentthe controller
is developed using the model and standard
control theory to meet the specifications.
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System Modelling
Dynamic behaviour of the system
Linear or non-linear fashion
System dynamicshow its outputchanges in response to a particular input
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Example
Furnace
The temperature of the furnace does not change
instantaneously for changes in fuel rate
Differential equation describes the influence of
time on the input response Differential equations are derived from first
principles
FurnaceFuel flow
rate (kg/s)
Temp (deg C)
F
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Example models
Liquid level tank
RC circuit
Car suspension
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Example 1: Liquid Level
Flow inFlow out = rate of accumulation
of liquid in the tank
Qin
Qout
h
C/S area = A
assume Qout= kh
(k is a constant)
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Example 1: Liquid Level
Flow inFlow out = rate of accumulation
of liquid in the tank
Qin
Qout
h
C/S area = A
assume Qout= kh
(k is a constant)
khdt
dh
AQ
dt
dhAkhQ
dt
dhAQQ
in
in
outin
First order differential equation
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Example 2: RC circuit
Differential equation that related Voutto Vin
R
CVin Vout
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Example 2: RC circuit
Differential equation that related Voutto Vin
R
CVin Vout
dt
dVCRVV
Rdt
dV
CiRVV
out
outin
outoutin
dtdvCi :currentCapacitor
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Example 3: Car Suspension
Mass/spring/damper system
m
Fin
k D
xout
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Example 3: Car Suspension
Mass/spring/damper system
m
Fin
k D
xoutkxF
dtdxDDvF
dt
xdMmaF
:Spring
:Damping
:Inertia2
2
inout
inout
Fkx
dt
dxD
dt
xdm
Fdt
dxDkx
dt
xdm
2
2
2
2
:LawSecondsNewton'Applying
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Todays lecture
Control is an intrinsic part of humans and a vital
part of many engineering systems
In order to control a system, we need to know
the system/plant itself and control methods Description of a system to be controlled
system model is a starting point of the control
system design
Tutorial sheet 1: On blackboard. Determining
differential equations for systems