CA1174751A - Control method and a control circuit arrangement for carrying the method into practice - Google Patents

Control method and a control circuit arrangement for carrying the method into practice

Info

Publication number
CA1174751A
CA1174751A CA000373333A CA373333A CA1174751A CA 1174751 A CA1174751 A CA 1174751A CA 000373333 A CA000373333 A CA 000373333A CA 373333 A CA373333 A CA 373333A CA 1174751 A CA1174751 A CA 1174751A
Authority
CA
Canada
Prior art keywords
section
value
plant
set value
control
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000373333A
Other languages
French (fr)
Inventor
Rudolf Herzog
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sulzer AG
Original Assignee
Gebrueder Sulzer AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gebrueder Sulzer AG filed Critical Gebrueder Sulzer AG
Application granted granted Critical
Publication of CA1174751A publication Critical patent/CA1174751A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B11/00Automatic controllers
    • G05B11/01Automatic controllers electric
    • G05B11/36Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
    • G05B11/42Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P.I., P.I.D.
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B5/00Anti-hunting arrangements
    • G05B5/01Anti-hunting arrangements electric

Abstract

ABSTRACT OF THE DISCLOSURE

The method serves to control sluggishly reacting systems in which rapid changes in set value occur. The controller (4) used has an integrating (I)-section (11) and a proportional (P)-section (20) separate from the I-section (11). The I-section (11) receives a control variation formed from the actual value and the set value, whereas the P-section (20) is supplied with the set value. The output signals of the I-section (11) and of the P-section (20) act on the plant (1). The I-section (11) is blocked or interrupted for the duration of an abrupt change in the set value. As a result of this relatively short interruption in operation of the I-section, the control provided by the plant is improved as compared with a method in which the change in set value acts on the I-section but with a delay determined by a delay element.

Description

~ 174751 A CONTROL METHOD AND A CONTROL CIRCUIT
ARRANGEMENT FOR CARRYING THE METHOD
INTO PRACTICE

The invention relates to a method for the control of sluggishly reacting systems in the event of abrupt set-value variations by means of a controller having at least one separate integral section, a control variation which is formed from the actual value and set value being supplied to the I-section and the set value being supplied to a separate proportional section, the output signals of the I-section and P-section acting on the plant.

In a known control method of this kind, a delay element is disposed on the route between the set-value sender and the I-section of the controller so that the set-value signal supplied to the I-section undergoes a delay. This circuit arrangement considerably improves the control but means that the characteristic of the plant must be known quantitatively since the delay element must be approximately adapted to such characteristic. As a rule, the apparatus required for the delay element is excessive.

It is the object of the invention to provide a control method as specified in the opening part hereof which obviates control disturbances due to abrupt changes in the set value without any of the disadvantages mentioned occurring.

In accordance with the invention, therefore, the I-section is blocked at least for the duration of the set value variation.

It has surprisingly been found that it is better to cut the I-section of the controller out of operation for a given relatively brief time than to let it operate fairly ~-J

~ 174751 incorrectly during this time. The novel method is very advantageous in cases in which the plant characteristic alters, e.g. in dependence on load.

The invention also relates to a control circuit arrangement for performing the method and comprising a controller having a separate I-section, the controller receiving the actual value of the plant and a set value by way of a subtraction point, the controller output acting on the plant, a set value signal which emanates from a set-value sender acting on the subtraction point additionally acting on the plant via a P-section. In accordance with the invention, the blocking means are provided between the subtraction point and the I-section and are so controlled by the set-value sender by way of an element responding to changes in the set value that the integration action of the I-section is interrupted at least for the duration of changes in the set value.

A circuit arrangement of this kind has the further advantage of being readily adjustable to plant characteristics and, where necessary, to alterations of characteristic, e.g. in dependence on load.

In a circuit arrangement which is very convenient so far as apparatus is concerned and which makes it possible to dispense with any mechanical relay, the output signal of the set-value sender is supplied to an inverter by way of a differentiator having a full wave rectifier limiter limiting the signal to one unit, and the inverter output is connected to one input of a multiplier whose other input receives the difference between the set value and the actual value and whose output is connected to the input of the I-section.

The invention will be described in greater detail with reference to two diagrammatically shown embodiments;
in the drawings:

~ ~7~75 1 Figs. 1 and 2 each show a control circuit arrangement.

A plant 1 has its output connected via a line 2 to an actual-value input 3 of a controller 4. The same also has a set-value input 6 connected to a set-value source or pickoff 5 and an output 7 which a line 8 connects to the input of the plant 1. Controller 4 comprises a P-section 10 and an I-section 11.

The P-section 10 of the present example also has a D-character but it could have a pure P character. Section 10 is directly connected to controller input 3 and is connected with a negative sign to controller output 7. A
control deviation is formed for the I-section 11 by subtraction at a subtraction station 14 of the signals introduced via the two controller inputs 3,6. The control variation is supplied by way of a switch 16 to the I-section 11, whose output is then supplied, additively to the output of the P-section 10, to controller output 7.

A line 18 connects the set-value input 6 of controller 4 to a P-section or member 20 having a characteristic, e.g. P'D', different from the P-section 10. The output of P-section 20 is also connected additively to controller output 7. A line 19 branches off line 18 and extends to a D-section 21 (differentiator) having an output x. The D-section 21 communicates with a converter 24 which also serves as a full-wave rectifier and as a signal limiter;
when the output signal x exceeds a predetermined positive or negative amplitude, the output ~ of converter 24 rises to a predetermined positive value p, whereas for the rest of the time output y remains at zero. Output y goes to an expansion member 26 in which the signal y is expanded to an adjustable period of time tv. The resulting signal z controls a relay 28 which comprises the switch 16 and opens the same for the duration tv of the signal ~., the switch 16 otherwise ~ :17~75 ~
remaining closed.

In the event of an abrupt alteration in the set value, the effect of the circuit arrangement described is that the input of the I-section ll is interrupted or blocked by the switch 16 for the period tv, so that the output of the I-section ll is retained for the same period. The period tv is such that the disturbance applied via the P-section 20 to the plant l can work itself out completely at the output of the plant before the I-section 11 cuts in again. If the P-section 20 is correctly dimensioned and if no third kind of disturbance has acted on the plant 1 during the period tv, the control variation at the station 14 returns to zero upon the expiry of the period tv; if not the I-section now starts to operate without over-shoot occurring.

In the embodiment shown in Fig. 2, the switch 16 of Fig. 1 is replaced by a multiplier element 36. The output of the D-section 21 goes to a converter 34 corresponding basically to the full-wave rectifier limiter 24 but having a characteristic with inclined flanks 38 instead of vertical flanks and limiting the output signal to a consistent value.
The output of converter 34 goes to an inverter 40 in which the differentce from a positive consistent signal + 1 is determined. The resulting difference is then supplied as factor to the multiplier element 36.

Operation is as follows:

In the event of an abrupt change in set value, the D-section 21 produces a steeply rising and fairly rapidly decaying triangular signal which the rectifier 34 converts to a trapezoidal signal and which is supplied to the inverter 40 as a value to be subtracted from the consistent signal + l.
If the converter 34 delivers zero output signal at subtraction station 40, the multiplier element 36 passes on unchanged to the I-section ll the control variation formed in the subtraction J

1 17~751 station 14. If, however, the converter 34 delivers a trapezoidal signal at the subtraction station 40, the multiplier element 36 first closes completely for the passage of the variation, then opens stepwise.

Basically, the circuit arrangement shown in Fig. 2 operates similarly to the circuit arrangement shown in Fig. 1 but with the difference that in the case of the circuit arrangement shown in Fig. 2 the I~section 11 remains interrupted for longer in response to relatively steep jumps in the set value than it does for less steep jumps.

In both cases an abrupt change in set value causes the I-section to be interrupted for longer than it takes for the set value to alter.

It may very occasionally be found in optimization of the P-section 20 that the same can be the same as the P-section 10. In this case no separate P-section 10 is of course necessary; instead, the control variation formed at the subtraction station 14 can be supplied, in place of the set value from the pickoff 5, to a P-element which can be considered as P-section 10 or P-section 20. This represents a special case of the invention. For some control functions, of course, a P-section 10 can be omitted and its duties not taken over by the P-section 20.

,. ,~
~ ~ i

Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:
1. A method for the control of a sluggishly reacting plant in the event of abrupt set-value variations, said control being effected by a controller of the type having at least one separate integral (I) section, a deviation formed by the difference between a particular actual value and a particular set value being supplied to the I-section, the set value being supplied to a separate proportional (P) section, the controller including means whereby output signals of the I-section and of the P-section are operatively transmitted to the plant to control the operation thereof, characterized in that the I-section is blocked at least for the duration of the set-value variation.
2. A control circuit for carrying out the control of a sluggishly reacting plant in the event of abrupt set-value variations, said circuit comprising a controller having a separate I-section, the controller receiving the actual value of the plant and a set value by way of a subtraction station, the controller output acting on the plant, a set value signal which emanates from a set-value source connected to the subtraction station additionally acting on the plant via a P-section, characterized in that the blocking means are provided between the subtraction station and the I-section and are so controlled by the set-value source by way of an element responding to changes in the set value that the integration action of the I-section is interrupted at least for the duration of changes in the set value.
3. An arrangement according to claim 2, characterized in that the output signal of the set-value source is supplied to an inverter by way of a differentiator having a full-wave rectifier limiter limiting the signal to one unit, and the inverter output is connected to one input of a multiplier whose other input receives the difference between the set value and the actual value and whose output is connected to the input of the I-section.
CA000373333A 1980-03-19 1981-03-18 Control method and a control circuit arrangement for carrying the method into practice Expired CA1174751A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH2156/80-2 1980-03-19
CH215680A CH642467A5 (en) 1980-03-19 1980-03-19 CONTROL PROCESS AND CIRCUIT TO EXECUTE THE PROCESS.

Publications (1)

Publication Number Publication Date
CA1174751A true CA1174751A (en) 1984-09-18

Family

ID=4227187

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000373333A Expired CA1174751A (en) 1980-03-19 1981-03-18 Control method and a control circuit arrangement for carrying the method into practice

Country Status (7)

Country Link
US (1) US4415966A (en)
EP (1) EP0036437B1 (en)
JP (1) JPS56147202A (en)
AU (1) AU542622B2 (en)
CA (1) CA1174751A (en)
CH (1) CH642467A5 (en)
DE (1) DE3068568D1 (en)

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JPS60193010A (en) * 1984-03-14 1985-10-01 Yoshiki Kogyo Kk Pid controller
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DE3727369A1 (en) * 1987-08-17 1989-03-02 Bosch Gmbh Robert CONTROL SYSTEM
JPH01186182A (en) * 1988-01-19 1989-07-25 Fanuc Ltd Servo motor controlling system
EP0330718B1 (en) * 1988-03-03 1992-08-05 MOOG GmbH Circuit for controlling the holding forre of a blank holder in a deep drawing press
JP2531796B2 (en) * 1989-07-07 1996-09-04 株式会社東芝 Adjuster
JPH0733975B2 (en) * 1990-02-28 1995-04-12 株式会社島津製作所 Electromagnetic force balance
DE4009234A1 (en) * 1990-03-22 1991-09-26 Teves Gmbh Alfred DEVICE FOR REGULATING A VEHICLE'S LEVEL
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US5504672A (en) * 1993-09-10 1996-04-02 Hardiman; Ted L. Industrial process controller and method of process control
JP3823455B2 (en) * 1997-07-08 2006-09-20 フジノン株式会社 Automatic control device
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Also Published As

Publication number Publication date
DE3068568D1 (en) 1984-08-23
EP0036437B1 (en) 1984-07-18
AU542622B2 (en) 1985-02-28
AU6848081A (en) 1981-09-24
JPS56147202A (en) 1981-11-16
EP0036437A1 (en) 1981-09-30
CH642467A5 (en) 1984-04-13
US4415966A (en) 1983-11-15

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