JP2021033739A - Control parameter tuning device and method - Google Patents

Abstract

To shorten a limit cycle method automatic tuning execution time.SOLUTION: A control parameter tuning device comprises: a limit cycle AT computation unit 6 that alternately outputs an amount of operation MV of a preliminarily set upper limit value and an amount of operation MV of a preliminarily set lower limit value to a control object; a ratio RE calculation unit 8 that calculates a ratio RE of an absolute value of a deviation in initial two extremal values of an amount of control PV generated by an output of the amount of operation MV of a deviation between a setting value SP of control and an amount of control PV thereof; and a two-position operation-amount correction unit 9 that calculates a value having the upper limit value of the amount of operation MV or the lower limit value thereof estimated to be appropriate on the basis of the ratio RE, and corrects the upper limit value or lower limit value to the calculated value. A limit cycle AT computation unit 6 is configured to calculate a control parameter of a controller on the basis of a response of an amount of control PV after the upper limit value of the amount of operation MV or the lower limit value thereof is corrected, and set the calculated control parameter to the controller.SELECTED DRAWING: Figure 2

Description

The present invention relates to a technique for adjusting parameters of a controller such as PID, and more particularly to a control parameter adjusting device and method for adjusting control parameters of a controller by a limit cycle method.

The adjustment of the PID parameter of the PID controller is usually easily performed by the auto-tuning (AT) function provided in the controller itself. A typical method of this AT function is a limit cycle method in which the manipulated variable MV is set in advance at two positions (OH_AT, OL_AT) to generate a limit cycle (see Patent Document 1).

Hereinafter, the limit cycle method will be briefly described. FIG. 15 is a waveform diagram for explaining the conventional limit cycle method, and FIG. 16 is a flowchart for explaining the processing flow of the conventional limit cycle method. However, in order to simplify the explanation, the set value SP when executing the PID control is used as the limit cycle switching point, but it is not essential that the limit cycle switching point is the set value SP.

When the AT is executed, the control amount PV and the set value SP are compared (step S300 in FIG. 16), and if the control amount PV is larger than the set value SP, the lower limit value OL_AT of the operation amount MV is output to the control target (step 16 in FIG. S301), when the control amount PV is equal to or less than the set value SP, the upper limit value OH_AT of the operation amount MV is output to the control target (step S302 in FIG. 16).

Next, a vertical dynamic pole value detection process for detecting the extreme value of the controlled variable PV is performed (step S303 in FIG. 16). When the processes of steps S300 to S303 are performed for each control cycle and four extreme values of the controlled variable PV are detected, the detection of the vertical dynamic pole values is completed. Here, the deviation Er between the set value SP and the controlled variable PV is obtained by the following equation.
Er = SP-PV ・ ・ ・ (1)

Then, as shown in FIG. 15, among the four detected extreme values, the deviation at the latest extreme value is the first extreme value deviation Er1, and the deviation at the second newest extreme value is the second extreme value deviation Er2. Let the deviation at the third newest extremum be the third extremum deviation Er3. Further, the time from the time t5 in which the positive / negative of the deviation Er1 is reversed immediately before the first extreme value deviation Er1 to the time t6 in which the first extreme value deviation Er1 is obtained is set as the first operation amount switching elapsed time Th1. Further, the time from the time t3 in which the positive / negative of the deviation Er is reversed immediately before the second extreme value deviation Er2 to the time t4 in which the second extreme value deviation Er2 is obtained is defined as the second operation amount switching elapsed time Th2. ..

Finally, the PID parameter composed of the proportional band Pb, the integration time Ti, and the differential time Td is calculated by the following equation, and the calculated PID parameter is set in the controller (step S304 in FIG. 16).
Pb = 250.0 | Er2-Er1 | / (OH_AT-OL_AT) ... (2)
Ti = 6.0 (Th1 + Th2) ... (3)
Td = 1.2 (Th1 + Th2) ... (4)
This completes AT.

As described above, there is a controller that executes AT by a preset two-position manipulated variable (OH_AT, OL_AT). Most commercially available controllers use the manipulated variable upper limit value OH and the manipulated variable lower limit value OL used during actual control as they are as the two-position manipulated variable. Usually, OH = 100% and OL = 0%, and therefore the two-position manipulated variable at AT is often OH_AT = 100% and OL_AT = 0%.

In a controlled object having high heat retention in temperature control, the manipulated variable MV required to maintain the controlled variable PV near the set value SP is considerably low, such as MV = 20% or less. In this situation, if MV = 0% to 100% AT is executed with OH_AT = 100% set, the temperature rises quickly and the temperature drops slowly (high heat retention and difficult to cool), so it takes a lot of time for AT. There is a problem that it is necessary (Fig. 17). In the example shown in FIG. 17, since the heat retention of the controlled object is high and it is difficult to cool, the operation amount lower limit value OL_AT is output for a longer time T_OL than the operation amount upper limit value OH_AT output time T_OH during AT. You can see that.

Regarding such a problem, not only when the operation amount upper limit value OH and the operation amount lower limit value OL used during the actual control are used as the two-position operation amount at the time of AT, the two-position operation set in advance is set in advance. If the quantity (OH_AT, OL_AT) corresponds to the one that gives an inappropriate waveform as in FIG. 17, the same problem occurs. As a coping method of the problem, an expert who can judge that AT is inappropriate can see the movement of the controlled variable PV at the time of AT using a recorder or the like to see the operation amount upper limit value OH and the operation amount lower limit value OL. I had to change the value to an appropriate value and re-execute the AT. Therefore, in many cases, the inadequacy of AT could be overlooked.

Therefore, when the balance of the two-position manipulated variable (OH_AT, OL_AT) at the time of AT by the limit cycle method is inappropriate, the two-position manipulated variable (OH_AT, OL_AT) that becomes an appropriate balance is automatically calculated and appropriate. An AT method has been proposed in which AT is automatically re-executed by a two-position manipulated variable (OH_AT, OL_AT) of balance (see Patent Document 2).

Hereinafter, the main points of the method disclosed in Patent Document 2 will be described. When the balance of the two-position manipulated variables (OH_AT, OL_AT) at the time of AT by the limit cycle method is improper, the AT waveform is as shown in FIG.

For example, in temperature control, when the temperature rises quickly and the temperature falls slowly, if the manipulated variable MV = OH_AT is output while the manipulated variable MV = OL_AT, the temperature rise starts with a steep gradient, so the temperature PV is set. The time below the value SP is short. That is, since the operation amount MV = OL_AT is switched when the temperature PV exceeds the set value SP, the time for which the operation amount MV = OH_AT is output is relatively short. Further, as the temperature rises on a steep slope, the temperature PV greatly exceeds the set value SP. That is, the absolute value of the amount (deviation Er1) at which the temperature PV exceeds the set value SP becomes relatively large.

On the other hand, since the temperature drop has a gentle gradient, it takes time for the temperature PV to return to the set value SP, and the time for the temperature PV to exceed the set value SP becomes long. While the temperature PV exceeds the set value SP, the manipulated variable MV = OL_AT, and the time during which the manipulated variable MV = OL_AT is output is relatively long. Further, since the temperature drop has a gentle gradient, the absolute value of the amount (deviation Er2) at which the temperature PV falls below the set value SP becomes relatively small.

In the above example, the OH_AT of the two-position manipulated variable (OH_AT, OL_AT) is too high as compared with the OL_AT, resulting in an improper balance. Therefore, if the ratio RE = | Er2 | / | Er1 | of the absolute value of the deviation is equal to or less than a specific threshold value, it can be determined that the manipulated variable OH_AT is relatively too high. On the contrary, if the ratio RE = | Er2 | / | Er1 | is equal to or higher than another specific threshold value, it can be determined that the manipulated variable OL_AT is relatively too low. When the extreme value deviation Er1 is the maximum value and the extreme value deviation Er2 is the minimum value, RE = | Er2 | / | Er1 |, but the extreme value deviation Er1 is the minimum value and the extreme value deviation Er2 is the maximum value. In the case of a value, RE = | Er1 | / | Er2 |. Needless to say, even when RE = | Er1 | / | Er2 |, an equivalent determination can be made.

It is possible to correct the two-position manipulated variable (OH_AT, OL_AT) assuming a linear relationship by the amount of the unbalanced ratio RE, and the more appropriate two-position manipulated variable (OH_AT, OL_AT) is expressed in the following equation. Can be calculated.
OL_AT_new = OL_AT + (OH_AT-OL_AT) (RE-1)
/ (RE + 1) ・ ・ ・ (5)
OH_AT_new = OH_AT + (OH_AT-OL_AT) (RE-1)
/ (RE + 1) ・ ・ ・ (6)

In the method disclosed in Patent Document 2, for example, when RE> 1.0, the manipulated variable lower limit value OL_AT is modified by the equation (5), and the manipulated variable upper limit value OH_AT is not modified. On the contrary, when RE <1.0, the manipulated variable upper limit value OH_AT is corrected by the equation (6), and the manipulated variable lower limit value OL_AT is not modified. When RE = 1.0, neither the manipulated variable lower limit value OL_AT nor the manipulated variable upper limit value OH_AT is modified.

As described above, according to the method disclosed in Patent Document 2, the two-position manipulated variable (OH_AT, OL_AT) having an appropriate balance is automatically calculated, and the two-position manipulated variable (OH_AT, OL_AT) having an appropriate balance is calculated. ) Can be automatically re-executed, but since the AT itself is substantially redone, there is a problem that the AT execution time (time required to complete) becomes long, and improvement is required. ..

Japanese Unexamined Patent Publication No. 2003-330504 Japanese Patent No. 4546437

The present invention has been made to solve the above problems, and an object of the present invention is to provide a control parameter adjusting device and a method capable of shortening the AT execution time of the limit cycle method.

According to the present invention, in a control parameter adjusting device having a limit cycle auto-tuning function for setting control parameters of a controller, a preset upper limit operation amount and a lower limit operation amount are alternately output to a control target. Of the deviation between the limit cycle auto-tuning calculation unit configured as described above and the control set value and the control amount, the deviation at each of the first two extreme values of the control amount generated by the output of the operation amount. The ratio calculation unit configured to calculate the ratio of absolute values and the value estimated to be appropriate for the upper limit value or the lower limit value are calculated based on the ratio, and the upper limit value or the lower limit value is calculated. The limit cycle auto-tuning calculation unit includes a correction unit configured to correct the value, and the limit cycle auto-tuning calculation unit controls the controller based on the response of the control amount after the upper limit value or the lower limit value is corrected. It is characterized in that parameters are calculated and the calculated control parameters are set in the controller.
Further, one configuration example of the control parameter adjusting device of the present invention further includes a correction coefficient setting unit configured to set a correction coefficient for a correction amount of the upper limit value or the lower limit value, and the correction unit is said to be described above. It is characterized in that an appropriate value of the upper limit value or the lower limit value is calculated based on the ratio and the correction coefficient.
Further, in one configuration example of the control parameter adjusting device of the present invention, the correction coefficient is set to a value smaller than 1.

Further, according to the present invention, in the control parameter adjusting method for setting the control parameters of the controller by the limit cycle method, the first operation amount of the preset upper limit value and the operation amount of the lower limit value are alternately output to the control target. A second calculation of the ratio of the absolute value of the deviation to each of the first two extreme values of the control amount generated by the output of the operation amount among the deviations between the step and the control set value and the control amount. A step, a third step of calculating an appropriate upper limit value or a value estimated to be appropriate for the lower limit value based on the ratio, and correcting the upper limit value or the lower limit value to the calculated value, and the upper limit value. Alternatively, it is characterized by including a fourth step of calculating the control parameter of the controller based on the response of the control amount after the lower limit value is corrected and setting the calculated control parameter in the controller. Is.

According to the present invention, the ratio of the absolute values of the two extreme value deviations detected in the first vertical movement of the limit cycle is calculated, and the two-position operation amount is corrected based on this ratio. Since an appropriate vertical movement of the control amount can be quickly obtained with the two-position operation amount, the AT execution time can be shortened.

Further, in the present invention, the correction error of the two-position operation amount can be corrected by correcting the two-position operation amount based on the ratio of the absolute values of the two extreme value deviations and the correction coefficient, and the control target. It is possible to prevent a decrease in AT accuracy even when the order of is higher.

FIG. 1 is a waveform diagram showing an example of changes in the manipulated variable and the controlled variable during AT execution. FIG. 2 is a block diagram showing a configuration of a control parameter adjusting device according to a first embodiment of the present invention. FIG. 3 is a block diagram showing a configuration of a controller to be adjusted by the control parameter adjusting device according to the first embodiment of the present invention. FIG. 4 is a flowchart illustrating the operation of the control parameter adjusting device according to the first embodiment of the present invention during AT execution. FIG. 5 is a waveform diagram showing an example of changes in the operation amount and the control amount during the conventional AT execution. FIG. 6 is a waveform diagram showing an example of changes in the operation amount and the control amount during the conventional AT execution. FIG. 7 is a waveform diagram showing an example of changes in the manipulated variable and the controlled variable during AT execution according to the first embodiment of the present invention. FIG. 8 is a waveform diagram showing an example of changes in the manipulated variable and the controlled variable during AT execution according to the first embodiment of the present invention. FIG. 9 is a block diagram showing a configuration of a control parameter adjusting device according to a second embodiment of the present invention. FIG. 10 is a flowchart illustrating the operation of the control parameter adjusting device according to the second embodiment of the present invention during AT execution. FIG. 11 is a diagram illustrating a correction error of the two-position manipulated variable that occurs in the case of a high-order control target. FIG. 12 is a waveform diagram showing an example of changes in the manipulated variable and the controlled variable during AT execution according to the second embodiment of the present invention. FIG. 13 is a waveform diagram showing an example of changes in the manipulated variable and the controlled variable during AT execution according to the second embodiment of the present invention. FIG. 14 is a block diagram showing a configuration example of a computer that realizes the control parameter adjusting device according to the first and second embodiments of the present invention. FIG. 15 is a waveform diagram for explaining a conventional limit cycle method. FIG. 16 is a flowchart illustrating a processing flow of the conventional limit cycle method. FIG. 17 is a waveform diagram for explaining the problems of the conventional limit cycle method.

[Principle of invention]
Behind the need for careful processing to re-execute the limit cycle is the recognition that the control amount PV needs to be moved up and down several times before the limit cycle stabilizes. The initial vertical movement of the controlled variable PV may be a large vertical movement as shown in FIG. 1 or a small vertical movement depending on the conditions at the start of AT. In particular, when the two-position manipulated variable (OH_AT, OL_AT) is improperly balanced, the first vertical movement will almost certainly result in an invalid vertical movement. That is, the reliability of the first extreme value (maximum value, minimum value) of the controlled variable PV at the start of AT is low.

The inventor noted that the first extremum of the limit cycle is unreliable, but the extremum ratio RE (the ratio RE of the maximum to the minimum) appears with high reliability. Then, if the inventor corrects the operation amount upper limit value OH_AT or the operation amount lower limit value OL_AT by using the extreme value ratio RE obtained at an early stage (for example, the first vertical movement) at the start of AT, the modified two positions Since the proper vertical movement can be quickly obtained with the operation amount (OH_AT, OL_AT), I came up with the idea that the AT execution time can be shortened.

[First Example]
Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing a configuration of a control parameter adjusting device according to the first embodiment of the present invention. In this embodiment, the denominator of the extreme value ratio RE is the absolute value of the deviation of the maximum side of the controlled variable PV (extreme value caused by temperature rise), and the molecule of the extreme value ratio RE is the minimum side of the controlled variable PV (extreme caused by temperature decrease). Adopt a formula that is the absolute value of the deviation of the value).

The control parameter adjusting device includes a set value SP acquisition unit 1 that acquires a switching point SP (set value SP) for AT execution, a control amount PV acquisition unit 2 that acquires a control amount PV during AT execution, and an AT execution unit. Operation amount MV output unit 3 for outputting the operation amount MV for, two-position operation amount lower setting unit 4 for setting the operation amount lower limit value OL_AT of the limit cycle AT, and the operation amount upper limit value of the limit cycle AT. The two-position operation amount upper setting unit 5 for setting OH_AT, the operation amount MV of the operation amount upper limit value OH_AT and the operation amount MV of the operation amount lower limit value OL_AT are alternately output, and the operation amount upper limit value OH_AT or the operation amount. The limit cycle AT calculation unit 6 that calculates the PID parameter of the controller based on the response of the control amount PV after the lower limit value OL_AT is corrected, and the limit cycle AT calculation unit that inputs the start instruction command of the limit cycle AT from the outside. Of the deviation between the start instruction unit 7 sent to 6 and the control set value SP and the control amount PV, the absolute value of the deviation at each of the first two extreme values of the control amount PV generated by the output of the operation amount MV. The ratio RE calculation unit 8 that calculates the ratio RE calculates the operation amount upper limit value OH_AT or the operation amount lower limit value OL_AT that is presumed to be appropriate based on the ratio RE, and operates the operation amount upper limit value OH_AT or the operation amount lower limit value. It is provided with a two-position operation amount correction unit 9 that corrects OL_AT to a calculated value.

FIG. 3 is a block diagram showing a configuration of a controller to be adjusted by the control parameter adjusting device of FIG. The controller controls the set value SP input unit 20, the control amount PV input unit 21, the operation amount MV output unit 22, and the deviation between the set value SP and the control amount PV during normal control operation after AT. It is provided with a PID control calculation unit 23 that performs a PID control calculation based on parameters and calculates an operation amount MV.

FIG. 4 is a flowchart illustrating the operation of the control parameter adjusting device during AT execution. The initial value of the operation amount lower limit value OL_AT of the limit cycle AT is preset in the two-position operation amount lower setting unit 4, and the operation amount upper limit value OH_AT of the limit cycle AT is set in the two-position operation amount upper setting unit 5. The initial value is set in advance.
When the start instruction unit 7 receives, for example, an start instruction command for the limit cycle AT from the operator, the start instruction unit 7 sends an start instruction command to the limit cycle AT calculation unit 6. As a result, the limit cycle AT calculation unit 6 is activated and the limit cycle AT is started (step S100 in FIG. 4).

The activated limit cycle AT calculation unit 6 compares the controlled variable PV with the set value SP (FIG. 4, step S101). The set value SP is set by the operator and is input to the limit cycle AT calculation unit 6 via the set value SP acquisition unit 1. The control amount PV is detected by a sensor (not shown) and is input to the limit cycle AT calculation unit 6 via the control amount PV acquisition unit 2.

When the control amount PV is larger than the set value SP, the limit cycle AT calculation unit 6 outputs the operation amount lower limit value OL_AT set by the two-position operation amount lower setting unit 4 to the operation amount MV output unit 3 as the operation amount MV. (FIG. 4, step S102). Further, when the control amount PV is equal to or less than the set value SP, the limit cycle AT calculation unit 6 sets the operation amount upper limit value OH_AT set by the two-position operation amount upper setting unit 5 as the operation amount MV to the operation amount MV output unit 3. Output (FIG. 4, step S103). The operation amount MV output unit 3 outputs the operation amount MV output from the limit cycle AT calculation unit 6 to the control target.

Next, the ratio RE calculation unit 8 detects two extreme deviations of the controlled variable PV obtained from the first vertical movement of the controlled variable PV according to the output of the manipulated variable MV during AT execution (FIG. 4, step S104). ). The extreme value deviation Er, which is the deviation between the set value SP and the extreme value of the controlled variable PV, is obtained by the equation (1). In this embodiment, of the two extreme value deviations, the deviation at the newest extreme value is defined as the first extreme value deviation Er1x, and the deviation at the previous extreme value is defined as the second extreme value deviation Er2x.

The processing of steps S101 to S103 is repeated for each control cycle, and when the extreme value deviations Er1x and Er2x can be detected (YES in step S104), the process proceeds to step S105.

Then, the ratio RE calculation unit 8 calculates the ratio RE of the absolute value of the first extreme value deviation Er1x and the absolute value of the second extreme value deviation Er2x (step S105 in FIG. 4). At this time, when the ratio RE calculation unit 8 has the maximum value of the newest extreme value and the minimum value of the previous extreme value among the first two extreme values of the control amount PV, the following equation is used. The ratio RE is calculated so that the first extreme value deviation Er1x on the maximum value side becomes the denominator and the second extreme value deviation Er2x on the minimum value side becomes the molecule.
RE = | Er2x | / | Er1x | ... (7)

Further, when the newer extreme value is the minimum value and the previous extreme value is the maximum value among the first two extreme values of the controlled variable PV, the ratio RE calculation unit 8 is as shown in the following equation. The ratio RE is calculated so that the first extreme value deviation Er1x on the minimum value side becomes the molecule and the second extreme value deviation Er2x on the maximum value side becomes the denominator.
RE = | Er1x | / | Er2x | ... (8)

Next, the two-position manipulated variable correction unit 9 determines whether or not the two-position manipulated variable (OH_AT, OL_AT) is set appropriately (step S106 of FIG. 4). When the ratio RE is larger than 1 (YES in step S107 in FIG. 4), the two-position manipulated variable correction unit 9 determines that the manipulated variable lower limit value OL_AT is inappropriate, and determines that the manipulated variable lower limit value OL_AT_new is modified as shown in the following equation. Is calculated, and this correction value OL_AT_new is output to the 2-position manipulated variable lower setting unit 4. The two-position manipulated variable lower setting unit 4 sets the correction value OL_AT_new in the limit cycle AT calculation unit 6 as a new value of the manipulated variable lower limit value OL_AT (step S108 in FIG. 4).
OL_AT_new = OL_AT + (OH_AT-OL_AT) (RE-1)
/ (RE + 1) ・ ・ ・ (9)

Further, when the ratio RE is smaller than 1 (YES in step S109 of FIG. 4), the 2-position manipulated variable correction unit 9 determines that the manipulated variable upper limit value OH_AT is inappropriate, and corrects the manipulated variable upper limit value as shown in the following equation. The value OH_AT_new is calculated, and this modified value OH_AT_new is output to the 2-position manipulated variable upper setting unit 5. The two-position manipulated variable upper setting unit 5 sets the correction value OH_AT_new as a new value of the manipulated variable upper limit value OH_AT in the limit cycle AT calculation unit 6 (step S110 in FIG. 4).
OH_AT_new = OH_AT + (OH_AT-OL_AT) (RE-1)
/ (RE + 1) ・ ・ ・ (10)

When the ratio RE is 1, the 2-position manipulated variable correction unit 9 determines that the setting of the 2-position manipulated variable (OH_AT, OL_AT) is appropriate, and does not correct the 2-position manipulated variable (OH_AT, OL_AT).
The processing of steps S105 to S110 is executed only once when the extreme value deviations Er1x and Er2x can be detected.

Even after the two-position manipulated variables (OH_AT, OL_AT) are corrected, the processes of steps S101 to S103 are repeatedly executed every control cycle, and AT continues.
Next, the limit cycle AT calculation unit 6 performs a vertical dynamic pole value detection process for detecting three extreme values of the controlled variable PV after correcting the two-position manipulated variable (OH_AT, OL_AT) (step S111 in FIG. 4). When three extreme values of the controlled variable PV are detected, the detection of the vertical dynamic pole value is completed. As described above, the limit cycle AT calculation unit 6 determines the deviation at the latest extreme value as the extreme value deviation Er1, the deviation at the second newest extreme value as the extreme value deviation Er2, and the deviation at the third newest extreme value as the extreme value. Let the deviation be Er3. Further, the limit cycle AT calculation unit 6 sets the time from the time when the positive / negative of the deviation Er1 is reversed immediately before the extreme value deviation Er1 to the time when the extreme value deviation Er1 is obtained as the operation amount switching elapsed time Th1 and sets the extreme value deviation. The time from the time when the positive / negative of the deviation Er2 is reversed immediately before Er2 to the time when the extreme value deviation Er2 is obtained is defined as the operation amount switching elapsed time Th2.

Then, the limit cycle AT calculation unit 6 calculates the PID parameter composed of the proportional band Pb, the integration time Ti, and the differential time Td by the equations (2) to (4), and sets the calculated PID parameter in the controller (FIG. 4 steps S112).

The processing of the limit cycle AT calculation unit 6 in steps S101 to S103, S111, and S112 is disclosed in, for example, Patent Document 1 and Patent Document 2. The limit cycle AT ends when the calculation / setting of the PID parameter is completed.

In the normal control operation after the end of AT, the PID control calculation unit 23 of the controller inputs the set value SP input from the set value SP input unit 20 and the control amount PV input from the control amount PV input unit 21. For example, the operation amount MV is calculated for each control cycle by performing a PID control operation such as the following transfer function formula.
MV = (100 / Pb) {1+ (1 / Tis) + Tds} (SP-PV)
... (11)
In equation (11), s is the Laplace operator. The manipulated variable MV calculated by the PID control calculation unit 23 is output to the control target via the manipulated variable MV output unit 22.

FIG. 5 is a waveform diagram showing an example of changes in the manipulated variable MV and the controlled variable PV during conventional AT execution, and FIG. 6 is an enlarged view of FIG. In the examples of FIGS. 5 and 6, the time is 20 sec. AT is started at the same time as the first set value SP change of, and the time is 520 sec. AT ends at this point. Then, the time after the end of AT is 800 sec. At the time of, the set value SP is changed again, and the temperature rise is controlled by the controller.

FIG. 7 is a waveform diagram showing an example of changes in the manipulated variable MV and the controlled variable PV during AT execution of this embodiment, and FIG. 8 is an enlarged view of FIG. 7. In the examples of FIGS. 7 and 8, the time is 20 sec. AT was started at the same time as the change of the first set value SP of, and the time was 470 sec. AT ends at this point. Then, the time after the end of AT is 800 sec. At the time of, the set value SP is changed again, and the temperature rise is controlled by the controller.

In the examples of FIGS. 7 and 8, the extreme deviations Er1x and Er2x were detected in the first vertical movement of the limit cycle, and the ratio RE was calculated, so that the upper limit of the manipulated variable OH_AT was changed from the first 100% to 16.9. It is corrected to%. As a result, as compared with the cases of FIGS. 5 and 6, the vertical movement time of the controlled variable PV after correcting the two-position manipulated variable (OH_AT, OL_AT) is shortened, and the AT execution time (time required to complete) is shortened. Has been done.

As described above, in this embodiment, the ratio RE is calculated from the extreme value deviations Er1x and Er2x detected in the first vertical movement of the limit cycle, and the two-position operation amount (OH_AT, OL_AT) is calculated based on this ratio RE. By modifying the above, the appropriate vertical movement of the control amount PV can be quickly obtained with the modified two-position operation amounts (OH_AT, OL_AT), so that the AT execution time can be shortened.

[Second Example]
Next, a second embodiment of the present invention will be described. FIG. 9 is a block diagram showing the configuration of the control parameter adjusting device according to the second embodiment of the present invention, and the same configurations as those in FIG. 2 are designated by the same reference numerals. The control parameter adjusting device of this embodiment includes a set value SP acquisition unit 1, a control amount PV acquisition unit 2, an operation amount MV output unit 3, a two-position operation amount lower setting unit 4, and a two-position operation amount upper side. Setting unit 5, limit cycle AT calculation unit 6, start instruction unit 7, ratio RE calculation unit 8, and correction coefficient setting unit 10 that sets the correction coefficient α of the correction amount of the two-position operation amount (OH_AT, OL_AT). And, based on the ratio RE and the correction coefficient α, the value estimated to be appropriate for the manipulated variable upper limit value OH_AT or the manipulated variable lower limit OL_AT is calculated, and the manipulated variable upper limit value OH_AT or the manipulated variable lower limit OL_AT is calculated. It is provided with a correction unit 11 with a two-position operation amount correction.

The controller to be adjusted by the control parameter adjusting device is as described in the first embodiment.
FIG. 10 is a flowchart illustrating the operation of the control parameter adjusting device of this embodiment during AT execution.
Set value SP acquisition unit 1, control amount PV acquisition unit 2, operation amount MV output unit 3, 2 position operation amount Lower setting unit 4 and 2 position operation amount Upper setting unit 5, limit cycle AT calculation unit 6, and start instruction unit The operation of 7 and the ratio RE calculation unit 8 (steps S100 to S105 in FIG. 10) is the same as that of the first embodiment.

In the correction coefficient setting unit 10, a correction coefficient α for appropriately correcting the correction amount of the two-position operation amount (OH_AT, OL_AT) is set in advance. As a result of diligent research by the inventor, when the two-position manipulated variable (OH_AT, OL_AT) is corrected using the ratio RE, the correction amount becomes large for higher-order controlled objects, and an error occurs in the correction. There was found.

As for the vertical movement of the controlled variable PV with respect to the manipulated variable MV output from the control parameter adjusting device or the controller, the higher the order of the controlled object, the more the behavior near the extreme value of the vertical motion is as shown by 110 in FIG. It changes from a linear behavior to a curvilinear behavior as shown by 111 and 112. When the curvilinear behavior near the extreme value of the controlled variable PV becomes large, the absolute values of the deviations on the maximum side and the minimum side become small at different magnifications as shown by ΔEr2x and ΔEr1x in FIG. 11, so that the ratio RE is biased. Affects the side with a large ratio (that is, the side where the ratio RE deviates from 1.0). Therefore, the amount of correction of the two-position operation amount (OH_AT, OL_AT) becomes large.

Therefore, in this embodiment, a value smaller than 1.0 is preset as the correction coefficient α. The correction unit 11 with the two-position manipulation amount correction determines whether or not the setting of the two-position manipulation amount (OH_AT, OL_AT) is appropriate as in the first embodiment (FIG. 10 step S106).

When the ratio RE is larger than 1 (YES in step S107 in FIG. 10), the correction unit 11 with 2-position manipulated variable determines that the manipulated variable lower limit value OL_AT is inappropriate, and corrects the manipulated variable lower limit as shown in the following equation. The value OL_AT_new is calculated, and this modified value OL_AT_new is output to the 2-position manipulated variable lower setting unit 4. The two-position manipulated variable lower setting unit 4 sets the correction value OL_AT_new in the limit cycle AT calculation unit 6 as a new value of the manipulated variable lower limit value OL_AT (step S108a in FIG. 10).
OL_AT_new = OL_AT + α (OH_AT-OL_AT) (RE-1)
/ (RE + 1) ・ ・ ・ (12)

Further, when the ratio RE is smaller than 1 (YES in step S109 of FIG. 10), the correction unit 11 with 2-position operation amount correction determines that the operation amount upper limit value OH_AT is inappropriate, and the operation amount upper limit value is as shown in the following equation. The correction value OH_AT_new of is calculated, and this correction value OH_AT_new is output to the 2-position manipulated variable upper setting unit 5. The two-position manipulated variable upper setting unit 5 sets the correction value OH_AT_new as a new value of the manipulated variable upper limit value OH_AT in the limit cycle AT calculation unit 6 (step S110a in FIG. 10).
OH_AT_new = OH_AT + α (OH_AT-OL_AT) (RE-1)
/ (RE + 1) ・ ・ ・ (13)

The operation (FIG. 10 steps S111, S112) of the limit cycle AT calculation unit 6 after the modification of the two-position manipulated variable (OH_AT, OL_AT) is the same as that of the first embodiment. The limit cycle AT ends when the calculation / setting of the PID parameter is completed.

FIG. 12 is a waveform diagram showing an example of changes in the manipulated variable MV and the controlled variable PV during AT execution of this embodiment, and FIG. 13 is an enlarged view of FIG. In the examples of FIGS. 12 and 13, the time is 20 sec. AT was started at the same time as the change of the first set value SP of, and the time was 464 sec. AT ends at this point. Then, the time after the end of AT is 800 sec. At the time of, the set value SP is changed again, and the temperature rise is controlled by the controller.

In this embodiment, by adopting the correction coefficient α = 0.95, the operation amount upper limit value OH_AT is corrected from the initial 100% to 21.0%. As a result, the behavior of the controlled variable PV is improved to a well-balanced vertical movement (vertical movement near time 400 sec.) As compared with the case of the first embodiment (FIGS. 7 and 8).
In this way, in this embodiment, it is possible to correct the correction error of the two-position manipulated variable (OH_AT, OL_AT) that occurs in the case of a high-order control target.

The control parameter adjusting device described in the first and second embodiments 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. A configuration example of this computer is shown in FIG.

The computer includes a CPU 200, a storage device 201, and an interface device (hereinafter, abbreviated as I / F) 202. For example, a temperature sensor, a controller, or the like is connected to the I / F 202. In such a computer, a program for realizing the control parameter adjusting method of the present invention is stored in the storage device 201. The CPU 200 executes the processes described in the first and second embodiments according to the program stored in the storage device 201.

The present invention can be applied to a technique for adjusting control parameters of a controller by a limit cycle method.

1 ... Set value SP acquisition unit, 2 ... Control amount PV acquisition unit, 3, 22 ... Operation amount MV output unit, 4 ... 2 Position operation amount lower setting unit, 5 ... 2 Position operation amount upper setting unit, 6 ... Limit Cycle AT calculation unit, 7 ... Start instruction unit, 8 ... Ratio RE calculation unit, 9 ... 2 position operation amount correction unit, 10 ... Correction coefficient setting unit, 11 ... 2 position operation amount correction correction unit, 20 ... Set value SP Input unit, 21 ... Control amount PV input unit, 23 ... PID control calculation unit.

Claims (6)

In a control parameter adjustment device equipped with a limit cycle auto-tuning function that sets controller control parameters,
A limit cycle auto-tuning calculation unit configured to alternately output the preset upper limit manipulated variable and lower bound manipulated variable to the control target.
Of the deviation between the control set value and the control amount, the ratio configured to calculate the ratio of the absolute value of the deviation at each of the first two extreme values of the control amount generated by the output of the operation amount. Calculation unit and
A correction unit configured to calculate an appropriate value of the upper limit value or the lower limit value based on the ratio and correct the upper limit value or the lower limit value to the calculated value is provided.
The limit cycle auto-tuning calculation unit calculates a control parameter of the controller based on the response of the control amount after the upper limit value or the lower limit value is corrected, and sets the calculated control parameter in the controller. A control parameter adjusting device characterized by. In the control parameter adjusting device according to claim 1,
Further, a correction coefficient setting unit configured to set a correction coefficient of the correction amount of the upper limit value or the lower limit value is provided.
The correction unit is a control parameter adjusting device that calculates an appropriate value of the upper limit value or the lower limit value based on the ratio and the correction coefficient. In the control parameter adjusting device according to claim 2.
A control parameter adjusting device, characterized in that the correction coefficient is set to a value smaller than 1. In the control parameter adjustment method that sets the control parameters of the controller by the limit cycle method,
The first step of alternately outputting the preset upper limit manipulated variable and the lower bound manipulated variable to the control target, and
A second step of calculating the ratio of the absolute value of the deviation to each of the first two extreme values of the control amount generated by the output of the operation amount among the deviations between the control set value and the control amount.
A third step of calculating an appropriate value of the upper limit value or the lower limit value based on the ratio and correcting the upper limit value or the lower limit value to the calculated value.
It is characterized by including a fourth step of calculating a control parameter of the controller based on the response of the control amount after the upper limit value or the lower limit value is corrected and setting the calculated control parameter in the controller. Control parameter adjustment method. In the control parameter adjusting method according to claim 4,
The third step includes a step of calculating an appropriate value of the upper limit value or the lower limit value based on the ratio and the correction coefficient of the upper limit value or the correction amount of the lower limit value. A control parameter adjustment method characterized by. In the control parameter adjusting method according to claim 5,
A control parameter adjusting method, characterized in that the correction coefficient is set to a value smaller than 1.

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