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Experiment InstructionsRT 0X0 RT 010 - RT 060 Principlesof Control EngineeringTable of Contentsiiiii 1 Introduction 2 Control and representation program 2 Installing the program 2 Starting the program 2 “System diagram” program component 2 “Charts” program component 2.4 Programmer 2 Simulation progr...

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Experiment Instructions RT 0X0

RT 010 - RT 060 Principles of Control Engineering

01/2013

RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

RT 0X0

Experiment Instructions

Publication-no.: 918.000 00 A 0X0 02 (A)

DTP_12

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING

Table of Contents 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2

Control and representation program . . . . . . . . . . . . . . . . . . . . . 3 2.1 Installing the program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Starting the program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3 “System diagram” program component . . . . . . . . . . . . . . . . . . . . . . . 5 2.4 “Charts” program component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4.1

Programmer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.5 Simulation program component. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.5.1

Simulation function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.5.2

Analysis of step responses . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.6 Network mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3

Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.1 RT 010 Liquid level control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.1.1

Control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.1.2

Continuous control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.1.3

Two-point control: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

3.2 RT 020 Flow control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.2.1

Control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3.2.2

Continuous control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3.2.3

Two-point control: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

3.3 RT 030 Pressure control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

ii

3.3.1

Control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.3.2

Continuous control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.3.3

Two-point control: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING

3.4 RT 040 Temperature control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.4.1

Control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

3.4.2

Continuous control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.4.3

Three-point control:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

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3.5 RT 050 Speed control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 3.5.1

Control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

3.5.2

Continuous control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

3.6 RT 060 Position control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4

3.6.1

Control loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

3.6.2

Continuous control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 4.1 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 4.2 Items supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 4.3 Monitoring and optimisation of controller settings . . . . . . . . . . . . . . 78 4.4 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

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RT 0X0 1

Introduction The RT 010 - RT 060 model equipment series provides a comprehensive introduction to the principles of control engineering and enables theoretical knowledge to be consolidated through clear experiments.

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

An integral component of the equipment concept is the associated software RT 010 - RT 060 Principles of control engineering. It provides up to date recording of control and measured data with a variety of functions based on “LabView” under Windows. It communicates with the relevant model via a USB interface. The software releases the pupil from routine activities and provides interactive support for the experiments. This allows uncomplicated and quick investigation of the effects of modifications to the system behaviour. The clear real loop model is closely related to reality and thus aids understanding to a greater extent than pure computer simulation. However, in order to handle control engineering questions for which a real loop is not available, the program is also capable of simulating up to 2nd order loops. The program’s software controller can be applied to the simulated loop with no restrictions. Due to the numerous transparent elements (covers, tanks, pipes etc.), all processes can easily be traced.

1 Introduction

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING The system deals with typical control loops from the world of engineering, including:

–

Liquid level

–

Flow

–

Pressure

–

Temperature

–

Speed

–

Position

For each model, an extensive individual experimental program is available, which includes the following areas:

•

Influence of controller design on control action and disturbance response

•

Stability of control loop

•

Controller optimisation

As all the equipment in the series are compact, table-top models that do not require much space, they are particularly suitable for pupils’ experiments in the classroom. The software’s networking capability means that teacher/pupil systems can be set up if required.

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1 Introduction

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING

2

Control and representation program

2.1

Installing the program

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

Hardware requirements:

–

PC with Pentium III 1000 MHz processor

–

1 USB port

–

128 MB RAM

–

Graphics card resolution (1024 x 768 pixels, True Color)

–

50 MB of available hard disk space

–

CD-ROM drive

–

Monitor, mouse, keyboard

–

Operating system: Windows 2000, XP

Procedure for installation :

2 Control and representation program

•

Insert “RT 010 - 060 Principles of control engineering” CD-ROM.

•

Call up the program “setup.exe” in the “ Installer” directory and follow the instructions in the subsequent dialog. The installation sequence is as follows:

–

GUNT control program

–

“LabJack” for USB communication

•

Connect experimental model to PC with USB cable.

•

Switch on experimental model.

•

Restart the PC.

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RT 0X0 2.2

Starting the program To start the control program, call it up using “Start \ All Programs \ G.U.N.T \ RT 0x0”. The first time the program is started after installation, a screen appears prompting you to select the language. Select your preferred language.

Fig. Language 2.1 selection

The selection made here can be changed at a later date if required. (This is done using the “About G.U.N.T.” button in the entry screen.)

The entry screen then appears. This is where you can select the appropriate experiment. To do this, select the model on the screen with the mouse (the picture is given a coloured background) and select it using the “Select” button.

Fig. Start 2.2 screen

The lower section of the entry screen also contains a toolbar with additional buttons that are also available in all subsequent sub-menus:

4

•

About GUNT For general information and to change the program language. The language can be changed at anytime and changes are effective immediately.

•

EXIT Exit the program.

•

Select Select the desired model.

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING 1

2

3

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

4

2.3

•

System diagram Call up the control function.

•

Charts Call up the control function with representation and plotting of the signal progressions over time.

•

Simulation Call up the function for simulation of a control loop.

•

Information fields: 1

Active model

2

Program version number

3

Current time

4

“Print screen” action (only possible if a printer is connected)

“System diagram” program component Under the “System diagram” program component, a diagram (5) appears in the left-hand section of the screen showing a schematic view of the loop for the selected control system. The current value of the control variable (e.g. the speed) is indicated numerically. Controller type >

2 Control and representation program

In the right-hand section of the screen, the controller type can be selected using a selection field. The options available are:

–

Manual (uncontrolled “manual mode”)

–

Continuous control

–

Step control

–

Three-point control

–

Programmer

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING 6 7

5

8 9 10

Fig. System 2.3 diagram example, RT 050

Manual regulation ratio > In manual mode, the control dial (8) can be used to select the manual regulation ratio from 0...100 %. Alternatively, the value can be entered directly in figures in the field below the control dial. To do this, double click on the field, enter the figure using the keyboard and confirm. In controller mode, the control dial (6) can be used to set the reference variable. Alternatively, the value can be entered directly in figures in the field below the control dial.

Parameter input >

6

The selection fields (7) for kp , Tn and Tv are used to enter the control parameters.

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING Display >

The display field (10) provides a scale illustrating the current values for: Reference variable

W in %

Control variable

X in %

Regulation ratio

Y in %

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

The general toolbar is available in the lower section of the screen.

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RT 0X0 2.4

RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING “Charts” program component 20 19

11

12

13 14 18 15 16

Fig. Charts 2.4 example, RT 050

17

Under the “Charts” program component, the screen shows a diagram for the continuous representation of the signal progression over time. All controller functions are also available in this program component and behave in the same way as in the “System diagram” component.

8

Controller type >

In the left-hand section of the screen, the controller type can be selected using a selection field (16). The control parameter are entered in the selection field (17).

Reference variable >

The selection field (12) is used to enter the reference variable W. Below it are two display fields (13) containing the values of the control variable X and the regulation ratio Y.

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING The setpoint can be limited using the selection field (14). The upper left section of the screen contains a control panel (11) that shows which signals are represented.

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

Curve colour >

The colour and type for the curves can be freely selected. To do this, click on the corresponding signal curve in the control panel and a self-explanatory dialog box opens up to make the settings. The background colour of the diagram can be changed using the selection field (18). NOTE: If a diagram is to be output directly on a printer, it makes sense to switch to a white background colour first.

Time base >

The feed time base for the signal diagram is set using the selection field (19). The scale on the time axis in the diagram is updated automatically when a value is entered and confirmed.

Axis scaling >

The scaling for the time axis and for the control variable axis in the diagram can also be set by directly selecting the starting or end value and then entering new numerical values. However, it must be ensured that the selected values are meaningful.

Cursor function >

To help with measuring a signal progression, the "Cursor" function(15) is available. When it is called up, two circular lines appear in the diagram and can be moved using the mouse pointer. The position values are displayed in a display field below the diagram.

2 Control and representation program

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RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING To assist you, continuous representation can be paused and then continued using the button to the bottom left of the diagram. Pause Continue Manage graph >

The selection files (20) above the diagram are used to manage the chart data.

•

Clear graph

Deletes the chart currently displayed and restarts continuous representation from the beginning.

•

Save graph

Opens a dialog box to save the current chart as a data record in the form of a list of measured values.

•

Print curve

Outputs the curve in a suitably prepared form on an optionally connected printer.

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RT 0X0 2.4.1

RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING Programmer

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

In the “Charts” program component, it is possible to select the “Programmer” operating mode.

Selecting the “Program” button opens up a separate window in which you can define a control program, e.g. with ramps etc. First of all, the initial value of the reference variable W is specified on the far left. The program is then defined step by step by entering pairs of values in each column. Fig. 2.5

Example of a control program for RT 030

The upper fields are used to enter time periods dt in seconds, in which a desired value for W is to be attained or maintained. The lower fields are used to enter the desired value W of the reference variable that is to be attained or maintained. The program definition is completed using “OK ” and the window is closed. In the “Charts” screen, the “Start” button (on the left below “Cursor ”) can now be used to activate execution of the program. Execution of the program then begins immediately.

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RT 0X0 2.5

RT 010 - RT 060 PRINCIPLES OF CONTROL ENGINEERING Simulation program component The control loops in the RT 010 - RT 060 series cannot generally be used to represent systems of higher order than PT1 behaviour (except RT 040 Temperature control). This program therefore provides the option of mathematically simulating up to 2nd level loops without the need for an actual loop. An oscillatory system with PT2S behaviour is simulated on the PC in the relevant frequency range in accordance with the general equation below.

G (s)

=

K 2 1 + T1 s + T2 s 2

2.1

with the attenuation factor

D

and the resonant frequency

w0

= =

T1 2T2 1 T2

the expression takes on the more familiar form:

G (s)

K

= 1 +

2D s w0

+

1 w0

2

2.2

s

2

The values of T1 and T2 or D and w can be freely selected and broad sections of the loop changed and adapted accordingly. NOTE! For simulation, all control functions provided by the program are applied without restriction to the imaginary loop and have exactly the same effect as they do on an actual loop. The mode of operation of the simulation is represented in the following block diagram (Fig. 2.6).

12

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RT 0X0

W(s)

Y(s)

E(s)

Z(s) _

GR(s)

X(s) GS(s)

All Rights Reserved G.U.N.T. Gerätebau GmbH, Barsbüttel, Germany 01/2013

_

Fig. 2.6

W(s)

:

Reference variable

GR(s) :

Controller transmission function

X(s)

:

Control variable

GS(s) :

Loop transmission f...