Control system and control method

Abstract

This compensates for the deviation that is insufficient when using feedforward control alone. [Solution] The data processing device 1 includes a controlled object model storage unit 10, a manipulated variable margin information designation unit 11 that specifies a time ΔT for the margin of model dead time of the controlled object model, a manipulated variable information generation unit 12 that executes a simulation that simulates the control response of a virtual control system consisting of a controlled object represented by the controlled object model and a controller, with the constraint being that a rectangular wave-shaped manipulated variable MV is output when a set value is changed, calculates a change pattern of the manipulated variable MV and a change pattern of the controlled variable PV that meets the evaluation conditions, and corrects the change pattern of the manipulated variable MV so that the maintenance time of the rectangular wave-shaped manipulated variable MV is shortened by the time ΔT, a controlled variable information storage unit 13 that stores time series data of the controlled variable PV, and a controlled variable information storage unit 14 that stores pattern information for generating time series data of the corrected controlled variable MV.

Description

[Technical Field]

[0001] The present invention relates to a control system and a control method that use both feedforward control and feedback control. [Background technology]

[0002] Regarding PID control, a technology for automatically adjusting PID parameters using a controlled object model to maintain optimal control performance when a set value SP is changed has been disclosed (Patent Document 1). This PID parameter adjustment technology is particularly applicable to temperature controllers, which are PID controllers for temperature control. More specifically, this is a method for searching for PID parameters so that the controlled variable PV follows a target trajectory, and theoretically, this method assumes feedback control (PID control) based on linear control theory for a controlled object with linear characteristics.

[0003] A linear characteristic is a characteristic in which the relationship between the theoretical manipulated variable MV and the output action to the actual controlled object is linear when the horizontal axis of the graph represents the output value of the theoretical manipulated variable MV from 0% to 100% and the vertical axis represents the output action to the actual controlled object from 0% to 100%, as shown in Fig. 22. However, for example, a slightly nonlinear characteristic (weakly nonlinear characteristic) as shown in Fig. 23 can be applied to the technology disclosed in Patent Document 1 as an allowable range for PID control.

[0004] The technique of Patent Document 1 (particularly the manipulated variable maintenance time search and calculation unit) can be interpreted as simultaneously designing feedforward control in which the target trajectory of the controlled variable PV is an ideal trajectory and the manipulated variable MV applied to generate that ideal trajectory is the manipulated variable MV_f of the feedforward control. However, this is only a target trajectory generation for the purpose of automatically adjusting PID parameters, and is not intended as a design for feedforward control that works in conjunction with feedback control. Therefore, if the technique disclosed in Patent Document 1 is applied to design a controller that performs feedforward control and feedback control, there is a possibility that the feedback control will not be able to compensate for the deviation that is insufficient in feedforward control alone (i.e., the feedforward control and feedback control will not work together appropriately), and improvements are needed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4223894 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a control system and a control method that can compensate for the deviation that is insufficient when using feedforward control alone. [Means for solving the problem]

[0007] The control system of the present invention includes a first storage unit configured to store a controlled object model for simulation; a manipulated variable margin information designation unit configured to designate a margin time of a model dead time of the controlled object model with respect to a maintenance time of a maximum manipulated variable that can be output by a controller that executes feedforward control and feedback control; and a control variable margin information designation unit configured to execute a simulation that simulates the control response of a virtual control system consisting of the controlled object represented by the controlled object model and the controller, with a constraint that a rectangular wave-shaped manipulated variable having a magnitude of the maximum value is output when a set value is changed, calculate a change pattern of the manipulated variable and a change pattern of the controlled variable that comply with specified evaluation conditions, and correct the change pattern of the manipulated variable so that the maintenance time of the rectangular wave-shaped manipulated variable is shortened by the margin time. The control system is characterized by comprising: a manipulated variable information generating unit; a second storage unit configured to store time series data of a change pattern of the manipulated variable; a third storage unit configured to store pattern information for generating time series data of the change pattern of the manipulated variable after correction; and a transmitting unit configured to transmit the time series data of the controlled variable stored in the second storage unit to a PID controller that performs feedforward control and feedback control, or to transmit data calculated based on the time series data of the controlled variable stored in the second storage unit to the PID controller, and to transmit the time series data of the controlled variable generated from the pattern information to the PID controller, or to transmit data calculated based on the time series data of the controlled variable generated from the pattern information to the PID controller.

[0008] In addition, in one configuration example of the control system of the present invention, the manipulated variable information generation unit executes the simulation multiple times to search for a change pattern of the manipulated variable and a change pattern of the controlled variable that meet the evaluation condition, and the evaluation condition is characterized in that the overshoot amount of the controlled variable is 0.0 and the maintenance time of the rectangular wave-shaped manipulated variable that the virtual controller outputs to the controlled object when the set value is changed is the longest among the multiple simulations. In addition, in one configuration example of the control system of the present invention, the constraint conditions further include a second operation amount upper limit value that is smaller than the first operation amount upper limit value set in the PID controller, and a second operation amount lower limit value that is larger than the first operation amount lower limit value set in the PID controller, and the change pattern of the operation amount calculated by the operation amount information generation unit is limited to a value that is equal to or larger than the second operation amount lower limit value and equal to or smaller than the second operation amount upper limit value. In addition, in one configuration example of the control system of the present invention, the pattern information is characterized in that it includes a settling-time manipulated variable for settling the controlled variable to the changed set value, an initial value of the manipulated variable, a time from the start of control to the change of the set value, a value of the rectangular wave-shaped manipulated variable, and a maintenance time for the rectangular wave-shaped manipulated variable.

[0009] In one configuration example of the control system of the present invention, the transmission unit, at a specified timing, sequentially retrieves control amount data for each control cycle from the time series data of the control amount stored in the second storage unit and sequentially transmits the data to the PID controller, and at the same time sequentially retrieves control amount data for each control cycle from the time series data of the control amount generated from the pattern information and sequentially transmits data of a control amount change range calculated from the retrieved data to the PID controller, and the PID controller receives the control amount transmitted from the transmission unit as a new value of a reference setting value and receives the control amount change range transmitted from the transmission unit as a new value of a change range of a feedforward control control amount, a control amount acquisition unit configured to acquire a measured value of the control amount, and a first control amount for one control cycle before The control system is characterized by comprising: a feedforward adder configured to calculate, as a second manipulated variable, a value obtained by adding a change range of the feedforward control manipulated variable received by the receiver to a manipulated variable; a feedback adder configured to use the reference set value and the measured value of the controlled variable as inputs, perform a speed-type PID calculation to calculate a change range of the feedback control manipulated variable, and calculate, as a new value of the first manipulated variable, a value obtained by adding the change range of the feedback control manipulated variable to the second manipulated variable; a limiting processor configured to limit the first manipulated variable calculated by the feedback adder to a value equal to or greater than a first manipulated variable lower limit value and equal to or less than a first manipulated variable upper limit value; and a manipulated variable output unit configured to output the first manipulated variable limit-processed by the limiting processor to a controlled object.

[0010] In one configuration example of the control system of the present invention, the transmission unit transmits the time series data of the controlled variable stored in the second storage unit to the PID controller, and at the same time transmits the time series data of the manipulated variable generated from the pattern information to the PID controller, and the PID controller includes a reception unit configured to receive the time series data of the controlled variable and the time series data of the manipulated variable transmitted from the transmission unit, a fourth storage unit configured to store the time series data of the controlled variable and the time series data of the manipulated variable received by the reception unit, and a start signal input unit configured to receive a start signal instructing the start of a control operation from an external device, and when the start signal input unit receives the start signal and the control operation is started, sequentially reads out the data of the controlled variable for each control period from the time series data of the controlled variable stored in the fourth storage unit as a new value of the reference set value for each control period, and simultaneously reads out the data of the controlled variable for each control period from the time series data of the controlled variable stored in the fourth storage unit as a new value of the reference set value for each control period. a readout unit configured to sequentially read out data on the manipulated variable for each control cycle from the time-series data on the manipulated variable stored in the memory unit as a new value of the feedforward control manipulated variable for each control cycle; a controlled variable acquisition unit configured to acquire a measured value of the controlled variable; a feedback calculation unit configured to perform PID calculation using the reference set value and the measured value of the controlled variable as inputs to calculate a first manipulated variable; a feedforward addition unit configured to add the feedforward control manipulated variable to the first manipulated variable to calculate a second manipulated variable; a limit processing unit configured to limit the second manipulated variable calculated by the feedback addition unit to a value equal to or greater than a first manipulated variable lower limit value and equal to or less than a first manipulated variable upper limit value; and a manipulated variable output unit configured to output the second manipulated variable limited by the limit processing unit to a controlled object.

[0011] The constraint method of the present invention includes a first step of specifying a time for a margin of a model dead time of a controlled object model relative to a time for maintaining a maximum manipulated variable that can be output by a controller that executes feedforward control and feedback control; a second step of executing a simulation to simulate a control response of a virtual control system consisting of the controlled object represented by the controlled object model and the controller, with a constraint condition that a rectangular wave-shaped manipulated variable having a magnitude of the maximum value is output when a set value is changed, calculating a change pattern of the manipulated variable and a change pattern of the controlled variable that meet specified evaluation conditions, and correcting the change pattern of the manipulated variable so that the time for maintaining the rectangular wave-shaped manipulated variable is shortened by the margin; and a third step of storing time series data of the modified manipulated variable; a fourth step of storing pattern information for generating time series data of a change pattern of the manipulated variable after correction; and a fifth step of transmitting the time series data of the controlled variable stored in the third step to a PID controller that performs feedforward control and feedback control, or transmitting data calculated based on the time series data of the controlled variable stored in the third step to the PID controller, and transmitting time series data of the controlled variable generated from the pattern information to the PID controller, or transmitting data calculated based on the time series data of the controlled variable generated from the pattern information to the PID controller. [Effects of the Invention]

[0012] According to the present invention, by providing a first storage unit, a manipulated variable margin information designation unit, a manipulated variable information generation unit, a second storage unit, a third storage unit, and a transmission unit, it is possible to adjust the time margin required for interlocking feedforward control and feedback control, and therefore it is possible to interlock feedback control to compensate for the deviation that is insufficient when using feedforward control alone. As a result, the present invention can reduce overshoot of the controlled variable and also reduce the time required for the controlled variable to settle. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram showing the configuration of a data processing device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing the configuration of a PID controller according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart illustrating the operation of the data processing device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of a simulation performed by the operation amount information generating unit according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a diagram showing another example of a simulation performed by the manipulated variable information generating unit according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing another example of a simulation performed by the manipulated variable information generating unit according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing another example of a simulation performed by the manipulated variable information generating unit according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing an example of a change pattern of the manipulated variable after correction by the manipulated variable information generating unit according to the first embodiment of the present invention. [Figure 9] FIG. 9 is a flowchart illustrating the operation of the PID controller according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of a search result by the operation amount information generating unit according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing an example of a simulation result of control according to the first embodiment of the present invention. [Figure 12] FIG. 12 is a diagram showing another example of the simulation results of the control according to the first embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing another example of the simulation results of the control according to the first embodiment of the present invention. [Figure 14] FIG. 14 is a diagram showing another example of the simulation results of the control according to the first embodiment of the present invention. [Figure 15] FIG. 15 is a diagram showing another example of the simulation results of the control according to the first embodiment of the present invention. [Figure 16] FIG. 16 is a block diagram showing the configuration of a data processing device according to the second embodiment of the present invention. [Figure 17] FIG. 17 is a block diagram showing the configuration of a PID controller according to a second embodiment of the present invention. [Figure 18] FIG. 18 is a flowchart illustrating the operation of the data processing device according to the second embodiment of the present invention. [Figure 19] FIG. 19 is a flowchart illustrating the operation of the PID controller according to the second embodiment of the present invention. [Figure 20] FIG. 20 is a flowchart illustrating the operation of the PID controller according to the second embodiment of the present invention. [Figure 21] FIG. 21 is a block diagram showing an example of the configuration of a computer that realizes a data processing device and a PID controller according to the first and second embodiments of the present invention. [Figure 22] FIG. 22 is a diagram illustrating a control target having linear characteristics. [Figure 23] FIG. 23 is a diagram illustrating a control target with weak nonlinear characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Principle 1] The inventors have noticed that when feedforward control is combined with feedback control (PID control) and the role of the feedback control is to compensate for the deviation that is insufficient when using feedforward control alone, it is important to be able to design (adjust) enough time to allow the feedback control to work in conjunction at the point where control performance is evaluated.

[0015] In this case, the relationship between the manipulated variable increase amount MV_u and the controlled variable increase rate ΔPV can be confirmed in advance using the controlled object model, and thereby the time for which the maximum manipulated variable value is maintained can be roughly calculated when the controlled variable MV changes in a rectangular wave shape, which results in the fastest response, as shown in Patent Document 1. The inventor then came up with the idea that, based on the change in the controlled variable MV in a rectangular wave shape, which results in the fastest response, the operation of the feedback control functions effectively when approaching settling at the setpoint SP (a representative evaluation point), by specifying a time ΔT (for example, a time 1.0 times or more of the model dead time Lm) for the model dead time of the controlled object model, and by back-calculating the manipulated variable maintenance time to be shorter based on this, it is possible to substantially design (adjust) the interlocking with feedback control.

[0016] When the generation of the manipulated variable for the feedforward control described above is realized by simulation using a control object model, it is preferable to use the response waveform obtained when the margin time ΔT is set to the minimum (0.0 times) as time-series data of the set value SP for feedback control.

[0017] [Principle 2] Since it is necessary to ensure a band in which the manipulated variable change (corresponding to the correction amount from the manipulated variable of feedforward control) for linking feedback control can be realized, when generating the manipulated variable for feedforward control, it is preferable to use an upper limit value OHx that is smaller than the manipulated variable upper limit value OH that is set when performing actual control, and a lower limit value OLx that is larger than the manipulated variable lower limit value OL that is set when performing actual control. The processing of Principle 2 of this invention is a distinctive processing resulting from the difference that the technology disclosed in Patent Document 1 is intended to determine PID parameters, while the present invention is intended to generate the manipulated variable for feedforward control.

[0018] [First Example] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment corresponds to the above-mentioned Principles 1 and 2 of the present invention. The present invention is premised on the execution of feedforward control and feedback control (PID control), but a realistic execution platform for this embodiment is assumed to be a higher-level device than a PID controller (such as a temperature controller), such as an industrial PC (Industrial Personal Computer: IPC) or a PLC (Programmable Logic Controller).

[0019] The control system of this embodiment comprises a data processing device and a PID controller. Fig. 1 is a block diagram showing the configuration of the data processing device 1 according to this embodiment. The data processing device 1 is configured, for example, by an industrial PC, and comprises a controlled object model storage unit 10 for storing a controlled object model for simulation, a controlled variable margin information designation unit 11 for specifying a time ΔT for a model dead time of the controlled object model relative to a maintenance time of a controlled variable MV of a maximum value that can be output by a controller, and an operation unit 12 for executing a simulation for simulating the control response of a virtual control system consisting of the controlled object represented by the controlled object model and the controller, with the constraint being that a rectangular wave-shaped controlled variable MV whose magnitude is the maximum value when a set value is changed, calculating a change pattern of the controlled variable MV and a change pattern of the controlled variable PV that conform to specified evaluation conditions, and correcting the change pattern of the controlled variable MV so that the maintenance time of the maximum value is shortened by the time ΔT for the margin. The control variable output unit 15 sequentially extracts the control variable PV data for each control period from the time series data of the control variable PV stored in the control variable information storage unit 13 at a specified timing and transmits the extracted data to the PID controller. The control variable output unit 15 and the control variable change range output unit 16 sequentially extract the control variable MV data for each control period from the time series data of the control variable MV generated from the pattern information stored in the control variable information storage unit 14 at a specified timing and transmits the extracted data to the PID controller. The control variable output unit 15 and the control variable change range output unit 16 constitute a transmission unit 17.

[0020] 2 is a block diagram showing the configuration of the PID controller 2 according to this embodiment. The PID controller 2 includes a set value input unit 20 that receives the controlled variable PV transmitted from the data processing device 1 as a new value of the reference set value SP_r, a controlled variable change width input unit 21 that receives the controlled variable change width ΔMV transmitted from the data processing device 1 as a new value of the feedforward control controlled variable change width ΔMV_f, a controlled variable acquisition unit 22 that acquires a measured value of the controlled variable PV, a feedforward addition unit 23 that calculates a value obtained by adding the feedforward control controlled variable change width ΔMV_f to the controlled variable MV_x' (first controlled variable) one control cycle before as the controlled variable MV_z (second controlled variable), and a calculation unit 24 that calculates the value of the reference set value SP_r and the controlled variable PV. The control system is provided with a feedback adder 24 that uses the measured value as input, performs a speed-type PID calculation to calculate a change range δMV_b of the feedback control operation variable, and calculates a new value of the operation variable MV_x' by adding the change range δMV_b of the feedback control operation variable to the operation variable MV_z obtained by the feedforward adder 23, a limit processing unit 25 that outputs an operation variable MV (third operation variable) that limits the operation variable MV_x' calculated by the feedback adder 24 to a value within the range between an operation variable upper limit value OH and an operation variable lower limit value OL, and an operation variable output unit 26 that outputs the operation variable MV obtained by the limit processing unit 25 to the controlled object.

[0021] The set value input unit 20 and the manipulated variable change range input unit 21 constitute a receiving unit 27. The transmitting unit 17 and the receiving unit 27 may transmit and receive data via wired communication or wireless communication. The present invention is not limited to a specific communication standard, and any appropriate communication standard may be selected as appropriate to realize communication between the data processing device 1 and the PID controller 2.

[0022] Figure 3 is a flowchart explaining the operation of the data processing device 1. A controlled object model Pm for simulation is stored in the controlled object model storage unit 10. In the case of temperature control, a controlled object model that is generally approximated by a transfer function formula of first-order lag + dead time or second-order lag + dead time is often adopted. The transfer function formula of first-order lag + dead time is shown in formula (1), and the transfer function formula of second-order lag + dead time is shown in formula (2). Pm=Kmexp(-Lms) / (1+Tm1s) ···(1) Pm=Kmexp(-Lms) / {(1+Tm1s)(1+Tm2s)}···(2)

[0023] Km is a model gain, Tm1 and Tm2 are model time constants, Lm is a model dead time, and s is a Laplace operator. In the present invention, a simple model that necessarily includes such approximation errors may be used. It is preferable to improve the approximation accuracy by appropriately setting nonlinearity in the model gain Km, etc.

[0024] The manipulated variable margin information specifying unit 11 specifies a time ΔT, which is a margin for the model dead time of the controlled object model, relative to the maintenance time of the maximum manipulated variable MV that the controller can output (step S100 in FIG. 3). The manipulated variable margin information specifying unit 11 sets the time ΔT in response to an instruction from an operator. The operator may determine the time ΔT in advance, for example, taking into consideration the linkage between feedforward control and feedback control, and the balance between the responsiveness and stability of feedback control. For example, the time may be specified as a specific time in comparison with the model dead time Lm, or as a magnification factor for the model dead time Lm. However, as a general rule, a time that is 1.0 times or more the model dead time Lm is specified.

[0025] Next, the manipulated variable information generating unit 12 performs a simulation to simulate the control response of a virtual control system consisting of a control object represented by the control object model Pm stored in the control object model storage unit 10 and a controller that performs feedforward control and feedback control, based on predetermined constraint conditions and simulation specifications (step S101 in FIG. 3).

[0026] One of the constraints is that the controller outputs a rectangular-wave manipulated variable MV that is the maximum value that can be output when the setpoint is changed. Further constraints include a manipulated variable upper limit OHx and a manipulated variable lower limit OLx. The manipulated variable upper limit OHx is preset to a value smaller than the manipulated variable upper limit OH used in the limit processing unit 25 of the PID controller 2. The manipulated variable lower limit OLx is preset to a value larger than the manipulated variable lower limit OL used in the limit processing unit 25.

[0027] The manipulated variable information generator 12 virtually generates a PID controller 2 using a preset controller algorithm. A virtual control system consisting of a controlled object represented by a controlled object model Pm and a PID controller represented by the controller algorithm operates in the same way as an actual control system. That is, the manipulated variable MV calculated by the feedforward control calculation and the feedback control calculation is limited to a value equal to or greater than the manipulated variable lower limit OLx and equal to or less than the manipulated variable upper limit OHx, and is output to the virtual controlled object. Therefore, the maximum value of the manipulated variable MV that the controller can output is equal to the manipulated variable upper limit OHx.

[0028] The simulation specifications include the initial value SP=SP1 of the setpoint SP, the changed setpoint SP=SP2, the initial value of the controlled variable PV (the same value as the initial value SP1 of the setpoint SP), the initial value of the manipulated variable MV, the settling-time manipulated variable MV_s for settling the controlled variable PV to the changed setpoint SP=SP2, the time from the start of the simulation to the step change (SP1→SP2) of the setpoint SP, the number of times the simulation is executed, and the total time per simulation. If the controlled object model is expressed as a first-order lag plus dead time or a second-order lag plus dead time, and only nonlinearity is added to this, the settling-time manipulated variable MV_s for settling to a specific setpoint SP can be uniquely calculated (the same applies to the technology disclosed in Patent Document 1).

[0029] The manipulated variable information generator 12 repeats the simulation until it finds a change pattern of the manipulated variable MV and the controlled variable PV that meets the evaluation conditions. In actual processing, a pattern that meets the evaluation conditions is searched for among a predetermined number of simulation runs. The evaluation conditions are set such that the amount of overshoot of the controlled variable PV is 0.0 and the duration of the rectangular wave-shaped manipulated variable MV that the controller outputs to the controlled object when changing the set value is the longest among multiple simulations.

[0030] When the manipulated variable information generating unit 12 has found a change pattern of the manipulated variable MV and a change pattern of the controlled variable PV that match the evaluation conditions (YES in step S102 in FIG. 3), it corrects the change pattern of the manipulated variable MV so that the maintenance time of the rectangular wave-shaped manipulated variable MV is shortened by the time ΔT set by the manipulated variable margin information specifying unit 11 (step S103 in FIG. 3). If the manipulated variable margin information specifying unit 11 specifies a magnification for the model dead time Lm, it is sufficient to convert it into the time ΔT and then correct the change pattern of the manipulated variable MV.

[0031] Next, the manipulated variable information generator 12 stores discrete time series data of the searched change pattern of the controlled variable PV in the controlled variable information storage unit 13 (step S104 in FIG. 3). The time series data of the controlled variable PV is accompanied by time information (time stamp) with the start of the simulation as time 0. The time interval of the time series data is preferably the same as the control period of the PID controller 2, but may be a time interval shorter than the control period.

[0032] Furthermore, the manipulated variable information generator 12 stores pattern information for generating discrete time-series data of the change pattern of the manipulated variable MV after the correction in the manipulated variable information storage unit 14 (step S105 in FIG. 3). If the controlled object model Pm is based on a first-order lag plus dead time or a second-order lag plus dead time, it is sufficient to store the settling-time manipulated variable MV_s, the initial value of the manipulated variable MV, the time from the start of control (start of simulation) to the change of the setpoint SP, the value (=OHx) of the rectangular wave-shaped manipulated variable MV that the controller outputs to the controlled object when the setpoint is changed, and the maintenance time TH of the rectangular wave-shaped manipulated variable MV as pattern information for generating time-series data of the manipulated variable MV, and it is not necessary to store them in the form of a time-series data set of the manipulated variable MV.

[0033] An example of the simulation will be explained with reference to Fig. 4 to Fig. 8. Here, the controlled object is approximated by a first-order delay plus dead time. The transfer function formula of the controlled object model Pm is shown in Equation (3). Pm=10.0exp(-40.0s) / (1+400.0s) ···(3)

[0034] In the examples of Figures 4 to 8, the upper limit value of the manipulated variable OHx is 90.0%, the initial value SP = SP1 of the set value SP is 50°C, the set value SP = SP2 after the change is 400°C, the initial value of the manipulated variable MV is 3%, the manipulated variable MV_s at settling time is 38%, and the time from the start of the simulation (0 seconds) to the time of the step change of the set value SP is 100 seconds.

[0035] The example in Figure 4 is an example where the maintenance time THx of the square-wave manipulated variable MV is temporarily set to 100 seconds, the example in Figure 5 is an example where the maintenance time THx is temporarily set to 150 seconds, the example in Figure 6 is an example where the maintenance time THx is temporarily set to 205 seconds, and the example in Figure 7 is an example where the maintenance time THx is temporarily set to 250 seconds. Because the manipulated variable upper limit value OHx is 90.0%, the change in MV at 100 seconds from the initial value of 3.0% of the manipulated variable MV before the temperature rise started is 87.0%.

[0036] The manipulated variable information generator 12 temporarily sets the maintenance time THx as in the examples of Figures 4 to 7 and repeats simulations multiple times to search for a change pattern of the manipulated variable MV and a change pattern of the controlled variable PV that meet the evaluation conditions, and obtains the search results shown in Figure 6. In Figure 7, an overshoot occurs in the controlled variable PV. On the other hand, in all of Figures 4 to 6, the amount of overshoot in the controlled variable PV is 0.0, but among these, the result in Figure 6 shows that the maintenance time THx of the rectangular wave-shaped manipulated variable MV is the longest.

[0037] Here, the margin time ΔT set by the manipulated variable margin information designation unit 11 is set to 40.0 seconds (a magnification of 1.0 with respect to the model dead time Lm). The manipulated variable information generation unit 12 corrects the change pattern of the manipulated variable MV so that the maintenance time THx = 205 seconds of the rectangular wave-shaped manipulated variable MV in the searched change pattern (FIG. 6) is shortened by the time ΔT = 40.0 seconds. The result of the correction is shown in FIG. 8. The maintenance time TH of the rectangular wave-shaped manipulated variable MV after the correction is 165 seconds.

[0038] A plurality of simulation specifications are set in advance in the manipulated variable information generator 12. The manipulated variable information generator 12 searches for a change pattern of the manipulated variable MV and a change pattern of the controlled variable PV that match the evaluation conditions for each simulation specification, and corrects the pattern of the manipulated variable MV. Therefore, the controlled variable information storage unit 13 stores time-series data of the controlled variable PV for each simulation specification, and the manipulated variable information storage unit 14 stores pattern information for generating time-series data of the manipulated variable MV for each simulation specification.

[0039] Next, at the specified timing (YES in step S106 in FIG. 3), the control amount output unit 15 selects a specified data set from the time-series data sets of the control amount PV stored in the control amount information storage unit 13. The control amount output unit 15 sequentially extracts data of the control amount PV for each control cycle of the PID controller 2 from the selected data set and sequentially transmits the data to the PID controller 2. At this time, the control amount output unit 15 transmits the data of the control amount PV for each control cycle so that the time intervals indicated by the timestamp values ​​of the data that it sequentially transmits match the control cycle of the PID controller 2 (step S107 in FIG. 3). The specified timing and the specified data set will be described later.

[0040] At a specified timing, the manipulated variable change range output unit 16 selects pattern information for generating a specified data set from the pattern information stored in the manipulated variable information storage unit 14, and generates a time series data set of the change pattern of the manipulated variable MV (for example, FIG. 8) from the selected pattern information.

[0041] The manipulated variable change range output unit 16 sequentially extracts data on the manipulated variable MV for each control cycle of the PID controller 2 from the generated data set, and sequentially transmits the manipulated variable change range ΔMV per control cycle calculated from the extracted data to the PID controller 2. At this time, the manipulated variable change range output unit 16 transmits the data on the manipulated variable change range ΔMV for each control cycle so that the time indicated by the timestamp value of the controlled variable PV data transmitted by the controlled variable output unit 15 is the same as the time indicated by the timestamp value of the data it transmits (the timestamp value of the manipulated variable MV extracted from the data set) (step S108 in FIG. 3). As a result, the time interval indicated by the timestamp value of the data sequentially transmitted by the manipulated variable change range output unit 16 matches the control cycle of the PID controller 2.

[0042] The manipulated variable change range δMV is the difference from the manipulated variable MV one control cycle before. The manipulated variable change range output unit 16 can calculate the manipulated variable change range δMV one by one from the selected data set. For example, if the manipulated variable MV at time t is 0, the manipulated variable MV at time t+1 is 1, the manipulated variable MV at time t+2 is 3, the manipulated variable MV at time t+3 is 4, and the manipulated variable MV at time t+4 is 2, the manipulated variable change range δMV at times t, t+1, t+2, t+3, and t+4 can be calculated as δMV = 0, 1, 2, 1, -2.

[0043] In addition, if the PID controller 2 has a data buffer, the control amount output unit 15 and the operation amount change range output unit 16 may transmit data on multiple control amounts PV and multiple operation amount MV that can be stored in the data buffer together.

[0044] The controlled variable output unit 15 and the manipulated variable change width output unit 16 repeatedly execute the processes of steps S107 and S108 until the transmission of the specified data set is completed (YES in step S109 in FIG. 3).

[0045] It is desirable that the controlled variable PV and the manipulated variable change width ΔMV, which require data synchronization, i.e., the same timestamp values, arrive at the PID controller 2 at the same time, but a time lag between their arrival is acceptable. If this time lag is small relative to the control period (for example, 1 second) of the PID controller 2, there is no practical problem. This completes the operation on the data processing device 1 side, and the data processing device 1 waits until the next specified timing.

[0046] Here, the above-mentioned specified timing and specified data set will be explained. For example, when an operator of the data processing device 1 manually changes the set value SP of the PID controller 2, the timing at which the operator instructs the change of the set value SP becomes the specified timing, and the data set of simulation specifications corresponding to the control conditions instructed by the operator (a set of time series data of the controlled variable PV and time series data of the manipulated variable MV) becomes the specified data set. The control conditions usually refer to the conditions for changing the set value SP (the initial value of the set value SP and the set value SP after the change) assumed in temperature rise control using the PID controller 2 (temperature controller), for example.

[0047] Furthermore, for example, when temperature control of a heating furnace or the like is automatically performed according to predetermined schedule information, the timing of changing the set value SP determined by the schedule information becomes the specified timing, and the data set of simulation specifications that corresponds to the control conditions determined by the schedule information becomes the specified data set.

[0048] 9 is a flowchart illustrating the operation of the PID controller 2. The set value input unit 20 of the PID controller 2 receives the controlled variable PV transmitted from the data processing device 1 as a new value of the reference set value SP_r (step S200 in FIG. 9). The simplest processing is to receive data on one controlled variable PV for each control cycle of the PID controller 2.

[0049] The manipulated variable change range input unit 21 receives the manipulated variable change range ΔMV transmitted from the data processing device 1 as a new value of the feedforward control manipulated variable change range ΔMV_f (step S201 in FIG. 9). The simplest processing is to receive one data value of the manipulated variable change range ΔMV for each control cycle of the PID controller 2.

[0050] In addition, when a data buffer is provided in the PID controller 2, and the control amount output unit 15 and the operation amount change range output unit 16 transmit data on multiple control amounts PV and multiple operation amount MVs that can be stored in the data buffer together, the set value input unit 20 and the operation amount change range input unit 21 can extract each piece of data on the control amount PV and the operation amount change range ΔMV stored in the data buffer one by one for each control period of the PID controller 2.

[0051] The controlled variable acquisition unit 22 acquires the measured value of the controlled variable PV (step S202 in FIG. 9). In the case of temperature control using the PID controller 2 (temperature controller), the value of the controlled variable PV is acquired from a temperature sensor.

[0052] Next, as shown in equation (4), the feedforward adder 23 adds the change width ΔMV_f of the feedforward control operation amount received by the operation amount change width input unit 21 to the operation amount MV_x calculated by the feedback adder 24 one control cycle ago (the value of MV_x' described below one control cycle ago), and sets the result as the operation amount MV_z (step S203 in Figure 9). MV_z=MV_x+δMV_f (4)

[0053] The feedback adder 24 receives the reference set value SP_r and the measured value of the controlled variable PV as input, and calculates the change range ΔMV_b of the feedback control manipulated variable by performing a speed-type PID calculation such as the transfer function formula shown in equation (5) so that the measured value of the controlled variable PV coincides with the reference set value SP_r (step S204 in FIG. 9). δMV_b=Kp{ΔEr+(1 / Ti)Er+TdΔ 2 Er} (5)

[0054] In equation (5), Er is the control deviation, which is the difference SP_r-PV between the reference set value SP_r and the measured value of the controlled variable PV. ΔEr is the first-order difference of the control deviation Er (the amount of change in the deviation Er per control cycle), Δ 2Er is the second-order difference of the control deviation Er (the amount of change in the deviation Er per control cycle), Kp is the proportional gain among the PID parameters, Ti is the integral time among the PID parameters, and Td is the derivative time among the PID parameters. Note that the proportional gain Kp and the proportional band Pb have a relationship of Kp=100 / Pb.

[0055] As shown in equation (6), the feedback adder 24 adds the change width ΔMV_b of the feedback control manipulated variable to the manipulated variable MV_z calculated by the feedforward adder 23, and sets the result as the manipulated variable MV_x' (step S205 in FIG. 9). MV_x'=MV_z+δMV_b (6)

[0056] When adding the change range ΔMV_b of the feedback control operation amount to the operation amount MV_z, the feedback addition unit 24 preferably performs the addition of the proportional action (P action) and the derivative action (D action) prior to the addition of the integral action (I action), and performs the addition of the integral action when the result of the addition of the proportional action and the derivative action is within the range between the operation amount upper limit value OH and the operation amount lower limit value OL, thereby obtaining the effect of anti-reset windup processing (processing that prevents unnecessary accumulation of integral action).

[0057] That is, the proportional action and differential action components ΔMV_b_pd of the change range ΔMV_b of the feedback control manipulated variable are expressed by equation (7), and the integral action (I action) component ΔMV_b_i is expressed by equation (8). δMV_b_pd=Kp(ΔEr+TdΔ 2 Er) (7) δMV_b_i=Kp(1 / Ti)Er (8)

[0058] Therefore, the sum MV_z′ of the manipulated variable MV_z and ΔMV_b_pd is expressed by equation (9). MV_z'=MV_z+δMV_pd (9)

[0059] When the addition result MV_z’ is greater than or equal to the operation amount lower limit value OL and less than or equal to the operation amount upper limit value OH, as shown in Equation (10), the feedback addition unit 24 further adds the integral operation component δMV_b_i of the change width δMV_b of the feedback control operation amount to the addition result MV_z’, and the result is used as the operation amount MV_x’. MV_x’ = MV_z’ + δMV_b_i ···(10)

[0060] Also, when the addition result MV_z’ is less than the operation amount lower limit value OL or greater than the operation amount upper limit value OH, the feedback addition unit 24 does not add δMV_b_i and uses the addition result MV_z’ as the operation amount MV_x’ as it is. MV_x’ = MV_z’ ···(11)

[0061] Since the change width δMV_f of the feedforward control operation amount specific to the present invention has also been added by the process of Equation (4), the process described in Equations (7) to (11) can obtain the effect of minimizing the calculation amount necessary for matching with the subsequent limit processing. However, the addition conditions for the integral operation may be appropriately added.

[0062] The limit processing unit 25 outputs the operation amount MV obtained by limiting the operation amount MV_x’ calculated by the feedback addition unit 24 to a value greater than or equal to the operation amount lower limit value OL and less than or equal to the operation amount upper limit value OH (step S206 in FIG. 9). That is, when the operation amount MV_x’ is less than the operation amount lower limit value OL (MV_x’ < OL), the limit processing unit 25 sets the operation amount MV = OL, and when the operation amount MV_x’ is greater than the operation amount upper limit value OH (MV_x’ > OH), the operation amount MV = OH. When the operation amount MV_x’ is greater than or equal to the operation amount lower limit value OL and less than or equal to the operation amount upper limit value OH (OL ≦ MV_x’ ≦ OH), the limit processing of setting the operation amount MV = MV_x’ is performed. The operation amount upper limit value OH preset in the PID controller 2 is 100%, and the operation amount lower limit value OL is 0%.

[0063] The manipulated variable output unit 26 outputs the manipulated variable MV that has been subjected to limit processing by the limit processing unit 25 to the controlled object (step S207 in FIG. 9). The manipulated variable MV is output to an operating 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 is a power regulator (not shown) that supplies power to the heater.

[0064] The PID controller 2 executes the processes of steps S200 to S207 for each control cycle until the control is terminated, for example, in response to a command from an operator (YES in step S208 in FIG. 9).

[0065] However, the set value input unit 20 and the manipulated variable change range input unit 21 stop updating the reference set value SP_r and the change range ΔMV_f of the feedforward control manipulated variable when a certain duration has elapsed since the measured value of the controlled variable PV stabilized (YES in step S209 in Figure 9) (step S210 in Figure 9). As a result, the reference setpoint SP_r and the variation width ΔMV_f of the feedforward control manipulated variable are fixed to the values ​​received one control cycle before.

[0066] The duration must be set so that the update of the reference setpoint SP_r and the variation width ΔMV_f of the feedforward control manipulated variable stops before the data transmission from the data processing device 1 ends.

[0067] Thereafter, the processes of steps S202 to S207 are executed every control cycle until the next specified timing comes and the processes of steps S200 to S203 are resumed.

[0068] 10 to 15 show a design example (simulation) of a control system to which this embodiment is applied. In all of Figs. 10 to 15, the transfer function model of equation (12) is used as the controlled object model. The model time constant Tm1 = 400.0 and the model dead time Lm = 40.0 are in units of seconds, and assuming a temperature control system, a high-order lag equivalent dead time is used for the model dead time Lm. The manipulated variable upper limit value OHx, which is set as a constraint condition, is 90.0%. Pm=10.0exp(-40.0s) / (1+400.0s) ···(12)

[0069] 10 shows the change patterns of the controlled variable PV and the controlled variable MV obtained by the search performed by the manipulated variable information generator 12 under the condition that the margin time ΔT=0. The maintenance time TH of the rectangular wave-shaped controlled variable MV is 205 seconds. If there is absolutely no model error for the actual target, when feedforward control and feedback control are linked using the change pattern of the controlled variable PV as the change pattern of the reference set value SP_r, no compensation operation by feedback control occurs, and the same control result as the simulation in the search can be obtained by feedforward control alone.

[0070] 11 and 12 show the simulation results in which the change patterns of the controlled variable PV and the manipulated variable MV shown in FIG. 10 are sent to the PID controller 2, and the PID controller 2 controls the temperature of the controlled object. FIG. 11 shows the results when the actual target process P has the characteristics of equation (13). Here, the process time constant is set to 300.0 seconds. In other words, a model error is given in which the time constant of the actual target process P is smaller than the model time constant Tm1 = 400.0 seconds. P=10.0exp(-40.0s) / (1+300.0s) ···(13)

[0071] As shown in FIG. 11, the feedback control works in conjunction with the feedforward control to compensate for the model error, so that the controlled variable PV is kept almost constant in following the reference set value SP_r. Figure 12 shows the results when the actual target process P has the characteristics of equation (14). Here, the process dead time is set to 60.0 seconds. In other words, a model error is given in which the dead time of the actual target process P is greater than the model dead time Lm = 40.0 seconds. P=10.0exp(-60.0s) / (1+400.0s) ···(14)

[0072] As shown in Fig. 12, when feedback control works in conjunction with feedforward control to compensate for the model error, there is insufficient time for the linkage to occur, so a significant overshoot occurs in the controlled variable PV, and as a result, the time required for the controlled variable PV to settle becomes longer.

[0073] 13 to 15 show the results of a control simulation using the change patterns of the controlled variable PV and the controlled variable MV searched for by the manipulated variable information generator 12 under the condition that the margin time ΔT = 40.0 seconds (multiplication factor for the model dead time Lm is 1.0). The result of the modified change pattern of the controlled variable MV after the search by the manipulated variable information generator 12 is the same as the pattern in Fig. 8. The maintenance time TH of the rectangular wave-shaped controlled variable MV is 165 seconds. FIG. 13 shows the control results when the actual target process P has the characteristics of equation (15) (no model error). P=10.0exp(-40.0s) / (1+400.0s) ···(15)

[0074] Even if there is absolutely no model error for the actual target, when feedforward control and feedback control are linked with the change pattern of the controlled variable PV as the change pattern of the reference set value SP_r, compensation action by feedback control occurs after maintaining the controlled variable MV = 90.0%. 14 shows the control results when the actual target process P has the characteristics of equation (16). Here, the process time constant is set to 300.0 seconds. That is, a model error is given in which the time constant of the actual target process P is smaller than the model time constant Tm1 = 400.0 seconds. P=10.0exp(-40.0s) / (1+300.0s) ···(16)

[0075] As shown in Fig. 14, feedback control works in conjunction with feedforward control to compensate for model errors, so that the controlled variable PV is kept almost constant in tracking the reference set value SP_r. It is difficult to say that there is a significant difference compared to Fig. 11, and in this case the effect of designing with ΔT = 40.0 seconds is small. Figure 15 shows the control results when the actual target process P has the characteristics of equation (17). Here, the process dead time is set to 60.0 seconds. In other words, a model error is given in which the dead time of the actual target process P is greater than the model dead time Lm = 40.0 seconds. P=10.0exp(-60.0s) / (1+400.0s) ···(17)

[0076] As shown in Fig. 15, when feedback control works in conjunction with feedforward control to compensate for model errors, there is more time available for the linkage than in the case of Fig. 12, so the overshoot of the controlled variable PV is reduced and the time required for the controlled variable PV to settle is also shorter than in the case of Fig. 12. There is a significant difference compared to Fig. 12, and in this case the effect of the design with ΔT = 40.0 seconds (feedback control operation functions effectively) is obtained. Because a simple rectangular change in the controlled variable MV is used, the behavior when combined with feedback control other than PID control can be intuitively predicted.

[0077] 12 and 15, the manipulated variable MV exceeds 90.0% and reaches 100.0% due to feedback control. The range in which the manipulated variable MV exceeds 90.0% and reaches 100.0% corresponds to the "band in which the manipulated variable change for linking feedback control can be realized" described in Principle 2 of the Invention.

[0078] [Second Example] Next, a second embodiment of the present invention will be described. Execution of simulations using a control target model and storage of numerous time-series data sets assuming various conditions should be performed by an industrial PC or other higher-level device rather than a PID controller (a local controller with limited calculation functions for the purpose of stable continuity) such as a temperature regulator, so distributed allocation of each function block is essential.

[0079] The inventors then realized that temperature controllers have limitations in real-time communication per control cycle, and that when data loss occurs in the setpoint SP due to poor communication, the differential operation (strictly speaking, a difference operation, since it is a discrete system) that references the setpoint SP can cause malfunctions in the manipulated variable MV. They then came up with the idea that a suitable configuration would be to send time-series data for the controlled variable PV to the PID controller in advance as the reference setpoint SP_r, and to send time-series data for the manipulated variable MV in advance as the manipulated variable MV_f for feedforward control. Based on this configuration, the amount of real-time communication between the PID controller (such as a temperature controller) and the host can be minimized, enabling improvements to instrumentation that can easily maintain stable continuity while adapting to strongly nonlinear characteristics.

[0080] 16 is a block diagram showing the configuration of a data processing device 1a constituting a control system according to this embodiment. The data processing device 1a includes a controlled object model storage unit 10, a manipulated variable margin information designation unit 11, a manipulated variable information generation unit 12, a controlled variable information storage unit 13, a manipulated variable information storage unit 14, a controlled variable output unit 15a, and a manipulated variable output unit 18 that transmits time-series data of the manipulated variable MV to the PID controller. The controlled variable output unit 15a and the manipulated variable output unit 18 constitute a transmission unit 19.

[0081] 17 is a block diagram showing the configuration of a PID controller 2a constituting the control system according to this embodiment. The PID controller 2a includes a set value receiving unit 30 that receives time-series data of the controlled variable PV transmitted from the data processing device 1a, a manipulated variable receiving unit 31 that receives time-series data of the manipulated variable MV transmitted from the data processing device 1a, a set value memory 32 that stores the time-series data of the controlled variable PV, a manipulated variable memory 33 that stores the time-series data of the manipulated variable MV, a set value reading unit 34 that sequentially reads out, for each control period, the data of the controlled variable PV from the time-series data stored in the set value memory 32 as a new value of the reference set value SP_r when a start signal input unit 36 ​​(described later) receives a start signal and a control operation is started, and a manipulated variable reading unit 35 that sequentially reads out, for each control period, the data of the controlled variable MV from the time-series data stored in the manipulated variable memory 33 as a new value of the feedforward control manipulated variable MV_f when the control operation is started.

[0082] The PID controller 2a also includes a start signal input unit 36 ​​that receives a start signal from the outside that instructs the start of a control operation, a control variable acquisition unit 37 that acquires a measured value of the control variable PV, a feedback calculation unit 38 that receives as input a reference set value SP_r and the measured value of the control variable PV and performs PID calculations to calculate a feedback control operation variable MV_b (first operation variable), a feedforward addition unit 39 that adds the feedforward control operation variable MV_f to the feedback control operation variable MV_b to calculate an operation variable MV_x' (second operation variable), a limit processing unit 40 that outputs an operation variable MV (third operation variable) that limits the operation variable MV_x' calculated by the feedforward addition unit 39 to a value within the range between an operation variable upper limit value OH and an operation variable lower limit value OL, and an operation variable output unit 41 that outputs the operation variable MV obtained by the limit processing unit 40 to the controlled object.

[0083] The set value receiving unit 30 and the operation amount receiving unit 31 constitute a receiving unit 43, the set value memory unit 32 and the operation amount memory unit 33 constitute a memory unit 44, and the set value reading unit 34 and the operation amount reading unit 35 constitute a reading unit 45.

[0084] The transmitter 19 and the receiver 43 may transmit and receive data via wired or wireless communication. The present invention is not limited to a specific communication standard, and any appropriate communication standard may be selected to realize communication between the data processing device 1a and the PID controller 2a.

[0085] Fig. 18 is a flowchart illustrating the operation of the data processing device 1a. The operations of the operation amount margin information designation unit 11, the operation amount information generation unit 12, the control amount information storage unit 13, and the operation amount information storage unit 14 (steps S100 to S105 in Fig. 18) are the same as those described in the first embodiment.

[0086] Next, the control amount output unit 15a transmits the time series data sets of the control amount PV stored in the control amount information storage unit 13 to the PID controller 2a (step S110 in FIG. 18). At this time, the control amount output unit 15a transmits all the time series data sets stored in the control amount information storage unit 13 to the PID controller 2a.

[0087] The manipulated variable output unit 18 generates a time series data set of the manipulated variable MV from the pattern information stored in the manipulated variable information storage unit 14. As described in the first embodiment, since the pattern information is stored for each simulation specification, it is possible to generate a time series data set of the manipulated variable MV for each simulation specification. The manipulated variable output unit 18 transmits all the generated time series data sets to the PID controller 2a (step S111 in FIG. 18). At this time, information on the simulation specification is added to the time series data set of the controlled variable PV and the time series data set of the manipulated variable MV for each simulation specification.

[0088] In this embodiment, the timing at which the controlled variable output unit 15a and the manipulated variable output unit 18 transmit data may be before a series of control operations using this data (for example, a temperature increase operation in temperature control) is started.

[0089] 19 and 20 are flowcharts illustrating the operation of the PID controller 2a. The set value receiving unit 30 of the PID controller 2a receives the time-series data set of the controlled variable PV transmitted from the data processing device 1a (step S300 in FIG. 19). The manipulated variable receiving unit 31 receives the time-series data set of the manipulated variable MV transmitted from the data processing device 1a (step S301 in FIG. 19).

[0090] The set value storage unit 32 stores the time-series data set of the controlled variable PV received by the set value receiving unit 30 (step S302 in FIG. 19). The manipulated variable storage unit 33 stores the time-series data set of the manipulated variable MV received by the manipulated variable receiving unit 31 (step S303 in FIG. 19).

[0091] Next, the start signal input unit 36 ​​receives a start signal that instructs the start of the control operation (YES in step S304 in FIG. 19). Information specifying the conditions for the control is added to this start signal.

[0092] For example, when an operator of the data processing device 1a manually changes the set value SP of the PID controller 2a, a start signal is transmitted from the data processing device 1a to the PID controller 2a at the timing when the operator instructs to change the set value SP. Also, the control conditions instructed by the operator are transmitted from the data processing device 1a to the PID controller 2a. Such instructions may be transmitted directly to the PID controller 2a, not via the data processing device 1a.

[0093] Furthermore, when temperature control of a heating furnace or the like is automatically performed according to predetermined schedule information, a start signal is transmitted from the data processing device 1a to the PID controller 2a at the timing of a change in the set value SP determined by the schedule information. Also, the data processing device 1a transmits the control conditions determined by the schedule information to the PID controller 2a.

[0094] When the start signal input unit 36 ​​receives the start signal and the control operation of the PID controller 2a starts, the set value reading unit 34 sequentially reads out, for each control period, the data of the controlled variable PV in the data set of the simulation specifications that corresponds to the control conditions instructed by the start signal from the time-series data set of the controlled variable PV stored in the set value storage unit 32, as a new value of the reference set value SP_r (step S305 in FIG. 19). As explained in the first embodiment, the control conditions usually refer to the conditions for changing the set value SP (the initial value of the set value SP and the set value SP after the change) assumed in temperature rise control using, for example, the PID controller 2 (temperature controller).

[0095] The manipulated variable reading unit 35 sequentially reads out, from the time series data sets of manipulated variables MV stored in the manipulated variable memory unit 33, the data of the manipulated variables MV for each control cycle in the data set of the simulation specifications that corresponds to the control conditions instructed by the received start signal, as a new value of the feedforward control manipulated variable MV_f for each control cycle (step S306 in Figure 19).

[0096] Since a timestamp is added to each data of the control amount PV stored in the set value memory unit 32 and the operation amount MV stored in the operation amount memory unit 33, it is possible to read out the data of the timestamp value (time) corresponding to the elapsed time from the time when the start signal was received (the time when the control operation started).

[0097] It is desirable that the controlled variable PV (reference setpoint SP_r) and the manipulated variable MV (feedforward control manipulated variable MV_f), which require data synchronization, i.e., the same timestamp value, be read out simultaneously, but a time lag between the readouts is acceptable. If this time lag is small relative to the control period (for example, 1 second) of the PID controller 2a, there is no practical problem.

[0098] When the start signal input unit 36 ​​receives the start signal and the control operation of the PID controller 2a starts, the controlled variable acquisition unit 37 acquires the measured value of the controlled variable PV (step S307 in FIG. 19).

[0099] Next, the feedback calculation unit 38 receives as input the reference set value SP_r read by the set value reading unit 34 and the measured value of the controlled variable PV acquired by the controlled variable acquisition unit 37, and performs PID calculation to calculate a feedback control manipulated variable MV_b so that the measured value of the controlled variable PV matches the reference set value SP_r. Specifically, when performing a speed-type PID calculation such as the transfer function formula shown in equation (5), the feedback calculation unit 38 calculates the manipulated variable change width ΔMV_b (step S308 in FIG. 19).

[0100] Then, as shown in equation (18), the feedback calculation unit 38 adds the operation amount MV_x calculated by the feedforward addition unit 39 one control cycle ago (the value of MV_x', described later, one control cycle ago) and the operation amount change width ΔMV_b to obtain the feedback control operation amount MV_b (step S309 in Figure 19). MV_b=MV_x+δMV_b (18)

[0101] It should be noted that the feedback calculation unit 38 may be provided with a general additional function such as anti-reset windup processing (processing to prevent unnecessary accumulation of integral operations).

[0102] The feedforward adder 39 calculates the manipulated variable MV_x' by adding the feedforward control manipulated variable MV_f read by the manipulated variable readout unit 35 to the feedback control manipulated variable MV_b (step S310 in FIG. 19). When the feedback calculator 38 performs a speed-type PID calculation, the feedforward adder 39 calculates the difference between the feedforward control manipulated variable MV_f of the current control cycle read out by the manipulated variable readout unit 35 and the feedforward control manipulated variable MV_f of the previous control cycle as the change width ΔMV_f. Then, the feedforward adder 39 adds the change width ΔMV_f to the feedback control manipulated variable MV_b as shown in equation (19) to calculate a new value of the manipulated variable MV_x'. MV_x'=MV_b+δMV_f (19)

[0103] Similar to the limit processing unit 25, the limit processing unit 40 outputs the manipulated variable MV obtained by limiting the manipulated variable MV_x' calculated by the feedforward addition unit 39 to a value equal to or greater than the manipulated variable lower limit value OL and equal to or less than the manipulated variable upper limit value OH (step S311 in FIG. 20). The manipulated variable output unit 41 outputs the manipulated variable MV that has been subjected to limit processing by the limit processing unit 40 to the controlled object (step S312 in FIG. 20).

[0104] The PID controller 2a executes the processes of steps S305 to S312 for each control cycle until the control is terminated by, for example, an instruction from an operator (YES in step S313 in FIG. 20).

[0105] However, the set value reading unit 34 and the manipulated variable reading unit 35 stop updating the reference set value SP_r and the feedforward control manipulated variable MV_f (step S315 in FIG. 20) when a certain duration has elapsed since the measured value of the controlled variable PV stabilized (YES in step S314 in FIG. 20). As a result, the reference set value SP_r and the feedforward control manipulated variable MV_f are fixed to the values ​​received one control cycle before.

[0106] The above duration must be set so that the updating of the reference set value SP_r and the feedforward control operation amount MV_f stops before the data stored in the set value memory unit 32 and the operation amount memory unit 33 ends. Thereafter, the processing of steps S307 to S312 is executed every control cycle until the timing for the next change of the set value SP arrives and the start signal is received again.

[0107] The data processing devices 1, 1a and PID controllers 2, 2a described in the first and second embodiments can each be realized by a computer equipped with a CPU (Central Processing Unit), a storage device, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 21.

[0108] The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202. In the case of the data processing device 1, 1a, the I / F 202 is connected to hardware such as a communication circuit for communicating with the PID controller 2, 2a. In the case of the PID controller 2, 2a, the I / F 202 is connected to a sensor that measures the controlled variable PV, hardware such as a communication circuit for communicating with the data processing device 1, 1a, a power regulator, etc. In such a computer, a program for realizing the control method of the present invention is stored in the storage device 201. The CPU 200 of each of the data processing device 1, 1a and the PID controller 2, 2a executes the processes described in the first and second embodiments in accordance with the program stored in the storage device 201. [Explanation of symbols]

[0109] 1, 1a... data processing device, 2, 2a... PID controller, 10... controlled object model storage unit, 11... manipulated variable margin information designation unit, 12... manipulated variable information generation unit, 13... controlled variable information storage unit, 14... manipulated variable information storage unit, 15, 15a... controlled variable output unit, 16... manipulated variable change range output unit, 17, 19... transmission unit, 18... manipulated variable output unit, 20... set value input unit, 21... manipulated variable change range input unit, 22, 37... controlled variable input unit Acquisition unit, 23, 39...feedforward addition unit, 24...feedback addition unit, 25, 40...limit processing unit, 26, 41...operated variable output unit, 27, 43...receiving unit, 30...set value receiving unit, 31...operated variable receiving unit, 32...set value memory unit, 33...operated variable memory unit, 34...set value reading unit, 35...operated variable reading unit, 36...start signal input unit, 38...feedback calculation unit, 44...memory unit, 45...reading unit.

Claims

1. a first storage unit configured to store a control object model for simulation; a manipulated variable margin information designation unit configured to designate a time period corresponding to a margin of a model dead time of the control target model with respect to a time period for maintaining a maximum manipulated variable that can be output by a controller that executes feedforward control and feedback control; a manipulated variable information generating unit configured to execute a simulation that simulates a control response of a virtual control system that includes the controlled object represented by the controlled object model and the controller, with a constraint that a manipulated variable having a rectangular wave shape whose magnitude is the maximum value is output when a set value is changed, calculate a change pattern of the manipulated variable and a change pattern of the controlled variable that meet specified evaluation conditions, and correct the change pattern of the manipulated variable so that a maintenance time of the rectangular wave-shaped manipulated variable is shortened by the margin time; a second storage unit configured to store time-series data of a change pattern of the controlled variable; a third storage unit configured to store pattern information for generating time-series data of a change pattern of the manipulated variable after the correction; a transmitting unit configured to transmit the time series data of the controlled variable stored in the second storage unit to a PID controller that performs feedforward control and feedback control, or to transmit data calculated based on the time series data of the controlled variable stored in the second storage unit to the PID controller, and to transmit time series data of the manipulated variable generated from the pattern information to the PID controller, or to transmit data calculated based on the time series data of the manipulated variable generated from the pattern information to the PID controller.

2. 2. The control system of claim 1, the manipulated variable information generating unit executes the simulation a plurality of times to search for a change pattern of the manipulated variable and a change pattern of the controlled variable that meet the evaluation condition, The control system is characterized in that the evaluation conditions are that the overshoot amount of the controlled variable is 0.0, and the maintenance time of the rectangular wave-shaped manipulated variable output by the virtual controller to the controlled object when the set value is changed is the longest among multiple simulations.

3. 2. The control system of claim 1, the constraint conditions further include a second manipulated variable upper limit value that is smaller than a first manipulated variable upper limit value that is set in the PID controller, and a second manipulated variable lower limit value that is larger than a first manipulated variable lower limit value that is set in the PID controller; A control system characterized in that a change pattern of the manipulated variable calculated by the manipulated variable information generating unit is limited to a value that is equal to or greater than the second manipulated variable lower limit value and is equal to or less than the second manipulated variable upper limit value.

4. 2. The control system of claim 1, a control system characterized in that the pattern information includes a settling-time manipulated variable for settling the controlled variable to a changed set value, an initial value of the manipulated variable, a time from the start of control to the change of the set value, a value of the rectangular wave-shaped manipulated variable, and a maintenance time for the rectangular wave-shaped manipulated variable.

5. 2. The control system of claim 1, the transmission unit, at a specified timing, sequentially extracts control amount data for each control period from the time series data of control amount stored in the second storage unit and sequentially transmits the data to the PID controller, and at the same time sequentially extracts control amount data for each control period from the time series data of control amount generated from the pattern information and sequentially transmits data of control amount change range calculated from the extracted data to the PID controller; The PID controller a receiving unit configured to receive the control amount transmitted from the transmitting unit as a new value of the reference set value and to receive the manipulated variable change range transmitted from the transmitting unit as a new value of a feedforward control manipulated variable change range; a control variable acquisition unit configured to acquire a measurement value of a control variable; a feedforward adder configured to calculate, as a second manipulated variable, a value obtained by adding a first manipulated variable from one control cycle before to a change width of the feedforward control manipulated variable received by the receiver; a feedback adder configured to receive the reference set value and the measured value of the controlled variable as inputs, perform a speed-type PID calculation to calculate a change range of a feedback control manipulated variable, and calculate a value obtained by adding the change range of the feedback control manipulated variable to the second manipulated variable as a new value of the first manipulated variable; a limiting processing unit configured to limit the first manipulated variable calculated by the feedback adding unit to a value that is equal to or greater than a first manipulated variable lower limit value and equal to or less than a first manipulated variable upper limit value; a manipulated variable output unit configured to output the first manipulated variable that has been limit-processed by the limit processing unit to a controlled object.

6. 2. The control system of claim 1, the transmission unit transmits the time series data of the controlled variable stored in the second storage unit to the PID controller, and simultaneously transmits the time series data of the manipulated variable generated from the pattern information to the PID controller; The PID controller a receiving unit configured to receive the time series data of the controlled variable and the time series data of the manipulated variable transmitted from the transmitting unit; a fourth storage unit configured to store the time series data of the controlled variable and the time series data of the manipulated variable received by the receiving unit; a start signal input unit configured to receive a start signal that instructs the start of a control operation from an external device; a readout unit configured to, when the start signal input unit receives the start signal and a control operation is started, sequentially read out, for each control period, the controlled variable data for each control period from the controlled variable time series data stored in the fourth storage unit as a new value of a reference set value, and simultaneously sequentially read out, for each control period, the controlled variable data for each control period from the controlled variable time series data stored in the fourth storage unit as a new value of a feedforward control controlled variable; a control variable acquisition unit configured to acquire a measurement value of a control variable; a feedback calculation unit configured to calculate a first manipulated variable by performing a PID calculation using the reference set value and the measured value of the controlled variable as inputs; a feedforward adder configured to add the feedforward control manipulated variable to the first manipulated variable to calculate a second manipulated variable; a limiting processing unit configured to limit the second manipulated variable calculated by the feedback adding unit to a value that is equal to or greater than a first manipulated variable lower limit value and equal to or less than a first manipulated variable upper limit value; a manipulated variable output unit configured to output the second manipulated variable that has been limit-processed by the limit processing unit to a controlled object.

7. a first step of specifying a time period for maintaining a maximum manipulated variable that can be output by a controller that executes feedforward control and feedback control, the time period being a margin for a model dead time of a controlled object model; a second step of executing a simulation to simulate a control response of a virtual control system consisting of the controlled object represented by the controlled object model and the controller, with a constraint that a rectangular wave-shaped manipulated variable having a magnitude of the maximum value is output when a set value is changed, calculating a change pattern of the manipulated variable and a change pattern of the controlled variable that meet specified evaluation conditions, and correcting the change pattern of the manipulated variable so that a maintenance time of the rectangular wave-shaped manipulated variable is shortened by the time margin; a third step of storing time series data of the change pattern of the controlled variable; a fourth step of storing pattern information for generating time-series data of the pattern of change in the manipulated variable after the correction; a fifth step of transmitting the time series data of the controlled variable stored in the third step to a PID controller that executes feedforward control and feedback control, or transmitting data calculated based on the time series data of the controlled variable stored in the third step to the PID controller, and also transmitting time series data of the manipulated variable generated from the pattern information to the PID controller, or transmitting data calculated based on the time series data of the manipulated variable generated from the pattern information to the PID controller.

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