JP4361851B2 - Control method - Google Patents

Description

  The present invention relates to a process control technique, and more particularly to a control method for controlling a relative quantity such as a state quantity difference measured in a control system having at least two control loops.

  FIG. 11A shows a configuration of a temperature controller which is a conventional control device (see, for example, Patent Document 1). A heat treatment work 1016 is carried into the furnace 1001, and the heater 1011, detection means 1012 for detecting the control temperature TC 1, detection means 1013 for detecting the surface temperature TC 2 of the work 1016, and the deepest temperature TC 3 of the work 1016. Detection means 1014 for detecting is arranged. Reference numeral 1002 denotes a power regulator. The control unit 1003 includes a comparator 1031 that compares the control temperature TC1 and the execution program pattern set value 1033, a control calculation unit 1032 such as PID controlled by the output of the comparator 1031, and the surface temperature TC2 of the workpiece 1016 and the deepest surface temperature TC2. A temperature difference detector 1034 that detects a difference from the temperature TC3, a temperature difference setter 1035 that sets a predetermined temperature difference, and an output of the temperature difference detector 1034 and an output of the temperature difference setter 1035 are compared. The comparator 1036, the change rate detector 1038 for detecting the temperature change rate of the deepest temperature TC3, and the output of the change rate detector 1038 are compared with the output of the change rate setter 1039 for setting a predetermined temperature change rate. The comparator 1040 to perform, the inclination calculation based on the output of the comparator 1036 and the output of the comparator 1040, and the execution program pattern set value 103 And an inclined calculator 1037 for controlling.

The maximum allowable temperature difference is set in the temperature difference setting unit 1035, and the maximum allowable temperature change rate is set in the change rate setting unit 1039. With the configuration of FIG. 11A, the inclination in the execution program pattern set value 1033 is constantly corrected so that one or both of the temperature difference and / or temperature change rate in the heat treatment workpiece 1016 fall within the specified temperature tolerance. The
When attention is paid to the portion surrounded by the broken line in FIG. 11A, the state quantity for calculating the temperature difference (TC2-TC3) and the temperature change rate dTC3 / dt based on the plurality of measured temperatures TC1, TC2, TC3. You can see that the conversion is taking place. That is, the temperature controller in FIG. 11A includes a state quantity conversion unit 1041 that calculates the temperature difference (TC2−TC3) and the temperature change rate dTC3 / dt (FIG. 11B).

  FIG. 12 (a) shows the configuration of a temperature control device that is another conventional control device (see, for example, Patent Document 2). In the figure, reference numeral 2002 denotes a reaction tube of the vertical heat treatment apparatus 2020. Inside the reaction tube 2002, a temperature sensor A for detecting the temperature in the vicinity of the semiconductor wafer mounted on the wafer board 2021 is provided. A temperature sensor B that detects the temperature of the outer surface of the reaction tube 2002 is provided. The deviation circuit unit 2031 outputs a deviation obtained by subtracting a correction value described later from the target value of the temperature sensor A, that is, the target value of the temperature sensor B. The deviation circuit unit 2032 outputs a deviation obtained by subtracting the detection value of the temperature sensor B from the target value of the temperature sensor B to the PID adjustment unit 2004. The PID adjustment unit 2004 performs PID calculation based on the input deviation and outputs the calculation result to the power control unit 2005. The power control unit 2005 uses the vertical heat treatment apparatus based on the output value of the PID adjustment unit 2004. The power supply amount to the heater 2006, which is a heating source of 2020, is controlled. On the other hand, when the detected value of the temperature sensor B converges to the target value, the correction value output unit 2007 calculates the difference (A−B) between the detected value of the temperature sensor A and the detected value of the temperature sensor B at the time of convergence. As a correction value, the target value of the temperature sensor B is corrected by the correction value. With the configuration of FIG. 12A, the detection value of the temperature sensor A converges to the target value.

When attention is paid to the portion surrounded by the broken line in FIG. 12A, it is understood that state quantity conversion for calculating the temperature difference (A−B) based on the plurality of measured temperatures A and B is performed. it can. That is, the temperature adjustment device in FIG. 12A includes the state quantity conversion unit 2008 that calculates the temperature difference (A−B) (FIG. 12B).
As described above, efforts have been made in the past to incorporate not only the actual state quantity itself but also the state quantity difference into the control system. The state quantity conversion unit is provided.

  Here, let us consider that in the two control loops, the state quantity average value PV1 'and the state quantity difference PV2' are controlled, not the state quantities PV1 and PV2 themselves. The control device in this case is shown in FIG. 13 includes a subtractor 3001 that outputs a difference between the set value SP1 ′ and the state quantity average value PV1 ′ with respect to the state quantity average value PV1 ′, and a set value SP2 ′ with respect to the state quantity difference PV2 ′ and the state quantity difference. Subtractor 3002 that outputs the difference from PV2 ′, controllers C1 and C2 that calculate operation amounts MV1 and MV2 based on the outputs of subtractors 3001 and 3002, and operation amounts for control target processes P1 and P2, respectively. Actuators A1 and A2 that perform operations according to MV1 and MV2 and a state quantity conversion unit 3003 are included.

The state quantity conversion unit 3003 multiplies multipliers 3004 and 3005 for multiplying the state quantities PV1 and PV2 of the control target processes P1 and P2 by 0.5 and −1 and 1 respectively for the state quantities PV1 and PV2. Multipliers 3006 and 3007 for multiplication, an adder 3008 for adding the outputs of the multipliers 3004 and 3005, and an adder 3009 for adding the outputs of the multipliers 3006 and 3007. By such a state quantity conversion unit 3003, the state quantity average value PV1 ′ and the state quantity difference PV2 ′ are expressed by the following equations.
PV1 ′ = 0.5PV1 + 0.5PV2 (1)
PV2 ′ = PV2-PV1 (2)
Further, the input / output relationship of the state quantity conversion unit 3003 is expressed as a matrix as follows.

  The controller C1 targets the state quantity average value PV1 ', and the controller C2 targets the state quantity difference PV2'. The controller C1 calculates the manipulated variable MV1 based on the deviation between the set value SP1 ′ and the state quantity average value PV1 ′, and the controller C2 calculates the manipulated variable MV2 based on the deviation between the set value SP2 ′ and the state quantity difference PV2 ′. calculate. At this time, since the state quantity average value PV1 ′ and the state quantity difference PV2 ′ are in a controllable state, the operation amount MV1 calculated by the controller C1 is sent to the actuator A1, and the operation calculated by the controller C2 is performed. The quantity MV2 is configured to be sent to the actuator A2. As a result, the actuator A1 operates to control the state quantity average value PV1 ', and the actuator A2 operates to control the state quantity difference PV2'. As described above, the controller C1 that directly controls the state quantity average value PV1 ′ and the state quantity difference PV2 can be obtained only by applying the state quantity conversion unit 3003 similar to that shown in FIGS. 11B and 12B. A multi-loop control system including a controller C2 that directly controls' can be configured, and the state quantity average value PV1 'and the state quantity difference PV2' can be controlled to desired values.

  However, when the state quantity PV1 is changed by the operation of the actuator A1, this change also affects the state quantity difference PV2 'by the action of the state quantity conversion unit 3003. Similarly, when the state quantity PV2 is changed by the operation of the actuator A2, this change also affects the state quantity average value PV1 'by the action of the state quantity conversion unit 3003. That is, in the control device shown in FIG. 13, the state quantity conversion unit 3003 is configured to artificially generate inter-loop interference.

  Since the coefficients multiplied by the state quantities PV1 and PV2 to calculate the state quantity average value PV1 ′ are both 0.5, the process gain Kp1 of the control target process P1 and the process gain Kp2 of the control target process P2 are approximately the same. Assuming that, the degree of influence on the state quantity average value PV1 ′ due to operation of the actuator A1 and the degree of influence on the state quantity average value PV1 ′ due to inter-loop interference when the actuator A2 operates (state due to the actuator A2) The degree of influence that disturbs the quantity average value PV1 ′) is about the same. Similarly, since the absolute values of the coefficients multiplied by the state quantities PV1 and PV2 in order to calculate the state quantity difference PV2 ′ are both 1, the degree of influence on the state quantity difference PV2 ′ due to the operation of the actuator A2; The degree of influence on the state quantity difference PV2 ′ due to interference between loops when the actuator A1 operates (the degree of influence that the state quantity difference PV2 ′ is disturbed by the actuator A1) is about the same. Therefore, simply applying the state quantity conversion unit inherently tends to increase the artificial inter-loop interference, which causes a problem that the controllability tends to deteriorate.

  Therefore, in order to realize non-interference between loops, it is easily conceivable to apply the cross controller disclosed in Non-Patent Document 1. The configuration of the control device disclosed in Non-Patent Document 1 is shown in FIG. 14 includes a subtractor 4001 that outputs a difference between the set value SP1 and the state quantity PV1, a subtractor 4002 that outputs a difference between the set value SP2 and the state quantity PV2, and outputs of the subtractors 4001 and 4002. Controller 4003 and 4004 for calculating the operation amounts MV1 and MV2, respectively, and a cross controller 4005 for outputting the operation amounts MV1 ′ and MV2 ′ obtained by converting the operation amounts MV1 and MV2, respectively.

The cross controller 4005 performs processing for previously canceling the influence due to the interference between the loops on the operation amounts MV1 and MV2, a multiplier 4007 that multiplies the operation amount MV1 by a coefficient M12, and a coefficient M21 on the operation amount MV2. Multiplier 4008 for multiplication, subtractor 4009 for outputting the difference between operation amount MV1 and the output of multiplier 4008 as operation amount MV1 ′, and the difference between operation amount MV2 and the output of multiplier 4007 as operation amount MV2 ′. And a subtractor 4010 for outputting. Here, for simplicity of explanation, dynamic characteristics such as process time constant and process dead time are ignored. Assuming that the process gains of the control target process 4006 for the manipulated variables MV1 ′ and MV2 ′ are Kp1 and Kp2, respectively, according to Non-Patent Document 1, the cross controller 4005 for non-interference can be designed as follows.
MV1 ′ = MV1 + (− 0.5Kp2 / 0.5Kp1) MV2 (4)
MV2 ′ = (Kp1 / Kp2) MV1 + MV2 (5)
Further, the input / output relationship of the cross controller 4005 is expressed in a matrix as follows.

  That is, the coefficient M12 is −Kp1 / Kp2, and the coefficient M21 is 0.5Kp2 / 0.5Kp1. The operation amount MV1 calculated by the controller 4003 is converted into the operation amount MV1 ′ by the cross controller 4005 and then sent to the control target process 4006 via an actuator (not shown). The operation amount MV2 calculated by the controller 4004 is After being converted into the operation amount MV2 ′ by the controller 4005, it is sent to the control target process 4006 via the actuator.

  FIG. 15 shows a configuration in which the cross controller 4005 shown in FIG. 14 is applied to the control device of FIG. By using the state quantity conversion unit 3003 and the cross controller 4005, only the first control loop centering on the controller C1 that exclusively controls the state quantity average value PV1 ′ and only the state quantity difference PV2 ′ are exclusively used. A multi-loop control system having a second control loop centered on the controller C2 to be controlled can be realized. The response characteristic of the controller C1 that exclusively controls the state quantity average value PV1 ′ is adjusted in the direction of emphasizing stability (low sensitivity), and the response characteristic of the controller C2 that exclusively controls the state quantity difference PV2 ′ is obtained. If adjustment is made in a direction that emphasizes responsiveness (high sensitivity), the state quantity difference PV2 ′ follows the set value SP2 ′ before the state quantity average value PV1 ′ follows the set value SP1 ′. Thus, it is possible to perform control such that the state quantity average value PV1 ′ is changed to a desired value while maintaining the state quantity difference PV2 ′ at a desired value.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP-A-8-095647 JP-A-9-199491 Kazuo Hiroi, “Basics and Applications of Digital Instrumentation Control System”, Industrial Technology Co., Ltd., October 1987, p. 152-156, ISBN4-905957-00-1

[First issue]
An actual actuator has upper and lower limits of output, and the controller must calculate an operation amount in consideration of the upper and lower limits. That is, in a state where the output of the actuator reaches the upper limit value or the lower limit value and the change in the state quantity is limited, the controller must not raise or lower the operation amount calculation result more than necessary. If a controller such as PID does not consider the physical upper and lower limits of the actuator, there is a problem of integral windup.

  Hereinafter, this integral windup will be specifically described. For example, when the state quantity is temperature and the actuator is a heater, the heater output is generally limited to a lower limit value of 0% and an upper limit value of 100%. When the operation amount MV calculated by the controller increases and reaches 100%, the heater output also reaches 100%. At this time, when the temperature measurement value PV is lower than the temperature set value SP, if the controller ignores the upper limit value 100% of the heater output, the controller calculates an operation amount MV larger than 100%. Become. However, since the heater output saturates at 100%, the increase in the temperature measurement value PV corresponding to the increase in the heater output reaches the limit, and as a result, the controller increases the manipulated variable MV to a larger value. .

  Then, it is assumed that the temperature set value SP is changed to a value lower than the temperature measurement value PV when the calculated value of the manipulated variable MV continues to increase and reaches, for example, 500%. By changing the temperature setting value SP, the controller lowers the operation amount MV from 500%, so that the operation amount MV lower than the upper limit value 100% of the heater output is output from the controller. It takes a long time. Therefore, although the temperature set value SP is changed to a value lower than the temperature measurement value PV, the controller outputs an operation amount of 100% for a long time, and as a result, the start of the temperature drop is greatly delayed. . As described above, the calculation result of the operation amount MV becomes higher than necessary, and the phenomenon that the decrease in the operation amount MV is delayed when the set value SP is changed to a small value is a phenomenon called integral windup. This is because the operation amount is not calculated in consideration of the physical upper and lower limits.

  In the control device shown in FIG. 15, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are converted into operation amounts MV1 ′ and MV2 ′ by the cross controller 4005. In other words, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are calculated as composite operation amounts for the plurality of actuators A1 and A2, and the operation amounts MV1 and MV2 of the controllers C1 and C2 and the actuators A1 and A2 are calculated. There is no one-to-one correspondence with the output of A2. Therefore, even if the controllers C1 and C2 calculate the operation amounts MV1 and MV2 in consideration of the upper and lower limits of the outputs of the actuators A1 and A2, the operation amounts MV1 and MV2 are actually output to the actuators A1 and A2. Since the combined operation amounts MV1 ′ and MV2 ′ are generated, there is a possibility that an operation amount output that does not consider the upper and lower limits of the outputs of the actuators A1 and A2 is performed on the actuators A1 and A2. For this reason, the control apparatus shown in FIG. 15 has a problem that the integral windup similar to that of the PID controller described above occurs.

[Second problem]
Moreover, in a normal controller, parameters must be adjusted according to the characteristics of the control target. An example of parameter adjustment is PID parameter adjustment in a PID controller. Conventionally, adjustment methods and automatic adjustment functions for realizing such parameter adjustment have been devised, but this adjustment method and automatic adjustment function basically consists of a controller, an actuator, a controlled object, and a measuring means physically. It is a necessary condition to support.

  Hereinafter, the conventional parameter adjustment will be specifically described. For example, consider a case where the state quantity is temperature, the actuator is a heater, the controlled object is a furnace, and the measuring means is a temperature sensor such as a thermocouple. At this time, as shown in FIG. 16, assuming two control loops, controllers 5003 and 5004, heaters 5005 and 5006 as actuators, furnaces 5007 and 5008 as control objects, and temperature sensors as measurement means. 5009, 5010. In FIG. 16, reference numeral 5001 denotes a subtractor that outputs the difference between the temperature set value SP1 and the temperature measurement value PV1, and 5002 denotes a subtractor that outputs the difference between the temperature set value SP2 and the temperature measurement value PV2.

  In the configuration of FIG. 16, although some inter-loop interference is allowed, the controller 5003 outputs the operation amount MV1 to the heater 5005, the heater 5005 mainly heats the furnace 5007, and the temperature sensor 5009 is a temperature near the furnace 5007. And the controller 5003 must execute a control calculation so as to control the temperature measurement value PV1. Similarly, the controller 5004 outputs the operation amount MV2 to the heater 5006, the heater 5006 mainly heats the furnace 5008, the temperature sensor 5010 measures the temperature near the furnace 5008, and the controller 5004 controls the temperature measurement value PV2. The control operation must be executed as follows. In this way, the controller 5003, 5004, the heaters 5005, 5006, the furnace 5007, 5008, and the temperature sensors 5009, 5010 are physically compatible with each other, so that an adjustment method or an automatic adjustment function that has been devised in the past is applied. It becomes a necessary condition to do. In other words, the controller 5003 calculates the operation amounts MV1 and MV2 distributed at the same level between the heaters 5005 and 5006 as one combined operation amount, and the controller 5004 is also equivalent to the heaters 5005 and 5006. If the operation amounts MV1 and MV2 distributed at the level of 1 are calculated as one composite operation amount, it becomes impossible to apply a conventionally devised adjustment method or automatic adjustment function.

  In the control device shown in FIG. 15, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are converted into operation amounts MV1 ′ and MV2 ′ by the cross controller 4005. In other words, the operation amounts MV1 and MV2 calculated by the controllers C1 and C2 are calculated as composite operation amounts for the plurality of actuators A1 and A2, and the operation amounts MV1 and MV2 of the controllers C1 and C2 and the actuators A1 and A2 are calculated. There is no one-to-one correspondence with the output of A2. That is, the basic condition that the controller, the actuator, the controlled object, and the measuring means physically correspond to each other is not satisfied. Therefore, with the control device shown in FIG. 15, it is impossible to apply a conventionally devised adjustment method or automatic adjustment function, and controller parameter adjustment such as PID parameter adjustment becomes very difficult. was there.

  The present invention has been made to solve the above-described problems, and changes an absolute amount such as an average value of a plurality of state quantities to a desired value while maintaining a relative amount between the plurality of state quantities at a desired value. It is an object of the present invention to provide a control method that can prevent integral windup in a control system that performs such control, and that can apply a conventionally devised parameter adjustment method, automatic adjustment function, and the like.

The present invention provides a control method for a control system having at least two parallel PID control loops, wherein a weighted average value of the state quantities of the at least two PID control loops is used as a reference state quantity, When the amount of state controlled so as to maintain a predetermined amount is the tracking state amount, the absolute value of the deviation between the tracking state amount set value SPi and the tracking state amount measured value PVi is determined for each PID control loop. A weight correction procedure for calculating and adaptively correcting the weight of the weighted average value with respect to the state quantity as the PID control loop having a larger absolute value, and a plurality of control calculation input values input to the PID controller for controlling the following state quantity A tracking state quantity set value SPi is converted into a tracking state quantity internal set value SPi ′, and then input to the PID controller. As the control calculation input value, the reference state quantity setting value SPm set as the weighted average value, the measured reference state quantity measurement value PVm, the preset tracking state quantity setting value SPi, and the measured tracking when the the state quantity measurement value PVi inputted, the follow-up state quantity measurement value first coefficient Bi define the degree of conformability to the reference state quantity measurement value PVm of PVi, the reference state quantity measurement value by using the second coefficient Is it define the degree of responsiveness to the reference state quantity setting value SPm of PVm, 'SPi a' the follow-up state quantity internal set point SPi = AmSPm + (1-Am ) PVm + Bi ( SPi−SPm) + (1−Bi) (PVi−PVm) to calculate the reference state quantity measurement value PVm to the reference state quantity set value SPm, the following state quantity measurement value PVi, and the reference state quantity Measured value Is obtained by the following capability of a difference which is a difference Vm relative amounts PVi-PVm of follow-up state quantity set point SPi and the reference state quantity set value SPm to the relative amounts SPi-SPm to be separately controlled.

Also, in one configuration example of the control method of the present invention, the weight correction procedure is such that the PID control loop having a larger absolute value has the highest absolute value instead of adaptively correcting the weight of the weighted average value with respect to the state quantity. The weighted average value for the state quantity of the large PID control loop is set to 1, and the weight for the state quantity of the other PID control loop is set to 0 .
Further, in one configuration example of the control method of the present invention , instead of the calculation procedure, the tracking state quantity measured value PVi among the plurality of control calculation input values input to the PID controller that controls the tracking state quantity is set to the tracking state. A calculation procedure for converting the measured value into an internal measured value PVi ′ and inputting the value to the PID controller is provided. The calculation procedure is performed by measuring a preset reference state quantity set value SPm as the control calculation input value. When a reference state quantity measurement value PVm, a preset tracking state quantity setting value SPi, and a measured tracking state quantity measurement value PVi are input, the reference state quantity measurement value of the tracking state quantity measurement value PVi is input. The first coefficient Bi that defines the degree of followability to PVm, and the second coefficient Am that defines the degree of responsiveness of the reference state measurement value PVm to the reference state quantity set value SPm; Is used to calculate the tracking state quantity internal measurement value PVi ′ by PVi ′ = (1−Am) SPm + AmPVm + (1−Bi) (SPi−SPm) + Bi (PVi−PVm). The followability of PVm to the reference state quantity set value SPm and the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measured value PVi and the reference state quantity measured value PVm, and the reference state quantity set value SPm The followability to the relative amount SPi-SPm, which is the difference between the two, is separated and controlled .
Further, in one configuration example of the control method of the present invention, a tracking state amount deviation Eri calculated based on a plurality of control calculation input values input to a PID controller that controls the tracking state amount instead of the calculation procedure. Is converted into a follow-up state quantity internal deviation Eri ′ and input to the controller, and the calculation procedure includes a reference state quantity set value SPm set in advance as the control calculation input value, and a measurement When the reference state quantity measurement value PVm, the preset tracking state quantity setting value SPi, and the measured tracking state quantity measurement value PVi are input, the reference state quantity of the tracking state quantity measurement value PVi is input. The first coefficient Bi that defines the degree of followability to the measured value PVm, and the second coefficient that defines the degree of responsiveness of the reference state quantity measured value PVm to the reference state quantity set value SPm. By using Am, the tracking state quantity internal deviation Eri ′ is calculated by Eri ′ = Am (SPm−PVm) + Bi {(SPi−SPm) − (PVi−PVm)}, thereby obtaining a reference state quantity measurement value PVm. Of the following state quantity set value SPm and the following state quantity set value SPm of the relative quantity PVi-PVm, which is the difference between the follow state quantity measured value PVi and the reference state quantity measured value PVm. The followability to the relative amount SPi-SPm, which is the difference, is controlled separately.

  According to the present invention, in a control system having at least two control loops, a weighted average value of the state quantities of each control loop is used as a reference state quantity, and a relative amount with respect to the reference state quantity is maintained in a predetermined value. When the state quantity controlled so as to be the tracking state quantity, one of a plurality of control calculation input values input to the controller that controls the tracking state quantity is converted into an internal input value and then input to the controller. In this calculation procedure, the internal input value is calculated as the sum of the first element with respect to the reference state quantity and the second element with respect to the relative quantity, so that the state of the reference state quantity and the follow-up state quantity It is possible to realize control for changing a reference state quantity such as a state quantity average value to a desired value while maintaining a relative quantity such as a quantity difference at a desired value. Further, in the present invention, since a control system in which the operation amount of the controller and the actual actuator output correspond one-to-one can be configured, integral wind-up can be prevented, and parameters conventionally devised. The controller can be adjusted by applying an adjustment method or automatic adjustment function. Further, by using a value obtained by multiplying the element of the input value for control calculation with respect to the relative quantity by the first coefficient as the second element of the internal input value, the reference state quantity is controlled while preferentially controlling the relative quantity. Can also be controlled simultaneously. Furthermore, in the present invention, when there is a disturbance in the control of the relative amount due to control system constraints, among the controllers that control the follow-up state amount, the control loop that is less restricted than the controller of the restricted control loop By executing a weight correction procedure that adaptively corrects the weighted average value so that the control of the controller is more strongly required to control the disturbance of the relative quantity, the relative quantity such as the state quantity difference is reduced. Even when control constraints such as operation amount saturation occur in unexpected ways, the effect of reducing the state quantity difference, which is the original purpose, is impaired. Can be avoided.

[Principle of the Invention]
Hereinafter, in the present invention, an absolute state quantity serving as a reference, such as a state quantity average value, is set as a reference state quantity, and a relative amount (for example, a state quantity difference) with the reference state quantity is maintained at a predetermined value. The controlled state quantity is referred to as a follow-up state quantity. Also, the setting value for the reference state quantity is the reference state quantity setting value, the measurement value for the reference state quantity is the reference state quantity measurement value, the setting value for the tracking state quantity is the tracking state quantity setting value, and the tracking state quantity measurement value is the tracking state Measured value, set value for the relative amount of the reference state amount and the tracking state amount is the tracking state amount relative setting value, and the measured value of the relative amount of the reference state amount and the tracking state amount is the tracking state amount relative measured value, the reference state An internal set value set inside the controller with respect to the quantity is referred to as a reference state quantity internal set value, and an internal set value set inside the controller with respect to the follow-up state quantity is referred to as a follow-up state quantity internal set value. Examples of the state quantity include temperature, pressure, and flow rate.

  In the present invention, the manipulated variable MV is calculated using the state quantity internal set value SP 'set inside the controller, separately from the state quantity set value SP given from the outside. At this time, the state quantity internal set value SP ′ is separated into an element SPm for the reference state quantity and an element ΔSP for the relative quantity of the reference state quantity and the follow-up state quantity (SP ′ = SPm + ΔSP). Further, in the present invention, the set values SPm and ΔSP that are actually given by the interpolation and extrapolation calculation (SP ′ = ASP + (1−A) PV) with the state quantity measurement values are applied as they are. Focusing on the fact that the characteristics of the controller can be substantially shifted to the low sensitivity side or the high sensitivity side, the sensitivity of the reference state quantity and the sensitivity of the relative quantity of the reference state quantity and the tracking state quantity are It is converted into a state quantity internal set value SP ′ that can be individually shifted.

  Thus, in the present invention, the state quantity internal set value SP ′ is separated into the element SPm for the reference state quantity and the element ΔSP for the relative quantity between the reference state quantity and the follow-up state quantity, and this state quantity internal set value SP ′. Is obtained by interpolating and extrapolating the state quantity set value SP and the state quantity measurement value PV, and used for calculating the operation amount MV. Thus, in the present invention, the response characteristic is shifted to the low sensitivity side for the reference state quantity such as the average value of the state quantity, and the response is made for the relative quantity between the reference state quantity and the tracking state quantity such as the state quantity difference. If the characteristic is shifted to the high sensitivity side, the tracking state quantity relative measurement value ΔPV follows the tracking state quantity relative setting value ΔSP before the reference state quantity measurement value PVm follows the reference state quantity setting value SPm. Therefore, it is possible to perform control such that the reference state quantity is changed to a desired value while maintaining the relative amount between the reference state quantity and the follow-up state quantity at a desired value.

  Further, according to the configuration of the present invention, the only difference from the normal control system is that the state quantity set value SP is converted into the state quantity internal set value SP '. That is, a control that controls the reference state quantity at the same time while preferentially controlling the relative quantity between the reference state quantity and the follow-up state quantity in a form in which the operation amount of the controller and the actual actuator output have a one-to-one correspondence. A method can be provided.

Here, of the above two points of interest, calculation of the state amount internal set value SP ′ by interpolation / extrapolation between the state amount set value SP and the state amount measured value PV (hereinafter referred to as the first point of interest). ). With reference to the state quantity set value SP and the state quantity measurement value PV, it is considered to convert to a state quantity internal set value SP ′ set in the controller by the following formula using a specific coefficient A.
SP ′ = ASP + (1-A) PV (7)
However, the coefficient A is a real number larger than 0. At this time, if A = 1, SP ′ = SP, which means that the state quantity set value SP is not converted at all.

  If the value of the coefficient A is 0 <A <1 in the equation (7), the converted state quantity internal set value SP ′ is a numerical value between the original state quantity set value SP and the state quantity measured value PV ( Interpolation). Therefore, for example, when the deviation is calculated by a PID controller or the like, as shown in FIG. 1, the state quantity internal set value SP ′ is larger than the deviation Er = SP−PV between the state quantity set value SP and the state quantity measured value PV. The deviation Er ′ = SP′−PV from the state quantity measurement value PV has a smaller absolute value. As a result, the change in the operation amount is more gradual when the operation amount MV ′ is calculated based on the deviation Er ′ than when the controller calculates the operation amount MV based on the deviation Er. That is, if the value of the coefficient A is 0 <A <1, the response characteristic of the controller shifts to a characteristic in which stability is emphasized (low sensitivity).

  On the other hand, if the value of the coefficient A is A> 1, the converted state quantity internal setting value SP ′ is a numerical value that is further away from the state quantity measurement value PV than the original state quantity setting value SP (extrapolation relationship). become. Therefore, for example, when the deviation is calculated by a PID controller or the like, as shown in FIG. 2, the state quantity internal set value SP ′ is larger than the deviation Er = SP−PV between the state quantity set value SP and the state quantity measured value PV. The deviation Er ′ = SP′−PV from the state quantity measurement value PV has a larger absolute value. As a result, the change in the operation amount becomes more severe when the operation amount MV ′ is calculated based on the deviation Er ′ than when the controller calculates the operation amount MV based on the deviation Er. In other words, if the value of the coefficient A is A> 1, the response characteristic of the controller shifts to a characteristic in which the responsiveness is emphasized (high sensitivity).

Next, of the above two points of interest, the state quantity internal set value SP ′ is separated into an element for the reference state quantity and an element for the relative quantity of the reference state quantity and the follow-up state quantity (hereinafter referred to as the second quantity). Will be described). When simultaneously controlling the reference state quantity and the relative quantity of the reference state quantity and the follow-up state quantity, the state quantity set value SP is expressed by the element SPm with respect to the reference state quantity, the reference state quantity, and the follow-up state as shown in the following equation. It can be separated into the element ΔSPm with respect to the relative amount to the amount.
SP = SPm + ΔSPm (8)

Further, according to the state quantity set value SP, the state quantity measurement value PV can also be separated into a reference state quantity measurement value PVm and a follow-up state quantity relative measurement value ΔPVm as in the following equation.
PV = PVm + ΔPVm (9)

Here, the first focus point and the second focus point are summarized as follows from the equations (7) to (9).
SP ′ = A (SPm + ΔSPm) + (1-A) (PVm + ΔPVm)
= ASPm + (1-A) PVm + AΔSPm + (1-A) ΔPVm
(10)

At this time, ASPm + (1-A) PVm in the equation (10) is an element relating to the reference state quantity, and AΔSPm + (1-A) ΔPVm is an element relating to the relative quantity between the reference state quantity and the follow-up state quantity. That is, since both are separated into linear combination equations that give an interpolating relationship and an extrapolating relationship, respectively, the interpolating relationship and the extrapolating relationship are given by individual coefficients A and B as follows. It becomes possible.
SP ′ = ASPm + (1-A) PVm + BΔSPm + (1-B) ΔPVm
(11)

In Expression (11), A is a coefficient related to the reference state quantity, and B is a coefficient related to the relative quantity between the reference state quantity and the follow-up state quantity. When there are a plurality of control loops, the coefficient B relating to the relative amount of the reference state quantity and the follow-up state quantity is preferably given to each control loop individually. In this case, i (i is 1, 2 in the plurality of control loops). , 3,...) The following state quantity set value SPi may be converted for the following tracking state quantity.
SPi ′ = AmSPm + (1−Am) PVm + BiΔSPim
+ (1-Bi) ΔPVim (12)

  In Formula (12), SPi ′ is an internal set value for the i-th tracking state quantity, ΔSPim is a tracking state quantity relative setting value that is a relative value between the reference state quantity and the i-th tracking state quantity, and ΔPVim is A follow-up state quantity relative measurement value, which is a measurement value of a relative quantity between the reference state quantity and the i-th follow-up state quantity, Bi is a coefficient relating to a relative quantity between the reference state quantity and the i-th follow-up state quantity. The coefficient Am related to the reference state quantity may be given to each control loop or may be given to each control loop individually.

In the equation (12), it is needless to say that ΔSPim = SPi−SPm and ΔPVim = PVi−PVm, and the following equivalent substitution can be easily performed.
SPi ′ = AmSPm + (1−Am) PVm + BiΔSPim
+ (1-Bi) (PVi-PVm) (13)
SPi '= AmSPm + (1-Am) PVm + Bi (SPi-SPm)
+ (1-Bi) (PVi-PVm) (14)

  Note that the processing inside the control device is simply different between the case where the follow-up state quantity relative measurement value ΔPVim is adopted and the case where the difference PVi−PVm between the follow-up state quantity measurement value PVi and the reference state quantity measurement value PVm is adopted. Only. On the other hand, when the follow-up state quantity relative set value ΔSPim is adopted, the operator sets the reference state quantity set value SPm and the follow-up state quantity relative set value ΔSPim through the user interface. When the difference SPi−SPm between the amount setting value SPi and the reference state amount setting value SPm is adopted, the operator sets the reference state amount setting value SPm and the tracking state amount setting value SPi through the user interface. Since there is a difference between these two cases, it will be treated as a different configuration.

Further, the equations (13) and (14) can be easily arranged into the following equivalent equations.
SPi ′ = PVi + Am (SPm−PVm)
+ Bi {ΔSPim− (PVi−PVm)} (15)
SPi ′ = PVi + Am (SPm−PVm)
+ Bi {(SPi-SPm)-(PVi-PVm)} (16)

Further, when considered as SPi = SPi ″ + ΔSPi ″ and PVi = PVi ″ + ΔPVi ″, the following equivalent conversion can be easily performed in the equation (14).
SPi '= AmSPm + (1-Am) PVm + Bi (SPi-SPm)
+ (1-Bi) (PVi-PVm)
= AmSPm + (1-Am) PVm + Bi (SPi ″ + ΔSPi ″ −SPm) + (1-Bi) (PVi ″ + ΔPVi ″ −PVm)
= AmSPm + (1-Am) PVm + Bi (SPi "-SPm")
+ (1-Bi) (PVi "-PVm") (17)

In Expression (17), SPi ″ and ΔSPi ″ are an element SPi ″ corresponding to an absolute amount and an element ΔSPi ″ corresponding to a relative amount when the follow-up state amount setting value SPi is further separated into another absolute amount and a relative amount. Yes, PVi ″ and ΔPVi ″ are an element PVi ″ corresponding to the absolute quantity and an element ΔPVi ″ corresponding to the relative quantity when the follow-up state quantity measurement value PVi is similarly separated into another absolute quantity and relative quantity. Here, SPm ″ = SPm−ΔSPi ″ and PVm ″ = PVm−ΔPVi ″. That is, replacing SPm or PVm with another SPm ″ or PVm ″ in an element related to the relative amount of the reference state quantity and the follow-up state quantity is an equivalent linear combination expression as long as the relationship between the two is clear. However, it does not substantially depart from the scope of the basic technical idea of the present invention.
According to the above principle, the state quantity internal set value SP ′ is obtained that can individually shift the sensitivity of the reference state quantity and the sensitivity of the relative quantity of the reference state quantity and the tracking state quantity.

  Next, the principle of preferentially controlling the relative amount between the reference state amount and the follow-up state amount will be described. In Expression (14), if the relationship between the coefficient Am related to the reference state quantity and the coefficient Bi related to the relative quantity between the reference state quantity and the follow-up state quantity is Am = Bi = 1, SPi ′ = SPi. At this time, the state quantity internal set value SPi 'is not changed from the state quantity set value SPi at all, and the sensitivity is not changed at all from the normal control.

Here, what is particularly important is the coefficient Bi relating to the relative amount between the reference state amount and the follow-up state amount. By setting Bi> 1, the sensitivity is improved particularly with respect to the relative amount between the reference state amount and the follow-up state amount. The controller can be operated to preferentially control the amount. Therefore, even if the coefficient Am related to the reference state quantity is always set to Am = 1, the problem solving in the present invention can be achieved. Therefore, the conversion to the state quantity internal set value SPi ′ as described below may be performed.
SPi ′ = SPm + BiΔSPim + (1−Bi) (PVi−PVm) (18)
SPi ′ = SPm + Bi (SPi−SPm) + (1−Bi) (PVi−PVm)
... (19)
SPi ′ = PVi + (SPm−PVm) + Bi {ΔSPim− (PVi−PVm)}
... (20)
SPi ′ = PVi + (SPm−PVm)
+ Bi {(SPi-SPm)-(PVi-PVm)} (21)

  However, simply improving the sensitivity of the relative amount of the reference state amount and the follow-up state amount will make the control system unstable because the sensitivity will be excessive before sufficient control characteristics can be obtained for the relative amount. It can happen. In such a case, the instability is eliminated by setting the coefficient Am related to the reference state quantity to Am <1, instead of returning the coefficient Bi related to the relative quantity between the reference state quantity and the follow-up state quantity to a small value. It is also possible to avoid sacrificing the priority of the relative amount of the reference state amount and the follow-up state amount. Therefore, it is more preferable to employ a conversion formula in which the coefficient Am related to the reference state quantity can be adjusted.

  Using the principle described above, the inventor preferentially controls a relative amount such as a state amount difference in a manner in which the controller operation amount and the actual actuator output have a one-to-one correspondence. A control method that can simultaneously control a reference state quantity such as an average value has been proposed (Japanese Patent Application Nos. 2004-128227, 2004-128236, and 2004-128240). In the control method of the prior application, the reference state quantity is a simple average value of the state quantity of each control loop, a weighted average value of fixed weight, or simply a specific one state quantity. These can be said to be weighted average values with a fixed weight if viewed by broad broad concepts. When each state quantity can be controlled without restriction, it is effective to use a weighted average value with a fixed weight as the reference state quantity. In particular, the simple average value is a well-balanced and fair reference state quantity.

  However, if control restrictions such as manipulated variable saturation occur in a virtually unexpected manner, the fixed weight may adversely affect. Hereinafter, problems of the control method of the prior application will be described with reference to FIGS. 3 (a) and 3 (b). Here, there are three temperature control loops I, II, and III, and the purpose of the control is to reduce the temperature difference (relative amount) between the control loops. FIG. 3A shows the disturbance response of the control system when a disturbance is applied in a state where the tracking state amount setting values SP of the control loops I, II, and III are all set to 30. FIG. ) Indicates the manipulated variable MV output from the controllers of the control loops I, II, and III when a disturbance is applied.

  The output upper limit value of the manipulated variable MV of the controller of loop III was experimentally set to 16% to facilitate output saturation. For this reason, when the reference state quantity is a simple average value of the temperatures of the control loops I, II, and III (state quantity measurement values PV), the manipulated variable MV of the loop III is saturated during the disturbance response, and the rate of temperature increase Suppose that has reached its peak. Then, only the temperature of the loop III becomes insufficient, and the temperature of the loop III becomes far from the temperatures of the loops I and II as shown in FIG. Since the reference state quantity is a simple average value of the temperatures of loops I, II, and III, if a difference occurs between the temperature of loop III and the temperature of loops I and II, the temperature of loops I and II is higher than the temperature of loop III. The value closer to is the reference state quantity measurement value. Therefore, the controller of each loop I, II, III does not try to reduce the temperature difference by bringing the temperature of loop I, II close to the temperature of loop III, but the temperature of loop III is set to the temperature of loop I, II. Try to reduce the temperature difference.

  However, as described above, the manipulated variable MV of the loop III is already saturated and the rate of temperature rise has reached its peak, so that the action of causing the temperature of the loop III to quickly approach the temperature of the loops I and II does not occur. Therefore, the effect that the reference state quantity can be controlled simultaneously while the temperature difference is controlled with priority is not obtained. As described above, the control method of the prior application has a problem in that the original effect is greatly impaired depending on control restrictions.

  On the other hand, in the present invention, it is noted that there is a cause of the above-described problem where the reference state quantity is a weighted average value of fixed weights of the state quantities of each control loop. That is, the above-described problem is that, for example, when the temperature of loop III deviates from the temperatures of loops I and II due to operation amount saturation or the like, the reference state quantity measurement value to be aimed at by each control loop is larger than the loop III temperature. This is due to the fact that the controller of Loop III, which is originally restricted, is more strongly required to control the state quantity difference in order to become the value closer to the temperature of I and II.

  The present invention adaptively corrects the weighted average weight when there is a control loop that is a factor that disturbs the control of the state quantity difference due to some restrictions based on the above point of view. The above-mentioned problem is solved by making it possible to more strongly request the control of the state quantity difference to the controller of the non-control loop. Specifically, the weighted average weight is adaptively corrected so that the reference state quantity measurement value approaches the state quantity measurement value of the control loop which is the most disturbing factor of the state quantity difference control.

  In the present invention, it is assumed that control is performed so that the state quantity difference of each loop becomes small in n control loops. It is not always possible to reliably grasp a control loop in which control restrictions such as operation amount saturation occur in an unexpected manner. However, if such a constraint is a factor that disturbs the control of the state quantity difference, the response of the control loop receiving the constraint is delayed and the follow-up to other loops is insufficient. The situation is most likely. Therefore, it is only necessary to adaptively correct the weighted average weight so that other control loops are matched with the control loops with delayed responses.

  Specifically, the weight for the state quantity of the loop having the largest absolute value of the deviation between the follow-up state quantity set value SPi and the follow-up state quantity measurement value PVi is 1, and the weight for the state quantity of the other control loop is 0. Thus, the weighted average weight of the state quantity is adaptively corrected. In this case, if the weight changes suddenly, the control operation tends to be discontinuous. For example, if no overshoot occurs in the response waveform of each control loop, even if the weight for the state quantity of the loop having the largest deviation is suddenly changed to 1, an extreme discontinuity occurs in the control response The probability of doing is low. However, when the overshoot occurs in the response waveform, if the weight for the state quantity of the loop having the largest deviation is suddenly changed to 1, the loop having the largest absolute value becomes the tracking state quantity setting value SPi. Since a situation can occur where the upper side and the lower side suddenly change, an extreme discontinuity occurs. Therefore, it is preferable to apply a time delay filter to the weight correction process so that the weight gradually changes.

  The method of adaptively correcting the weight is not limited to a method in which the weight for the state quantity of the loop having the largest absolute value of the deviation is set to 1. For example, the weight for the state quantity of the loop having the largest absolute value of the deviation is set to 0. As shown in FIG. 8, if the remaining weight of 0.2 is equally divided as the weight of the state quantity of other loops, the weight is increased as the loop with a larger absolute value of the deviation becomes effective. Is obtained.

[Embodiment]
FIG. 4 is a block diagram showing the configuration of the control device according to the embodiment of the present invention. In this embodiment, there are three control loops, an average value of the three control loops is used as the reference state quantity, and each of the three control loops is used as the follow-up state quantity. However, if two or more control loops are used, a similar control system can be configured based on the same principle.

  The control device of FIG. 4 includes, as the configuration of the first control system related to the first follow-up state quantity, a follow-up state quantity set value SP1 input unit 1-1, a follow-up state quantity measured value PV1 input unit 2-1, and an operation. An amount MV1 output unit 3-1, a PID control calculation unit (PID controller) 4-1, a coefficient B1 storage unit 5-1, and a follow-up state amount internal set value SP1 ′ calculation unit 6-1 are provided. Further, the control device of FIG. 4 includes, as a configuration of the second control system related to the second follow-up state quantity, a follow-up state quantity set value SP2 input unit 1-2, a follow-up state quantity measured value PV2 input unit 2-2, , An operation amount MV2 output unit 3-2, a PID control calculation unit 4-2, a coefficient B2 storage unit 5-2, and a follow-up state amount internal set value SP2 ′ calculation unit 6-2. In addition, the control device of FIG. 4 includes, as a third control system configuration related to the third follow-up state quantity, a follow-up state quantity set value SP3 input unit 1-3, a follow-up state quantity measured value PV3 input unit 2-3, , An operation amount MV3 output unit 3-3, a PID control calculation unit 4-3, a coefficient B3 storage unit 5-3, and a follow-up state amount internal set value SP3 ′ calculation unit 6-3.

  4 includes a reference state quantity set value SPm calculation unit 7 that calculates a weighted average value of the follow-up state quantity set values SP1, SP2, and SP3 as the reference state quantity set value SPm as a configuration related to the reference state quantity. The reference state quantity measurement value PVm calculation unit 8 that calculates the weighted average value of the following state quantity measurement values PV1, PV2, and PV3 as the reference state quantity measurement value PVm, the coefficient Am storage unit 9, and the reference state quantity measurement value PVm A weight storage unit 10 that stores weights α1, α2, and α3 for calculation.

  Further, the control device of FIG. 4 has, as a configuration relating to weighted adaptive correction, the absolute value of the deviation between the tracking state quantity setting value SP1 and the tracking state quantity measurement value PV1, the tracking state quantity setting value SP2, and the tracking state quantity measurement value PV2. A maximum deviation control system search unit 11 that compares the absolute value of the deviation and the absolute value of the deviation between the follow-up state quantity set value SP3 and the follow-up state quantity measurement value PV3 and searches for a control system having the largest absolute value of the deviation; A weight calculation unit 12 that calculates adaptive correction values of the weights α1, α2, and α3 and sets them in the weight storage unit 10 so as to maximize the weight on the state quantity of the maximum deviation control system.

  FIG. 5 is a block diagram of the control system in the present embodiment. In FIG. 5, Er1 ′ is a deviation between the internal set value SP1 ′ of the first follow-up state quantity and the measured value PV1 of the first follow-up state quantity, and Er2 ′ is an internal set value SP2 ′ of the second follow-up state quantity. The deviation of the second follow-up state quantity from the measured value PV2, Er3 ′ is the deviation between the third follow-up state quantity internal set value SP3 ′ and the third follow-up state quantity measured value PV3, and Am is the reference state quantity. A coefficient, B1 is a coefficient relating to a state quantity difference between the first following state quantity and the reference state quantity, B2 is a coefficient relating to a state quantity difference between the second following state quantity and the reference state quantity, and B3 is a third following state quantity. Is a coefficient relating to the difference between the state quantity and the reference state quantity, A1 is an actuator for controlling the first following state quantity, A2 is an actuator for controlling the second following state quantity, and A3 is an actuator for controlling the third following state quantity. , P1 is a control pair related to the first follow-up state quantity. Process, P2 is a control target process related to the second follow-up state quantity, P3 is a control target process related to the third follow-up state quantity, Gp1 is a transfer function of a block including the actuator A1 and the process P1, and Gp2 is an actuator A2 A transfer function Gp3 of the block including the process P2 is a transfer function of a block including the actuator A3 and the process P3.

  Tracking state quantity set value SP1 input unit 1-1, tracking state quantity measured value PV1 input unit 2-1, operation amount MV1 output unit 3-1, PID control calculation unit 4-1, and tracking state quantity internal setting The value SP1 ′ calculation unit 6-1, the actuator A1, and the process P1 constitute a first control system (first control loop). Follow-up state quantity set value SP2 input section 1-2, follow-up state quantity measured value PV2 input section 2-2, manipulated variable MV2 output section 3-2, PID control calculation section 4-2, and follow-up state quantity internal setting The value SP2 ′ calculating unit 6-2, the actuator A2, and the process P2 constitute a second control system (second control loop). The follow-up state quantity set value SP3 input unit 1-3, the follow-up state quantity measured value PV3 input unit 2-3, the operation amount MV3 output unit 3-3, the PID control calculation unit 4-3, the follow-up state quantity The internal set value SP3 ′ calculating unit 6-3, the actuator A3, and the process P3 constitute a third control system (third control loop).

  Next, the operation of the control device of the present embodiment will be described with reference to FIG. First, the follow-up state quantity set value SP1 is set by the operator of the control device, and the follow-up state quantity set value SP1 ′ calculating unit 6-1 and the reference state quantity setting are set via the follow-up state quantity set value SP1 input unit 1-1. The value SPm calculation unit 7 and the maximum deviation control system search unit 11 are input (step S101 in FIG. 6). The follow-up state quantity set value SP2 is set by the operator, and follows the follow-up state quantity set value SP2 ′ calculating unit 6-2 and the reference state quantity set value SPm calculating unit 7 via the follow-up state quantity set value SP2 input unit 1-2. And the maximum deviation control system search unit 11 (step S102). The follow-up state quantity set value SP3 is set by the operator, and follows the follow-up state quantity set value SP3 ′ calculator 6-3 and the reference state quantity set value SPm calculator 7 via the follow-up state quantity set value SP3 input unit 1-3. Are input to the maximum deviation control system search unit 11 (step S103).

  The follow-up state quantity measurement value PV1 is detected by first detection means (not shown), and the PID control calculation unit 4-1 and the follow-up state quantity internal set value SP1 ′ are calculated via the follow-up state quantity measurement value PV1 input unit 2-1. Input to the unit 6-1, the reference state quantity measurement value PVm calculation unit 8, and the maximum deviation control system search unit 11 (step S104). The follow-up state quantity measurement value PV2 is detected by a second detection unit (not shown), and the PID control calculation unit 4-2 and the follow-up state quantity internal set value SP2 ′ are calculated via the follow-up state quantity measurement value PV2 input unit 2-2. The data is input to the unit 6-2, the reference state quantity measurement value PVm calculation unit 8, and the maximum deviation control system search unit 11 (step S105). The follow-up state quantity measurement value PV3 is detected by a third detection unit (not shown), and the PID control calculation unit 4-3 and the follow-up state quantity internal set value SP3 ′ are calculated via the follow-up state quantity measurement value PV3 input unit 2-3. The data is input to the unit 6-3, the reference state measured value PVm calculation unit 8, and the maximum deviation control system search unit 11 (step S106).

Next, the maximum deviation control system search unit 11 calculates the absolute value | Er1 | of the deviation between the follow-up state quantity set value SP1 and the follow-up state quantity measured value PV1, and the follow-up state quantity set value SP2 and the follow-up state quantity measured value PV2. The absolute value | Er2 | of the deviation and the absolute value | Er3 | of the deviation between the follow-up state quantity set value SP3 and the follow-up state quantity measured value PV3 are calculated as follows (step S107).
| Er1 | = | SP1-PV1 | (22)
| Er2 | = | SP2-PV2 | (23)
| Er3 | = | SP3-PV3 | (24)
Then, the maximum deviation control system search unit 11 specifies a control system j having the largest deviation absolute value (hereinafter referred to as the maximum deviation control system j) based on the calculated absolute value of the deviation of each control system (step “step”). S108).

  The weight calculation unit 12 calculates correction values of the weights α1, α2, and α3 so that the weight for the state quantity of the maximum deviation control system j approaches 1 and the weight for the state quantity of the other control system approaches 0. The correction value is set in the weight storage unit 12 as new values of the weights α1, α2, and α3 (step S109). The weights α1, α2, and α3 are corrected in such a manner that the weights α1, α2, and α3 of the previous control cycle are updated at the pace of the time constant Ta in the control cycle dT. The time constant Ta is determined with reference to, for example, an integration time Ti described later (for example, Ta = Ti).

When the first control system is the maximum deviation control system j, the corrected values α1 ′, α2 ′, α3 ′ are calculated as follows with respect to the weights α1, α2, α3 before one control cycle.
α1 ′ = (α1Ta + 1.0dT) / (Ta + dT) (25)
α2 ′ = (α2Ta + 0.0dT) / (Ta + dT) (26)
α3 ′ = (α3Ta + 0.0dT) / (Ta + dT) (27)

When the second control system is the maximum deviation control system j, the correction values α1 ′, α2 ′, α3 ′ are calculated as follows:
α1 ′ = (α1Ta + 0.0dT) / (Ta + dT) (28)
α2 ′ = (α2Ta + 1.0dT) / (Ta + dT) (29)
α3 ′ = (α3Ta + 0.0dT) / (Ta + dT) (30)

When the third control system is the maximum deviation control system j, the correction values α1 ′, α2 ′, α3 ′ are calculated as follows:
α1 ′ = (α1Ta + 0.0dT) / (Ta + dT) (31)
α2 ′ = (α2Ta + 0.0dT) / (Ta + dT) (32)
α3 ′ = (α3Ta + 1.0dT) / (Ta + dT) (33)

Further, when the two control systems simultaneously become the maximum deviation control system j, for example, when the first control system and the second control system become the maximum deviation control system j, only the first control system is changed to the maximum deviation control system j. Treated as the control system j, the correction values α1 ′, α2 ′, and α3 ′ may be calculated by the equations (25), (26), and (27), respectively. If the three control systems simultaneously become the maximum deviation control system j (| Er1 | = | Er2 | = | Er3 |), similarly, only the first control system is treated as the maximum deviation control system j and corrected. The values α1 ′, α2 ′, and α3 ′ may be calculated by the equations (25), (26), and (27), respectively.
The weight calculation unit 12 sets the correction values α1 ′, α2 ′, α3 ′ calculated as described above in the weight storage unit 12 as new values of the weights α1, α2, α3.

The reference state quantity set value SPm calculation unit 7 uses a weighted average value of the follow-up state quantity set value SP1, the follow-up state quantity set value SP2, and the follow-up state quantity set value SP3 as a reference state quantity set value SPm as shown in the following equation. The reference state quantity set value SPm is calculated and the follow-up state quantity internal set value SP1 ′ calculating section 6-1, the follow-up state quantity internal set value SP2 ′ calculating section 6-2, and the follow-up state quantity internal set value SP3 ′ calculating section 6 are calculated. To -3 (step S110).
SPm = α1SP1 + α2SP2 + α3SP3 (34)

The reference state quantity measurement value PVm calculation unit 8 uses a weighted average value of the tracking state quantity measurement value PV1, the tracking state quantity measurement value PV2, and the tracking state quantity measurement value PV3 as the reference state quantity measurement value PVm as in the following equation. The reference state quantity measurement value PVm is calculated, and the tracking state quantity internal setting value SP1 ′ calculation section 6-1, the tracking state quantity internal setting value SP2 ′ calculation section 6-2, and the tracking state quantity internal setting value SP3 ′ calculation section 6 are calculated. To -3 (step S111).
PVm = α1PV1 + α2PV2 + α3PV3 (35)

The coefficient Am storage unit 9 stores a coefficient Am related to the reference state quantity in advance, and the coefficient B1 storage unit 5-1 stores a coefficient B1 related to the state quantity difference between the first follow-up state quantity and the reference state quantity in advance. is doing. The tracking state quantity internal set value SP1 ′ calculation unit 6-1 is based on the coefficients Am, B1, the reference state quantity setting value SPm, the reference state quantity measurement value PVm, the tracking state quantity setting value SP1, and the tracking state quantity measurement value PV1. Then, the tracking state quantity internal set value SP1 ′ is calculated as shown in the following equation (step S112).
SP1 ′ = AmSPm + (1-Am) PVm + B1 (SP1-SPm)
+ (1-B1) (PV1-PVm) (36)

The coefficient B2 storage unit 5-2 stores in advance a coefficient B2 related to the state quantity difference between the second follow-up state quantity and the reference state quantity. The tracking state quantity internal set value SP2 ′ calculation unit 6-2 is based on the coefficients Am, B2, the reference state quantity setting value SPm, the reference state quantity measurement value PVm, the tracking state quantity setting value SP2, and the tracking state quantity measurement value PV2. Then, the tracking state quantity internal set value SP2 ′ is calculated as shown in the following equation (step S113).
SP2 ′ = AmSPm + (1-Am) PVm + B2 (SP2-SPm)
+ (1-B2) (PV2-PVm) (37)

The coefficient B3 storage unit 5-3 stores in advance a coefficient B3 related to the state quantity difference between the third follow-up state quantity and the reference state quantity. The tracking state quantity internal set value SP3 ′ calculating section 6-3 is based on the coefficients Am, B3, the reference state quantity setting value SPm, the reference state quantity measurement value PVm, the tracking state quantity setting value SP3, and the tracking state quantity measurement value PV3. Then, the tracking state amount internal set value SP3 ′ is calculated as follows (step S114).
SP3 ′ = AmSPm + (1-Am) PVm + B3 (SP3-SPm)
+ (1-B3) (PV3-PVm) (38)

Next, the PID control calculation unit 4-1 performs the PID control calculation as in the following transfer function equation to calculate the manipulated variable MV1 (step S115).
MV1 = (100 / Pb1) {1+ (1 / Ti1s) + Td1s} (SP1 ′
-PV1) (39)
In Expression (39), Pb1 is a proportional band, Ti1 is an integration time, Td1 is a differentiation time, and s is a Laplace operator. When the calculated operation amount MV1 is smaller than the lower limit value OL1 of the output of the actuator A1, the PID control calculation unit 4-1 sets the operation amount MV1 = OL1 and the calculated operation amount MV1 is the upper limit value OH1 of the output of the actuator A1. If larger, an operation amount upper / lower limit process for setting the operation amount MV1 = OH1 is performed as a measure for integral windup.

The PID control calculation unit 4-2 performs a PID control calculation such as the following transfer function equation to calculate the operation amount MV2 (step S116).
MV2 = (100 / Pb2) {1+ (1 / Ti2s) + Td2s} (SP2 ′
-PV2) (40)
In Expression (40), Pb2 is a proportional band, Ti2 is an integration time, and Td2 is a differentiation time. When the calculated operation amount MV2 is smaller than the lower limit value OL2 of the output of the actuator A2, the PID control calculation unit 4-2 sets the operation amount MV2 = OL2 and the calculated operation amount MV2 is larger than the upper limit value OH2 of the output of the actuator A2. In this case, the operation amount upper / lower limit process for setting the operation amount MV2 = OH2 is performed as a measure against the integral windup.

The PID control calculation unit 4-3 calculates a manipulated variable MV3 by performing a PID control calculation such as the following transfer function equation (step S117).
MV3 = (100 / Pb3) {1+ (1 / Ti3s) + Td3s} (SP3 ′
-PV3) (41)
In Expression (41), Pb3 is a proportional band, Ti3 is an integration time, and Td3 is a differentiation time. When the calculated operation amount MV3 is smaller than the lower limit value OL3 of the output of the actuator A3, the PID control calculation unit 4-3 sets the operation amount MV3 = OL3, and the calculated operation amount MV3 is larger than the upper limit value OH3 of the output of the actuator A3. In this case, the operation amount upper / lower limit process for setting the operation amount MV3 = OH3 is performed as a measure against the integral windup.

  The operation amount MV1 output unit 3-1 outputs the operation amount MV1 calculated by the PID control calculation unit 4-1 to the actuator A1 (step S118). The actuator A1 operates to control the first follow-up state amount based on the operation amount MV1. The operation amount MV2 output unit 3-2 outputs the operation amount MV2 calculated by the PID control calculation unit 4-2 to the actuator A2 (step S119). The actuator A2 operates to control the second follow-up state quantity based on the operation quantity MV2. The operation amount MV3 output unit 3-3 outputs the operation amount MV3 calculated by the PID control calculation unit 4-3 to the actuator A3 (step S120). The actuator A3 operates to control the third follow-up state quantity based on the operation quantity MV3.

  The processes in steps S101 to S120 as described above are repeatedly executed for each control cycle dT until the operator instructs the end of the control (YES in step S121).

  FIG. 7 is a diagram showing a simulation result of a control apparatus to which the prior application is applied and the state quantity difference is set not to be controlled. 8 and 9 are diagrams showing simulation results of the control device proposed in the prior application. FIG. 10 is a diagram illustrating a simulation result of the control device according to the present embodiment. 7 to 10 show the disturbance response of the control system when a disturbance is applied in a state where SP1 = SP2 = SP3 = 30. The simulation conditions are as follows.

First, the transfer function Gp1 of the block including the actuator A1 and the process P1, the transfer function Gp2 of the block including the actuator A2 and the process P2, and the transfer function Gp3 of the block including the actuator A3 and the process P3 are set as follows: To do. Here, it is assumed that there is no interference between control loops.
Gp1 = 1.2exp (−2.0 s) / {(1 + 70.0 s) (1 + 10.0 s)}
... (42)
Gp2 = 1.6exp (−2.0s) / {(1 + 60.0s) (1 + 10.0s)}
... (43)
Gp3 = 2.0exp (−2.0s) / {(1 + 50.0s) (1 + 10.0s)}
... (44)

The operation amount lower limit value OL1 of the PID control calculation unit 4-1 is 0%, the upper limit value OH1 is 100%, the operation amount lower limit value OL2 of the PID control calculation unit 4-2 is 0%, and the upper limit value OH2 is 100%. The operation amount lower limit value OL3 of the PID control calculation unit 4-3 is set to 0%, and the upper limit value OH3 is set to 16%.
The follow-up state quantity measurement values PV1, PV2, and PV3 are determined as follows according to the operation amounts MV1, MV2, and MV3.
PV1 = Gp1MV1 (45)
PV2 = Gp2MV2 (46)
PV3 = Gp3MV3 (47)

  The proportional band Pb1, which is the PID parameter of the PID control calculation unit 4-1, is 50.0, the integration time Ti1 is 35.0, the differential time Td1 is 20.0, and the proportionality is the PID parameter of the PID control calculation unit 4-2. The band Pb2 is 66.7, the integration time Ti2 is 35.0, the differentiation time Td2 is 20.0, the proportional band Pb3, which is the PID parameter of the PID control calculation unit 4-3, is 100.0, and the integration time Ti3 is 35. 0, the differential time Td3 is 20.0.

The simulation result shown in FIG. 7 is obtained by applying the above prior application and setting Am = B1 = B2 = B3 = 1, and the relative state quantity (state quantity difference) is not controlled. Quantity measurement values PV1, PV2, and PV3 are not aligned.
The simulation result shown in FIG. 8 applies the prior application, and the reference state quantity is a simple average of the tracking state quantity of each control loop (corresponding to a weighted average of α1 = α2 = α3 = 0.333 in the present embodiment). It is obtained by setting Am = 0.7 and B1 = B2 = B3 = 4.0. Compared with the result of FIG. 7, the effect of the control device of the prior application that the state quantity difference between the control loops is reduced appears. However, since there is a restriction that the operation amount upper limit value OH3 of the PID control calculation unit 4-3 is 16%, MV3 is saturated before the operation amounts MV1 and MV2, and PV3 follows the follow-up state amount measurement values PV1 and PV2. The original effect of the prior application is greatly impaired.

  In the simulation result shown in FIG. 9, the prior application is applied and the reference state quantity is fixed to the third following state quantity itself (corresponding to the weighted average of α1 = α2 = 0 and α3 = 1 in the present embodiment). , Am = 0.7 and B1 = B2 = B3 = 4.0. For this reason, the follow-up state quantity measurement values PV1 and PV2 follow PV3, and the effect of the prior application of reducing the state quantity difference between the control loops is not impaired. As a result, it is possible to verify that the follow-up state quantity measurement values PV1, PV2, and PV3 are aligned to the level shown in FIG. 9 when the simulation conditions are controlled without any loss of the effect of reducing the state quantity difference.

  The simulation results shown in FIG. 10 are obtained by setting Am = 0.7 and B1 = B2 = B3 = 4.0 in this embodiment, and the control results are substantially the same as those in FIG. It can be verified that the effect of reducing the state quantity difference is not impaired at all.

  Note that the control device described in this embodiment can be realized by a computer including an arithmetic device, a storage device, and an interface, and a program that controls these hardware resources.

  In the present embodiment, the tracking state quantity set value SPi is an internal input value of the tracking state quantity set value SPi among the plurality of control calculation input values input to the PID control calculation unit that controls the tracking state quantity. However, the principle of the present invention can also be applied to the case where other input values for control calculation are converted into internal input values. The same effect can be obtained. Other control calculation input values include a follow-up state quantity measurement value PVi and a follow-up state quantity deviation Eri.

In order to convert the i-th follow-up state quantity measurement value PVi into the follow-up state quantity internal measurement value PVi ′, which is an internal input value, the conversion may be performed according to the following equation.
PVi ′ = (1−Am) SPm + AmPVm + (1−Bi) (SPi−SPm)
+ Bi (PVi-PVm) (48)
Then, the tracking state quantity internal measurement value PVi ′ may be input to the i-th PID control calculation unit, and the tracking state quantity set value SPi may be input as it is without being converted. At this time, the PID control calculation unit calculates the operation amount MVi by the following equation.
MVi = (100 / Pbi) {1+ (1 / Tiis) + Tdis} (SPi
−PVi ′) (49)
In Equation (49), Pbi is a proportional band, Tii is an integration time, and Tdi is a differentiation time.

On the other hand, when the i-th tracking state quantity deviation Eri is converted into the tracking state quantity internal deviation Eri ′, which is an internal input value, the conversion may be performed by the following equation.
Eri '= Am (SPm-PVm)
+ Bi {(SPi-SPm)-(PVi-PVm)} (50)
Then, the follow-up state amount internal deviation Eri ′ may be input to the i-th PID control calculation unit. At this time, the PID control calculation unit calculates the operation amount MVi by the following equation.
MVi = (100 / Pbi) {1+ (1 / Tiis) + Tdis} Eri ′
... (51)

  The present invention can be applied to a process control technique.

It is a figure for demonstrating the change of the response characteristic of the controller by the state quantity internal setting value of this invention. It is a figure for demonstrating the change of the response characteristic of the controller by the state quantity internal setting value of this invention. It is a figure for demonstrating the problem of the control method of a prior application. It is a block diagram which shows the structure of the control apparatus used as embodiment of this invention. It is a block diagram of the control system in the embodiment of the present invention. It is a flowchart which shows operation | movement of the control apparatus in embodiment of this invention. It is a figure which shows the simulation result of operation | movement of the control apparatus which applied the prior application and set it as the setting which does not control a state quantity difference. It is a figure which shows the simulation result of operation | movement of the control apparatus in a prior application. It is a figure which shows the simulation result of operation | movement of the control apparatus in a prior application. It is a figure which shows the simulation result of operation | movement of the control apparatus in embodiment of this invention. It is a block diagram which shows the structure of the conventional control apparatus. It is a block diagram which shows the structure of the other conventional control apparatus. It is a block diagram which shows the structure of the conventional control apparatus which makes a control object the state quantity average value and a state quantity difference. It is a block diagram which shows the structure of the conventional control apparatus using a cross controller. It is a block diagram which shows the structure which applied the cross controller of FIG. 14 to the control apparatus of FIG. It is a figure for demonstrating the conventional parameter adjustment.

Explanation of symbols

4-1, 4-2, 4-3... PID control calculation unit, 5-1... Coefficient B1 storage unit, 5-2... Coefficient B2 storage unit, 5-3. Quantity internal set value SP1 ′ calculating section, 6-2... Tracking state quantity internal setting value SP2 ′ calculating section, 6-3... Tracking state quantity internal setting value SP3 ′ calculating section, 7. 8: Reference state quantity measurement value PVm calculation unit, 9: Coefficient Am storage unit, 10: Weight storage unit, 11: Maximum deviation control system search unit, 12: Weight calculation unit

Claims (4)

In a control method of a control system having at least two parallel PID control loops,
The weighted average value of the state quantities of the at least two PID control loops is used as a reference state quantity, and the state quantity controlled so that the relative quantity with respect to the reference state quantity maintains a predetermined value is defined as a follow-up state quantity. When
The absolute value of the deviation between the follow-up state quantity set value SPi and the follow-up state quantity measurement value PVi is calculated for each PID control loop, and the weight of the weighted average value with respect to the state quantity is adaptively corrected larger in the PID control loop having a larger absolute value. A weight correction procedure;
Calculation procedure for converting the follow-up state quantity set value SPi out of a plurality of control calculation input values inputted to the PID controller for controlling the follow-up state quantity into the follow-up state quantity internal set value SPi ′ and then inputting it into the PID controller And
The calculation procedure includes, as the control calculation input value, a reference state quantity setting value SPm set as the weighted average value, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi. If, when the measured follow-up state quantity measurement value PVi is input, the first and the coefficient Bi define the degree of conformability to the reference state quantity measurement value PVm of the follow-up state quantity measurement value PVi, by using the second coefficient Am you define the degree of responsiveness to the reference state quantity setting value SPm of the reference state quantity measurement value PVm, 'SPi a' the follow-up state quantity internal set point SPi = AmSPm + ( By calculating by 1-Am) PVm + Bi (SPi-SPm) + (1-Bi) (PVi-PVm),
The followability of the reference state quantity measurement value PVm to the reference state quantity set value SPm and the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measurement value PVi and the reference state quantity measurement value PVm A control method characterized by separating and controlling follow-up to a relative quantity SPi-SPm, which is a difference between state quantity set values SPm. The control method according to claim 1,
In the weight correction procedure, instead of adaptively correcting the weight of the weighted average value for the state quantity as the PID control loop having a larger absolute value, the weighted average value for the state quantity of the PID control loop having the largest absolute value is used. A control method characterized by adaptively correcting so that a weight is set to 1 and a weight for a state quantity of another PID control loop is set to 0 . The control method according to claim 1 or 2 ,
In place of the calculation procedure according to claim 1 or 2, the tracking state quantity measured value PVi is used as the tracking state quantity internal measurement value PVi among a plurality of control calculation input values input to the PID controller that controls the tracking state quantity. A calculation procedure for inputting to the PID controller after converting to '
In the calculation procedure, a preset reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi are measured as the input values for control calculation. When the follow-up state quantity measurement value PVi is input, the first coefficient Bi defining the degree of followability of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm, and the reference state quantity By using the second coefficient Am that defines the degree of responsiveness of the measured value PVm to the reference state quantity set value SPm, the tracking state quantity internal measured value PVi ′ is expressed as PVi ′ = (1−Am) SPm + AmPVm +. By calculating by (1-Bi) (SPi-SPm) + Bi (PVi-PVm),
The followability of the reference state quantity measurement value PVm to the reference state quantity set value SPm, the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measurement value PVi and the reference state quantity measurement value PVm, and the reference A control method characterized by separating and controlling follow-up to a relative quantity SPi-SPm, which is a difference between state quantity set values SPm . The control method according to claim 1 or 2 ,
Instead of the calculation procedure described in claim 1 or 2, a tracking state quantity Eri calculated based on a plurality of control calculation input values input to a PID controller that controls the tracking state quantity is calculated as a tracking state quantity. A calculation procedure for converting into an internal deviation Eri ′ and inputting to the controller,
In the calculation procedure, a preset reference state quantity setting value SPm, a measured reference state quantity measurement value PVm, and a preset follow-up state quantity setting value SPi are measured as the input values for control calculation. When the follow-up state quantity measurement value PVi is input, the first coefficient Bi defining the degree of followability of the follow-up state quantity measurement value PVi to the reference state quantity measurement value PVm, and the reference state quantity Using the second coefficient Am that defines the degree of responsiveness of the measured value PVm to the reference state quantity set value SPm, the following state quantity internal deviation Eri ′ is set to Eri ′ = Am (SPm−PVm) + Bi. By calculating by {(SPi-SPm)-(PVi-PVm)},
The followability of the reference state quantity measurement value PVm to the reference state quantity set value SPm, the follow-up state quantity set value SPi of the relative amount PVi-PVm, which is the difference between the follow-up state quantity measurement value PVi and the reference state quantity measurement value PVm, and the reference A control method characterized by separating and controlling follow-up to a relative quantity SPi-SPm, which is a difference between state quantity set values SPm .

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