JP3047654B2 - Control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for performing a proportional, integral and differential operation, so-called PID operation, and more particularly to a control device in which the differential operation is improved.

[0002]

2. Description of the Related Art Conventionally, as a PID-type control device of this type, a speed-type PID structure as shown in FIG. 9 is often used because it is easy to switch between manual and automatic operation. I have. In this configuration, the target value SVn
Is added to the proportional change calculating unit 3 and the integral change calculating unit 5 and the input signal PVn is added to the differential change calculating unit 7, and the proportional change calculating unit 3 The PID change obtained by adding the calculation outputs ΔPn and ΔIn from the integration change calculation unit 5 by the addition unit 9 and subtracting the calculation output ΔDn from the differential change calculation unit 7 by the addition unit 11 from the addition output. The signal .DELTA.PIDn is applied to the speed / position type converter 13, and the PID change signal .DELTA.PI
Dn and the PID signal P before the temporary point (time point n-1)
The speed / position type converter 13 calculates a PID signal PIDn from ID (n-1), and outputs the PID signal PIDn as an output signal MVn via an output limiter 15. (N-1) is indicated by () in the drawing.
Is omitted (the same applies hereinafter).

Further, when the PID signal PIDn exceeds the upper limit value MH or the lower limit value ML of the output limiter 15, the conversion control unit 17 cuts off the PID change signal ΔPIDn that exceeds the limit value ML or MH. The speed / position type converter 13 is controlled. In the control device having the speed-type PID configuration, even if the output signal MVn greatly changes due to a change in the target value SVn or the like, the output limiter 15 limits the output signal MVn to the limit values MH to ML, and the conversion control unit 17 controls the speed. By controlling the position / position shape converter 13, the phenomenon that the input signal PVn goes beyond the target value SVn due to excessive integration, the so-called reset windup phenomenon, is suppressed.

That is, the speed / position type converter 13 normally performs an operation such as PIDn = PID (n-1) +. DELTA.PIDn PID (n-1) = PIDn, but the PID signal PIDn indicates the limit value MH or ML. When it exceeds, the conversion control unit 17 changes the PID signal PIDn as follows. When PIDn> MH: PIDn = MH, PID (n-
1) = MH When PIDn <ML: PIDn = ML, PID (n−
1) = ML

[0005] Further, as for a control device having a position type PID configuration similar to the speed type PID configuration, an integral control section capable of arbitrarily changing the integral value as shown in FIG. 10 so that output processing similar to the speed type PID configuration can be performed. Is provided. In this configuration, the control deviation En from the subtraction unit 1 is applied to the proportional operation unit 19 and the integral operation unit 21 and the input signal PVn is applied to the differential operation unit 23. The proportional operation unit 19, the integral operation unit 21 and the differential operation unit The arithmetic outputs Pn, In, and Dn from the adder 23 are added and subtracted by an adder 25, and the obtained PID signal PIDn is output as an output signal MVn via an output limiter 15, and the PID signal PIDn at time n is output from the output limiter 15 When the limit value MH or ML is exceeded, the integral control unit 27 outputs the integral output In from the integral operation unit 21 to MH− (Pn−Dn) or ML−.
Correction control is performed to (Pn-Dn).

In this position type PID control device, the integration operation unit 21 is controlled via the integration control unit 27,
Excessive integration is suppressed to reduce the amount of input signal PV passing, thereby suppressing the reset windup phenomenon. That is, the integral operation unit 21 in FIG. 10 normally performs an operation such as In = I (n-1) + ΔIn I (n-1) = In, but when the PID signal PIDn exceeds the limit value MH or ML. , The integral control unit 27 changes the integral value In as follows. When PIDn> MH: In = MH- (Pn-Dn),
When I (n-1) = In PIDn <ML: In = ML- (Pn-Dn),
I (n-1) = In

Each of the above-described control devices differentiates only the input signal PVn which does not change stepwise for the following reason. Generally, in this type of control device, as described above, the PID signal PIDn and the integral I
By changing the value of n, the reset windup phenomenon can be suppressed. On the other hand, when the differential operation is performed on the deviation En, if the target value SV is changed in a step-like manner, the PID signal PIDn once becomes the limit value MH or M
After reaching L, a so-called differential pull-back phenomenon occurs, in which the pull-back is largely returned within the limit value.

FIG. 11 is a diagram for explaining such a differential pullback phenomenon. The dashed line in FIG. 11 indicates that the control device in FIG. 9 or FIG. 10 has a differential differentiation configuration, and when the target value SV is changed stepwise, the conversion control unit 17 and the integration control unit 2
7 is a target value change response of the PID signal PIDn in the case where the output signal MVn is not provided and the output signal MVn has a peak A
It has a pulsed waveform having points. In response to the PID signal PIDn, in the configuration of FIG.
The peak point A of the D signal PIDn is suppressed to the upper limit value MH of the output limiter 15, and in the configuration of FIG. 10, the integration control unit 27 changes the integration value In to MH− (Pn−Dn),
Each PID signal PIDn is processed to be equal to the upper limit value MH.

This is equivalent to applying a bias to the waveform indicated by the one-dot chain line in FIG. 11 and moving the peak point A downward in parallel to the upper limit value MH. Therefore, when the conversion control unit 17 and the integration control unit 27 are added, the PID signal P
After reaching the upper limit value MH at the timing of the change of the target value as shown by the dotted line in FIG.
L side), and as a result, there occurs a problem that the response of the input signal PV is delayed as indicated by the dotted line in FIG.
For this reason, the above-described conventional configurations of FIGS. 9 and 10 have an input differentiation configuration for differentiating the input signal PV that does not change stepwise.

[0010]

However, when the control device is configured as an input differential PID as described above, the response to the step change of the target value SV is good, but the target value SV changes continuously with the time function. If the input signal PV is made to follow the target value SV, the differential operation is not effective for the target value SV. However, as shown in FIG.
n is added to the proportional change calculating section 3, the integral change calculating section 5 and the differential calculating section 23, and the calculation outputs ΔPn and ΔIn from the proportional change calculating section 3 and the integral change calculating section 5 are added to the adding section 9.
And the PI output signal ΔPIn, which is the added output, is applied to the speed / position conversion unit 13, and the PI output PIn from the speed / position conversion unit 13 is output to the first output limiter 29.
The PID signal PIDn obtained by adding the PI output PIn ′ limited by the above to the addition unit 31 and the calculation output Dn from the differentiation calculation unit 23 in the addition unit 31 is added to the second output limiter 33. A configuration in which the output signal MVn is output from the second output limiter 33 has also been proposed. The conversion control unit 17 is the same as in FIG. 9 described above.

In this configuration, only the operation outputs ΔPn and ΔIn from the proportional change operation section 3 and the integral change operation section 5 are combined to form the speed / position conversion section 13 and the conversion control section 17.
And then adds the differential operation output Dn from the differential operation section 23 to the control deviation En. The differential pull-back phenomenon does not occur for the step-like target value change SV, but the differential pull-back still occurs. Since the effect in the direction is strong, the return of the output signal MVn is fast, and the response of the input signal PV is easily delayed. The present invention has been made in order to solve such conventional disadvantages, and the differential operation function appropriately acts on the improvement of the control response with respect to the change of the target value,
An object of the present invention is to provide a control device that does not cause pullback of an output signal due to a differential operation.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a control device according to the present invention provides proportional, integral and differential operations on input signals and target values so that the input signals coincide with target values. a control apparatus for obtaining an output signal by performing an operation comprising, on the deviation between these target values and the input signal
A first PID signal obtained from a proportional and integral operation output and a differential operation output of the input signal,
The first PID output restricted by the output limiter
A signal is added to the differential operation output of the target value to output a second PID signal, and the second PID signal is limited by a second output limiter to obtain the output signal.

Further, according to the present invention, when the first PID signal exceeds the limit value of the first output limiter, the first
Can be formed so as to be equal to the limit value. Further, in the present invention, the limit values of the first and second output limiters may be selected to be the same value, and the target value may be multiplied by a coefficient to perform a differential operation.

[0014]

According to the present invention having such means, the derivative of the control deviation is separated into the derivative of the input signal and the derivative of the target value signal, and the magnitude relation between the limit value of the output limiter to prevent over-integration. The PID signal that compares
A first PID signal obtained from the proportional and integral operation output and the differential operation output of the input signal, and the first PID signal
When the signal exceeds the limit value of the first output limiter, the first PID signal is formed so as to match the limit value. Can be smoothly obtained from the relationship between the proportional, differential and integral calculations with respect to the movement of the robot, and the amount of overrun is suppressed under an appropriate response speed. Moreover, since the first PID signal does not include the derivative with respect to the target value, the output pullback phenomenon is suppressed when the target value changes stepwise.

Then, the first PID signal is limited by the first output limiter, and the second PID signal obtained by adding the result to the differential operation output of the target value is limited by the second output limiter. Since the output signal is used, when the target value is a time function that changes continuously, the target value followability is improved. Further, in the configuration in which the limit values of the first and second output limiters are selected to be the same value, if any one of the limit values is set, the both are set in conjunction. Furthermore, in a configuration in which the target value is multiplied by a coefficient to perform a differential operation, the manner in which the differential output of the target value is effective can be varied without causing a pullback phenomenon of the output signal.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals are given to parts common to the related art.
First, in order to facilitate understanding of the present invention, an outline of a control device of the present invention will be described. FIG. 1 is a block diagram showing an outline of a control device according to the present invention using the configuration of FIG. 10 described above. In FIG. 1, a control deviation En is calculated from an input signal SVn and a target value PVn by a subtraction unit 1 and added to a proportional calculation unit 19 and an integration calculation unit 21, and the input value PVn is calculated by an input differentiation calculation unit 2
3a, the target value SVn is added to the target value differential calculator 35, and the adder 25 adds the proportional, integral and input differential calculation output P.
first PID signal PI obtained by adding n, In, and Dpn
Dpn is limited by the first output limiter 29, and the limited first PID signal PIDpn ′ and the target value differential calculation unit 35
A second PID signal PIDn obtained by adding the differential operation output Dsn from the adder 37 to the second output limiter 33, the second PID signal is limited by the second output limiter 33, and the output signal MVn.

That is, in the present invention, the input signal PVn and the target value SVn are differentiated separately. FIG. 2 is a block diagram specifically showing an embodiment of the control device of the present invention, in which the present invention is applied to the above-mentioned speed-type PID configuration of FIG. In FIG. 2, a subtraction unit 1 subtracts an input signal PVn from a target value SVn to obtain a control deviation En. The subtraction unit 1 is connected to a proportional change calculation unit 3 and an integral change calculation unit 5, and performs a differential change calculation. The input signal PVn is connected to a unit (particularly, an input differential change calculation unit) 7a.

The proportional change calculating section 3, the integral change calculating section 5 and the input differential change calculating section 7a have a control deviation En.
And input signals PVn to calculate operation outputs ΔPn, ΔIn,
It outputs ΔDpn and is connected to the adder 9.
The adder 9 outputs a PID change signal ΔPIDpn obtained by adding and subtracting the arithmetic outputs ΔPn, ΔIn, and ΔDpn, and is connected to the speed / position converter 13. The speed / position conversion unit 13 outputs the PID change signal ΔPIDpn and the PID signal PIDp (n
-1) to output the first PID signal PIDpn, and is connected to the first output limiter 29 and the conversion control unit 17.

The first output limiter 29 is connected to the first P
When the ID signal PIDpn exceeds the limit value MH or ML, the ID signal PIDpn is suppressed to the limit value MH or ML to output the limited first PID signal PIDpn ′.
And a conversion control unit 17. The coefficient section 41 multiplies the target value SVn by a coefficient α, and is connected to the target value differential operation section 35 described with reference to FIG. 1. The target value differential operation section 35 outputs a differential operation output Dsn to the addition section 37. Things. The coefficient α by which the target value SVn is multiplied by the coefficient unit 41 can be arbitrarily variably selected from 0 to 1.

The adder 37 calculates the first PID signal PIDpn ′ from the first output limiter 29 and the target value differential calculator 3
5 to output the second PID signal PIDn by adding the differential operation output Dsn from the second output limiter 33 to the second output limiter 33.
It is connected to the. When the second PID signal PIDn exceeds the same limit value MH or ML as the first output limiter 29, the second output limiter 33 sets it to the limit value MH.
Alternatively, it is output as the output signal MVn while being suppressed to ML.

The conversion control unit 17 receives the first PID signal PI
Dpn is the limit value MH or ML of the first output limiter 29
Is exceeded, the speed / position type converter 13 is controlled so that the portion exceeding the limit value ML or MH in the PID change signal ΔPIDpn is discarded. The operation of the control device having such a configuration in which the input signal PVn and the target value SVn are separately differentiated and the output signal MVn is output will be described.

First, the operation output ΔPn from the proportional change operation unit 3 for the control deviation En, the operation output ΔIn from the integral change operation unit 5, and the operation output ΔDpn from the input differential change operation unit 7a for the input signal PVn are calculated. The addition is performed by the adder 9, and ΔPIDpn = ΔPn + ΔIn−ΔDpnPID
A change signal ΔPIDpn is obtained. This PID change signal ΔP
IDpn is converted into a position type by the speed / position type conversion unit 13 to obtain a first PID signal PIDpn. PIDpn = PIDp (n−1) + ΔPIDpn PIDp (n−1) = PIDpn (where PIDp (n−1) is the first PID before the temporary point)
Signal. )

The conversion control section 17 compares the first PID signal PIDpn with the limit value MH or ML of the first output limiter 29, and when the first PID signal PIDpn exceeds the limit value MH or ML. , The first PI
Modify the D signal PIDpn. When PIDpn> MH: PIDpn = MH PIDp (n-1) = MH When PIDpn <ML: PIDpn = ML PIDp (n-1) = ML

On the other hand, the differential operation for the target value SVn is performed by multiplying the coefficient α in the coefficient section 41 to perform the target value differential operation, and the operation output Dsn from the target value differential operation section 35 is added to the adding section 37.
In addition, the addition unit 37 adds the limited first PID signal PIDpn ′ from the first output limiter 29 to obtain a second PID signal PIDn. PIDn = PIDpn ′ + Dsn This second PID signal PIDn is output to the second output limiter 3
3, the same limit value MH as the limit value of the first output limiter 29
Alternatively, the output signal MVn is output after being limited by ML.

In such a configuration, assuming that the differentiation time (proportional constant of the derivative) is TD and the proportional constant is Kp, Dsn = Kp · TD [d / dt (α · SVn)] ΔDpn = Kp · TD [d2 / dt2 (PVn)]. Here, d / dt () represents first-order differentiation in (), and d2 / dt2 () represents second-order differentiation in ().

Since the integral operation output ΔDpn is converted by the speed / position type converter 13 with a minus sign, assuming that the total differential output is Dn, Dn = Dsn + ∫ (−ΔDpn) dt = Kp · TD [ d / dt (α · SVn)] + ∫ [(− Kp · TD (d2 / dt2 (PVn)] dt = Kp · TD [d / dt (α · SVn) −d / dt (P
Vn)] = Kp · TD [d / dt (α · SVn−PVn)], and when the coefficient α is “1”, Dn = Kp · TD [d / dt (SVn−PVn)] = Kp · TD [d / dt (En)].

Therefore, the range where the first PID signal PIDpn is not changed by the conversion control unit 17, that is, M
In the range of L ≦ PIDpn ≦ MH, the characteristic is the same as the deviation derivative, and when the target value SV changes continuously with a time function, the followability is further improved as compared with the PID calculation only for the derivative of the input signal PV. On the other hand, the differential operation output Dsn from the target value differential operation unit 35 for the target value SV is added to the first PID signal PIDpn ′ after the first output limiter 29 and is not subjected to the processing of the conversion control unit 17. In the case of deviation differentiation, the phenomenon of output pullback due to differentiation when the target value is changed does not occur.

Further, since the input differentiation acts on the movement of the input signal PV which is a feedback from the control target (not shown), the first PID signal PIDpn is set to the limit value MH or ML of the first output limiter 29. Since the conversion control unit 17 smoothly obtains the over-integration prevention effect for the step-like change of the target value SV exceeding the above, the overrun amount can be suppressed at an appropriate response speed. The control device of the present invention described above is actually a CPU or this CPU.
Is generally implemented by a microcomputer including a ROM or the like in which the above operation program is built.

The operation of the control device shown in FIG. 2 will now be described with reference to the flowchart of FIG. Thereby, the control device of the present invention will be better understood. Note that the following processing is executed at every predetermined sampling period. When the process is started in FIG.
At ΔPn, ΔIn, ΔDpn and ΔPIDpn (= Δ
Pn + ΔIn−ΔDpn), and in step 302, the first PID signal PIDp (n−1) before the primary point and the PI
The first PID signal PIDpn before restriction is calculated from the D change signal ΔPIDpn to convert from the velocity type to the position type.

In the following step 303, the first PID signal P
IDpn is compared with a limit value ML or MH and the first PI
When the D signal PIDpn is smaller than the lower limit value ML, the first PID signal PIDpn ′ after the restriction is set to the lower limit value ML in step 304, and the process proceeds to step 305.
In step 5, the first PID signal PIDpn is converted and controlled to the lower limit value ML, and the routine proceeds to step 306. First PID signal PID
When pn is larger than the upper limit value MH, the process moves from step 303 to step 307, and in step 307, the first PI
Step 308: The D signal PIDpn ′ is set to the upper limit value MH.
To step 308, where the first PID signal PIDpn
Is converted to the upper limit value MH, and the routine proceeds to step 306.

The first PID signal PIDpn has a limit value ML
To MH, the process proceeds from step 303 to step 309, where the first PID signal P
The process proceeds to step 306 by setting IDpn ′ to PIDpn.
In step 306, the first PID signal PIDp (n-
1) is replaced with PIDpn, and in step 310, a differential operation output Dsn of the target value SVn is obtained, and the subsequent step 31
1 to the first PID signal PIDpn ′ and the differential operation output Ds
n is added to calculate the second PID signal PIDn, and the routine goes to Step 312.

In step 312, the second PID signal PI
Dn is compared with the limit value ML or MH, and when the second PID signal PIDn is smaller than the lower limit value ML, step 31 is executed.
In step 3, the output signal MVn is set to the lower limit value ML, and the process ends. Second
When the PID signal PIDn is larger than the upper limit value MH, the process moves from step 312 to step 314, and
In step 14, the output signal MVn is set to the upper limit value MH, and the processing is terminated.
When the PID signal PIDn is within the range of the limit values ML to MH, the process moves from step 312 to step 315, and in step 315, the output signal MVn is output to the second PID signal PI.
Dn, and the process ends.

As described above, in the control device of the present invention, the first and second output limiters 29 limit the PID signal obtained from the proportional and integral operation output with respect to the control deviation En and the differential operation output of the input signal PV. And outputs a PID signal of the differential signal with respect to the target value SV and the first PID signal.
Since the second PID signal obtained by adding the ID signal is limited by the second output limiter 33 so as to obtain the output signal MVn, the differential operation function of the change of the target value SV changes the control response. This appropriately acts on the improvement, and the pullback of the output signal MVn by the differential operation does not occur. Moreover, when the first PID signal exceeds the limit value ML or MH of the first output limiter 29, the first PID signal is made to match the limit value ML or MH. The reset windup phenomenon can be suppressed by the overintegration prevention effect.

Further, the first and second output limiters 2
If the limit values ML or MH of 9, 33 are selected to be the same value,
These can be set in conjunction with each other to improve operability, and since the differential operation is performed by multiplying the target value SV by a coefficient, the effect of the differential operation output Dsn can be adjusted, and it is possible to cope with various control targets. The control device shown in FIG. 2 can be simplified as shown in FIG.
1. Considering that the input differential operation unit 23a and the addition unit 25 correspond to the proportional change operation unit 3, the integral change operation unit 5, the input differential change operation unit 7a, and the addition unit 9, the speed / position type conversion unit 13 Can be considered to be inherent.

FIG. 4 is a block diagram specifically showing another embodiment of the control device of the present invention, which is applied to the above-described position type PID configuration of FIG. In FIG. 4, the subtraction unit 1 is connected to a proportional operation unit 19 and an integral operation unit 21, and a differential operation unit (particularly an input differential operation unit) 23
The input signal PVn is connected to a. These proportional operation section 19, integral operation section 21 and input differential operation section 23a
Is connected to the addition unit 25, and the addition unit 25 is connected to the first output limiter 29 and the integration control unit 27. The first output limiter 29 is connected to the addition unit 37 and the integration control unit 27. I have.

Coefficient section 41 for multiplying target value SVn by coefficient α.
Is connected to a target value differential operation unit 35, which outputs a differential operation output Dsn to an addition unit 37. In the control device having such a configuration, an operation of separately differentiating the input signal PVn and the target value SVn and outputting the output signal MVn will be described below.

The operation output Pn from the proportional operation unit 19 with respect to the control deviation En, the operation output In from the integration operation unit 21,
The adder 25 adds and subtracts the operation output Dpn from the input differential operation unit 23a with respect to the input PVn, obtains PIDpn = Pn + In-Dpn, obtains the first PID signal PIDpn, and adds it to the first output limiter 29. Here, the integral value In is usually In = I (n-1) + [Delta] In I (n-1) = In (where I (n-1) is the integral value one time before, and [Delta] In is the current integral change). Is calculated.

The integration control section 27 controls the first PID signal PI
Dpn and the limit value MH or ML of the first output limiter 29
And correct the integral value In as follows. When PIDpn> MH: In = MH- (Pn-D
pn) I (n-1) = In When PIDpn <ML: In = ML- (Pn-D
pn) I (n-1) = In

On the other hand, the differential operation for the target value SVn is performed by multiplying the coefficient α by the coefficient unit 41 to perform the target value differentiation, and the operation output Dsn from the target value differential operation unit 35 is added to the addition unit 37. The second PID signal PIDn is obtained by adding the limited first PID pn ′ from the first output limiter and the operation output Dsn. PIDn = PIDp
n ′ + Dsn This second PID signal PIDn is converted by the second output limiter 33 to the limit value MH of the first output limiter 29.
Alternatively, the output signal MVn is output under control with the same limit value MH or ML as ML.

In such a configuration, the differential time is TD,
Assuming that the proportionality constant is Kp, Dsn = Kp · TD [d / dt (α · SVn)] Dpn = Kp · TD [d / dt (PVn)] Here, d / dt () indicates that the inside of () is first-order differentiated.

Considering the sign at the time of addition, the total differential output Dn is given by: Dn = Dsn−Dpn = Kp · TD [d / dt (α · SVn−PVn)] where α is “1” Dn = Kp · TD [d / dt (SVn−PVn)] = Kp · TD [d / dt (En)], and the conversion control unit 27 sets the first PID signal PI.
A range where Dpn is not changed, that is, ML ≦ PIDpn
In the case of ≤ MH, if the characteristic coincides with the deviation derivative and the target value SV changes continuously with a time function, the PID of only the input derivative
Followability is improved as compared with the calculation.

The point that the output pullback phenomenon does not occur due to the differentiation when the target value is changed in the case of deviation differentiation and that the over-integration preventing effect can be obtained smoothly are the same as in the configuration of FIG. FIG. 5 is a flowchart showing the operation of the control device shown in FIG. In FIG. 5, when the process is started, Pn, In (= I (n−1) + ΔI) in step 501.
n), Dpn, and PIDpn (= Pn + In-Dpn), and in step 502, the first PID signal PIDpn
Is compared with the limit value MH or ML.

The first PID signal PIDpn is lower than the lower limit ML.
If smaller than step 502 to step 503
Then, the first PID signal PIDpn 'is set to the lower limit value ML, and the routine goes to Step 504.
n is integrated to ML− (Pn−Dpn), and step 5 is performed.
Move to 05. The first PID signal PIDpn is equal to the upper limit value MH
If it is larger, the steps 502 to 506 are performed.
To step 506, where the first PID signal PIDp
The value n 'is set to the upper limit value MH, and the process proceeds to step 507. In step 507, the integral value In is integrated and controlled to MH- (Pn-Dpn), and the process proceeds to step 505.

When the first PID signal PIDpn is equal to the limit value ML
To MH, the process proceeds from step 502 to step 508, where the first PID signal P
IDpn 'is set to PIDpn, and the routine proceeds to step 505.
In step 505, the integrated value I (n-1) one time earlier is calculated as I
In step 509, a differential operation output Dsn of the target value SVn is obtained, and in step 510, the first PI
The differential operation output Dsn is added to the D signal PIDpn ′ to calculate the second PID signal PIDn, and the process proceeds to step 511.

In step 511, the second PID signal PI
Dn is compared with the limit value MH or ML, and when the second PID signal PIDn is smaller than the lower limit value ML, step 51
In step 2, the output signal MVn is set to the lower limit value ML, and the process ends. Second
When the PID signal PIDn is larger than the upper limit value MH, the process moves from step 511 to step 513 and the output signal MV
n is set to the upper limit value MH, and the processing is terminated.
If n is in the range of limit values ML to MH, step 5
11 to step 514, where the output signal MVn is
, And terminates.

Next, a state in which the response characteristic of the control device of the present invention is simulated by control will be described. FIG. 6 shows the target value SV in the control device shown in FIGS.
Shows the control response when changing to a step shape,
FIG. 7 shows a control response when the target value SV is changed in a stepwise manner when the conventional control device shown in FIGS. As can be seen from FIGS. 6 and 7, in the conventional example, when the target value is changed, an output pull-back phenomenon occurs due to differentiation, the output signal MV is pulled back from the upper limit value MH to the lower limit value ML, and the response of the input signal PV is delayed. However, according to the present invention, the pull-back phenomenon of the output signal MV does not occur, and the input signal PV is quickly controlled to the target value SV.

FIG. 8 shows a control response in the case where the target value SV changes like a ramp. The conventional example in which only the input signal PV can be differentiated, and the present invention in which the input signal and the target value are separately differentiated. Are compared with each other in the control characteristics. As can be seen from FIG. 8, when the target value SV changes in a ramp shape, the deviation differentiation configuration is effective, and as a result of the output signal MV rapidly changing with respect to the change in the target value SV, the input signal PV is changed. The rise is fast, and the excess amount when the target value SV changes from the ramp state to a constant value is also small.

The configurations according to the conventional example and the present invention described above are described in terms of a discrete (digital) operation, but the same effect can be obtained by using a similar configuration as a continuous (analog type) operation. Can be obtained. That is, the present invention can be implemented in both a discrete type (digital type) and a continuous type (analog type). In this case, differentiation (dx / dt) and integration (∫xdt), which are continuous operations, are
Each can be replaced by [{xn-x (n-1)} / τ] and Σ (τ · xn) in a discrete operation. The symbol t is time, the symbol τ is a sampling period, and the time t is nτ.

[0049]

As described above, according to the present invention, the input signal and the target value are differentiated separately, and the first PID is calculated from the output of the proportional and integral operation of the control deviation and the output of the differential operation of the input signal.
And obtaining a second PID signal by adding a differential operation output of a target value to the limited first PID signal to obtain a second PID signal. Is limited by the second output limiter to output the output signal MV. Therefore, the differential operation function appropriately acts on the improvement of the control response to the change of the target value, and the output signal is pulled back by the differential operation. Does not occur. When the first PID signal exceeds the limit value of the first output limiter, the first PID signal is formed so as to be equal to the limit value. Can be suppressed. Furthermore, in the configuration in which the limit values of the first and second output limiters are selected to be the same value, it is possible to link the setting of the limit values, thereby improving operability. Furthermore, in a configuration in which the target value is multiplied by a coefficient to perform a differential operation, the manner in which the differential output of the target value is effective can be varied, so that various controls can be supported.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a control device according to the present invention.

FIG. 2 is a block diagram specifically showing one embodiment of a control device of the present invention.

FIG. 3 is a flowchart illustrating an operation of the control device illustrated in FIG. 2;

FIG. 4 is a block diagram specifically showing another embodiment of the control device of the present invention.

5 is a flowchart illustrating the operation of the control device shown in FIG.

FIG. 6 is a diagram showing an operation response of the control device of the present invention.

FIG. 7 is a diagram showing an operation response of a conventional control device.

FIG. 8 is a diagram showing operation responses of the present invention and a conventional control device.

FIG. 9 is a block diagram illustrating an example of a conventional control device.

FIG. 10 is a block diagram showing another conventional control device.

FIG. 11 is a diagram illustrating the operation of the control device in FIGS. 9 and 10;

FIG. 12 is a block diagram showing a control device serving as a reference of the present invention.

[Explanation of symbols]

 Reference Signs List 1 subtraction unit 3 proportional change calculation unit 5 integral change calculation unit 7 differential change calculation unit 7a input differential change calculation unit (differential change calculation unit) 9, 11, 25, 31, 37 addition unit 13 speed / position Shape conversion unit 15 Output limiter 17 Conversion control unit 19 Proportional operation unit 21 Integral operation unit 23 Differential operation unit 23a Input differential operation unit (differential operation unit) 27 Integral control unit 29 First output limiter 33 Second output limiter 35 Target Value differential operation section

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-98702 (JP, A) JP-A-4-10104 (JP, A) JP-A-2-129702 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G05B 11/00-13/04

Claims (4)

(57) [Claims] 1. A proportional to their input signal and the target value to match the input signal to the target value, the control device for obtaining an output signal by performing operations including integration and differential operation, the target value and the input signal A first PID signal obtained from the proportional and integral operation output with respect to a deviation from the output signal and a differential operation output of the input signal, the first PID signal being output after being limited by a first output limiter; A control device for adding a differential operation output of the target value to output a second PID signal, and limiting the second PID signal by a second output limiter to obtain the output signal. 2. The control according to claim 1, wherein when the first PID signal exceeds a limit value of the first output limiter, the first PID signal is made to match the limit value. apparatus. 3. The control device according to claim 1, wherein the limit values of the first and second output limiters are selected to be the same value. 4. The control device according to claim 1, wherein said target value is differentiated by multiplying by a coefficient.