control system

BNJ 30703 Why do we study control systems? Hanani bt Abd Wahab

What do these two have in common?

Controlled vs Uncontrolled

Boeing 777

Tornado • Highly nonlinear, complicated dynamics!

• Both are capable of transporting goods and people over long distances

BUT • One is controlled, and the other is not. • Control is “the hidden technology that you meet every day” • It heavily relies on the notion of “feedback”

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Controlled vs Uncontrolled

What is Control? Control is a term that describes the process of forcing a system to behave in a desired way in order to achieve certain objective(s)/goal(s). Control is the process of making a system variable adhere to a particular value, called the reference value.

What is Control System? Control system is a group of components which maintains desired results (goals) by manipulating the value of another variable in the system.

How to Control? Compute Control “Law”

Actuate Gas Pedal/ Brake

Sense Vehicle Speed

Goals (Desired results)

Stability: system maintains desired operating point Performance: system responds rapidly to changes Robustness: system tolerates perturbations in dynamics

Control = Sensing + Computation + Actuation In Feedback “Loop”

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Feedback Control System In general

Room Temperature Control

Main Components: • Plant: Process + Actuator • Controller • Sensor • Disturbance

More Examples Control is “the hidden technology that you meet every day” Control System in Nature Historical Examples Modern Examples

Control Systems in Nature Pancreas: regulate blood sugar.

Adrenalin automatically generated to increase heart-rate and oxygen intake in times of flight.

Eyes able to follow a moving object.

Hand: able to pick up an object and place it at a predetermined location

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Flyball Governor

Historical Examples Ancient Greece [1 – 300 BC]: water float regulation, water clock, automatic oil lamp. 17th Century: Cornelis Drebbel – temperature control. 18th Century: James Watt – Flyball governor Late 19th Century to mid 20th Century: Development of “Classical Control Theory” 1960’s – present “Modern Control Theory”

Regulate speed of steam engine Reduce effects of variations in load (disturbance rejection) Major advance of industrial revolution

Valve closes, slowing engine

Steam engine

Boulton-Watt steam engine

Modern Examples

Balls fly out as speed increases,

Flyball governor

http://www.heeg.de/~roland/SteamEngine.html

Control in Transportation

Control System in Transportation System Control in Process Industry Control in Manufacturing Industry Control in Home Automotive: Engine regulation, active suspension, anti-lock braking system (ABS). Steering of missiles, planes, aircrafts and ships at sear.

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Control in Process Industry In the process industries, control is used to regulate level, pressure and temperature of refinery vessel.

Control in Manufacturing Systems

In steel rolling mill, the position of the rolls is controlled according to the measure of thickness of the steel coming off the finishing line.

Control in Home CD Players, the position of the laser spot in relation to the microscopic pits in a CD is controlled. Video Recorder, the tracking of the record and play back head is controlled by controlling the velocity of the tape. Air conditioning system uses thermostat and control the temperature in the room.

Control in Home CD Player

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Open-loop vs. Closed-loop An open-loop control system utilizes an actuating device to control the process directly without using feedback.

Open-loop vs. Closed-loop A closed-loop control system uses a measurement of the output and feedback of the output signal to compare it with the desired output (reference or command).

Missile launcher system

Control is “the hidden technology that you meet every day”

Why do we study control systems?

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Summary Goals (Desired results) Stability: system maintains desired operating point

Performance: system responds rapidly to changes

Robustness: system tolerates perturbations in dynamics

Main References : Ogata K., Modern Control Engineering, Prentice Hall, New Jersey, 2002 Fourth Edition.

Others References : J. Dorf, Modern Control Engineering, Addison Wesley Publishing , 2004. Norman S. Nise Control System Engineering, The Benjamin Cummings Publishing Co. Inc. , 2004 Fourth.Edition, Introduction to Matlab 7 for Engineers, McGraw.Hill International Edition, 2005

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