Parameter estimation apparatus and method

Abstract

To improve efficiency in determining and adjusting an appropriate parameter for an overshoot prevention function.SOLUTION: A parameter estimation device 1 comprises: an operation amount difference detection unit 10 that detects a change in an amount of operation MV in settings before and after application of disturbance when an overshoot prevention function of a control unit 2 is invalid; an overshoot amount detection unit 11 that detects a maximum value of the amount of overshoot; a disturbance deviation detection unit 12 that detects a maximum value of a disturbance deviation; a proportional band acquisition unit 13 that acquires a proportional band set to the control unit 2; a post-correction deviation estimation unit 14 that, on the basis of the change in the amount of operation MV and the proportional band, estimates a post-correction deviation to be ensured in deviation correction of the control unit 2 for overshoot prevention; and a proper value calculation unit 15 that calculates a proper value of a parameter for the deviation correction on the basis of a ratio between the maximum value of the amount of overshoot and the maximum value of the disturbance deviation and the post-correction deviation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for estimating parameters of a control device, and more particularly to a parameter estimation device and method for estimating parameters for an overshoot suppression function. [Background technology]

[0002] PID control, a typical feedback control, operates in the form of recovery control (disturbance recovery response) when a disturbance is applied to a temperature control system, and overshooting of the controlled variable often occurs due to factors such as the high heat retention of heating devices.

[0003] The heating device in Fig. 10 is composed of a heat treatment furnace 100 that heats the workpiece to be treated, an electric heater 101, a temperature sensor 102 that measures the temperature inside the heat treatment furnace 100, a temperature controller 103 that controls the temperature inside the heat treatment furnace 100, a power regulator 104, a power supply circuit 105, and a PLC (Programmable Logic Controller) 106 that controls the entire heating device. The temperature controller 103 calculates a manipulated variable MV so that the temperature PV (controlled variable) measured by the temperature sensor 102 matches the temperature set point SP. The power regulator 104 determines the power corresponding to the manipulated variable MV and supplies this determined power to the electric heater 101 via the power supply circuit 105.

[0004] Fig. 11 is a diagram showing an example of an overshoot that occurs during temperature control of the heating device shown in Fig. 10. The example in Fig. 11 shows an example in which a disturbance that causes the controlled variable PV to drop occurs during temperature control, and when the manipulated variable MV corresponding to the disturbance is output from the temperature controller 103 and disturbance recovery control is performed, an overshoot occurs in which the controlled variable PV exceeds the temperature set value SP = 300°C due to excessive manipulated variable correction.

[0005] An overshoot suppression function has been proposed to deal with the phenomenon shown in Fig. 11 (see Patent Document 1). In the technology disclosed in Patent Document 1, a correction amount Erx for the deviation Er (=SP-PV) between the set value SP and the controlled variable PV is calculated using a parameter ξ during the first half of the disturbance application (when the temperature is decreasing in Fig. 11), and the correction amount Erx is calculated using a parameter λ during the second half of the disturbance application (when the disturbance is converging).

[0006] Specifically, when the deviation Er is a positive or negative value and its absolute value |Er| increases, it is determined that a disturbance has been applied, and the deviation correction amount Erx is calculated as follows: Erx=ξEr (1)

[0007] The parameter ξ is, for example, 0.8. Next, a convergence calculation is performed so that the deviation correction amount Erx gradually converges to 0 according to a fixed rule. Specifically, the deviation correction amount Erx' after the convergence calculation is calculated as follows: Erx' = λErx (2)

[0008] The parameter λ (0<λ<1) is, for example, λ=0.95. By correcting the deviation Er using the deviation correction amount Erx' as described above (Er-Erx'), overshoot is suppressed. The effect of the technology disclosed in Patent Document 1 is shown in FIG. 12. Note that FIG. 12 shows the corrected set value SPh=SP-Erx' instead of the deviation correction amount Erx'. As disclosed in Patent Document 1, the deviation correction Er-Erx' is equivalent to the set value correction (SP-Erx')-PV.

[0009] In the technology disclosed in Patent Document 1, the parameter ξ is a constant. If an appropriate value for the parameter ξ specific to the target control system can be determined, there is no need to frequently change the value. However, the conventional technology disclosed in Patent Document 1 has a problem in that it has not been possible to realize a technology for determining an appropriate parameter ξ. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 3437807 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made to solve the above-mentioned problems, and aims to provide a parameter estimation device and method that can efficiently determine and adjust appropriate parameters for the overshoot suppression function of a control device. [Means for solving the problem]

[0012] a proportional band acquisition unit configured to acquire a proportional band among PID parameters set in the control device; a corrected deviation estimating unit configured to estimate a corrected deviation to be ensured in deviation correction of the control device to suppress overshoot, based on the change in the control variable and the proportional band; an optimum value calculation unit configured to calculate an optimum value of a parameter ξ for the deviation correction, based on the corrected deviation and the ratio of the maximum value of the overshoot amount to the maximum value of the disturbance deviation; and an optimum value output unit configured to output the optimum value of the parameter ξ.

[0013] In one configuration example of the parameter estimation device of the present invention, the optimum value calculation unit estimates an overshoot amount of the controlled variable with respect to the set value after a set value correction equivalent to the deviation correction is performed in the control device, based on the ratio between the maximum value of the overshoot amount and the maximum value of the disturbance deviation and the parameter ξ, and corrects the parameter ξ so that the overshoot amount becomes equal to or less than a specified ratio with respect to a deviation correction amount obtained by multiplying the deviation by the parameter ξ.

[0014] Furthermore, the present invention A parameter estimation method for estimating parameters of a control device using a computer having a CPU and a storage device, comprising: a first step of detecting a change in a manipulated variable output from the control device during settling after application of a disturbance when a disturbance is applied to the controlled object relative to a manipulated variable output from the control device during settling before application of the disturbance, in a state in which a function of the control device to correct a deviation between a set value and a controlled variable to suppress an overshoot of the controlled variable is disabled; a second step of detecting a maximum value of an overshoot amount of the controlled variable generated after application of the disturbance; a third step of detecting a maximum value of a disturbance deviation when the disturbance is applied; a fourth step of acquiring a proportional band in a PID parameter set in the control device; a fifth step of estimating a corrected deviation to be secured in deviation correction of the control device for suppressing overshoot based on the change in the manipulated variable and the proportional band; and a fifth step of estimating a corrected deviation to be secured in deviation correction of the control device for suppressing overshoot based on the ratio of the maximum value of the overshoot amount to the maximum value of the disturbance deviation and the corrected deviation. ξ a sixth step of calculating an appropriate value of the parameter ξ and a seventh step of outputting the correct value of and causing the CPU to execute the program stored in the storage device. It is characterized by the following.

[0015] In one configuration example of the parameter estimation method of the present invention, the sixth step includes a step of estimating an amount of overshoot of the controlled variable with respect to the set value after a set value correction equivalent to the deviation correction is performed in the control device, based on the ratio between the maximum value of the overshoot amount and the maximum value of the disturbance deviation and the parameter ξ, and correcting the parameter ξ so that the amount of overshoot becomes equal to or less than a specified rate with respect to a deviation correction amount obtained by multiplying the deviation by the parameter ξ. [Effects of the Invention]

[0016] According to the present invention, by providing an operation amount difference detection unit, an overshoot amount detection unit, a disturbance deviation detection unit, a proportional band acquisition unit, a corrected deviation estimator, an optimum value calculation unit, and an optimum value output unit, it is possible to efficiently determine and adjust an appropriate parameter ξ for the overshoot suppression function of the control device. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing the configuration of a parameter estimation device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart illustrating the operation of the control device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart illustrating the operation of the parameter estimation device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the simulation results of the disturbance recovery response by a control device to which the conventional technology is applied. [Figure 5] FIG. 5 is a diagram showing the simulation results of the disturbance recovery response of a conventional control device in which the overshoot suppression function is disabled. [Figure 6] FIG. 6 is a diagram showing the simulation results of the disturbance recovery response of the control device after the parameters are adjusted to appropriate values. [Figure 7]FIG. 7 is a diagram showing the simulation results of the disturbance recovery response of a conventional control device in which the overshoot suppression function is disabled. [Figure 8] FIG. 8 is a diagram showing the simulation results of the disturbance recovery response by the control device after the parameters are adjusted to appropriate values. [Figure 9] FIG. 9 is a block diagram showing an example of the configuration of a computer that realizes a parameter estimation device and a control device according to an embodiment of the present invention. [Figure 10] FIG. 10 is a block diagram showing the configuration of the heating device. [Figure 11] FIG. 11 is a diagram showing an example of an overshoot that occurs during temperature control of a heating device. [Figure 12] FIG. 12 is a diagram showing the effect of the conventional overshoot suppression function. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Principle of the Invention] In the following explanation, the principle of the invention will be explained with the understanding that it involves correcting the setpoint SP. When considered as an operation for correcting the setpoint SP, the operation of the technology disclosed in Patent Document 1 causes the corrected setpoint SPg (=SP-Erx) to decrease in synchronization with a decrease in the controlled variable PV at a ratio defined by the parameter ξ. In other words, the deviation input to the PID calculation becomes smaller than the actual deviation Er, and the change in the manipulated variable MV also decreases in response to the decrease in the deviation. Considering that it is appropriate to reduce the manipulated variable MV by the amount that contributes to overshoot, it is preferable to correct the setpoint SP so that the change ΔMV in the manipulated variable MV during settling before and after the disturbance recovery response remains.

[0019] Disturbances can be broadly divided into step disturbances and impulse disturbances, with step disturbances generating a change ΔMV in the manipulated variable MV, while impulse disturbances do not. Since the mixture of these two types makes it difficult to determine the parameter ξ, it is sufficient to try a disturbance recovery response at least once and determine the parameter ξ according to the change ΔMV in the manipulated variable MV at that time.

[0020] In the present invention, it is assumed that, for example, after the parameter λ has been appropriately adjusted, there is a change in the nature of the controlled object or the disturbance related to the parameter ξ. However, it is also possible to adjust the parameter λ by trial and error after adjusting the parameter ξ.

[0021] [Example] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a parameter estimation device according to an embodiment of the present invention. The parameter estimation device 1 includes a manipulated variable difference detection unit 10 for detecting a change ΔMV in the manipulated variable MV output from the control device 2 to the controlled object during settling after the application of a disturbance, relative to the manipulated variable MV output from the control device 2 to the controlled object during settling before the application of the disturbance, when a disturbance is applied to the controlled variable PV in a state in which a function of the control device 2 to correct the deviation Er between a setpoint SP and a controlled variable PV to suppress overshoot of the controlled variable PV is disabled; an overshoot amount detection unit 11 for detecting a maximum value OS_max of the amount of overshoot of the controlled variable PV generated after the application of the disturbance; and a disturbance deviation detection unit 22 for detecting a maximum value Er_max of the disturbance deviation when the disturbance is applied. a proportional band acquisition unit 13 that acquires a proportional band Pb in the PID parameters set in the control device 2; a corrected deviation estimation unit 14 that estimates a corrected deviation Erh that should be secured in the deviation correction of the control device 2 to suppress overshoot, based on the change ΔMV in the manipulated variable MV and the proportional band Pb; an optimum value calculation unit 15 that calculates an optimum value of a parameter ξ for deviation correction, based on the ratio of the maximum value OS_max of the overshoot amount to the maximum value Er_max of the disturbance deviation, and the corrected deviation Erh; and an optimum value output unit 16 that outputs the optimum value of the parameter ξ.

[0022] The control device 2 includes a control quantity input unit 20 that takes the control quantity PV as an input, a set value input unit 21 that takes the set value SP as an input, a subtraction unit 22 that subtracts the control quantity PV from the set value SP to calculate the deviation Er, a disturbance application detection unit 23 that determines whether a disturbance has been applied based on the deviation Er for each control cycle, and determines that a disturbance has been applied when the absolute value of the deviation Er increases, a deviation correction quantity calculation unit 24 that calculates a deviation correction quantity Erx based on the magnitude of the deviation Er when the application of the disturbance is detected by the disturbance application detection unit 23, a deviation correction quantity convergence calculation unit 25 that performs a convergence operation so that the deviation correction quantity Erx calculated by the deviation correction quantity calculation unit 24 gradually converges to 0 according to a certain rule, a control calculation unit 26 that calculates the operation quantity MV by PID control calculation based on the deviation Er and the deviation correction quantity after the convergence operation, and an operation quantity output unit 27 that outputs the operation quantity MV to the control target.

[0023] First, before explaining the parameter estimation device 1, the operation of the control device 2 disclosed in Patent Document 1 will be briefly explained. FIG. 2 is a flowchart for explaining the operation of the control device 2. The control quantity PV measured by a sensor (not shown) is input to the control quantity input unit 20 (step S101 in FIG. 2).

[0024] The set value SP set by the operator is input to the set value input unit 21 (step S102 in FIG. 2). The subtraction unit 22 calculates the deviation Er = SP - PV between the set value SP and the control quantity PV (step S103 in FIG. 2).

[0025] Next, the disturbance application detection unit 23 determines whether a disturbance has been applied for each control cycle, and outputs a start signal s1 to the deviation correction quantity calculation unit 24 when it is determined that a disturbance has been applied (step S104 in FIG. 2). Specifically, the disturbance application detection unit 23 determines that a disturbance has been applied when the deviation Er is a positive value and the absolute value |Er| is increasing (when Er > 0 and Er > Er' (Er' is the deviation in the previous control cycle) holds), or when the deviation Er is a negative value and the absolute value |Er| is increasing (when Er < 0 and Er < Er' holds).

[0026] When the start signal s1 is output from the disturbance application detection unit 23 (YES in step S104), the deviation correction amount calculation unit 24 calculates the deviation correction amount Erx by multiplying the deviation Er by the parameter ξ as shown in equation (1), and outputs this to the deviation correction amount convergence calculation unit 25 (step S105 in FIG. 2).

[0027] Next, the deviation correction amount convergence calculation unit 25 calculates the deviation correction amount Erx' after the convergence calculation as shown in Equation (2) (Step S106 in FIG. 2). The parameter λ is a constant (0<λ<1). The deviation correction amount calculation unit 24 outputs the deviation correction amount Erx only when the disturbance application detection unit 23 determines that a disturbance has been applied. In other words, when the situation in which the absolute value |Er| of the deviation increases (the situation in which the control amount PV deviates from the set value SP) ends, the output of the start signal s1 stops, and the output of the deviation correction amount Erx by the deviation correction amount calculation unit 24 stops.

[0028] When the deviation correction amount Erx is not output from the deviation correction amount calculation unit 24, the deviation correction amount convergence calculation unit 25 performs the convergence calculation of equation (2) using the deviation correction amount Erx' that was used in the convergence calculation one control cycle ago as the deviation correction amount Erx of the current control cycle. The initial value of the deviation correction amount Erx' (Erx) is 0.

[0029] The control calculation unit 26 performs PID control calculation as shown in the following equation based on the value obtained by subtracting the deviation correction amount Erx' after the convergence calculation from the deviation Er, to calculate the manipulated variable MV (step S107 in FIG. 2). MV=(100 / Pb){1+(1 / Tis)+Tds}(Er-Erx') ···(3)

[0030] In equation (3), Pb is the proportional band, Ti is the integral time, Td is the differential time, and s is the Laplace operator. The manipulated variable MV calculated by the control calculation unit 26 is output to the controlled object (actually, for example, the power regulator 104 in FIG. 10) via the manipulated variable output unit 27 (step S108 in FIG. 2).

[0031] The control device 2 executes the processes of steps S101 to S108 for each control cycle until the control is terminated, for example, in response to an instruction from an operator (YES in step S109 in FIG. 2).

[0032] Next, the operation of the parameter estimation device 1 of this embodiment will be described with reference to Fig. 3. The parameter estimation device 1 is connected to the control device 2 when adjusting the parameter ξ. First, the manipulated variable difference detection unit 10 disables the overshoot suppression function of the control device 2 (step S200 in FIG. 3). When the overshoot suppression function is disabled, the deviation correction amount Erx' becomes 0, and therefore the control calculation unit 26 of the control device 2 calculates the manipulated variable MV using the following equation (4) instead of equation (3). MV=(100 / Pb){1+(1 / Tis)+Tds}Er...(4)

[0033] After the disturbance application detection unit 23 of the control device 2 determines that a disturbance has been applied while the overshoot suppression function of the control device 2 is disabled (YES in step S201 of FIG. 3), when the controlled variable PV has settled due to the disturbance recovery response (YES in step S202 of FIG. 3), the controlled variable difference detection unit 10 detects the change ΔMV in the controlled variable MV at the time of settling after the disturbance application relative to the controlled variable MV at the time of settling before the disturbance application (step S203 of FIG. 3).

[0034] In the case of the heating device shown in FIG. 10, for example, during an experiment to determine the parameter ξ, it is possible to intentionally generate a disturbance that causes the temperature inside the heat treatment furnace 100 (control variable PV) to drop by temporarily opening the door of the heat treatment furnace 100.

[0035] The overshoot amount detection unit 11 detects the maximum value OS_max of the overshoot amount of the controlled variable PV that occurs due to the disturbance recovery response after the disturbance is applied when the overshoot suppression function of the control device 2 is disabled (step S204 in FIG. 3 ). This is the difference PV_max-SP between the maximum value PV_max of the increased controlled variable PV and the set value SP.

[0036] The disturbance deviation detection unit 12 detects the maximum value Er_max of the disturbance deviation when a disturbance is applied while the overshoot suppression function of the control device 2 is disabled (the difference SP-PV_min between the set value SP and the minimum value PV_min of the decreased control amount PV) (step S205 in FIG. 3). The proportional band acquisition unit 13 acquires the proportional band Pb from the PID parameters set in the control calculation unit 26 of the control device 2 (step S206 in FIG. 3).

[0037] The corrected deviation estimating unit 14 estimates the corrected deviation Erh to be ensured in correcting the deviation Er for suppressing overshoot, based on the change ΔMV in the manipulated variable MV detected by the manipulated variable difference detecting unit 10 and the proportional band Pb acquired by the proportional band acquiring unit 13 (step S207 in FIG. 3). Specifically, the corrected deviation Erh is a deviation required for generating the manipulated variable change ΔMV by only the proportional action of the control device 2 defined by the proportional band Pb. The corrected deviation estimating unit 14 calculates the corrected deviation Erh using the following equation. Erh = ΔMV(Pb / 100) (5)

[0038] The optimum value calculation unit 15 calculates an optimum value candidate (provisional value) ξa of the parameter ξ by the following equation based on the maximum value Er_max of the disturbance deviation detected by the disturbance deviation detection unit 12 and the corrected deviation Erh calculated by the corrected deviation estimation unit 14 (step S208 in FIG. 3). ξa=(Er_max-Erh) / Er_max ···(6)

[0039] The formula (6) is obtained from the relationship of the deviation correction amount Erx=ξEr_max=Er_max−Erh. Next, since the corrected setting value SPg can be estimated using the appropriate value candidate ξa of the parameter ξ, the appropriate value calculation unit 15 estimates the overshoot amount OSx of the controlled variable PV with respect to the setting value SPg after setting value correction equivalent to the deviation correction, based on the appropriate value candidate ξa, the maximum overshoot amount OS_max detected by the overshoot amount detection unit 11, and the maximum disturbance deviation Er_max detected by the disturbance deviation detection unit 12, using the following equation (step S209 in FIG. 3). OSx=ErhOS_max / Er_max =(Er_max-ξaEr_max)OS_max / Er_max ·(7)

[0040] Equation (7) is derived from the property that when there is no change in the characteristics of the PID control system of the control device 2, the ratio between the disturbance deviation and the overshoot amount (overshoot rate) is maintained (Er_max:OS_max=Erh:OSx).

[0041] The corrected set value SPg assumed in the calculation of equation (7) is not the corrected set value SPh=SP-Erx' itself, which corresponds to the corrected deviation used by the control device 2 when calculating the manipulated variable MV, but is the value SPg=SP-Erx obtained by correcting the set value SP using the deviation correction amount Erx. Therefore, the deviation correction in the above-mentioned "set value correction equivalent to deviation correction" means Er-Erx, not Er-Erx'.

[0042] If the calculated overshoot amount OSx is greater than the deviation correction amount Erx=ξaEr_max (in the case of FIG. 12, the overshoot amount is greater than the drop in the corrected set value SPh, causing the controlled variable PV to exceed the pre-correction set value SP), then overshoot suppression is insufficient. More precisely, the overshoot amount OSx occurs while the deviation correction amount Erx is converging to the pre-correction set value SP. The period during which the parameter λ is converged to the set value SP is a time period that is approximately 1.5 times the time constant T when the parameter λ is equivalently converted to the time constant T. The relationship between the parameter λ and the time constant T is as shown in Equation (8). dt is the control period of the control device 2. λ=T / (T+dt) (8)

[0043] Therefore, when the overshoot amount OSx exceeds a specified ratio with respect to the deviation correction amount Erx, specifically when OSx>Erx / (2.718×1.5) is established (YES in step S210 in FIG. 3), the optimum value calculation unit 15 corrects the optimum value candidate ξa of the parameter ξ using the following equation (step S211 in FIG. 3). ξa_new=ξa+0.01 (9)

[0044] The above 2.718 is a value corresponding to the convergence amount of the deviation correction amount Erx, and is the Napier's constant used in exponential functions. The optimum value calculation unit 15 sets the calculated ξa_new as a new optimum value candidate ξa, and returns to the calculation process of the overshoot amount OSx in step S209. In this way, the optimum value calculation unit 15 repeats the processes of steps S209 to S211 until the overshoot amount OSx becomes equal to or less than the specified ratio with respect to the deviation correction amount Erx, that is, until OSx≦Erx / (2.718×1.5) is established (NO in step S210).

[0045] The optimum value calculation unit 15 determines the optimum value candidate ξa when OSx≦Erx / (2.718×1.5) is satisfied as the optimum value of the parameter ξ. The optimum value output unit 16 outputs the optimum value of the parameter ξ (step S212 in FIG. 3). An example of the output is a display of the optimum value. The operator looks at the displayed optimum value and changes the parameter ξ set in the control device 2. Alternatively, the optimum value output unit 16 may automatically update the parameter ξ set in the deviation correction amount calculation unit 24 of the control device 2 to the optimum value.

[0046] It is preferable to predefine the upper limit of the parameter ξ as ξ_max = 0.99. In this case, the optimum value calculation unit 15 ends the search process of steps S209 to S211 when ξa_new in equation (9) reaches the upper limit ξ_max before OSx≦Erx / (2.718×1.5) is satisfied, and determines the upper limit ξ_max as the optimum value of the parameter ξ.

[0047] This completes the adjustment of the parameter ξ. After the adjustment is complete, the operator operates the parameter estimation device 1 to reactivate the overshoot suppression function of the control device 2, and releases the connection between the parameter estimation device 1 and the control device 2 (step S213 in FIG. 3).

[0048] 4 to 6 show verification examples of this embodiment when a change with a strong tendency toward impulse disturbance occurs in the controlled variable PV (change in the manipulated variable MV ΔMV=1.0%). Note that this verification example is premised on the assumption that the time constant T corresponding to the parameter λ of the control device 2 is adjusted to a generally appropriate value at T=120 seconds. However, after adjusting the parameter ξ by the parameter estimation device 1, the time constant T (parameter λ) may be fine-tuned by trial and error.

[0049] Fig. 4 is a diagram showing the simulation results of the disturbance recovery response by the control device 2 to which the technology disclosed in Patent Document 1 is applied. In the example of Fig. 4, the time constant T corresponding to the parameter λ is set to a generally appropriate value of T = 120 seconds, but the parameter ξ is set to an inappropriate value of ξ = 0.50, and therefore, when a disturbance occurs that causes the controlled variable PV to decrease, an overshoot occurs in which the controlled variable PV exceeds the set value SP = 300°C due to excessive correction of the manipulated variable.

[0050] Here, it is assumed that the parameter ξ and the time constant T were originally adjusted appropriately, but that the balance between the impulse disturbance tendency and the step disturbance tendency changed, causing the parameter ξ to become inappropriate. In other words, it is assumed that the parameter ξ is the one that needs to be adjusted.

[0051] Fig. 5 is a diagram showing the simulation results of the disturbance recovery response by the control device 2 under the same conditions as Fig. 4, but with the overshoot suppression function disclosed in Patent Document 1 disabled. That is, the example in Fig. 5 corresponds to the disturbance recovery response performed in steps S200 to S205. In the example in Fig. 5, the change in the manipulated variable MV is small, ΔMV = 1.0%, and there is a tendency for the disturbance to be impulsive.

[0052] In this embodiment, the overshoot amount detection unit 11 detects the maximum value of the overshoot amount OS_max=8°C, and the disturbance deviation detection unit 12 detects the maximum value of the disturbance deviation Er_max=20°C. The proportional band Pb set in the control calculation unit 26 of the control device 2 is 100%. The optimum value calculation unit 15 in this embodiment calculates the optimum value of the parameter ξ to be ξ=0.95.

[0053] Fig. 6 is a diagram showing the simulation results of the disturbance recovery response by the control device 2 after the parameter ξ is adjusted to an appropriate value. In the example of Fig. 6, it can be seen that the time constant T corresponding to the parameter λ is set to a roughly appropriate value of T = 120 seconds, and further the parameter ξ is set to an appropriate value of ξ = 0.95, thereby appropriately suppressing the overshoot of the controlled variable PV.

[0054] 7 and 8 show examples of verification of this embodiment when a change with a strong tendency toward a step disturbance occurs in the controlled variable PV (change in the manipulated variable MV ΔMV=30.0%). Note that this verification example is based on the premise that the time constant T corresponding to the parameter λ of the control device 2 is adjusted to a generally appropriate value of T=230 seconds.

[0055] Fig. 7 is a diagram showing the simulation results of the disturbance recovery response by the control device 2 in which the overshoot suppression function disclosed in Patent Document 1 is disabled. That is, the example in Fig. 7 corresponds to the disturbance recovery response performed in steps S200 to S205. In the example in Fig. 7, the change in the manipulated variable MV is large at ΔMV = 30.0%, which indicates a tendency toward a step disturbance.

[0056] In this embodiment, the overshoot amount detection unit 11 detects the maximum value of the overshoot amount OS_max=5.5°C, and the disturbance deviation detection unit 12 detects the maximum value of the disturbance deviation Er_max=23°C. The proportional band Pb set in the control calculation unit 26 of the control device 2 is 100%. The optimum value calculation unit 15 in this embodiment calculates the optimum value of the parameter ξ to be ξ=0.50.

[0057] Fig. 8 is a diagram showing the simulation results of the disturbance recovery response by the control device 2 after the parameter ξ is adjusted to an appropriate value. In the example of Fig. 8, it can be seen that the time constant T corresponding to the parameter λ is set to a roughly appropriate value of T = 230 seconds, and further the parameter ξ is set to an appropriate value of ξ = 0.50, thereby appropriately suppressing the overshoot of the controlled variable PV.

[0058] In this embodiment, the parameter estimation device 1 and the control device 2 are provided separately, but the parameter estimation device 1 may be provided inside the control device 2.

[0059] The parameter estimation device 1 and the control device 2 of this embodiment can each be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface with the outside, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Fig. 9. The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202.

[0060] In the case of the parameter estimation device 1, the control device 2, a display device, etc. are connected to the I / F 202. In the case of the control device 2, the parameter estimation device 1, a sensor, a power regulator, etc. are connected to the I / F 202. A program for realizing the parameter estimation method of the present invention is stored in the storage device 201. The CPU 200 of each device executes the processing described in this embodiment in accordance with the program stored in the storage device 201. [Industrial Applicability]

[0061] The present invention can be applied to a technique for estimating parameters of a control device. [Explanation of symbols]

[0062] 1...parameter estimation device, 2...control device, 10...operated variable difference detection unit, 11...overshoot amount detection unit, 12...disturbance deviation detection unit, 13...proportional band acquisition unit, 14...corrected deviation estimation unit, 15...optimum value calculation unit, 16...optimum value output unit, 20...controlled variable input unit, 21...set value input unit, 22...subtraction unit, 23...disturbance application detection unit, 24...deviation correction amount calculation unit, 25...deviation correction amount convergence calculation unit, 26...control calculation unit, 27...operated variable output unit

Claims

1. a manipulated variable difference detection unit configured to detect, when a disturbance is applied to the controlled variable, a change in the manipulated variable output from the control device to the controlled object during settling after the application of the disturbance, relative to the manipulated variable output from the control device during settling before the application of the disturbance, in a state in which a function of the control device to correct a deviation between a set value and a controlled variable to suppress overshoot of the controlled variable is disabled; an overshoot amount detection unit configured to detect a maximum value of an overshoot amount of the controlled variable that occurs after the disturbance is applied; a disturbance deviation detection unit configured to detect a maximum value of the disturbance deviation when the disturbance is applied; a proportional band acquisition unit configured to acquire a proportional band among PID parameters set in the control device; a corrected deviation estimating unit configured to estimate a corrected deviation to be ensured in deviation correction of the control device for suppressing overshoot, based on the change in the manipulated variable and the proportional band; an optimum value calculation unit configured to calculate an optimum value of a parameter ξ for the deviation correction based on the ratio between the maximum value of the overshoot amount and the maximum value of the disturbance deviation and the corrected deviation; and an optimum value output unit configured to output an optimum value of the parameter ξ.

2. 2. The parameter estimation device according to claim 1, the optimum value calculation unit estimates an amount of overshoot of the controlled variable with respect to the set value after a set value correction equivalent to the deviation correction is performed in the control device, based on a ratio between a maximum value of the overshoot amount and a maximum value of the disturbance deviation, and on the parameter ξ, and corrects the parameter ξ so that the amount of overshoot is equal to or less than a specified ratio of a deviation correction amount obtained by multiplying the deviation by the parameter ξ.

3. A parameter estimation method for estimating parameters of a control device using a computer having a CPU and a storage device, a first step of detecting, when a disturbance is applied to the controlled variable, a change in the manipulated variable output from the control device to the controlled object during settling after the application of the disturbance, with respect to the manipulated variable output from the control device during settling before the application of the disturbance, in a state in which a function of the control device to correct a deviation between a set value and a controlled variable to suppress an overshoot of the controlled variable is disabled; a second step of detecting a maximum value of an overshoot amount of the controlled variable that occurs after the disturbance is applied; a third step of detecting a maximum value of the disturbance deviation when the disturbance is applied; a fourth step of acquiring a proportional band among the PID parameters set in the control device; a fifth step of estimating a corrected deviation to be ensured in deviation correction of the control device for suppressing overshoot, based on the change in the manipulated variable and the proportional band; a sixth step of calculating an appropriate value of a parameter ξ for correcting the deviation based on the ratio of the maximum value of the overshoot amount to the maximum value of the disturbance deviation and the corrected deviation; a seventh step of outputting an appropriate value of the parameter ξ; A parameter estimation method characterized by causing the CPU to execute the program stored in the storage device.

4. 4. The parameter estimation method according to claim 3, the sixth step includes a step of estimating an amount of overshoot of the controlled variable with respect to the set value after a set value correction equivalent to the deviation correction is performed in the control device, based on a ratio between a maximum value of the overshoot amount and a maximum value of the disturbance deviation, and on the parameter ξ, and correcting the parameter ξ so that the amount of overshoot is equal to or less than a specified rate with respect to a deviation correction amount obtained by multiplying the deviation by the parameter ξ.

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