JP6974143B2 - Control device and control method - Google Patents

Description

The present invention relates to a technique for additionally applying feedforward control to a feedback controller, and more particularly to a control device and a control method suitable for performing arbitrary operation amount addition or operation amount subtraction by an operator's operation.

A multifunctional general-purpose feedback controller (temperature controller) may be used to handle a device including one or more control loops (see Patent Document 1). FIG. 25 shows an example of a heating device targeted by a general-purpose feedback controller (temperature controller).

In the example of FIG. 25, the heating device is heated by a heat treatment furnace 100 for heating an object to be heated, a plurality of heaters H1 to H4 installed inside the heat treatment furnace 100, and heaters H1 to H4, respectively. A plurality of temperature sensors S1 to S4 for measuring the temperature of the temperature control zones Z1 to Z4 in the heat treatment furnace 100, a regulator 101 for calculating the operation amounts MV1 to MV4 to be output to the heaters H1 to H4, and a regulator 101. It is composed of power regulators 102-1 to 102-4 that supply power corresponding to the operation amounts MV1 to MV4 output from the heaters H1 to H4. The controller 101 calculates the operation amounts MV1 to MV4 so that the temperatures PV1 to PV4 measured by the temperature sensors S1 to S4 coincide with the temperature set values SP1 to SP4. In the heating device shown in FIG. 25, four control loops for controlling the temperatures PV1 to PV4 are formed.

In a device including a plurality of control loops, the occurrence of interference between control zones may make it impossible to obtain a desired control result by feedback control alone. Further, even if only one control loop is used, a desired control result may not be obtained only by feedback control due to the influence of strong non-linearity or the like.

Therefore, a method of adding a feedforward amount to PID control, which is a typical feedback control, has been proposed (see Patent Document 2). The feedforward control + PID control disclosed in Patent Document 2 has a particular problem of not causing an overshoot (improvement of the control result).

When realizing feedforward control + PID control, it is practically a good idea to use a commercially available general-purpose feedback controller (temperature controller) for temperature control as a feedback control function part (PID control function part). .. In this case, since intermediate variables and the like in the PID calculation inside the temperature controller cannot be manipulated, it is not always possible to simply additionally apply the feedforward control, and problems may occur, so improvement is required.

Japanese Unexamined Patent Publication No. 2012-048370 Japanese Unexamined Patent Publication No. 2007-102816

The present invention has been made to solve the above problems, and is a control device capable of reducing the occurrence of defects when feedforward control is additionally applied to a general-purpose feedback controller (for example, a PID-controlled temperature controller). And to provide a control method.

The control device of the present invention has an operation amount calculation unit configured to calculate an operation amount by a PID control calculation by inputting a set value and a control amount, and a target value of a change amount of a feed forward with respect to the operation amount. The change amount target value acquisition unit configured to be acquired, and the change that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired. The change amount calculation unit configured to calculate the amount and the operation amount calculated by the operation amount calculation unit are changed by the change amount calculated by the change amount calculation unit. A change unit, a limit processing unit configured to perform limit processing for limiting the operation amount changed by this operation amount change unit to a value equal to or more than the operation amount lower limit value and not more than the operation amount upper limit value, and this limit processing. The operation amount output unit is configured to output the operation amount to the control target, and the change amount calculation unit uses the first parameter regarding the time of the change amount as the PID parameter of the operation amount calculation unit. It is characterized by being automatically determined in conjunction with each other.
Further, the control device of the present invention has an operation amount calculation unit configured to calculate an operation amount by PID control calculation by inputting a set value and a control amount, and a target of a change amount of a feedforward amount with respect to the operation amount. When the change amount target value acquisition unit configured to acquire the value and the target value of the change amount different from the zero value are acquired, the target value of the change amount is approached and then gradually converges to the zero value. The change amount calculation unit configured to calculate the change amount to be performed, and the operation amount calculated by the operation amount calculation unit are configured to be changed by the change amount calculated by the change amount calculation unit. The operation amount change unit, the limit processing unit configured to perform limit processing for limiting the operation amount changed by the operation amount change unit to a value equal to or more than the operation amount lower limit value and not more than the operation amount upper limit value, and this limit. The operation amount output unit configured to output the processed operation amount to the control target is provided, and the target value of the change amount is a value obtained by step-changing the operation amount by the feedforward amount.

Further, in one configuration example of the control device of the present invention, the target value of the change amount is the operation amount addition value which is the target value of the addition amount with respect to the operation amount, and the change amount calculation unit is different from the zero value. When the operation amount addition value is acquired, the operation amount addition amount is calculated as the change amount that gradually converges to the zero value after approaching the operation amount addition value, and the operation amount change unit performs the operation amount change unit. It is characterized in that the operation amount addition amount calculated by the change amount calculation unit is added to the operation amount calculated by the calculation unit.
Further, in one configuration example of the control device of the present invention, the target value of the change amount is the operation amount subtraction value which is the target value of the subtraction amount with respect to the operation amount, and the change amount calculation unit is different from the zero value. When the operation amount subtraction value is acquired, the operation amount subtraction amount is calculated as the change amount that gradually converges to the zero value after approaching the operation amount subtraction value, and the operation amount change unit performs the operation amount change unit. It is characterized in that the operation amount subtraction amount calculated by the change amount calculation unit is subtracted from the operation amount calculated by the calculation unit.
Further, in one configuration example of the control device of the present invention, the target value of the change amount is an operation amount addition value which is a target value of an addition amount with respect to the operation amount and an operation which is a target value of a subtraction amount with respect to the operation amount. It is an amount subtraction value, and when the operation amount addition value different from the zero value is acquired, the change amount calculation unit operates as the change amount that gradually converges to the zero value after approaching the operation amount addition value. When the amount addition amount is calculated and the operation amount subtraction value different from the zero value is acquired, the operation amount subtraction amount is calculated as the change amount that gradually converges to the zero value after approaching the operation amount subtraction value. When the operation amount addition amount is calculated by the change amount calculation unit, the operation amount change unit adds the operation amount addition amount to the operation amount calculated by the operation amount calculation unit, and the change amount. When the operation amount subtraction amount is calculated by the calculation unit, the operation amount subtraction amount is subtracted from the operation amount calculated by the operation amount calculation unit.

Further , in one configuration example of the control device of the present invention, the change amount calculation unit is characterized in that a second parameter defining the size of feedforward is automatically determined in conjunction with the first parameter. It is something to do .

Further, in the control method of the present invention, the first step of calculating the operation amount by the PID control calculation by inputting the set value and the control amount, and the first step of acquiring the target value of the change amount of the feed forward with respect to the operation amount. The second step, and the third step of calculating the change amount that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired. The fourth step of changing the operation amount calculated in the first step by the amount of the change amount calculated in the third step, and the operation amount changed in the fourth step are operated with the operation amount lower limit value or more. a fifth step of performing a limiting process to limit the amount upper limit value or less of the value, seen including a sixth step of outputting the operation amount obtained by the limiting process in the control target, the third step, the change amount It is characterized by including a step of automatically determining a first parameter relating to the time of the above in conjunction with the PID parameter of the PID control operation.
Further, in the control method of the present invention, the first step of calculating the operation amount by the PID control calculation by inputting the set value and the control amount, and the first step of acquiring the target value of the change amount of the feedforward amount with respect to the operation amount. The second step, and the third step of calculating the change amount that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired. The fourth step of changing the operation amount calculated in the first step by the amount of the change amount calculated in the third step, and the operation amount changed in the fourth step are operated with the operation amount lower limit value or more. The target value of the change amount includes the fifth step of performing limit processing for limiting the amount to a value equal to or less than the upper limit of the amount and the sixth step of outputting the operation amount of this limit processing to the control target, and the target value of the change amount is the operation amount. Is the value obtained by step-changing by the amount of feedforward.

According to the present invention, when the feedforward control is additionally applied to the feedback control by the operation amount calculation unit by providing the change amount target value acquisition unit, the change amount calculation unit, and the operation amount change unit, the feedback control is performed. It is possible to reduce the occurrence of defects.

Further, in the present invention, by automatically determining the first parameter regarding the time of the change amount in conjunction with the PID parameter of the operation amount calculation unit, the change of the feedforward amount of the operation amount is controlled up and down. The elapsed time from the time when the feedforward amount is changed to the maximum change amount of the feedforward amount is roughly matched with the time of the first parameter. Can be done.

Further, in the present invention, the maximum change amount for the feedforward of the operation amount is set as the target of the change amount by automatically determining the second parameter that defines the size of the feedforward in conjunction with the first parameter. It can be roughly matched to the value.

FIG. 1 is a block diagram showing a configuration of a control device according to an embodiment of the present invention. FIG. 2 is a block diagram of a control system according to an embodiment of the present invention. FIG. 3 is a flowchart illustrating the operation of the control device according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of changes in the controlled variable and the manipulated variable when the temperature is controlled without executing feedforward. FIG. 5 is a diagram showing an operation amount addition amount and an operation amount subtraction amount when the temperature is controlled without executing feedforward. FIG. 6 is a diagram showing an example of changes in the control amount and the operation amount when the operation amount is changed for the feedforward amount and the feedforward amount is immediately returned to 0% after a certain period of time has elapsed. FIG. 7 is a diagram showing another example of changes in the control amount and the operation amount when the operation amount is changed for the feedforward amount and the feedforward amount is immediately returned to 0% after a certain period of time has elapsed. FIG. 8 is a diagram showing an example of changes in the control amount and the operation amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 9 is a diagram showing an example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 10 is a diagram showing another example of changes in the control amount and the operation amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 11 is a diagram showing another example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 12 is a diagram showing another example of changes in the control amount and the operation amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 13 is a diagram showing another example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 14 is a diagram showing another example of changes in the control amount and the operation amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 15 is a diagram showing another example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 16 is a diagram showing an example of changes in the controlled variable and the manipulated variable when the temperature is controlled with the parameter related to the time of the manipulated variable subtracted as a value smaller than that of the embodiment of the present invention. FIG. 17 is a diagram showing an example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by setting the parameter related to the time of the manipulated variable subtraction amount to a value smaller than that of the embodiment of the present invention. FIG. 18 is a diagram showing an example of changes in the controlled variable and the manipulated variable when the temperature is controlled with the parameter relating to the time of the manipulated variable subtracted as a value larger than that of the embodiment of the present invention. FIG. 19 is a diagram showing an example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by setting the parameter related to the time of the manipulated variable subtraction amount to a value larger than that of the embodiment of the present invention. FIG. 20 is a diagram showing an example of changes in the controlled variable and the manipulated variable when the temperature is controlled without executing feedforward. FIG. 21 is a diagram showing an operation amount addition amount and an operation amount subtraction amount when the temperature is controlled without executing feedforward. FIG. 22 is a diagram showing another example of changes in the control amount and the operation amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 23 is a diagram showing another example of changes in the manipulated variable addition amount and the manipulated variable subtraction amount when the temperature is controlled by the control device according to the embodiment of the present invention. FIG. 24 is a block diagram showing a configuration example of a computer that realizes the control device according to the embodiment of the present invention. FIG. 25 is a diagram showing a configuration example of a heating device including a plurality of control loops.

[Principle 1 of the invention]
Arbitrary operation amount addition (including subtraction) by the operator can be positioned as feedforward in the control structure.
For the manipulated variable output by the PID calculation of the temperature controller, the output saturation is determined only by the manipulated variable MV calculated by the thermometer, and the anti-reset windup process for the integral operation is performed. Therefore, it is necessary to solve the problem that the temperature controller does not function normally if the feedforward portion that remains constantly is added to the feedback portion (operation amount MV by PID calculation). For example, when the temperature controller outputs an operation amount MV = 60% with sufficient margin for output saturation, when 50% feedforward is added, it becomes 110%, and the output exceeds 100%. Although it becomes saturated, there is an inconsistency that the anti-reset windup process is not executed as the temperature controller.

Therefore, the inventor applies the feedforward portion to the feedback portion gradually (stepwise, substantially continuously), and gradually (the feedforward portion) to a value of zero at a speed that can be replaced by the feedback portion (stepwise, substantially continuously). It was conceived that the inconvenience could be alleviated because the effect on the PID operation would be temporary and continuous if it was passed through the filter element that converges (stepwise, almost continuously).

[Principle 2 of the invention]
The parameter Tf (first parameter) relating to the time of the change amount for the feedforward with respect to the manipulated variable MV is automatically determined in conjunction with the PID parameter (for example, the integration time Ti). As a result, it is possible to easily maintain the change of the feedforward amount of the manipulated variable MV so as to be substantially in agreement with the cycle when the vertical movement of the control occurs.

In addition, the parameter Kx (second parameter) that defines the size of feedforward in conjunction with the time parameter Tf so that the parameter value set by the operator is maintained at a physical quantity that is visually easy for the operator to understand. It is preferable to automatically change. For example, it is conceivable to internally process each parameter so that the parameter value set by the operator always corresponds to the maximum feedforward application amount.

[Principle 3 of the invention]
By designating the feedforward portion to mean the stepwise addition of the operation amount addition amount or the operation amount subtraction amount, it becomes easy for the operator to manually operate the feedforward amount. In addition, the instruction content for automatically reproducing this operation can be simplified.

[Example]
Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a control device according to an embodiment of the present invention. This embodiment is an example corresponding to the above-mentioned principle 1, the principle 2 of the invention, and the principle 3 of the invention. Here, an example of application to a general-purpose feedback controller (PID-controlled temperature controller) will be described.

The control device has an operation amount calculation unit 1 that calculates an operation amount MV by PID control calculation using a set value SP and a control amount PV as inputs, and an operation amount addition that is a target value of an addition amount for feed forward to the operation amount MV. The FF addition value acquisition unit 2 that acquires the value FF_P (target value of the change amount) and the operation amount subtraction value FF_M (target value of the change amount) that is the target value of the subtraction amount for the feed forward with respect to the operation amount MV are acquired. When the FF subtraction value acquisition unit 3 and the operation amount addition value FF_P different from the zero value are acquired, the operation amount addition amount MV_P (change amount) gradually converges to the zero value after approaching the operation amount addition value FF_P. When the addition amount calculation unit 4 to be calculated and the operation amount subtraction value FF_M different from the zero value are acquired, the operation amount subtraction amount MV_M (change amount) gradually converges to the zero value after approaching the operation amount subtraction value FF_M. When the operation amount addition amount MV_P is calculated by the subtraction amount calculation unit 5 and the addition amount calculation unit 4, this operation amount addition amount MV_P is added to the operation amount MV calculated by the operation amount calculation unit 1. , When the operation amount subtraction amount MV_M is calculated by the subtraction amount calculation unit 5, the operation amount change unit 6 for subtracting the operation amount subtraction amount MV_M from the operation amount MV calculated by the operation amount calculation unit 1 and the operation amount. Outputs the limit processing unit 7 that performs limit processing that limits the operation amount MV_F calculated by the change unit 6 to a value that is equal to or more than the operation amount lower limit value OL and the operation amount upper limit value OH or less, and the limit processing operation amount MV_F'. It is provided with an operation amount output unit 8.

The FF addition value acquisition unit 2 and the FF subtraction value acquisition unit 3 constitute a change amount target value acquisition unit 10. The addition amount calculation unit 4 and the subtraction amount calculation unit 5 constitute a change amount calculation unit 11.
FIG. 2 is a block diagram of the control system of this embodiment. P in FIG. 2 indicates a control target.

Next, the operation of the control device of this embodiment will be described with reference to FIG. The set value SP (for example, the temperature set value) is set by an operator of the control device and is input to the operation amount calculation unit 1 (step S100 in FIG. 3).
The controlled variable PV (for example, a temperature measured value) is measured by a measuring instrument (for example, a temperature sensor that measures the temperature of the object to be heated) (not shown), and is input to the manipulated variable calculation unit 1 (step S101 in FIG. 3).

The operation amount calculation unit 1 inputs the set value SP and the control amount PV, and performs a PID control operation such as the following transfer function formula so that the control amount PV matches the set value SP, and the operation amount MV. Is calculated (FIG. 3, step S102).
MV = (100 / Pb) {1+ (1 / Tis) + Tds} (SP-PV)
... (1)
Pb is the proportional band, Ti is the integration time, Td is the differential time, and s is the Laplace operator.

The FF addition value acquisition unit 2 acquires the operation amount addition value FF_P, which is the target value of the addition amount for the feedforward with respect to the operation amount MV. Specifically, the FF addition value acquisition unit 2 acquires the operation amount addition value FF_P input from the outside, but acquires the value sent by communication at a predetermined timing, or the operator has an input function. There is a form of acquiring a value appropriately input by using the above, and a form of acquiring a value automatically generated by changing the set value SP input to the operation amount calculation unit 1.

The FF subtraction value acquisition unit 3 acquires the operation amount subtraction value FF_M, which is the target value of the subtraction amount for the feedforward with respect to the operation amount MV. Specifically, the FF subtraction value acquisition unit 3 acquires the operation amount subtraction value FF_M input from the outside, but acquires the value sent by communication at a predetermined timing, or the operator has an input function. There is a form of acquiring an appropriately input value by using the above, and a form of acquiring a value automatically generated by changing the set value SP input to the operation amount calculation unit 1.

That is, in the system to which the control device of this embodiment is applied, for example, in order to suppress a disturbance assumed during control, an operation is performed from the host device to the control device at a specified timing or at a timing of changing the set value SP. It is conceivable that the amount addition value FF_P and the operation amount subtraction value FF_M are automatically input, or the operator manually inputs the operation amount addition value FF_P and the operation amount subtraction value FF_M during control.

When the FF addition value acquisition unit 2 acquires the operation amount addition value FF_P different from the zero value (YES in step S103 of FIG. 3), the addition amount calculation unit 4 gradually approaches the operation amount addition value FF_P and then gradually reaches the zero value. The operation amount addition amount MV_P that converges to is calculated (FIG. 3, step S104). Specifically, the addition amount calculation unit 4 calculates the operation amount addition amount MV_P by the following transfer function formula.
MV_P = {Kxs / (1 + Tfs) ² } FF_P ... (2)

Tf in the equation (2) is a parameter relating to the time of the manipulated variable addition amount MV_P. The addition amount calculation unit 4 may set the PID parameter set in the operation amount calculation unit 1, specifically, a value obtained by α times the integration time Ti as Tf (Tf = αTi, the predetermined value α is, for example, α =). 0.1 to 2.0). As a result, the change in the feedforward amount of the manipulated variable MV to which the manipulated variable MV_P is added almost coincides with the cycle when the vertical movement of the control occurs. Further, the elapsed time from the time when the feedforward amount is added to the operation amount MV until the feedforward amount reaches the maximum change amount almost coincides with the time of the parameter Tf.

Kx in equation (2) is a parameter that defines the size of feedforward. The addition amount calculation unit 4 may set the value β times the parameter Tf to Kx (Kx = βTf, the predetermined value β is, for example, 2.75). As a result, the maximum change amount for the feedforward of the operation amount MV generally matches the operation amount addition value FF_P. The initial value of the operation amount addition amount MV_P before the FF addition value acquisition unit 2 acquires the operation amount addition value FF_P is zero.

When the FF subtraction value acquisition unit 3 acquires the operation amount subtraction value FF_M different from the zero value (YES in step S105 of FIG. 3), the subtraction amount calculation unit 5 gradually approaches the operation amount subtraction value FF_M and then gradually reaches the zero value. The operation amount subtraction amount MV_M that converges to is calculated (FIG. 3, step S106). Specifically, the subtraction amount calculation unit 5 calculates the operation amount subtraction amount MV_M by the following transfer function formula.
MV_M = {Kxs / (1 + Tfs) ² } FF_M ... (3)

Similar to the addition amount calculation unit 4, the subtraction amount calculation unit 5 may set the value of α times the integration time Ti as Tf (Tf = αTi, the predetermined value α is, for example, 0.1 to 2.0). Further, the subtraction amount calculation unit 5 may set a value β times the parameter Tf to Kx (Kx = βTf, a predetermined value β is, for example, 2.75). As a result, the maximum change amount for the feedforward of the operation amount MV becomes substantially the same as the operation amount subtraction value FF_M (operation amount subtraction amount MV_M in FIGS. 8, 10, 12, and 14 described later). The initial value of the operation amount subtraction amount MV_M before the FF subtraction value acquisition unit 3 acquires the operation amount subtraction value FF_M is zero.

The operation amount changing unit 6 adds the operation amount addition amount MV_P calculated by the addition amount calculation unit 4 to the operation amount MV calculated by the operation amount calculation unit 1, and further performs the operation calculated by the subtraction amount calculation unit 5. The result of subtracting the amount subtraction amount MV_M is calculated as the operation amount MV_F (FIG. 3, step S107).
MV_F = MV + MV_P-MV_M ... (4)

The limit processing unit 7 limits the operation amount MV_F calculated by the operation amount change unit 6 to a value equal to or higher than the predetermined operation amount lower limit value OL, and the operation amount MV_F is equal to or less than the predetermined operation amount upper limit value OH. The upper limit processing for limiting the value is performed (step S108 in FIG. 3).
IF MV_F <OL THEN MV_F'= OL ... (5)
IF MV_F> OH THEN MV_F'= OH ... (6)
That is, the limit processing unit 7 sets the operation amount MV_F'= OL when the MV_F is smaller than the operation amount lower limit value OL, and sets the operation amount MV_F'= OH when the operation amount MV_F is larger than the operation amount upper limit value OH.

The operation amount output unit 8 outputs the operation amount MV_F'that has been limit-processed by the limit processing unit 7 to the control target (step S109 in FIG. 3). The output destination of the operation amount MV_F'is an operation unit (not shown) such as a heater or a valve. In the case of a heater, the actual output destination of the manipulated variable MV_F'is a power regulator (not shown) that supplies electric power to the heater.

The control device executes the processes of steps S100 to S109 of FIG. 3 for each control cycle until the control is completed, for example, by an instruction of the operator (YES in step S110 of FIG. 3).

As described above, the manipulated variable addition amount MV_P is a value that gradually converges to a zero value after approaching the manipulated variable addition value FF_P, and the manipulated variable subtraction amount MV_M is a zero value after approaching the manipulated variable subtraction value FF_M. It is a value that gradually converges to. Therefore, after the FF addition value acquisition unit 2 acquires the operation amount addition value FF_P different from the zero value, the determination is always YES in step S103, and the addition amount calculation unit 4 repeatedly executes the calculation of the operation amount addition amount MV_P. Since the operation amount addition amount MV_P finally converges to the zero value, the addition amount calculation unit 4 may stop the calculation when the operation amount addition amount MV_P reaches the zero value. Similarly, after the FF subtraction value acquisition unit 3 acquires the operation amount subtraction value FF_M different from the zero value, the determination is always YES in step S105, and the subtraction amount calculation unit 5 repeatedly executes the calculation of the operation amount subtraction amount MV_M. Since the operation amount subtraction amount MV_M finally converges to the zero value, the subtraction amount calculation unit 5 may stop the calculation when the operation amount subtraction amount MV_M reaches the zero value.

The transfer functions of the equations (2) and (3) adopted in this embodiment are typical examples conforming to the principle 1 of the invention and the principle 2 of the invention, and are not limited thereto. For example, although the second-order lag of the denominator of the transfer function is set to the same time constant Tf, it is possible to change it to a different time constant or change the order. Further, if the coefficient β is adjusted according to the order of the time constant and how to select the balance, the principle 2 of the invention can be surely applied.

In the case of the configuration of the FF addition value acquisition unit 2 and the addition amount calculation unit 4 or the configuration of the FF subtraction value acquisition unit 3 and the subtraction amount calculation unit 5 in this embodiment, the operator can use the input function to perform arbitrary timing. If it is specified in the above to mean a stepwise change of the operation amount addition amount or the operation amount subtraction amount, the feed forward process of the present invention can be appropriately started. That is, it corresponds to the principle 3 of the invention.

Hereinafter, the effect of this embodiment will be verified by simulation. In the following example, the control target is a heating control system that can be approximated by a first-order lag transfer function having a process gain Kp = 8, a process time constant Tp = 200 seconds, and a process waste time Lp = 50 seconds. That is, the model formula Gp to be controlled can be described as the following formula.
Gp = Kpexp (-Lps) / (1 + Tps) ... (7)

Further, the PID parameters set in the manipulated variable calculation unit 1 are set to the proportional band Pb = 200 ° C., the integration time Ti = 200 seconds, and the differential time Td = 0 seconds (that is, PI control), and the set value SP is set from 100 ° C. to 350 ° C. The temperature was changed to ° C. Although only the operation amount subtraction amount MV_M is changed, the operation amount addition amount MV_P may be changed as described later.

4 and 5 are diagrams showing comparison targets for confirming the effect of this embodiment, and FIG. 4 is an example of changes in the controlled variable PV and the manipulated variable MV when the temperature is controlled without executing feed forward. 5 is a diagram showing an operation amount addition amount MV_P = 0% and an operation amount subtraction amount MV_M = 0% in this case. In the example of FIG. 4, in conjunction with the large decrease in the control amount PV (temperature) around 400 seconds, the decrease in the control amount PV is conspicuous even after 600 seconds, and a state that cannot be said to be a clear settling occurs. There is.

6 and 7 are diagrams showing an example of changes in the control amount PV and the operation amount MV when the feedback amount is changed to the operation amount MV and the feedforward amount is immediately returned to 0% after a certain period of time has elapsed. , It is a figure which shows the problem of the discontinuous feedback control. In the example of FIG. 6, the operation amount subtraction amount MV_M is changed from 0% to 16% at the same time as the set value SP is changed from 100 ° C. to 350 ° C., maintained for 120 seconds, and then returned to 0%. At the same time as changing the set value SP, the operation amount subtraction amount MV_M is changed from 0% to 16%, maintained for 90 seconds, and then returned to 0%.

In the example of FIG. 6, since the operation amount subtraction amount MV_M = 16% is maintained for 120 seconds, it is possible to suppress a large decrease in the control amount PV (temperature) around 400 seconds, and the control amount after 600 seconds. It can be said that the drop of PV became inconspicuous and the settling state was reached earlier than in FIG. On the other hand, in the example of FIG. 7, since the operation amount subtraction amount MV_M = 16% is maintained only for 90 seconds, the effect of changing the operation amount subtraction amount MV_M to a constant value 16% is clearly insufficient as compared with FIG. Rather, it can be said that the result is closer to that of FIG.

In this way, when the manipulated variable subtraction amount MV_M is immediately returned to 0% after a certain period of time, the magnitude of the manipulated variable MV causes discontinuous and extremely different time points. The control result may differ greatly depending on the situation. In other words, even if good control results are obtained once by maintaining the operation amount subtraction amount MV_M = 16% for 120 seconds as shown in FIG. 6, when the characteristics of the controlled object change even slightly. It is possible that the control results will deteriorate rapidly and clearly.

FIG. 8 shows the control amount PV when the temperature is controlled while changing the operation amount subtraction amount MV_M from 0% → 16% → 0% with the parameter Tf = 60.0 seconds (corresponding to Tf = 0.3Ti) in this embodiment. FIG. 9 is a diagram showing an example of a change in the manipulated variable MV, and FIG. 9 is a diagram showing a change in the manipulated variable subtraction amount MV_M in this case (the manipulated variable addition amount MV_P is fixed at 0%). In this example, the manipulated variable subtraction value FF_M = 16%, the parameter Kx = 165.0, and the parameter Tf = 60.0 seconds.

Similar to the example of FIG. 6, since the control amount PV (temperature) can be suppressed from dropping significantly around 400 seconds, the drop of the control amount PV after 600 seconds becomes inconspicuous, which is compared with FIG. It can be said that the settling state was reached at an early time.

FIG. 10 shows the control amount PV when the temperature is controlled while changing the operation amount subtraction amount MV_M from 0% → 16% → 0% with the parameter Tf = 80.0 seconds (corresponding to Tf = 0.4Ti) in this embodiment. FIG. 11 is a diagram showing an example of a change in the manipulated variable MV, and FIG. 11 is a diagram showing a change in the manipulated variable subtraction amount MV_M in this case (the manipulated variable addition amount MV_P is fixed at 0%). In this example, the manipulated variable subtraction value FF_M = 16%, the parameter Kx = 220.0, and the parameter Tf = 80.0 seconds. According to FIG. 10, it can be seen that the same control result as in the case of FIG. 8 is obtained.

FIG. 12 shows the control amount PV when the temperature is controlled while changing the operation amount subtraction amount MV_M from 0% → 16% → 0% with the parameter Tf = 100.0 seconds (corresponding to Tf = 0.5Ti) in this embodiment. FIG. 13 is a diagram showing an example of a change in the manipulated variable MV, and FIG. 13 is a diagram showing a change in the manipulated variable subtraction amount MV_M in this case (the manipulated variable addition amount MV_P is fixed at 0%). In this example, the operation amount subtraction value FF_M = 16%, the parameter Kx = 275.0, and the parameter Tf = 100.0 seconds. According to FIG. 12, it can be seen that the same control results as in the cases of FIGS. 8 and 10 are obtained.

FIG. 14 shows the control amount PV when the temperature is controlled while changing the operation amount subtraction amount MV_M from 0% → 16% → 0% with the parameter Tf = 120.0 seconds (corresponding to Tf = 0.6Ti) in this embodiment. FIG. 15 is a diagram showing an example of a change in the manipulated variable MV, and FIG. 15 is a diagram showing a change in the manipulated variable subtraction amount MV_M in this case (the manipulated variable addition amount MV_P is fixed at 0%). In this example, the manipulated variable subtraction value FF_M = 16%, the parameter Kx = 330.0, and the parameter Tf = 120.0 seconds. According to FIG. 14, it can be seen that the same control results as in the cases of FIGS. 8, 10 and 12 are obtained.

As described above, according to this embodiment, the effect of alleviating the problem of discontinuous feedforward control can be obtained. That is, when the feedforward control is additionally applied, the occurrence of a defect can be reduced and the convenience for the operator can be improved.

In FIG. 16, in order to confirm the effect of the principle 2 of the above invention, the parameter Tf is set to a value Tf = 8.0 seconds (corresponding to Tf = 0.04Ti) smaller than that of this embodiment, and the operation amount subtraction amount MV_M is set to 0% → A diagram showing an example of changes in the controlled variable PV and the manipulated variable MV when the temperature is controlled while changing from 16% to 0%, and FIG. 17 is a diagram showing the changes in the manipulated variable subtraction amount MV_M in this case (manipulation amount). Addition amount MV_P is fixed at 0%). In this example, the operation amount subtraction value FF_M = 16%, the parameter Kx = 22.0, and the parameter Tf = 8.0 seconds.

The examples of FIGS. 16 and 17 can be regarded as setting examples in which the parameter Tf is too small for the integration time Ti and the integration time Ti is not substantially referred to. Since the feedforward operation is completed in a short time with respect to the control behavior, the effect of feedforward is hardly obtained.

In FIG. 18, in order to confirm the effect of the principle 2 of the above invention, the parameter Tf is set to a value Tf = 800.0 seconds (corresponding to Tf = 4.0Ti) larger than that of this embodiment, and the operation amount subtraction amount MV_M is set to 0% → A diagram showing an example of changes in the controlled variable PV and the manipulated variable MV when the temperature is controlled while changing from 16% to 0%, and FIG. 19 is a diagram showing the changes in the manipulated variable subtraction amount MV_M in this case (manipulation amount). Addition amount MV_P is fixed at 0%). In this example, the manipulated variable subtraction value FF_M = 16%, the parameter Kx = 2200.0, and the parameter Tf = 800.0 seconds.

The examples of FIGS. 18 and 19 can be regarded as setting examples in which the parameter Tf is too large for the integration time Ti and the integration time Ti is not substantially referred to. Since the feedforward operation tends to be delayed for a long time with respect to the control behavior, the effect of feedforward is hardly obtained.

Next, the effect of this embodiment is verified by another simulation. In the following example, the control target is a heating control system that can be approximated by a first-order delay transfer function with a process gain Kp = 8, a process time constant Tp = 200 seconds, and a process waste time Lp = 50 seconds. The PID parameters to be set were proportional band Pb = 600 ° C., integration time Ti = 200 seconds, and differential time Td = 0 seconds (that is, PI control). Then, it is assumed that the temperature drop disturbance occurs in a state where the set value SP = control amount PV = 300 ° C. is set. Although only the operation amount addition amount MV_P is changed, the operation amount subtraction amount MV_M may be changed as described above.

FIG. 20 is a diagram showing a comparison target for confirming the effect of this embodiment, and FIG. 20 is a diagram showing an example of changes in the controlled variable PV and the manipulated variable MV when the temperature is controlled without executing feed forward. 21 is a diagram showing an operation amount addition amount MV_P = 0% and an operation amount subtraction amount MV_M = 0% in this case. In the example of FIG. 20, the controlled variable PV (temperature) drops significantly from around 100 seconds and reaches about 220 ° C. It takes about 1000 seconds to settle by the disturbance response.

FIG. 22 shows the control amount PV when the temperature is controlled while changing the operation amount addition amount MV_P = 0% → 40% → 0% with the parameter Tf = 20.0 seconds (corresponding to Tf = 0.1Ti) in this embodiment. FIG. 23 is a diagram showing an example of a change in the manipulated variable MV, and FIG. 23 is a diagram showing a change in the manipulated variable addition amount MV_P in this case (the manipulated variable subtraction amount MV_M is fixed at 0%). In this example, the operation amount addition value FF_P = 40%, the parameter Kx = 55.0, and the parameter Tf = 20.0 seconds are set, and the operation amount addition value FF_P = 40% is input at the timing of the disturbance application to input the operation amount addition amount. The change of MV_P has started.

According to FIG. 22, it can be seen that the control amount PV (temperature) can be suppressed from dropping significantly to about 250 ° C. in the vicinity of 100 seconds as in the case of FIG. 20. Further, it takes about 600 seconds to settle by the disturbance response, and it can be said that the settling state can be reached earlier than in the case of FIG. 20.

It should be noted that the present invention can also be realized by providing, for example, only the configuration on the addition side and giving the operation amount addition value FF_P as a negative value when performing the processing as the configuration on the subtraction side. Similarly, for example, when processing is performed as the configuration on the addition side by providing only the configuration on the subtraction side, a realization method in which the operation amount subtraction value FF_M is given as a negative value is also possible. However, by providing both the addition side and the subtraction side configurations, the operation amount addition amount MV_P and the operation amount subtraction amount MV_M can be simultaneously superimposed on the operation amount MV, so that the addition side as shown in FIG. It is preferable to have both the subtraction side and the subtraction side separately.

The control device described in this embodiment can be realized by a computer provided with a CPU (Central Processing Unit), a storage device, and an interface, and a program for controlling these hardware resources. An example of the configuration of this computer is shown in FIG. The computer includes a CPU 600, a storage device 601 and an interface device (hereinafter, abbreviated as I / F) 602. For example, a temperature sensor and a power regulator are connected to the I / F 602. In such a computer, a program for realizing the control method of the present embodiment is stored in the storage device 601. The CPU 600 executes the process described in this embodiment according to the program stored in the storage device 601.

This embodiment can be applied to a control device.

1 ... Operation amount calculation unit, 2 ... FF addition value acquisition unit, 3 ... FF subtraction value acquisition unit, 4 ... Addition amount calculation unit, 5 ... Subtraction amount calculation unit, 6 ... Operation amount change unit, 7 ... Limit processing unit, 8 ... Operation amount output unit, 10 ... Change amount target value acquisition unit, 11 ... Change amount calculation unit.

Claims (8)

An operation amount calculation unit configured to calculate an operation amount by PID control calculation with a set value and a control amount as inputs,
A change amount target value acquisition unit configured to acquire a target value of a change amount for feedforward with respect to the operation amount, and a change amount target value acquisition unit.
A change amount calculation unit configured to calculate a change amount that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired.
An operation amount changing unit configured to change the operation amount calculated by the operation amount calculation unit by the amount of the change amount calculated by the change amount calculation unit.
A limit processing unit configured to perform limit processing that limits the operation amount changed by this operation amount change unit to a value that is equal to or more than the operation amount lower limit value and less than or equal to the operation amount upper limit value.
It is equipped with an operation amount output unit configured to output this limit-processed operation amount to the control target .
The change amount calculation unit is a control device characterized in that a first parameter relating to the time of the change amount is automatically determined in conjunction with the PID parameter of the operation amount calculation unit. An operation amount calculation unit configured to calculate an operation amount by PID control calculation with a set value and a control amount as inputs,
A change amount target value acquisition unit configured to acquire a target value of a change amount for feedforward with respect to the operation amount, and a change amount target value acquisition unit.
A change amount calculation unit configured to calculate a change amount that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired.
An operation amount changing unit configured to change the operation amount calculated by the operation amount calculation unit by the amount of the change amount calculated by the change amount calculation unit.
A limit processing unit configured to perform limit processing that limits the operation amount changed by this operation amount change unit to a value that is equal to or more than the operation amount lower limit value and less than or equal to the operation amount upper limit value.
It is equipped with an operation amount output unit configured to output this limit-processed operation amount to the control target.
A control device characterized in that the target value of the change amount is a value obtained by step-changing the operation amount by a feedforward amount. In the control device according to claim 1 or 2.
The target value of the change amount is an operation amount addition value which is a target value of the addition amount with respect to the operation amount.
The change amount calculation unit calculates the operation amount addition amount as the change amount that gradually converges to the zero value after approaching the operation amount addition value when the operation amount addition value different from the zero value is acquired. ,
The operation amount changing unit is a control device characterized in that the operation amount addition amount calculated by the change amount calculation unit is added to the operation amount calculated by the operation amount calculation unit. In the control device according to claim 1 or 2.
The target value of the change amount is an operation amount subtraction value which is a target value of the subtraction amount with respect to the operation amount.
When the operation amount subtraction value different from the zero value is acquired, the change amount calculation unit calculates the operation amount subtraction amount as the change amount that gradually converges to the zero value after approaching the operation amount subtraction value. ,
The operation amount changing unit is a control device characterized in that the operation amount subtraction amount calculated by the change amount calculation unit is subtracted from the operation amount calculated by the operation amount calculation unit. In the control device according to claim 1 or 2.
The target value of the change amount is an operation amount addition value which is a target value of an addition amount with respect to the operation amount and an operation amount subtraction value which is a target value of a subtraction amount with respect to the operation amount.
The change amount calculation unit calculates the operation amount addition amount as the change amount that gradually converges to the zero value after approaching the operation amount addition value when the operation amount addition value different from the zero value is acquired. , When the operation amount subtraction value different from the zero value is acquired, the operation amount subtraction amount is calculated as the change amount that gradually converges to the zero value after approaching the operation amount subtraction value.
When the operation amount addition amount is calculated by the change amount calculation unit, the operation amount change unit adds the operation amount addition amount to the operation amount calculated by the operation amount calculation unit, and calculates the change amount. A control device characterized in that when the operation amount subtraction amount is calculated by the unit, the operation amount subtraction amount is subtracted from the operation amount calculated by the operation amount calculation unit. In the control device according to claim 1,
The change amount calculation unit is a control device characterized in that a second parameter defining the size of feedforward is automatically determined in conjunction with the first parameter. The first step of calculating the operation amount by PID control calculation with the set value and the control amount as input, and
The second step of acquiring the target value of the change amount for the feedforward with respect to the operation amount, and
The third step of calculating the change amount that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired.
A fourth step of changing the operation amount calculated in the first step by the amount of change calculated in the third step, and
The fifth step of performing limit processing for limiting the operation amount changed in the fourth step to a value equal to or more than the operation amount lower limit value and not more than the operation amount upper limit value.
And a sixth step of outputting the limit processing manipulated variable to the controlled object seen including,
The third step is a control method including a step of automatically determining a first parameter relating to the time of the change amount in association with the PID parameter of the PID control calculation. The first step of calculating the operation amount by PID control calculation with the set value and the control amount as input, and
The second step of acquiring the target value of the change amount for the feedforward with respect to the operation amount, and
The third step of calculating the change amount that gradually converges to the zero value after approaching the target value of the change amount when the target value of the change amount different from the zero value is acquired.
A fourth step of changing the operation amount calculated in the first step by the amount of change calculated in the third step, and
The fifth step of performing limit processing for limiting the operation amount changed in the fourth step to a value equal to or more than the operation amount lower limit value and not more than the operation amount upper limit value.
Including the sixth step of outputting this limit-processed operation amount to the control target,
A control method characterized in that the target value of the change amount is a value obtained by step-changing the operation amount by a feedforward amount.

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