industrial electronic department copyright of german malaysian institute. all rights reserved

Industrial Electronic DepartmentCopyright of German Malaysian Institute. All rights

reserved


reserved

Represent the relationship between signal and instruments for the whole system

- Formalize control system as “Pictures”.

- Have mathematical models to system components.

- Components can be combined to produce an overall mathematical description of systems.

- Interaction between elements is well defined.

Why we need Signal Flow/Block Diagram?

DEFINITIONDEFINITION


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MEASURINGELEMENT

Set Point

CONTROL LAW

Final controlElement

PROCESSX

y

z

w e

CONTROLLER

SIGNAL BLOCK DIAGRAMSIGNAL BLOCK DIAGRAM


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MEASURINGELEMENT

Set Point

CONTROL LAW

FCE PROCESSx

y

z

w e

CONTROLLER

e or Xd – error/control difference/deviation - the difference between set point and measured value (controlled variable) xd = w-x or e =SP-PV

w – set point/command variable - the value that we desired

y – correcting/manipulated variable – is a controller output or a value has a direct effect to the control element

z – disturbances/unwanted variable - the unwanted variable that affect the process

x – controlled/measured variable - the system/variable that we going to controlled

ANNOTATIONSANNOTATIONS


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• Command Variable (w) / Set Point (SP)– The required value of the process variable may be set by the

operator or by the output of another controller (cascaded)

• Control difference (Xd) / Error (E)– Measure how far the process variable is from the set point– Defined as SP-PV

• Controlled Variable (x) / Process Variable (PV)– The measured value of the variable to be controlled

• Correcting Variable (y) / Manipulated Variable (MV)– The variable that is adjusted to correct any error

• Disturbance Variable (z)– The variable that drive the controlled variable away from their

desired or setpoint conditions

TERMS & DEFINITIONSTERMS & DEFINITIONS


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DINJIS,ANSI,

BS

Controlled

Variablex PV

Set

Variablew SV

Manipulated

Variabley MV

Disturbance

Variablez D

ANNOTATIONSANNOTATIONS


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RECTANGLE BLOCKRECTANGLE BLOCK


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Gx y

G

x1yx2

x3x4

RECTANGLE BLOCKRECTANGLE BLOCK

y = G.x

y = ? (Not allowed)

Indicates Function


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z = ?x

y

abc

d

e = ?

• Two input: z = ?

SUMMING POINTSUMMING POINT

• Three or more : e = ?

Indicates Combination of Signal


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X1

X1

X1

X1

X1

X1

X1

BRANCH POINTBRANCH POINT

Division of a signal to give two or more paths without modification


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INTERACTION BETWEEN INTERACTION BETWEEN ELEMENTELEMENT


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MANIPULATION OF BLOCK DIAGRAMMANIPULATION OF BLOCK DIAGRAM

A(s)X(s)

B(s)Y(s) Z(s)

In using block diagrams to analyze control problems it is important to be able to convert from one form to another.

A(s)B(s)X(s) Z(s)

A(s)X(s)

B(s)

Z(s)+

+A(s) + B(s)

X(s) Z(s)

A(s)X(s)

Y(s)

Z(s)+

-

A(s)X(s)

Y(s)

Z(s)+

-

A(s)

A(s)X(s) Z(s)+

- A(s)1+A(s)

X(s) Z(s)


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MANIPULATION OF BLOCK DIAGRAMMANIPULATION OF BLOCK DIAGRAM


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CONCLUSIONCONCLUSION


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- Setpoint : Desired Speed

- Controlled Variable: Actual Speed

- Measuring Element: Tachometer measurement + Noise

- Signal Type: Voltage

- Disturbance: Variation of Load Torque

1. DC Motor Speed Control

W

x

EXAMPLE OF C/L CONTROLEXAMPLE OF C/L CONTROL


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2. Aircraft Autopilot

-Goal: Keep aircraft on desired path

-Disturbance: Wind,air density and etc

-Feedback: To reject Disturbance

EXAMPLE OF C/L CONTROLEXAMPLE OF C/L CONTROL


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THERMOSTAT

Set Point

CONTROL LAW

VALVEHOME

HEATINGX

y

z

w e

TEMPERATURE CONTROLLER

Home Heating System

industrial electronic department copyright of german malaysian institute. all rights reserved

Documents

rights reserved objectives

variable mvthe variable

manipulated variable

variable y

signal flowblock diagram

single control loop

control system

system components