Digital PID control apparatus

• US 5,745,362 A
• Filed: 06/19/1996
• Issued: 04/28/1998
• Est. Priority Date: 06/20/1995
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yamamoto, Yoshiyuki, Hiroi, Kazuo
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): Nguyen, Cuong H.
• Application Number:
  US08/666,089
• Time in Patent Office: 678 Days
• Field of Search: 364/158, 364/157, 364/149, 364/160-163, 364/164-165, 364/567, 364/150-151, 364/148, 364/174, 364/176, 318/632, 318/609-610, 318/561
• US Class Current: 700/42
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance

Abstract

In the digital PID (P:proportional, I:integral, D:derivative) control apparatus of the present invention, in which a deviation is obtained from a controlling amount of an object to be controlled, and a target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation or the controlling amount, these velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, the derivation processing unit includes the judgment unit for judging whether K=2·Δt/(Δt+2η·TD)≦1, or K>1 by using a control operation period Δt, a derivative time TD and a derivative gain 1/η, and the operation unit which carries out a lagged derivative operation by a bilinear transfer method when K≦1, or carries out an exact derivative operation when K>1.

Claims

1. A digital PID (P:

proportional, I;

integral, D;

derivative) control apparatus, in which a deviation is obtained from a controlling amount of an object to be controlled, and an input target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation of the controlling amount, the velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, said digital PID control apparatus comprising;

a derivation processing unit comprising;

a judgment unit for judging a control operating period is a predetermined value or less; and

an operation unit which carries out a lagged derivative operation by a bilinear transfer method when the control operation period is at the predetermined value or less, or carries out an exact derivative operation when the control operation period is larger than the predetermined value.

2. A digital PID (P:

proportional, I;

integral, D;

derivative) control apparatus, in which a deviation is obtained from a controlling amount of an object to be controlled, and an input target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation of the controlling amount, the velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, said digital PID control apparatus comprising;

a derivation processing unit comprising;

a judgment unit for judging whether K=2-Δ

t/(Δ

t+2η

·

TD)≦

1, or K>

1 by using a control operation at Δ

t, a derivative time TD and a derivative gain 1/η

; and

an operation unit which carries out a lagged derivative operation by a bilinear transfer method when K≦

1, or carries out an exact derivative operation when K>

1.

3. A digital PID (P:

proportional, I;

integral, D;

derivative) control apparatus, in which a deviation is obtained from a controlling amount of an object to be controlled, and an input target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation of the controlling amount, the velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, said digital PID control apparatus comprising;

a derivation processing unit further comprising;

a judgement unit for judging whether K=2-Δ

t/(Δ

t+2η

·

TD)≦

1, or K>

1 by using a control operation period Δ

t, a derivative time TD and a derivative gain 1/η

;

means for carrying out the velocity D control operation on the deviation, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

n={(2·

TD)/(Δ

t+2η

·

TD)}·

(e_n ·

e_n-1)-K·

D_n-1

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n ={(2-TD)/(Δ

t+2η

·

TD)}·

(e_n -2e_n-1 +e_n-2)

D_n =D_n-1 +Δ

D'"'"'_n ; and

means for carrying out the velocity type D control operation on the controlling amount, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

D_n ={(2·

TD)/(Δ

t+2η

·

TD)}·

(PV_n-1 -PV_n)-K·

D_n-1,

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n ={(2·

TD)/(Δ

t+2η

·

TD)}·

(2PV_n-1 -PV_n -PV_n-2)

D_n =D_n-1 +Δ

D'"'"'_n,

where e_n ;

the amount of deviation at the present time, e_n-1 ;

the amount of deviation at the time of the immediately previous control operation period, e_n-2 ;

the amount of deviation at the time of one before the immediately previous control operation period, PV_n-1 ;

the control amount at the time of the immediately previous control operation period, PV_n-2 ;

the control amount at the time of one before the immediately previous control operation period, D_n ;

the derivative output at present time, and D_n-1 ;

the derivative output at the time of the immediately previous control operation period.

4. A digital PID (P:

proportional, I;

integral, D;

derivative) control apparatus, in which a deviation is obtained from a controlling amount of an object to be controlled, and an input target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation of the controlling amount, the velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, said digital PID control apparatus comprising;

a derivation processing unit further comprising;

a judgement unit for judging whether K=2·

Δ

t/(Δ

t+2η

·

TD)≦

1, or K>

1 by using a control operation period Δ

t, a derivative time TD and a derivative gain 1/η

;

means for carrying out the velocity D control operation on the deviation, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

D_n ={(2·

TD)/(Δ

t+2η

·

TD)}·

(e_n -e_n-1)-K·

D_n-1

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n =(TD/Δ

t)·

(e_n -2e_n-1 +e_n-2)

D_n =D_n-1 +Δ

D'"'"'_n ; and

means for carrying out the velocity type D control operation on the controlling amount, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1

Δ

D_n ={(2·

TD)/(Δ

t+2η

·

TD)}·

(PV_n-1 -PV_n)-K·

D_n-1

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n =(TD/Δ

t)·

(2PV_n-1 -PV_n -PV_n-2)

D_n =D_n-1 +Δ

D'"'"'_n,

where e_n ;

the amount of deviation at the present time, e_n-1 ;

the amount of deviation at the time of the immediately previous control operation period, e_n-2 ;

the amount of deviation at the time of one before the immediately previous control operation period, PV_n ;

the control amount at the present time, PV_n-1 ;

the control amount at the time of the immediately previous control operation period, PV_n-2 ;

the control amount at the time of one before the immediately previous control operation period, D_n ;

the derivative output at present time, and D_n-1 ;

the derivative output at the time of the immediately previous control operation period.

5. A digital PID (P:

proportional, I;

integral, D;

derivative) control apparatus, in which a deviation is obtained from a controlling amount of an object to be controlled, and an input target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation of the controlling amount, the velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, said digital PID control apparatus comprising;

a derivation processing unit further comprising;

a judgement unit for judging whether K=2·

Δ

t/(Δ

t+2η

·

TD)≦

1, or K>

1 by using a control operation period Δ

t, a derivative time TD and a derivative gain 1/η

; and

means for carrying out the velocity D control operation on the deviation, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

D_n {(2·

TD)/(Δ

t+2η

·

TD)}·

(e_n -e_n-1)-K·

D_n-1

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n =(TD/Δ

t)·

(e_n -e_n-1) -{(Δ

t+2η

·

TD)/(2·

Δ

t)}·

D_n-1

D_n =D_n-1 +Δ

D'"'"'_n ; and

means for carrying out the velocity type D control operation on the controlling amount, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

D_n ={(2·

TD)/(Δ

t+2η

·

TD) ·

(PV_n-1 -PV_n)-K·

D_n-1

Δ

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n =(TD/Δ

t)·

(PV_n-1 -PV_n) -{(Δ

t+2η

·

TD)/(2·

Δ

t)}·

D_n-1

D_n =D_n-1 +Δ

D'"'"'_n,

where e_n ;

the amount of deviation at the present time, e_n-1 ;

the amount of deviation at the time of immediately previous control operation period, PV_n ;

the control amount at present time, PV_n-1 ;

the control amount at the time of the immediately previous control operation period, D_n ;

the derivative output at present time, and D_n-1 ;

the derivative output at the time of the immediately previous control operation period.

6. A digital PID (P:

proportional, I;

integral, D;

derivative) control apparatus, in which a deviation is obtained from a controlling amount of an object to be controlled, and an input target value, a velocity type PI control operation is carried out on the deviation, a velocity type D control operation is carried out on the deviation of the controlling amount, the velocity type control operation outputs are synthesized, and then converted into a position type manipulation signal, and this signal is supplied to the object to be controlled, said digital PID control apparatus comprising;

a derivation processing unit further comprising;

a judgement unit for judging whether K=2·

Δ

t/(Δ

t+2η

·

TD)≦

1, or K>

1 by using a control operation period Δ

t, a derivative time TD and a derivative gain 1/η

;

means for carrying out the velocity D control operation on the deviation, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

D_n ={(2·

TD)/(Δ

t+2η

·

TD)}·

(e_n -e_n-1)-K·

D_n-1

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n =(TD/Δ

t)·

(e_n -e_n-1) -{Δ

t/(Δ

t+η

·

TD)}·

D_n-1

D_n =D_D-1 +Δ

D'"'"'_n ; and

means for carrying out the velocity type D control operation on the controlling amount, including a means for extracting velocity type D control operation results Δ

D_n, Δ

D'"'"'_n and a derivative output D_n by performing the following operation;

when K≦

1,

Δ

D_n ={(2·

TD)/(Δ

t+2η

·

TD)}·

(PV_n-1 -PV_n)-K·

D_n-1

D_n =D_n-1 +Δ

D_n

when K>

1,

Δ

D'"'"'_n =(TD/Δ

t)·

(PV_n-1 -PV_n) -{Δ

t/(Δ

t+η

·

TD)}·

D_n-1

D_n =D_n-1 +Δ

D'"'"'_n,

where e_n ;

the amount of deviation at the present time, e_n-1 ;

the amount of deviation at the time of the immediately previous control operation period, e_n-2 ;

the amount of deviation at the time of one before the immediately previous control operation period, PV_n ;

the control amount at the present time, PV_n-1 ;

the control amount at the time of the immediately previous control operation period, PV_n-2 ;

the control amount at the time of one before the immediately previous control operation period, D_n ;

the derivative output at present time, and D_n-1 ;

the derivative output at the time of the immediately previous control operation period.