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�

Define a control system and describe some applications

Describe historical developments leading to modern day control theory

Describe the basic features and configurations of control systems

Describe control systems analysis and design objectives

Describe a control system’s design process

Describe the benefit from studying control systems

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Control System Definition

A control system consists of subsystems and processes (or plants)

assembled for the purpose of obtaining a desired output with desired

performance, given a specified input.

Simplified description of a control system

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�Elevators

a. Early elevators were controlled by hand ropes or an elevator operator. Here, a rope is cut to demonstrate the safety brake, an innovation in early

elevators;

b. Modern Duo-lift elevators make their way up the Grande Arche in Paris, driven by one motor, with each car counterbalancing the other. Today, elevators are fully automatic, using control systems to regulate position and velocity.

Photos courtesy of United Technologies Otis Elevator.

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Advantages of Control Systems��Move large equipment with precision��Point huge antennas toward the farthest reaches��Elevators��Control systems regulate the position and speed��

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We build control systems for four primary reasons��1. Power amplification�2. Remote control�3. Convenience of input form�4. Compensation for disturbances��

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We build control systems for four primary reasons��1. Power amplification��

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We build control systems for four primary reasons�2. Remote control��

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�Rover was built to�work in �contaminated�areas at Three Mile�Island in Middleton,�PA, where a nuclear�accident occurred in�1979. The remote�controlled robot’s long arm can be seen at the front of the vehicle.

Photo © Hank Morgan/Rainbow/PNI.

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We build control systems for four primary reasons�3. Convenience of input form��

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We build control systems for four primary reasons�4. Compensation for disturbances��

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We build control systems for four primary reasons�4. Compensation for disturbances��

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A History of Control Systems��1. Liquid-Level Control (Water clock 300 BC Greeks)�2. Steam Pressure and Temperature Controls (Safety valve 1682 Denis Papin)�3. Speed Control (Windmill 1745 Edmund Lee)�4. Twentieth-Century Developments (Steering and stabilizing ships)�5. Contemporary Applications��

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A History of Control Systems��

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�a. Video laser disc�player;�b. objective lens�reading pits on a�laser disc;�c. optical path for�playback showing�tracking mirror rotated by a control system to keep the laser beam positioned on the pits.�

(a)

(b)

(c)

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�Elevator input and output

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�Block diagrams of control systems:�a. open-loop system;�b. closed-loop system

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Real time applications of open loop control��Traffic light controller��Electric washing machine��Automatic coffee server��Bread Toaster��Automatic Door opening and closing system��

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Real time applications of closed loop control��Human being��

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Real time applications of closed loop control��Home heating system��

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Real time applications of closed loop control�Ship Stabilization system��

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Real time applications of closed loop control�Manual speed control system��

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Real time applications of closed loop control�DC motor speed control system��

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Real time applications of closed loop control�Temperature control system��

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�Computer-Controlled Systems��Analysis and Design Objectives��Transient Response��Steady-State Response��Stability��Other Considerations��

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�Computer hard disk drive, showing disks and read/write head

Courtesy of Quantum Corp.

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�The search for�extraterrestrial life is�being carried out with�radio antennas like the one pictured here. A radio antenna is an�example of a system�with position controls.

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�Antenna azimuth position control system:

a. system concept;

b. detailed layout;

c. schematic;

d. functional block diagram

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�Antenna azimuth position control system:

a. system concept;

b. detailed layout;

c. schematic;

d. functional block diagram

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�Response of a position control system showing effect of high and low controller gain on the output response

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�The control system design process

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�Step 1: Transform Requirements Into a Physical System�Step 2: Draw a Functional Block Diagram�Step 3: Create a Schematic�Step 4: Develop a Mathematical Model (Block Diagram)�Step 5: Reduce the Block Diagram�Step 6: Analyze and Design

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�Equivalent block diagram for the antenna azimuth position control system

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Classification of control systems:- �1. Natural control system�2. Man-made control system�3. Combinational control system�4. Time variant and time invariant systems�5. linear and non-linear systems.�6. Continuous time and discrete time control systems�7. Deterministic and stochastic control systems�8. Lumped parameter and distributed parameter control systems�9. Single input single output and multi input and multi output control systems�10. Static and dynamic systems�11. Regenerative and degenerative feedback systems �12. Open loop and closed loop control systems �

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Requirements of good control systems:- �1. Accuracy�2. Sensitivity�3. External disturbance to noise�4. Stability �5. Bandwidth�6. Speed�7. Oscillations��

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Test waveforms used in control systems

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�Potentiometer

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�Aircraft attitude defined

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�Winder

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�Control of a nuclear reactor

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�Grinder system

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�High-speed proportional solenoid valve

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�RL network

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�RLC network

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�High-speed rail system showing pantograph and catenary