Control system and control method

Abstract

To obtain good control characteristics with respect to a control object with strong nonlinear characteristics.SOLUTION: An industrial PC1 generates and transmits time series data on a control amount and an operation amount, which correspond to an ideal control response. A PID controller 2 includes: a storage section 40 that stores the transmitted data; a reading section 41 that, when a start signal input section 32 receives a start signal, sequentially reads the data on the control amount for each control cycle stored in the storage section 40 as a reference set value, and sequentially reads the data on the operation amount for each control cycle as a feedforward control operation amount; a feedback calculation section 34 that calculates a first operation amount by performing PID calculation on the basis of the reference set value and a measured value of the control amount; a feedforward addition section 35 that calculates a second operation amount by adding the feedforward control operation amount to the first operation amount; and an operation amount output section 37 that outputs the second operation amount to a control object.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Regarding PID control, a technique for automatically adjusting PID parameters to maintain optimal control performance when a set value SP is changed has been disclosed (see Patent Document 1). This PID parameter adjustment technique is applicable to a temperature regulator, which is a PID controller for controlling temperature. In addition, this is a method for searching for PID parameters so as to follow a target trajectory of a controlled variable PV, and theoretically, this method assumes 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 output value of the theoretical manipulated variable MV is 0% to 100% on the horizontal axis of a graph and the output action to the actual controlled object is 0% to 100% on the vertical axis 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 method disclosed in Patent Document 1 cannot maintain good PID control performance for a control target with strongly nonlinear characteristics in which the relationship between theory and reality is as shown in Fig. 24. Such strongly nonlinear characteristics appear in temperature control systems that use special electric heaters, or flow control systems or pressure control systems that control fluids with valves.

[0005] 25 to 27 show the results of simulations when the manipulated variable MV (heater output) is 0% and the controlled variable PV (temperature) is heated to different target temperatures (set values ​​SP) using PID control, starting from a state where the manipulated variable MV (heater output) is 0% and the controlled variable PV (temperature) is stabilized at 50° C. In these simulations, when heating from 50° C. to 150° C. as shown in FIG. 25, the PID parameters are adjusted so that the controlled variable PV follows the target temperature.

[0006] Here, when the temperature is raised from 50°C to 250°C as shown in Fig. 26, if the same PID parameters as in Fig. 25 are used, the controlled variable PV will fluctuate up and down. Similarly, when the temperature is raised from 50°C to 350°C as shown in Fig. 27, if the same PID parameters as in Fig. 25 are used, even larger fluctuations in the controlled variable PV will occur. The reason why the controlled variable PV fluctuates up and down is that, as shown in Fig. 28, the theoretical and actual slopes of the manipulated variable MV (approximately 70% in Fig. 25, approximately 80% in Fig. 26, and approximately 90% in Fig. 27) for maintaining the target temperatures in Figs. 25 to 27 differ, and the larger the slope, the more likely it is that fluctuations in the controlled variable PV will occur.

[0007] As described above, it is difficult to obtain good control characteristics with PID control, for example, for a control target with strongly nonlinear characteristics. On the other hand, in order to maintain stable and safe control operation, the PID control loop is executed with a PID controller (such as a temperature controller) dedicated to PID calculation, which is also a standard instrumentation concept in industry, especially within manufacturing equipment. In other words, the limitations of PID control must be overcome while maintaining the reasons why PID controllers should be used, and improvements are required. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4223894 Summary of the Invention [Problem to be solved by the invention]

[0009] 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 obtain good control characteristics for a controlled object having strongly nonlinear characteristics. [Means for solving the problem]

[0010] The control system of the present invention is comprised of a host device and a PID controller, the host device comprising an ideal response generating unit configured to generate time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response, a first memory unit configured to store the time series data of the controlled variable and the time series data of the manipulated variable, and a transmitting unit configured to transmit the time series data of the controlled variable and the time series data of the manipulated variable stored in the first memory unit to the PID controller, the PID controller comprising 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 host device, a second memory 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 instructing the start of a control operation from an outside, and the start signal input unit being configured to receive the time series data of the controlled variable and the time series data of the manipulated variable. The control system is characterized in that it comprises a reading unit configured to, when a start signal is received and a control operation is started, sequentially read out data of the controlled variable for each control cycle from the time series data stored in the second memory unit as a new value of a reference set value for each control cycle, and simultaneously sequentially read out data of the manipulated variable for each control cycle from the time series data stored in the second memory unit as a new value of a feedforward control manipulated variable for each control cycle; a control variable acquisition unit configured to acquire a measured value of the controlled variable; a feedback calculation unit configured to perform a 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; and a manipulated variable output unit configured to output the second manipulated variable calculated by the feedforward addition unit to a controlled object.

[0011] In one configuration example of the control system of the present invention, the PID controller further includes a limit processing unit configured to output a third manipulated variable obtained by limiting the second manipulated variable calculated by the feedforward addition unit to a value within a range between a manipulated variable upper limit value and a manipulated variable lower limit value, and the transmission unit of the host device transmits to the PID controller time series data of the manipulated variable upper limit value and time series data of the manipulated variable lower limit value, which are obtained by assuming an error range of the manipulated variable stored in the first storage unit for each control cycle, together with the time series data of the controlled variable and the time series data of the manipulated variable, and the receiving unit of the PID controller receives the time series data of the manipulated variable upper limit value and the time series data of the manipulated variable transmitted from the host device. the second memory unit of the PID controller stores the time series data of the manipulated variable upper limit value and the time series data of the manipulated variable lower limit value received by the receiving unit, the readout unit of the PID controller sequentially reads out, for each control cycle, the data of the manipulated variable upper limit value and the data of the manipulated variable lower limit value from the time series data stored in the second memory unit as new values ​​to be used in the limit processing unit when the start signal input unit receives the start signal and a control operation is started, and the manipulated variable output unit of the PID controller outputs the third manipulated variable to the control object instead of outputting the second manipulated variable to the control object.

[0012] Moreover, in one configuration example of the control system of the present invention, the PID controller is characterized in that it further includes a manipulated variable update unit configured to update the time series data of the manipulated variable stored in the second memory unit based on the time series data of the third manipulated variable output from the manipulated variable output unit when a learning mode is set to on. Moreover, in one configuration example of the control system of the present invention, the transmission unit sets a value obtained by adding an upward margin value to the operation amount for each control cycle as the operation amount upper limit value, and sets a value obtained by subtracting a downward margin value from the operation amount for each control cycle as the operation amount lower limit value. In addition, in one configuration example of the control system of the present invention, the ideal response generating unit is characterized in that it generates time series data of controlled variables and time series data of manipulated variables corresponding to an ideal control response by utilizing a virtual controlled object model for reproducing the behavior of the controlled object on a computer.

[0013] Further, a control method of the present invention includes a first step in which a host device generates time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response, a second step in which the host device stores the time series data of the controlled variable and the time series data of the manipulated variable, a third step in which the host device transmits the time series data of the controlled variable and the time series data of the manipulated variable to a PID controller, a fourth step in which the PID controller receives the time series data of the controlled variable and the time series data of the manipulated variable transmitted from the host device, a fifth step in which the PID controller stores the time series data of the controlled variable and the time series data of the manipulated variable received in the fourth step, a sixth step in which the PID controller receives a start signal instructing the start of a control operation from an outside, and a sixth step in which the PID controller receives the start signal and starts a control operation. a seventh step of, when the reference set value and the measured value of the control variable are input, sequentially reading out data of the controlled variable for each control cycle from the time series data stored in the fifth step as a new value of a reference set value for each control cycle, and simultaneously sequentially reading out data of the manipulated variable for each control cycle from the time series data stored in the fifth step as a new value of a feedforward control manipulated variable for each control cycle; an eighth step of, by the PID controller, acquiring a measured value of the controlled variable; a ninth step of, by the PID controller, performing a PID calculation using the reference set value and the measured value of the controlled variable as input to calculate a first manipulated variable; a tenth step of, by the PID controller, adding the feedforward control manipulated variable to the first manipulated variable to calculate a second manipulated variable; and an eleventh step of, by the PID controller, outputting the second manipulated variable calculated in the tenth step to a control target.

[0014] Moreover, one configuration example of the control method of the present invention further includes a twelfth step of outputting a third manipulated variable obtained by limiting the second manipulated variable calculated in the eleventh step to a value within a range between a manipulated variable upper limit value and a manipulated variable lower limit value, the third step includes a step of transmitting to the PID controller time series data of the manipulated variable upper limit value and time series data of the manipulated variable lower limit value, which assume an error range of the manipulated variable stored in the second step for each control cycle, together with the time series data of the controlled variable and the time series data of the manipulated variable, and the fourth step includes a step of receiving the time series data of the manipulated variable upper limit value and the time series data of the manipulated variable lower limit value transmitted from the host device, the fifth step includes a step of storing the time series data of the manipulated variable upper limit value and the time series data of the manipulated variable lower limit value received in the fourth step, the seventh step includes a step of sequentially reading out, when the start signal is received and the control operation is started, data of the manipulated variable upper limit value and data of the manipulated variable lower limit value for each control cycle from the time series data stored in the fifth step as new values ​​to be used in the twelfth step, and the eleventh step includes a step of outputting the third manipulated variable to the control object instead of outputting the second manipulated variable to the control object.

[0015] Moreover, one configuration example of the control method of the present invention is characterized in that it further includes a thirteenth step of updating the time series data of the manipulated variable stored in the fifth step based on the time series data of the third manipulated variable output by the eleventh step when the learning mode is set to on. Moreover, in one configuration example of the control method of the present invention, the third step is characterized by including a step of setting a value obtained by adding an upward side margin value to the operation amount for each control cycle as the operation amount upper limit value, and setting a value obtained by subtracting a downward side margin value from the operation amount for each control cycle as the operation amount lower limit value. Moreover, in one configuration example of the control method of the present invention, the first step is characterized by including a step of generating time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response by utilizing a virtual controlled object model for reproducing the behavior of the controlled object on a computer. Effect of the Invention

[0016] According to the present invention, by providing the host device with an ideal response generating unit, a first storage unit, and a transmitting unit, and providing the PID controller with a receiving unit, a second storage unit, a start signal input unit, a reading unit, a controlled variable acquiring unit, a feedback calculation unit, a feedforward addition unit, and a manipulated variable output unit, it is possible to obtain good control characteristics for a controlled object with strong nonlinear characteristics while efficiently utilizing the PID controller. Also, in the present invention, good control characteristics can be obtained while minimizing the amount of real-time communication between the PID controller and the host device, so that instrumentation that is easy to maintain stable continuity can be realized. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing a configuration of a control system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining communication between an industrial PC and a PID controller according to an embodiment of the present invention, and an outline of calculations in the PID controller. [Diagram 3] FIG. 3 is a flowchart illustrating the operation of the industrial PC according to the embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart illustrating the operation of the PID controller according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart illustrating the operation of the PID controller according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing changes in the controlled variable and the manipulated variable that correspond to an ideal control response. [Figure 7] FIG. 7 is a diagram showing changes in the controlled variable and the manipulated variable that correspond to an ideal control response. [Figure 8] FIG. 8 is a diagram showing changes in the controlled variable and the manipulated variable that correspond to an ideal control response. [Figure 9] FIG. 9 is a diagram showing the result of executing only feedforward control on a control target with a strong nonlinear characteristic. [Figure 10] FIG. 10 is a diagram showing the result of executing only feedforward control on a control target with a strong nonlinear characteristic. [Figure 11] FIG. 11 is a diagram showing the result of executing only feedforward control on a control target with a strong nonlinear characteristic. [Figure 12] FIG. 12 is a diagram showing a simulation result of the control according to the embodiment of the present invention. [Figure 13] FIG. 13 is a diagram showing a simulation result of the control according to the embodiment of the present invention. [Figure 14] FIG. 14 is a diagram showing a simulation result of the control according to the embodiment of the present invention. [Figure 15] FIG. 15 is a diagram showing a simulation result of the control according to the embodiment of the present invention. [Figure 16] FIG. 16 is a diagram showing a simulation result of the control according to the embodiment of the present invention. [Figure 17] FIG. 17 is a diagram showing a simulation result of the control according to the embodiment of the present invention. [Figure 18] FIG. 18 is a diagram showing a simulation result when limit processing using the manipulated variable upper limit value and the manipulated variable lower limit value is not executed in the embodiment of the present invention. [Figure 19] FIG. 19 is a diagram showing a simulation result when limit processing using the manipulated variable upper limit value and the manipulated variable lower limit value is not executed in the embodiment of the present invention. [Figure 20] FIG. 20 is a diagram showing a simulation result when limit processing using the manipulated variable upper limit value and the manipulated variable lower limit value is not executed in the 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 control system according to an embodiment of the present invention. [Figure 22] FIG. 22 is a diagram for explaining a control target of linear characteristics. [Figure 23] FIG. 23 is a diagram for explaining a control target having weakly nonlinear characteristics. [Figure 24] FIG. 24 is a diagram for explaining a control target having a strongly nonlinear characteristic. [Diagram 25] FIG. 25 is a diagram showing a simulation result of PID control for a control target having a strongly nonlinear characteristic. [Figure 26] FIG. 26 is a diagram showing a simulation result of PID control for a control target having a strongly nonlinear characteristic. [Figure 27] FIG. 27 is a diagram showing a simulation result of PID control for a control target having a strongly nonlinear characteristic. [Figure 28] FIG. 28 is a diagram for explaining the reason why the controlled variable fluctuates up and down in PID control for a controlled object with nonlinear characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [Principle 1] It is possible to obtain changes in the controlled variable PV and the manipulated variable MV that are close to the ideal control response by using a simulation that uses a controlled object model (a virtual controlled object that reproduces the behavior of the controlled object on a computer based on mathematical formulas such as differential equations) that may include strongly nonlinear characteristics, or by using a control trial that uses an actual controlled object.

[0019] Therefore, if the time series data of the controlled variable PV obtained by simulation or control trial is used as the reference set value SP, and the time series data of the manipulated variable MV is used as the manipulated variable MV_f for feedforward control, it is in principle possible to realize feedback control (PID control) that follows the reference set value SP even for a controlled object with strongly nonlinear characteristics.

[0020] Incidentally, the execution of simulations using the control target model and the storage of numerous time-series data sets assuming various conditions should be performed by an industrial personal computer (IPC) or other device at a higher level than a PID controller (a local controller with limited calculation functions for the purpose of continued stability) such as a temperature regulator, making it necessary to distribute the placement of each function block.

[0021] The inventor then noticed that in a temperature controller, there is a limit to real-time communication for each control cycle, and in particular, when data loss occurs in the set value SP due to poor communication, a malfunction occurs in the manipulated variable MV due to a differential operation (strictly speaking, a difference operation because it is a discrete system) that references the set value SP. Therefore, the inventor came to the conclusion that a suitable configuration is to transmit the time series data of the controlled variable PV to the PID controller side in advance as a reference set value SP_r, and to transmit the time series data of 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 upper level can be reduced as much as possible, making it possible to improve the instrumentation to be easier to maintain stable continuity while dealing with strong nonlinear characteristics.

[0022] [Principle 2] In order to transmit the time series data in advance, the PID controller stores the time series data. Therefore, a learning mode is provided in particular, and the time series data of the manipulated variable MV, which is the result of actually carrying out feedback control (PID control), is regarded as the adaptive learning result for the time-dependent change of the manipulated variable MV_f of the feedforward control, and the time series data of the manipulated variable MV stored in the PID controller is updated (replaced), thereby making it possible to cope with the time-dependent change of the controlled object. Note that when updating the time series data of the manipulated variable MV, it is not necessary to perform a complete replacement, and it may be a de facto partial replacement, for example, by replacing the manipulated variable MV, which is the result of carrying out feedback control and feedforward control, with the weighted average value of the manipulated variable MV stored in the PID controller.

[0023] [Example] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment corresponds to the principles 1 and 2 of the invention, but will be described as a configuration in which, in addition to the basic configuration, a function that is not an obstacle to stable continuity but is rather preferable is added.

[0024] 1 is a block diagram showing the configuration of a control system according to this embodiment. The control system is made up of an industrial PC 1 (host device) and a PID controller 2. The industrial PC 1 includes an ideal response generating unit 10 that generates time series data of a controlled variable PV and time series data of a manipulated variable MV that correspond to an ideal control response, a controlled variable change memory unit 11 that stores the time series data of the controlled variable PV, a manipulated variable change memory unit 12 that stores the time series data of the controlled variable MV, a controlled variable output unit 13 that transmits the time series data of the controlled variable PV to a PID controller 2, a manipulated variable output unit 14 that transmits the time series data of the controlled variable MV to the PID controller 2, a manipulated variable upper limit value output unit 15 that transmits to the PID controller 2 time series data of a controlled variable upper limit value OH_x that assumes an error range of the controlled variable MV stored in the manipulated variable change memory unit 12 for each control period, and a manipulated variable lower limit value output unit 16 that transmits to the PID controller 2 time series data of a controlled variable lower limit value OL_x that assumes an error range of the controlled variable MV stored in the manipulated variable change memory unit 12 for each control period.

[0025] The control amount change memory unit 11 and the operation amount change memory unit 12 constitute a memory unit 17, and the control amount output unit 13, the operation amount output unit 14, the operation amount upper limit value output unit 15, and the operation amount lower limit value output unit 16 constitute a transmission unit 18.

[0026] The PID controller 2 includes a set value receiving unit 20 that receives time series data of the controlled variable PV transmitted from the industrial PC 1, a manipulated variable receiving unit 21 that receives time series data of the controlled variable MV transmitted from the industrial PC 1, a manipulated variable upper limit value receiving unit 22 that receives time series data of the controlled variable upper limit value OH_x transmitted from the industrial PC 1, a manipulated variable lower limit value receiving unit 23 that receives time series data of the controlled variable lower limit value OL_x transmitted from the industrial PC 1, a set value memory unit 24 that stores the time series data of the controlled variable PV, a manipulated variable memory unit 25 that stores the time series data of the manipulated variable MV, a manipulated variable upper limit value memory unit 26 that stores the time series data of the manipulated variable upper limit value OH_x, a manipulated variable lower limit value memory unit 27 that stores the time series data of the manipulated variable lower limit value OL_x, and a control period PV determining unit 28 that determines a control period PV from the time series data stored in the set value memory unit 24 when a start signal input unit 32 described later receives a start signal and a control operation is started. the control amount PV for each control cycle from the time series data stored in the control amount memory 25 as a new value of the feedforward control control amount MV_f for each control cycle when the control operation is started; a control amount upper limit value memory 26 for each control cycle from the time series data stored in the control amount upper limit value memory 26 when the control operation is started, the control amount PV for each control cycle from the time series data stored in the control amount upper limit value memory 26 as a new value to be used in a limit processing unit 36 ​​described later; and a control amount lower limit value memory 31 for each control cycle from the time series data stored in the control amount lower limit value memory 27 when the control operation is started, the control amount PV for each control cycle from the time series data stored in the control amount lower limit value memory 27 as a new value to be used in the limit processing unit 36 ​​when the control operation is started.

[0027] The PID controller 2 further includes a start signal input unit 32 that receives a start signal that instructs the start of a control operation from the outside, a controlled variable acquisition unit 33 that acquires a measured value of a controlled variable PV, a feedback calculation unit 34 that receives as input a reference set value SP_r and the measured value of the controlled variable PV and performs a PID calculation to calculate a feedback control manipulated variable MV_b (first manipulated variable), a feedforward addition unit 35 that adds a feedforward control manipulated variable MV_f to the feedback control manipulated variable MV_b to calculate a manipulated variable MV_x' (second manipulated variable), and The control system is provided with a limit processing unit 36 ​​that outputs a control amount MV (third control amount) obtained by limiting the control amount MV_x' calculated by the feed-forward addition unit 35 to a value within a range between a control amount upper limit value OH_x and a control amount lower limit value OL_x, a control amount output unit 37 that outputs the control amount MV obtained by the limit processing unit 36 ​​to a control target, and a control amount update unit 38 that updates the time series data of the control amount MV stored in the control amount memory unit 25 based on the time series data of the control amount MV output from the control amount output unit 37 when the learning mode is set to on.

[0028] The set value receiving unit 20, the operating amount receiving unit 21, the operating amount upper limit value receiving unit 22, and the operating amount lower limit value receiving unit 23 constitute a receiving unit 39, the set value memory unit 24, the operating amount memory unit 25, the operating amount upper limit value memory unit 26, and the operating amount lower limit value memory unit 27 constitute a memory unit 40, and the set value reading unit 28, the operating amount reading unit 29, the operating amount upper limit value reading unit 30, and the operating amount lower limit value reading unit 31 constitute a reading unit 41.

[0029] The transmitter 18 and the receiver 39 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 appropriately selected to realize communication between the industrial PC 1 and the PID controller 2.

[0030] FIG. 2 is a diagram for explaining the communication between the industrial PC 1 and the PID controller 2, and an outline of the calculation in the PID controller 2. FIG.

[0031] The ideal response generating unit 10 of the industrial PC 1 generates data on the time change of the controlled variable PV corresponding to the ideal control response and data on the time change of the manipulated variable MV output to the controlled object at the time of this control response (step S100 in FIG. 3). The ideal response generating unit 10 may search for an optimal solution in a simulation using a controlled object model that may include a strongly nonlinear characteristic, or may issue an automatic trial command for control using an actual controlled object, thereby obtaining a change in the controlled variable PV and a change in the manipulated variable MV that are close to the ideal control response. In the present invention, the method of generating data by the ideal response generating unit 10 is not particularly limited.

[0032] The ideal response generator 10 generates time series data of the controlled variable PV and time series data of the manipulated variable MV for each preset control condition. The control condition usually refers to the condition of changing the set value SP (the set value SP before the change and the set value SP after the change) assumed in the temperature rise control using, for example, the PID controller 2 (temperature regulator).

[0033] The generated time series data of the controlled variable PV and the time series data of the manipulated variable MV each have time information (time stamp) added, with the start time of the control action being time 0. The time interval of the generated 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.

[0034] The controlled variable change storage unit 11 stores a set of time-series data of the controlled variable PV generated for each control condition by the ideal response generating unit 10 (step S101 in FIG. 3). An ID corresponding to the control condition is added to the data set generated for each control condition by the ideal response generating unit 10. The controlled variable change storage unit 11 stores this ID together with the data set.

[0035] The manipulated variable change storage unit 12 stores a set of time-series data of the manipulated variable MV generated for each control condition by the ideal response generator 10 (step S102 in FIG. 3). As described above, an ID corresponding to the control condition is added to the data set generated for each control condition by the ideal response generator 10. The manipulated variable change storage unit 12 stores this ID together with the data set.

[0036] The ideal response generator 10 must end data generation when a specified end time has elapsed from the point in time when the controlled variable PV stabilizes after the set value SP is changed. The reason for this is that if data generation continues, the storage capacity of the controlled variable change storage unit 11 and the manipulated variable change storage unit 12 will become enormous.

[0037] Next, the controlled variable output unit 13 transmits the time series data set of the controlled variable PV stored in the controlled variable change storage unit 11 to the PID controller (step S103 in FIG. 3). As described above, when the ideal response generating unit 10 generates a data set for each control condition, it transmits all the data sets for each control condition (each ID) to the PID controller 2.

[0038] The manipulated variable output unit 14 transmits the time series data set of the manipulated variable MV stored in the manipulated variable change storage unit 12 to the PID controller 2 (step S104 in FIG. 3). As described above, when the ideal response generating unit 10 generates a data set for each control condition, it transmits all the data sets for each control condition (each ID) to the PID controller 2.

[0039] The manipulated variable upper limit value output unit 15 calculates a manipulated variable upper limit value OH_x assuming an error range of the manipulated variable MV for each control cycle in the time series data set transmitted by the manipulated variable output unit 14. The manipulated variable upper limit value OH_x is calculated for each manipulated variable MV for each control cycle, thereby generating a time series data set of the manipulated variable upper limit value OH_x. The same timestamp as that of the manipulated variable MV data on which the calculation is based is added to each data of the manipulated variable upper limit value OH_x. The manipulated variable upper limit value output unit 15 transmits the calculated time series data set of the manipulated variable upper limit value OH_x to the PID controller 2 (step S105 in FIG. 3).

[0040] The simplest process is to predefine an upward margin centered on the manipulated variable MV. The manipulated variable upper limit value output unit 15 may calculate, as the manipulated variable upper limit value OH_x, a value obtained by adding the upward margin value to the manipulated variable MV for each control period in the time series data set transmitted by the manipulated variable output unit 14. As described above, when the ideal response generating unit 10 generates a data set for each control condition, a time series data set of the manipulated variable upper limit value OH_x is generated for each control condition (each ID), and all the time series data sets are transmitted to the PID controller 2.

[0041] The manipulated variable lower limit output unit 16 calculates a manipulated variable lower limit value OL_x assuming an error range of the manipulated variable MV for each control cycle in the time series data set transmitted by the manipulated variable output unit 14. The manipulated variable lower limit value OL_x is calculated for each manipulated variable MV for each control cycle, thereby generating a time series data set of the manipulated variable lower limit value OL_x. The same timestamp as that of the data of the manipulated variable MV on which the calculation is based is added to each data of the manipulated variable lower limit value OL_x. The manipulated variable lower limit output unit 16 transmits the calculated time series data set of the manipulated variable lower limit value OL_x to the PID controller 2 (step S106 in FIG. 3).

[0042] The simplest process is to predefine a downward margin centered on the manipulated variable MV. The manipulated variable lower limit value output unit 16 may calculate, as the manipulated variable lower limit value OL_x, a value obtained by subtracting the downward margin value from the manipulated variable MV for each control period in the time series data set transmitted by the manipulated variable output unit 14. As described above, when the ideal response generating unit 10 generates a data set for each control condition, a time series data set of the manipulated variable lower limit value OL_x is generated for each control condition (each ID), and all the time series data sets are transmitted to the PID controller 2.

[0043] In this embodiment, the timing at which the controlled variable output unit 13, the operated variable output unit 14, the operated variable upper limit value output unit 15, and the operated variable lower limit value output unit 16 transmit data may be before a series of control operations that use these data (e.g., a heating operation in temperature control) are started.

[0044] 4 and 5 are flowcharts for explaining the operation of the PID controller 2. The set value receiving unit 20 of the PID controller 2 receives the time-series data set of the controlled variable PV transmitted from the industrial PC 1 (step S200 in FIG. 4). The manipulated variable receiving unit 21 receives the time-series data set of the manipulated variable MV transmitted from the industrial PC 1 (step S201 in FIG. 4).

[0045] The manipulated variable upper limit value receiving unit 22 receives the time-series data set of the manipulated variable upper limit value OH_x transmitted from the industrial PC 1 (Step S202 in FIG. 4). The manipulated variable lower limit value receiving unit 23 receives the time-series data set of the manipulated variable lower limit value OL_x transmitted from the industrial PC 1 (Step S203 in FIG. 4).

[0046] The set value storage unit 24 stores the time-series data set of the controlled variable PV received by the set value receiving unit 20 (step S204 in FIG. 4). The manipulated variable storage unit 25 stores the time-series data set of the manipulated variable MV received by the manipulated variable receiving unit 21 (step S205 in FIG. 4).

[0047] The manipulated variable upper limit storage unit 26 stores the time-series data set of the manipulated variable upper limit value OH_x received by the manipulated variable upper limit receiving unit 22 (Step S206 in FIG. 4). The manipulated variable lower limit storage unit 27 stores the time-series data set of the manipulated variable lower limit value OL_x received by the manipulated variable lower limit receiving unit 23 (Step S207 in FIG. 4).

[0048] Next, the start signal input unit 32 receives a start signal that instructs the start of a control operation (YES in step S208 in FIG. 4). This start signal includes information that specifies the control condition (ID).

[0049] For example, when an operator of the industrial PC 1 manually changes the set value SP of the PID controller 2, a start signal is transmitted from the industrial PC 1 to the PID controller 2 at the timing when the operator instructs to change the set value SP. In addition, an ID corresponding to the control condition instructed by the operator is transmitted from the industrial PC 1 to the PID controller 2. Such an instruction may be given directly to the PID controller 2, not via the industrial PC 1.

[0050] Furthermore, for example, when temperature control of a heating furnace or the like is automatically executed according to predetermined schedule information, a start signal is transmitted from the industrial PC 1 to the PID controller 2 at the timing of changing the set value SP determined by the schedule information. Also, an ID corresponding to the control condition determined by the schedule information is transmitted from the industrial PC 1 to the PID controller 2.

[0051] When the start signal input unit 32 receives a start signal and the control operation of the PID controller 2 starts, the set value reading unit 28 sequentially reads out, from the time series data set of the control amount PV stored in the set value memory unit 24, the data of the control amount PV for each control cycle in the time series data set corresponding to the control condition (ID) instructed by the start signal as a new value of the reference set value SP_r for each control cycle (step S209 in FIG. 4).

[0052] The manipulated variable reading unit 29 sequentially reads out, from the time series data set of the manipulated variable MV stored in the manipulated variable memory unit 25, the data of the manipulated variable MV for each control cycle in the time series data set corresponding to the control condition (ID) instructed by the received start signal, as a new value of the feedforward control manipulated variable MV_f for each control cycle (step S210 in FIG. 4).

[0053] The operating volume upper limit value reading unit 30 sequentially reads out, from the time series data set of the operating volume upper limit values ​​OH_x stored in the operating volume upper limit value memory unit 26, the operating volume upper limit values ​​OH_x for each control cycle in the time series data set corresponding to the control condition (ID) instructed by the received start signal as a new value to be used in the limit processing unit 36 ​​(step S211 in FIG. 4).

[0054] The manipulated variable lower limit reading unit 31 sequentially reads out, from the time series data set of the manipulated variable lower limit values ​​OL_x stored in the manipulated variable lower limit memory unit 27, the manipulated variable lower limit values ​​OL_x for each control cycle in the time series data set corresponding to the control condition (ID) instructed by the received start signal, as new values ​​to be used in the limit processing unit 36 ​​for each control cycle (step S212 in FIG. 4).

[0055] As described above, a timestamp is added to each piece of data, i.e., the controlled variable PV stored in the set value memory unit 24, the controlled variable MV stored in the controlled variable memory unit 25, the controlled variable upper limit value OH_x stored in the controlled variable upper limit value memory unit 26, and the controlled variable lower limit value OL_x stored in the controlled variable lower limit value memory unit 27, so it is possible to read out data of the timestamp value (time) corresponding to the elapsed time from the time the start signal was received (the time when the control operation started).

[0056] It is desirable to read out the controlled variable PV (reference set value SP_r), the manipulated variable MV (feedforward control manipulated variable MV_f), the manipulated variable upper limit value OH_x, and the manipulated variable lower limit value OL_x, which require data synchronization, i.e., the same time stamp value, at the same time, but a time lag in reading them is acceptable. If this time lag is a small amount of time relative to the control period of the PID controller 2 (for example, 1 second), there is no practical problem.

[0057] When the start signal input unit 32 receives the start signal and the control operation of the PID controller 2 starts, the controlled variable acquisition unit 33 acquires the measured value of the controlled variable PV (step S213 in FIG. 4). In the case of temperature control using the PID controller 2 (temperature regulator), the value of the controlled variable PV is acquired from a temperature sensor.

[0058] Next, the feedback calculation unit 34 receives as input the reference set value SP_r read by the set value reading unit 28 and the measured value of the controlled variable PV acquired by the controlled variable acquisition unit 33, and performs PID calculation to calculate a feedback control manipulated variable MV_b so that the measured value of the controlled variable PV coincides with the reference set value SP_r. Specifically, when performing a speed-type PID calculation such as the transfer function formula shown in Equation (1), the feedback calculation unit 34 calculates a manipulated variable change width ΔMV_b (step S214 in FIG. 4). ΔMV_b=Kp{ΔEr+(1 / Ti)Er+TdΔ 2 Er} ···(1)

[0059] In formula (1), 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 2 Er is the second difference of the control deviation Er (the amount of change in the deviation Er per control cycle), Kp is the proportional gain of the PID parameters, Ti is the integral time of the PID parameters, and Td is the differential time of the PID parameters. Note that the proportional gain Kp has a relationship with the proportional band Pb of Kp=100 / Pb.

[0060] Then, the feedback calculation unit 34 adds the control input MV_x calculated by the feedforward addition unit 35 one control cycle ago (the value of MV_x' one control cycle ago, described later) and the control input change range ΔMV_b to obtain the feedback control control input MV_b (step S215 in FIG. 4), as shown in equation (2) (FIG. 4). MV_b = MV_x + ΔMV_b (2)

[0061] In addition, the feedback calculation unit 34 may be provided with a general additional function such as anti-reset windup processing (processing for preventing unnecessary accumulation of integral operations).

[0062] The feed-forward addition unit 35 adds the feed-forward control operation amount MV_f read by the operation amount reading unit 29 to the feedback control operation amount MV_b to calculate the operation amount MV_x' (step S216 in FIG. 4). When the feedback calculation unit 34 performs a velocity-type PID calculation, the feed-forward addition unit 35 calculates the difference between the feed-forward control operation amount MV_f in the current control cycle read by the operation amount reading unit 29 and the feed-forward control operation amount MV_f in the previous control cycle as the change width ΔMV_f. Then, as shown in Equation (3), the feed-forward addition unit 35 adds the change width ΔMV_f to the feedback control operation amount MV_b to calculate a new value of the operation amount MV_x'. MV_x’=MV_b+ΔMV_f ···(3)

[0063] The limit processing unit 36 outputs the operation amount MV obtained by limiting the operation amount MV_x' calculated by the feed-forward addition unit 35 to a value that is greater than or equal to the operation amount lower limit value OL_x and less than or equal to the operation amount upper limit value OH_x in the current control cycle (step S217 in FIG. 5). That is, when the operation amount MV_x' is less than the operation amount lower limit value OL_x (MV_x' < OL_x), the limit processing unit 36 sets the operation amount MV = OL_x; when the operation amount MV_x' is greater than the operation amount upper limit value OH_x (MV_x' > OH_x), the limit processing unit 36 sets the operation amount MV = OH_x; and when the operation amount MV_x' is greater than or equal to the operation amount lower limit value OL_x and less than or equal to the operation amount upper limit value OH_x (OL_x ≤ MV_x' ≤ OH_x), the limit processing unit 36 sets the operation amount MV = MV_x'.

[0064] Normally, limit processing with a standard operation amount upper limit value of 100% and an operation amount lower limit value of 0% for a thermostat is further performed. That is, when the operation amount MV is less than the operation amount lower limit value of 0%, the limit processing unit 36 sets the operation amount MV to 0%; when the operation amount MV is greater than the operation amount upper limit value of 100%, the limit processing unit 36 sets the operation amount MV to 100%.

[0065] The manipulated variable output unit 37 outputs the manipulated variable MV that has been subjected to limit processing by the limit processing unit 36 ​​to the controlled object (step S218 in FIG. 5). The output destination of the manipulated variable MV is 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.

[0066] When the learning mode is set to ON (YES in step S219 in FIG. 5), the manipulated variable update unit 38 temporarily stores the manipulated variable MV output from the manipulated variable output unit 37 (step S220 in FIG. 5). At this time, a timestamp with the start signal reception time as time 0 is added to the stored manipulated variable MV data. Then, the manipulated variable update unit 38 updates the data of the manipulated variable MV read out by the manipulated variable readout unit 29 as the feedforward control manipulated variable MV_f in the current control cycle, from the time-series data set of the manipulated variable MV stored in the manipulated variable storage unit 25, to the value of the manipulated variable MV output from the manipulated variable output unit 37 (step S221 in FIG. 5).

[0067] The learning mode can be turned on / off by an operator operating the PID controller 2, or can be set by the operator via the industrial PC 1. Note that the updated value may be a weighted average of the manipulated variable MV (feedforward control manipulated variable MV_f) to be updated stored in the manipulated variable storage unit 25 and the manipulated variable MV output from the manipulated variable output unit 37.

[0068] The PID controller 2 executes the processes of steps S209 to S221 for each control cycle until the control is ended by, for example, a command from an operator (YES in step S222 in FIG. 5).

[0069] However, the set value reading unit 28, the operating volume reading unit 29, the operating volume upper limit value reading unit 30, and the operating volume lower limit value reading unit 31 stop updating the reference set value SP_r, the feedforward control operating volume MV_f, the operating volume upper limit value OH_x, and the operating volume lower limit value OL_x (step S224 in FIG. 5) when a certain duration has elapsed from the point in time when the measured value of the controlled volume PV has stabilized (YES in step S223 in FIG. 5).

[0070] As a result, the reference set value SP_r, the feedforward control manipulated variable MV_f, the manipulated variable upper limit value OH_x, and the manipulated variable lower limit value OL_x are fixed to the values ​​received one control cycle ago. However, the manipulated variable upper limit value readout unit 30 may return the manipulated variable upper limit value OH_x to its initial value (100%), and the manipulated variable lower limit value readout unit 31 may return the manipulated variable lower limit value OL_x to its initial value (0%).

[0071] The above durations need to be set so that the updating of the reference set value SP_r, the feedforward control manipulated variable MV_f, the manipulated variable upper limit value OH_x, and the manipulated variable lower limit value OL_x stops before the data stored in the set value memory unit 24, the manipulated variable memory unit 25, the manipulated variable upper limit value memory unit 26, and the manipulated variable lower limit value memory unit 27 ends. Thereafter, the processes of steps S213 to S221 are executed every control period until the timing for the next change of the set value SP arrives and the start signal is received again.

[0072] In this embodiment, the data of the manipulated variable MV stored in the manipulated variable memory unit 25 is updated each time the manipulated variable MV is output from the manipulated variable output unit 37. However, after the updating of the reference set value SP_r, the feedforward control manipulated variable MV_f, the manipulated variable upper limit value OH_x, and the manipulated variable lower limit value OL_x has stopped, or after a series of control operations has been completed, the time series data set of the manipulated variable MV may be updated all at once using the data of the manipulated variable MV stored in the unit itself.

[0073] In the case of a batch update, the manipulated variable update unit 38 updates the time series data set so that the data of the manipulated variable MV to be updated in the time series data set corresponding to the control condition (ID) instructed by the start signal is updated to the value of the manipulated variable MV output from the manipulated variable output unit 37 at the time (the elapsed time from the time of reception of the start signal, which is an integer multiple of the control period) that matches the timestamp value of this data. As described above, the weighted average of the manipulated variable MV to be updated and the manipulated variable MV output from the manipulated variable output unit 37 may be used as the updated value.

[0074] Next, the effect of this embodiment will be described with reference to an example (simulation) of application to a controlled object with strongly nonlinear characteristics shown in Fig. 24. Here, the ideal response generating unit 10 generates time series data of the controlled variable PV and time series data of the manipulated variable MV that correspond to an ideal control response by a simulation using a controlled object model.

[0075] If the nonlinear characteristic of FIG. 24 is modeled, the manipulated variable MV in the settled state after the temperature rise can be obtained from the model for the temperature rise control shown in FIG. 25 to FIG. 27, so simple data such as those shown in FIG. 6 to FIG. 8 can be generated. FIG. 6 shows the change in the controlled variable PV (temperature) and the change in the manipulated variable MV corresponding to the ideal control response when the temperature is raised from 50°C to 150°C as shown in FIG. 25. FIG. 7 shows the change in the controlled variable PV and the change in the manipulated variable MV corresponding to the ideal control response when the temperature is raised from 50°C to 250°C as shown in FIG. 26. FIG. 8 shows the change in the controlled variable PV and the change in the manipulated variable MV corresponding to the ideal control response when the temperature is raised from 50°C to 350°C as shown in FIG. 27.

[0076] The controlled variable change storage unit 11 stores a set of time series data of the controlled variable PV generated by the ideal response generating unit 10 for each control condition. The manipulated variable change storage unit 12 stores a set of time series data of the manipulated variable MV generated by the ideal response generating unit 10 for each control condition. An ID corresponding to the control condition is added to the data set generated for each control condition by the ideal response generating unit 10. In the example of Figs. 6 to 8, different IDs are assigned to the data set when the temperature is increased from 50°C to 150°C, the data set when the temperature is increased from 50°C to 250°C, and the data set when the temperature is increased from 50°C to 350°C. 6 to 8, the change in the set value SP is also shown for convenience, but it is not necessary to store the set value SP.

[0077] Here, we will explain practical problems when the changes in the manipulated variable MV shown in Figures 6 to 8 are performed using only feedforward control, that is, when not combined with the feedback control of the PID controller 2. The strongly nonlinear characteristics of the controlled object are generally characteristics that appear when several types of complex characteristics overlap, and do not involve high-precision reproducibility. Therefore, Figures 9 to 11 show the results of performing only feedforward control with a 3% error between the model and the actual object.

[0078] Fig. 9 shows the results of only executing feedforward control when the temperature is raised from 50°C to 150°C. Fig. 10 shows the results of only executing feedforward control when the temperature is raised from 50°C to 250°C. Fig. 11 shows the results of only executing feedforward control when the temperature is raised from 50°C to 350°C. When only feedforward control is executed, an error occurs in the manipulated variable MV in the settled state after the temperature is raised, and it can be seen that an offset remains in the set value SP and the controlled variable PV, as shown in Figs. 9 to 11.

[0079] Next, a case where this embodiment is applied will be described. As shown in Fig. 2, an important characteristic is that a data set of an ideal control response is stored in an industrial PC 1, a time series data set of a controlled variable PV is transmitted from the industrial PC 1 to a PID controller 2 before a series of control operations are started, and the PID controller 2 stores the time series data set of the controlled variable PV. Another important characteristic is that a time series data set of a manipulated variable MV is transmitted from the industrial PC 1 to the PID controller 2 before a series of control operations are started, and the PID controller 2 stores the time series data set of the manipulated variable MV. Although this is almost impossible in reality, if the model error is 0%, the same results as those shown in Figures 6 to 8 will be obtained. In other words, feedback control becomes unnecessary.

[0080] Therefore, the error between the controlled object model used in the simulation by the ideal response generating unit 10 and the actual object is set to 5%, and the feedforward control and feedback control are operated simultaneously. As for the feedback control, as shown in Fig. 25 to Fig. 27, depending on the target temperature, unnecessary fluctuations in the manipulated variable MV occur, so it is preferable to regulate it by the manipulated variable upper limit value OH_x and the manipulated variable lower limit value OL_x.

[0081] Specifically, up to the time 150 seconds (50 seconds after the change in the set value SP), the upper margin value and the lower margin value are each set to 10% of the manipulated variable MV of the ideal control response, and after the time 150 seconds, the upper margin value and the lower margin value are each set to 5%. The results of this embodiment, which includes these processes, are shown in Figures 12 to 17.

[0082] Fig. 12 shows the changes in the reference set value SP_r, the measured value of the controlled variable PV, and the manipulated variable MV output by the manipulated variable output unit 37 when the temperature is raised from 50°C to 150°C. Fig. 13 shows the changes in the reference set value SP_r, the measured value of the controlled variable PV, and the manipulated variable MV output by the manipulated variable output unit 37 when the temperature is raised from 50°C to 250°C. Fig. 14 shows the changes in the reference set value SP_r, the measured value of the controlled variable PV, and the manipulated variable MV output by the manipulated variable output unit 37 when the temperature is raised from 50°C to 350°C.

[0083] Fig. 15 shows changes in the manipulated variable MV, manipulated variable upper limit value OH_x, and manipulated variable lower limit value OL_x output by the manipulated variable output unit 37 when the temperature is raised from 50°C to 150°C. Fig. 16 shows changes in the manipulated variable MV, manipulated variable upper limit value OH_x, and manipulated variable lower limit value OL_x output by the manipulated variable output unit 37 when the temperature is raised from 50°C to 250°C. Fig. 17 shows changes in the manipulated variable MV, manipulated variable upper limit value OH_x, and manipulated variable lower limit value OL_x output by the manipulated variable output unit 37 when the temperature is raised from 50°C to 350°C.

[0084] 12 to 17, this embodiment can also handle control objects with strongly nonlinear characteristics, and the amount of real-time communication between the PID controller 2 and the industrial PC 1 is reduced as much as possible, making it possible to realize instrumentation that is easy to maintain stable continuity.

[0085] For reference, the results when limit processing using the manipulated variable upper limit value OH_x and the manipulated variable lower limit value OL_x is not executed are shown in Figures 18 to 20. Since there is no effect of regulation by limit processing, more unnecessary up and down fluctuations due to the strong nonlinear characteristics of the controlled object occur than in the cases of Figures 12 to 17, but a significantly improved control response is obtained compared to Figures 25 to 27.

[0086] In this way, the limit processing unit 36 ​​is not an essential component of the present invention. If the limit processing unit 36 ​​is not provided, the operation amount output unit 37 outputs the operation amount MV_x' calculated by the feedforward addition unit 35 to the control target. If the limit processing unit 36 ​​is not provided, it becomes unnecessary to transmit the operation amount upper limit value OH_x and the operation amount lower limit value OL_x from the industrial PC 1, and it becomes unnecessary to store and read out the operation amount upper limit value OH_x and the operation amount lower limit value OL_x in the PID controller 2.

[0087] In addition, when the time interval of the time series data generated by the ideal response generating unit 10 is longer than the control period of the PID controller 2, the set value reading unit 28 may appropriately interpolate the time series data of the controlled variable PV stored in the set value storage unit 24, and sequentially output the data of the controlled variable PV for each control period as a new value of the reference set value SP_r for each control period. The manipulated variable reading unit 29 may appropriately interpolate the time series data of the manipulated variable MV stored in the manipulated variable storage unit 25, and sequentially output the data of the manipulated variable MV for each control period as a new value of the feedforward control manipulated variable MV_f for each control period. The manipulated variable upper limit value reading unit 30 may appropriately interpolate the time series data of the manipulated variable upper limit value OH_x stored in the manipulated variable upper limit value storage unit 26, and sequentially output the manipulated variable upper limit value OH_x for each control period as a new value to be used in the limit processing unit 36 ​​for each control period. The operating volume lower limit value reading unit 31 appropriately interpolates the time series data of the operating volume lower limit value OL_x stored in the operating volume lower limit value memory unit 27, and sequentially outputs the operating volume lower limit value OL_x for each control cycle as a new value to be used in the limit processing unit 36 ​​for each control cycle.

[0088] The industrial PC 1 and the PID controller 2 described in this embodiment 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 FIG.

[0089] The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202. In the case of the industrial PC 1, the I / F 202 is connected to hardware of a communication circuit for communication with the PID controller 2, etc. In the case of the PID controller 2, the I / F 202 is connected to a sensor that measures the controlled variable PV, hardware of a communication circuit for communication with the industrial PC 1, 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 industrial PC 1 and the PID controller 2 executes the processing described in this embodiment according to the program stored in the storage device 201. [Industrial Applicability]

[0090] The present invention can be applied to a control system. [Explanation of symbols]

[0091] 1...industrial PC, 2...PID controller, 10...ideal response generation unit, 11...controlled variable change memory unit, 12...operated variable change memory unit, 13...controlled variable output unit, 14...operated variable output unit 37, 15...operated variable upper limit value output unit, 16...operated variable lower limit value output unit, 17, 40...memory unit, 18...transmitter, 20...set value receiver, 21...operated variable receiver, 22...operated variable upper limit value receiver, 23...operated variable lower limit value receiver, 24...set value memory unit, 2 5...operated variable memory unit, 26...operated variable upper limit value memory unit, 27...operated variable lower limit value memory unit, 28...set value reading unit, 29...operated variable reading unit, 30...operated variable upper limit value reading unit, 31...operated variable lower limit value reading unit, 32...start signal input unit, 33...control variable acquisition unit, 34...feedback calculation unit, 35...feedforward addition unit, 36...limit processing unit, 37...operated variable output unit, 38...operated variable update unit, 39...receiving unit, 41...reading unit.

Claims

1. It is composed of a host device and a PID controller, The host device is an ideal response generating unit configured to generate time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response; a first storage unit configured to store time series data of the controlled variable and time series data of the manipulated variable; a transmission unit configured to transmit the time series data of the controlled variable and the time series data of the manipulated variable stored in the first storage unit to the PID controller, The PID controller is 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 host device; a second 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 outside source; a readout unit configured to, when the start signal input unit receives the start signal and a control operation is started, sequentially read out data on a controlled variable for each control cycle from the time series data stored in the second storage unit as a new value of a reference set value for each control cycle, and simultaneously sequentially read out data on an operation variable for each control cycle from the time series data stored in the second storage unit as a new value of a feedforward control operation variable for each control cycle; 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 input; a feedforward adder configured to add the feedforward control operation amount to the first operation amount to calculate a second operation amount; a manipulated variable output unit configured to output the second manipulated variable calculated by the feedforward adder to a controlled object.

2. 2. The control system of claim 1, the PID controller further includes a limit processing unit configured to output a third manipulated variable obtained by limiting the second manipulated variable calculated by the feedforward addition unit to a value within a range between an manipulated variable upper limit value and an manipulated variable lower limit value, the transmission unit of the host device transmits to the PID controller time series data of the manipulated variable upper limit value and time series data of the manipulated variable lower limit value, which are obtained by assuming an error range of the manipulated variable stored in the first storage unit for each control period, together with the time series data of the controlled variable and the time series data of the manipulated variable; the receiving unit of the PID controller receives the time series data of the manipulated variable upper limit value and the time series data of the manipulated variable lower limit value transmitted from the host device, the second storage unit of the PID controller stores the time series data of the manipulated variable upper limit value and the time series data of the manipulated variable lower limit value received by the receiving unit, when the start signal input unit receives the start signal and a control operation is started, the readout unit of the PID controller sequentially reads out the data of the manipulated variable upper limit value and the data of the manipulated variable lower limit value for each control cycle from the time-series data stored in the second storage unit as new values ​​to be used in the limit processing unit for each control cycle; The control system according to claim 1, wherein the manipulated variable output unit of the PID controller outputs the third manipulated variable to a control object, instead of outputting the second manipulated variable to the control object.

3. 3. The control system of claim 2, a control system comprising: a control input updating unit configured to update the time series data of the manipulated variable stored in the second storage unit based on the time series data of the third manipulated variable output from the manipulated variable output unit when a learning mode is set to on;

4. 3. The control system of claim 2, a control system characterized in that the transmission unit sets the manipulated variable upper limit value to a value obtained by adding an upward margin value to the manipulated variable for each control cycle, and sets the manipulated variable lower limit value to a value obtained by subtracting a downward margin value from the manipulated variable for each control cycle.

5. A control system according to any one of claims 1 to 4, The ideal response generating unit generates time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response by utilizing a virtual controlled object model for reproducing the behavior of the controlled object on a computer.

6. A first step in which a host device generates time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response; a second step in which the host device stores time series data of the controlled variable and time series data of the manipulated variable; a third step in which the host device transmits the time series data of the controlled variable and the time series data of the manipulated variable to a PID controller; a fourth step in which the PID controller receives the time series data of the controlled variable and the time series data of the manipulated variable transmitted from the host device; a fifth step in which the PID controller stores the time series data of the controlled variable and the time series data of the manipulated variable received in the fourth step; a sixth step of receiving a start signal from the outside by the PID controller instructing the start of a control operation; a seventh step of, when the PID controller receives the start signal and starts a control operation, sequentially reading out data of a controlled variable for each control cycle from the time series data stored in the fifth step as a new value of a reference set value for each control cycle, and simultaneously sequentially reading out data of an operation variable for each control cycle from the time series data stored in the fifth step as a new value of a feedforward control operation variable for each control cycle; an eighth step of the PID controller acquiring a measured value of a controlled variable; a ninth step in which the PID controller performs a PID calculation using the reference set value and the measured value of the controlled variable as inputs to calculate a first manipulated variable; a tenth step in which the PID controller calculates a second manipulated variable by adding the feedforward control manipulated variable to the first manipulated variable; and an eleventh step in which the PID controller outputs the second manipulated variable calculated in the tenth step to a controlled object.

7. 7. The control method according to claim 6, a twelfth step of outputting a third manipulated variable obtained by limiting the second manipulated variable calculated in the eleventh step to a value within a range between an upper manipulated variable limit value and a lower manipulated variable limit value, the third step includes a step of transmitting, to the PID controller, time series data of the manipulated variable upper limit value and time series data of the manipulated variable lower limit value, which are obtained by assuming an error range of the manipulated variable stored in the second step for each control cycle, together with the time series data of the controlled variable and the time series data of the manipulated variable; the fourth step includes a step of receiving the time series data of the operation volume upper limit value and the time series data of the operation volume lower limit value transmitted from the host device, the fifth step includes a step of storing the time series data of the operation volume upper limit value and the time series data of the operation volume lower limit value received in the fourth step; the seventh step includes a step of sequentially reading out, when the start signal is received and the control operation is started, data on the manipulated variable upper limit value and data on the manipulated variable lower limit value for each control cycle from the time-series data stored in the fifth step as new values ​​to be used in the twelfth step, The control method according to claim 11, further comprising the step of outputting the third manipulated variable to a control target, instead of outputting the second manipulated variable to the control target.

8. 8. The control method according to claim 7, a thirteenth step of updating the time series data of the manipulated variable stored in the fifth step based on the time series data of the third manipulated variable output in the eleventh step when a learning mode is set to on.

9. 8. The control method according to claim 7, the third step including a step of setting a value obtained by adding an upward side margin value to the manipulated variable for each control cycle as the manipulated variable upper limit value, and setting a value obtained by subtracting a downward side margin value from the manipulated variable for each control cycle as the manipulated variable lower limit value.

10. 10. The control method according to claim 6, a control method characterized in that the first step includes a step of generating time series data of a controlled variable and time series data of a manipulated variable corresponding to an ideal control response by utilizing a virtual controlled object model for reproducing the behavior of the controlled object on a computer.

Images