Control system, control method, and program

Abstract

Practicality related to a model predictive control function and an interference suppression function is improved. A disturbance estimation unit (2) estimates, on the basis of a first manipulated variable and a controlled variable, disturbance with respect to a control object (Ob1) that outputs the controlled variable in accordance with the first manipulated variable, and outputs an estimation signal including the disturbance amount. The model predictive controller (3) calculates a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable. A modification unit (4) modifies the second manipulated variable by referring to modification information based on the disturbance variable, thereby providing an output signal including the first manipulated variable as the thus modified second manipulated variable. The model predictive controller (3) comprises one or more first processors. The interference estimation section (2) comprises one or more second processors. The model predictive controller (3) outputs a control signal at a first output cycle. The interference estimation unit (2) outputs the estimated signal at a second output cycle. The modification section (4) provides the output signal at a third output period. Both the second output period and the third output period are shorter than the first output period.

Description

Technical Field

[0001] The present disclosure generally relates to control systems, control methods, and programs. More particularly, the present disclosure relates to control systems, control methods, and programs having a model predictive control function. Background Art

[0002] Patent Document 1 discloses a control system comprising: multiple input / output devices (as control targets); and a controller for using a model predictive control function to predict the behavior of the multiple input / output devices when a disturbance is applied to the input / output devices, thereby controlling the disturbance. The controller includes a controlled variable prediction error calculation unit, a disturbance estimation unit, and a disturbance suppression unit. The controlled variable prediction error calculation unit calculates a controlled variable prediction error, which is the difference between a controlled variable prediction value calculated using the model predictive control function and a controlled variable signal output by the multiple input / output devices. The disturbance estimation unit calculates a disturbance estimation value based on a step response final value previously acquired using the model predictive control function and the controlled variable prediction error calculated by the controlled variable prediction error calculation unit. The disturbance suppression unit modifies the manipulated variable calculated using the model predictive control function based on the disturbance estimation value calculated by the disturbance estimation unit, thereby outputting the modified manipulated variable. The technology of Patent Document 1 can improve disturbance suppression even when model predictive control is applied to multiple input / output devices. The control system of Patent Document 1 can be implemented at a low cost with significantly reduced computational complexity. In addition, the control system of Patent Document 1 can also be configured to rely only on the results of the step response test without even deviating from the constraints on the manipulated variables according to the model predictive control.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-204784 Summary of the Invention

[0006] However, if the computational complexity of the model predictive control is greater than that of the disturbance estimator, the processing using the disturbance estimator is delayed in synchronization with the model predictive control, which results in a decrease in the function of removing or at least suppressing disturbances (i.e., the disturbance suppression function). Although Patent Document 1 teaches that the disturbance estimator can perform its control with a control cycle shorter than that of the model predictive control function, the control system of Patent Document 1 still has room for improvement in terms of practicality.

[0007] In view of the foregoing background, it is therefore an object of the present disclosure to provide a control system, a control method, and a program, all of which contribute to improved practicality in terms of a model predictive control function and a disturbance suppression function.

[0008] A control system according to one aspect of the present disclosure provides an output signal including a first manipulated variable to a controlled object. The control system includes a disturbance estimator, a model predictive controller, and a modification unit. The disturbance estimator estimates a disturbance generated by or applied to the controlled object based on the first manipulated variable and a controlled variable, and outputs an estimated signal including the disturbance amount as a result of the estimation. The controlled object outputs a controlled variable signal including the controlled variable based on the first manipulated variable. The model predictive controller calculates a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable. The modification unit modifies the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the modified second manipulated variable. The model predictive controller includes one or more first processors for performing processing related to model predictive control. The disturbance estimator includes one or more second processors for performing processing related to disturbance estimation. The model predictive controller outputs the control signal with a first output period. The disturbance estimator outputs the estimated signal with a second output period. The modification unit provides the output signal with a third output period. Both the second and third output periods are shorter than the first output period.

[0009] According to another aspect of the present disclosure, a control method is provided for a control system that provides an output signal including a first manipulated variable to a controlled object. The control method includes a disturbance estimation step, a model predictive control step, and a modification step. The disturbance estimation step includes estimating a disturbance generated by or applied to the controlled object based on the first manipulated variable and a controlled variable, and outputting an estimated signal including the disturbance amount as the estimation result. The controlled object outputs a controlled variable signal including the controlled variable based on the first manipulated variable. The model predictive control step includes calculating a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable. The modification step includes modifying the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the modified second manipulated variable. The model predictive control step is performed by one or more first processors configured to perform processing related to model predictive control. The disturbance estimation step is performed by one or more second processors configured to perform processing related to disturbance estimation. The model predictive control step includes outputting the control signal with a first output period. The disturbance estimation step includes outputting the estimated signal with a second output period. The modifying step includes providing the output signal with a third output period. Both the second output period and the third output period are shorter than the first output period.

[0010] A program according to yet another aspect of the present disclosure is designed to cause one or more processors to perform the above-mentioned control method.

[0011] The present disclosure achieves advantages that contribute to improved practicality in terms of model predictive control functions and disturbance suppression functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 illustrates a block structure of a control system according to an exemplary embodiment;

[0013] Figure 2A Illustrate the block structure of the model predictive controller included in the control system;

[0014] Figure 2B An example of a block structure of a disturbance estimation unit included in the control system is provided;

[0015] Figure 3A is a graph for comparison showing manipulated variables in a case where correction to be performed by a correction section included in the control system is not applied;

[0016] Figure 3B is a graph showing a manipulated variable in a case where correction by a correction section of the control system is applied;

[0017] Figure 4 is a flow chart illustrating the process of operation of the control system;

[0018] Figure 5 A block structure is illustrated for explaining a first exemplary application of the control system;

[0019] Figure 6 A block structure for illustrating a second exemplary application of the control system is illustrated;

[0020] Figure 7 A block structure according to a first modification of the control system is illustrated;

[0021] Figure 8 illustrates a block configuration according to a second modification of the control system; and

[0022] Figure 9 A block configuration according to a third modified example of the control system is illustrated. DETAILED DESCRIPTION

[0023] (summary)

[0024] The control system, control method and program according to the exemplary embodiment and its variant will now be described with reference to the accompanying drawings. Note that the embodiment and its variant to be described below are merely exemplary embodiments and its variant among the various embodiments and its variants of the present disclosure and should not be construed as restrictive. On the contrary, without departing from the scope of the present disclosure, the exemplary embodiment and its variant can be easily modified in various ways according to design choices or any other factors. Optionally, the configuration according to any variant to be described later can be appropriately adopted in combination with the structure of the exemplary embodiment or (one or more than one) any other variant.

[0025] According to one aspect, a control system 1 (reference Figure 1 ) is a system that uses the function of model predictive control (hereinafter abbreviated as "MPC") for predicting future responses at each time point and performing optimization. The control system 1 sends a signal to the control object Ob1 (reference Figure 1 ) provides an output signal including a first manipulated variable. That is, control system 1 uses the prediction results of MPC to provide a control input (as the first manipulated variable) to controlled object Ob1. Specifically, MPC solves an optimization problem based on a model of controlled object Ob1 for each control cycle, and control system 1 performs feedback control on controlled object Ob1 based on the results.

[0026] As used herein, the control object Ob1 is not limited to any particular type. Examples of the control object Ob1 may include a servo motor for driving a load device and a detection unit (such as an encoder) for detecting the position, speed, and other parameters of the servo motor.

[0027] If the control object Ob1 includes a servo motor, the first manipulated variable may be, for example, one or more control values ​​for the servo motor. The one or more control values ​​may be, for example, one or more parameter values ​​selected from the group consisting of a drive current, a drive voltage, a torque, a thrust, a speed, and a position of the servo motor. The control object Ob1 outputs a controlled variable signal including a controlled variable according to the first manipulated variable. In this case, the controlled variable is a quantity for indicating the state of the control object Ob1, and may include, for example, the position, speed, and other parameters of the servo motor detected by the detection unit. The MPC uses the controlled variables detected by the detection unit (such as the position and speed of the servo motor, etc.) to perform feedback control.

[0028] like Figure 1 As shown, the control system 1 includes a disturbance estimating portion 2 , a model predictive controller 3 , and a modifying portion 4 .

[0029] The disturbance estimating portion 2 estimates a disturbance generated by or applied to the controlled object Ob1 based on the first manipulated variable and the controlled variable, and outputs an estimation signal including an amount of the disturbance as a result of the estimation.

[0030] The model predictive controller 3 has an MPC function. The model predictive controller 3 calculates a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable. The modifying unit 4 modifies the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the modified second manipulated variable.

[0031] That is, the control system 1 has an MPC function, and a function for estimating a disturbance amount and modifying a manipulated variable predicted by MPC to reduce the influence of the disturbance (hereinafter referred to as a “disturbance suppression function”).

[0032] The model predictive controller 3 includes one or more first processors P1 (refer to Figure 2A The interference estimation unit 2 includes one or more second processors P2 (refer to Figure 2B The model predictive controller 3 outputs a control signal with a first output period. The disturbance estimator 2 outputs an estimation signal with a second output period. The modification unit 4 provides an output signal with a third output period. Both the second output period and the third output period are shorter than the first output period.

[0033] In this control system 1, the model predictive control function and the disturbance estimation function are performed by separate processors. The second output period of the disturbance estimator 2 and the third output period of the modification unit 4 are both shorter than the first output period of the model predictive controller 3. In other words, the second output period of the disturbance estimator 2 and the third output period of the modification unit 4 are set independently of the first output period of the model predictive controller 3. This reduces the likelihood of degradation in the function for removing or suppressing disturbances (i.e., the disturbance suppression function) compared to, for example, delaying the processing using the disturbance estimator 2 in synchronization with the MPC. Furthermore, this allows for a structure that facilitates setting the second output period of the disturbance estimator 2 and the third output period of the modification unit 4 independently of the first output period of the model predictive controller 3 with good stability. In particular, this makes it easier to provide the model predictive control function for a first device including a processor with relatively high processing performance (i.e., a relatively expensive processor), and to provide the disturbance estimation function for a second device including a processor with lower processing performance than the processor of the first device (i.e., a relatively inexpensive processor). For example, the second device can be positioned closer to the controlled object Ob1 than the first device, shortening the length of the cable connecting the second device to the controlled object Ob1. This reduces communication delays and the likelihood of degrading interference suppression functionality. Consequently, this control system 1 achieves advantages that contribute to improved practicality in terms of both model predictive control and interference suppression functionality.

[0034] According to another aspect, a control method is a control method for controlling a control system 1. The control method includes a disturbance estimation step, a model predictive control step, and a modification step. The disturbance estimation step includes estimating a disturbance occurring or applied to a controlled object Ob1 based on a first manipulated variable and a controlled variable, and outputting an estimated signal including the disturbance amount as the estimation result. The controlled object Ob1 outputs a controlled variable signal including the controlled variable based on the first manipulated variable. The model predictive control step includes calculating a second manipulated variable based on the controlled variable and outputting a control signal including the second manipulated variable. The modification step includes modifying the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the modified second manipulated variable. The model predictive control step is performed by one or more first processors P1 that perform processing related to model predictive control. The disturbance estimation step is performed by one or more second processors P2 that perform processing related to disturbance estimation. The model predictive control step includes outputting a control signal with a first output period. The disturbance estimation step includes outputting an estimated signal with a second output period. The modification step includes providing an output signal with a third output period. The second output period and the third output period are both shorter than the first output period.This control method achieves an advantage of contributing to improved practicality in terms of the model predictive control function and the disturbance suppression function.

[0035] The control method is used on a computer system (i.e., control system 1). That is, the control method can also be implemented as a computer program. According to another aspect, the program is designed to cause one or more processors to perform the control method described above. Optionally, the program can be stored on a non-transitory storage medium that is readable by a computer.

[0036] (Details)

[0037] (1) Overall structure

[0038] Next, refer to Figure 1 、 Figure 2A and Figure 2B An overall system including the control system 1 and its peripheral components according to the present embodiment will be described in detail.

[0039] The control system 1 is electrically connected to a control object Ob1 (such as a device or the like), and is configured to provide an output signal (electrical signal) including a first manipulated variable (control input) to the control object Ob1. Figure 1 As shown, interference d (ie, unnecessary signal) may be applied to the output signal supplied to the controlled object Ob1 from the control system 1. The interference d may be applied not only to the output signal but also generated by or applied to the controlled object Ob1.

[0040] In the following description, it is assumed that there is only one type of first manipulated variable. There is one control input (first manipulated variable) to the controlled object Ob1. For example, the first manipulated variable may be a manipulated variable regarding the (drive) current used to drive control the controlled object Ob1. However, this is merely an example and should not be interpreted as limiting. Alternatively, there may be multiple types of first manipulated variables (including current, voltage, position, torque, and speed). In this case, the control system 1 may provide an output signal corresponding to each type of the first manipulated variable of these multiple types to the controlled object Ob1.

[0041] As described above, the controlled object Ob1 may include, for example, a load device, a servo motor for driving the load device, and a detection unit (such as an encoder) for detecting the position, speed, and other parameters of the servo motor. The controlled object Ob1 outputs a controlled variable signal including a controlled variable (device output) in response to an input first manipulated variable (which may include a disturbance d). As used herein, a "controlled variable (device output)" refers to a quantity used to indicate the state of the controlled object Ob1.

[0042] In the following description, it is assumed that there is only one type of controlled variable. That is, there is one device output (controlled variable) provided by the control object Ob1. For example, in the control object Ob1, the servo motor is driven according to the driving current that may include the disturbance d (first manipulated variable), and the detection unit outputs a controlled variable signal including the speed (controlled variable) of the servo motor to an external device (i.e., the control system 1). Alternatively, there may be multiple types of controlled variables (including current, voltage, position, torque, and speed). In this case, the control object Ob1 can output a controlled variable signal corresponding to each of these multiple types of controlled variables to the control system 1. That is, the control object Ob1 can be a multi-input / output device.

[0043] Furthermore, in the following description, it is assumed that the signal cycle of the controlled variable signal output by the controlled object Ob1 is approximately the same as the signal cycle of the output signal including the control input to the controlled object Ob1 (ie, the first manipulated variable).

[0044] Control system 1 includes a computer system comprising one or more processors and memory. At least some of the functions of control system 1 are performed by having the computer system's processor execute a program stored in the computer system's memory. The program may be pre-stored in the memory. Alternatively, the program may be downloaded via a telecommunications line such as the Internet, or distributed after being stored on a non-transitory storage medium such as a memory card.

[0045] like Figure 1As shown, the control system 1 includes a disturbance estimator 2, a model predictive controller 3, a modification unit 4, a correction unit 5, an upsampler Up1, and a D / A converter 6. In other words, the control system 1 has the functions of the disturbance estimator 2, the model predictive controller 3, the modification unit 4, the correction unit 5, the upsampler Up1, and the D / A converter 6. These functions of the control system 1 can be accommodated in a single housing or distributed separately in a plurality of housings, whichever is appropriate.

[0046] The model predictive controller 3 has MPC function. Figure 2A As shown, the model predictive controller 3 includes a storage device 34. The storage device 34 includes an electrically programmable nonvolatile semiconductor memory such as a flash memory. The storage device 34 stores a prediction model related to the control object Ob1. As the prediction model, for example, a transfer function model or a state space model can be used.

[0047] The model predictive controller 3 is electrically connected to the control object Ob1 to receive the controlled variable signal from the control object Ob1. Figure 2A As shown, the model predictive controller 3 includes one or more (e.g., one) first processor P1 for operating in a first operating cycle to perform processing related to model predictive control. The first operating cycle corresponds to, for example, a sampling cycle Tmpc, in which data related to the controlled variable included in the controlled variable signal output by the control object Ob1 is sampled. The model predictive controller 3 uses a prediction model to calculate a second manipulated variable based on the controlled variable per sampling cycle Tmpc (i.e., the first operating cycle). The second manipulated variable is a physical quantity of the same type as the first manipulated variable. For example, if the first manipulated variable is a manipulated variable related to the drive current of the servo motor, the second manipulated variable is also a manipulated variable related to the drive current of the servo motor.

[0048] The model predictive controller 3 outputs a control signal including the second manipulated variable thus calculated. The control signal output by the model predictive controller 3 is a digital signal. Figure 1 As shown, the model predictive controller 3 outputs a control signal to the upsampler Up1 at the subsequent stage of the model predictive controller 3 .

[0049] In this case, the model predictive controller 3 outputs the control signal with a first output period. The first output period is equal to or longer than the first operation period. In this embodiment, it is assumed that the first output period is as long as the first operation period (i.e., the sampling period Tmpc) to make the description easy to understand. Therefore, in the following description, the first output period will sometimes be referred to as "first output period Tmpc" (refer to Figure 1). However, this is merely an example and should not be construed as limiting. Alternatively, the first output period may be longer than the sampling period Tmpc.

[0050] like Figure 2A As shown, the first processor P1 includes an arithmetic unit 31, a first sampler 32, and a timer 33 operating at a constant cycle.

[0051] The first sampler 32 downsamples the controlled variable toward the first operating cycle (i.e., sampling cycle Tmpc). The first sampler 32 may include a downsampler. The controlled variable signal including the controlled variable output by the controlled object Ob1 is sometimes a continuous analog signal and sometimes a discrete digital signal. If the signal cycle of the controlled variable signal is shorter than the first operating cycle (i.e., sampling cycle Tmpc), the first processor P1 causes the first sampler 32 to perform cycle conversion on the controlled variable to convert the signal cycle of the controlled variable signal to the first operating cycle (i.e., sampling cycle Tmpc) that is longer than the signal cycle of the controlled variable signal, thereby performing data sampling.

[0052] The arithmetic unit 31 uses the controlled variable indicating the state of the controlled object Ob1 to perform a finite-time prediction of the second manipulated variable. Specifically, the arithmetic unit 31 operates in a first operation cycle based on the sampling results of the first sampler 32 to perform arithmetic processing related to model predictive control. The arithmetic unit 31 operates in a first operation cycle based on a constant cycle of the timer 33 to perform arithmetic processing related to model predictive control. For example, the arithmetic unit 31 may operate in a first operation cycle based on a clock cycle of the timer 33.

[0053] In some cases, the controlled object Ob1 may have been affected by a disturbance d, and the controlled variable used to indicate the state of the controlled object Ob1 may also have been affected by the disturbance d. For example, if the controlled variable used to indicate the state of the controlled object Ob1 is the position or speed of the servo motor, the position or speed (controlled variable) can be input to the model predictive controller 3 while taking the disturbance d into account. In this embodiment, the control system 1 includes the disturbance estimating section 2 as a function for removing the disturbance d from the prediction result (second manipulated variable) output by the model predictive controller 3.

[0054] The interference estimation section 2 includes one or more (eg, one in this example) second processors P2 (see FIG. 1 ) for operating in a second operation cycle to perform processing related to interference estimation. Figure 2B ).like Figure 1As shown, the disturbance estimator 2 is electrically connected to the controlled object Ob1 to receive a controlled variable signal from the controlled object Ob1. In addition, the disturbance estimator 2 is also electrically connected to the connection node N1 (node) between the modification unit 4 and the D / A converter 6 to receive the output signal (first manipulated variable) of the modification unit 4. The disturbance estimator 2 estimates the disturbance generated by or applied to the controlled object Ob1 based on the first manipulated variable output by the modification unit 4 and the controlled variable provided by the controlled object Ob1, thereby outputting an estimated signal including the disturbance amount as the estimation result. The disturbance estimator 2 is implemented as a disturbance observer (DOB) for calculating (or estimating) the disturbance amount based on the first manipulated variable and the controlled variable. The estimated signal output by the disturbance estimator 2 is a digital signal.

[0055] The interference estimation unit 2 outputs the estimation signal with a second output period. The second output period is equal to or longer than the second operation period. In this embodiment, it is assumed that the second output period is as long as the second operation period (i.e., the sampling period Tdob) to make the description easy to understand. Therefore, in the following description, the second output period will sometimes be referred to as "second output period Tdob" (refer to Figure 1 ). However, this is merely an example and should not be construed as limiting. Alternatively, the second output period may be longer than the sampling period Tdob.

[0056] like Figure 2B As shown, the second processor P2 includes an operation unit 21 and a second sampler 22. The second sampler 22 performs data sampling related to the controlled variable included in the controlled variable signal provided by the control object Ob1 when the second operation cycle is set to the sampling cycle Tdob. The operation unit 21 operates with the second operation cycle to perform operation processing on the result of the sampling performed by the second sampler 22 to estimate the disturbance amount. The operation unit 21 compares the first manipulated variable output by the modification unit 4 with the controlled variable provided by the control object Ob1 to estimate the disturbance amount. The disturbance estimation unit 2 outputs an estimation signal including the calculation result (i.e., the disturbance amount) obtained by the operation unit 21 with the second output cycle Tdob to feed back the estimation signal to the control input of the control object Ob1. Note that in this embodiment, the correction unit 5 is provided at the subsequent stage of the disturbance estimation unit 2 and receives the estimation signal from the disturbance estimation unit 2.

[0057] In this embodiment, the second output period Tdob is shorter than the first output period Tmpc and satisfies Tmpc=n·Tdob (where n>1). Specifically, in this embodiment, the first output period Tmpc and the second output period Tdob are set to satisfy Tmpc>Tdob≥Ts, where Ts is a constant period, Tmpc is a first operation period, and Tdob is a second operation period. In other words, the first output period Tmpc and the second output period Tdob are set independently of each other to reduce their mutual dependence.

[0058] The upsampler Up1 performs period conversion to convert the control signal having the first output period Tmpc output by the model predictive controller 3 into a signal having the second output period Tdob, and outputs the signal thus converted to the modification section 4. The upsampler Up1 may include an upsampler. In the present embodiment, the second output period Tdob is shorter than the first output period Tmpc. This is why, in order to enable the modification section 4 at the subsequent stage of the upsampler Up1 to more easily modify the second manipulated variable (i.e., in order to synchronize the timing of the modification calculation of the manipulated variable with the second output period Tdob), the upsampler Up1 shortens the period of the control signal provided by the model predictive controller 3 (i.e., upsamples the control signal provided by the model predictive controller 3). The upsampler Up1 outputs the control signal that has been period-converted to the modification section 4.

[0059] The modification unit 4 modifies the second manipulated variable (i.e., compensates for the second manipulated variable) by referring to the modification information based on the estimated interference amount, and provides an output signal including the first manipulated variable as the modified (or compensated) second manipulated variable. The modification unit 4 provides the output signal with a third output period. The output signal provided by the modification unit 4 is a digital signal. Both the second output period Tdob and the third output period are shorter than the first output period Tmpc. In this embodiment, as an example, the second output period Tdob is the same length as the third output period. However, this is merely an example and should not be construed as limiting. Alternatively, the second output period Tdob may have a different length from the third output period.

[0060] In the present embodiment, the D / A converter 6 is arranged at a subsequent stage of the modification section 4 , so that the modification section 4 supplies the D / A converter 6 with an output signal including the first manipulated variable as the modified second manipulated variable.

[0061] In this embodiment, the modification information is information including the result of correction performed by the correction unit 5 (described later). However, the control system 1 does not necessarily need to include the correction unit 5. If the correction unit 5 is not provided, the modification information may be information based on the amount of interference included in the estimation signal provided by the interference estimation unit 2.

[0062] Next, before explaining the correction unit 5, reference will be made to Figure 3A The graph shown here is used to illustrate what function the modification section 4 would have if the correction section 5 were not provided. Figure 3A In the graph shown, the horizontal axis indicates time (t), and the vertical axis indicates the manipulated variable (u). That is, Figure 3A Shows time series data of the manipulated variables.

[0063] Figure 3A The bold line shown in indicates the data (digital signal waveform) of the second manipulated variable Umpc output by the model predictive controller 3. Figure 3A , a portion of the graph representing the second manipulated variable Umpc that falls within the range from time t=k to time t=k+1 corresponds to one cycle (ie, the first output cycle Tmpc) (before upsampling by the upsampler Up1).

[0064] In addition, Figure 3A , the difference between the bold line and the dotted line indicates data (digital signal waveform) related to the modification amount Udob (modification information) relative to the disturbance amount, which can be added to (or subtracted from) the second manipulated variable Umpc indicated by the bold line. The modification amount Udob and the disturbance amount provided by the disturbance estimation unit 2 have the same absolute value, but have opposite signs to each other. The modification amount Udob is an amount used to offset the disturbance d. Therefore, if the sign of the disturbance amount is positive, the sign of the modification amount Udob is negative. On the other hand, if the sign of the disturbance amount is negative, the sign of the modification amount Udob is positive. In the following description, the disturbance amount estimated by the disturbance estimation unit 2 will be designated by "d^" hereinafter. Note that in equations (5) and (8) to be referenced later, d^ is expressed as:

[0065] [Mathematical expression 1]

[0066]

[0067] exist Figure 3A In the example shown, the second output period Tdob of the disturbance variable d^ (i.e., the second output period Tdob of the modification variable Udob) output by the disturbance estimator 2 is one-fourth the first output period Tmpc of the second manipulated variable Umpc output by the model predictive controller 3. That is, in Tmpc=N·Tdob, N=4. Therefore, it can be considered that the output of the disturbance estimator 2 has a higher frequency than the output of the model predictive controller 3.

[0068] The modification section 4 adds the modification amount Udob to (or subtracts the modification amount Udob from) the second manipulated variable Umpc (which has been upsampled by the upsampler Up1 ) every second output period Tdob to provide an output signal.

[0069] As from Figure 3A It can be seen that, without the function of the correction section 5 , adding the modification amount Udob to the second manipulated variable Umpc would cause the first manipulated variable to exceed the upper limit value Umax (to be described later).

[0070] The correction unit 5 is configured to correct the interference amount estimated by the interference estimation unit 2 to meet the predetermined constraint condition. Figure 1 As shown, the correction section 5 is provided between the disturbance estimation section 2 and the modification section 4. The modification section 4 modifies the second manipulated variable using the result of correction performed by the correction section 5 as modification information.

[0071] In this embodiment, the predetermined constraint condition is that the value related to the first manipulated variable based on the corrected interference quantity falls within a predetermined constraint range having a lower limit value and an upper limit value. As used herein, "constraint condition" refers to a condition related to the constraint imposed on the device (as the control object Ob1) and / or a condition related to the power supply voltage of the controller of the device (such as a servo drive, etc.) (such as the maximum amplitude of the voltage, etc.), and varies according to the type and specification (standard) of the device included in the control system. In the following description, it is assumed that the "value related to the first manipulated variable" is the value of the first manipulated variable. However, this is only an example and should not be interpreted as restrictive. Alternatively, the "value related to the first manipulated variable" may also be the change in the first manipulated variable.

[0072] Now refer to Figure 3B The function of the correction unit 5 is explained by the graph shown. Figure 3B In the graph shown, Figure 3A As in the graph shown in FIG. 1 , the horizontal axis indicates time (t), and the vertical axis indicates the manipulated variable (u). That is, Figure 3B The time series data of the manipulated variables are shown. In addition to the modification amount Udob (indicated by the difference between the bold line and the dotted line), Figure 3B and Figure 3A The same, so its description will be appropriately omitted in this article.

[0073] In this embodiment, if Figure 3A and 3BAs shown, a lower limit value Umin and an upper limit value Umax are set for the modified second manipulated variable Umpc. Correction unit 5 corrects the disturbance variable so that when modification unit 4 adds modification value Udob to the second manipulated variable Umpc every second output period Tdob, the second manipulated variable Umpc falls within the predetermined constraint range defined by lower limit value Umin and upper limit value Umax. For example, if the controlled object Ob1 is a servo motor, once the drive current (manipulated variable) provided as the control input exceeds upper limit value Umax and falls outside the constraint range, the torque and / or speed of the servo motor may saturate. In particular, if the manipulated variable is output to the controlled object Ob1 every second output period Tdob (which is shorter than the first output period Tmpc) (i.e., frequently), as in this embodiment, the possibility of the manipulated variable exceeding the constraints imposed on the device (i.e., controlled object Ob1) and / or the constraints imposed on the controller of the device increases.

[0074] The correction unit 5 corrects the disturbance amount in advance before the modification unit 4 processes it, so as to prevent the modified second manipulated variable (i.e., the first manipulated variable) from falling outside the constraint range when the modification unit 4 adds the modification amount Udob corresponding to the disturbance amount to the second manipulated variable Umpc indicated by the bold line every second output period Tdob. For example, if the modified second manipulated variable (i.e., the first manipulated variable) is greater than the upper limit value Umax, the correction unit 5 corrects the disturbance amount in advance before the modification unit 4 processes it, so that the modified second manipulated variable is equal to the upper limit value Umax (refer to Figure 3B ). On the other hand, for example, if the modified second manipulated variable (i.e., the first manipulated variable) is less than the lower limit value Umin, the correction section 5 corrects the disturbance amount in advance before processing by the modification section 4 so that the modified second manipulated variable is equal to the lower limit value Umin.

[0075] Specifically, if the modified second manipulated variable calculated by adding the modification amount Udob to the second manipulated variable Umpc (ie, the first manipulated variable) is u′, u′=Umpc+Udob is satisfied.

[0076] In this case, the correction section 5 corrects the disturbance amount (which has the same absolute value as the modification amount Udob but has an opposite sign to the modification amount Udob) so as to satisfy the inequality 0≤Umin≤u′≤Umax.

[0077] In other words, if the upper limit value and lower limit value of the modification amount Udob that satisfies the constraint condition for the second manipulated variable Umpc(k) at time t=k are Udomax(k) and Udomin(k), respectively, then these upper limit values ​​and lower limit values ​​are given by the following equation (1). Note that the second manipulated variable Umpc(k) at time t=k will be constant until time t=k+1, so the upper limit value Udomax(k) and the lower limit value Udomin(k) will also be constant until time t=k+1 (refer to Figure 3B ). At time t=k+1, the second manipulated variable is Umpc(k+1), so the upper limit value and the lower limit value of the modification amount Udob are variable.

[0078] [Mathematical expression 2]

[0079] u dobMax (k)=u Max -u mpc (k)

[0080] u dobmin (k)=u min -u mpc (k) …Equation (1)

[0081] The correction unit 5 calculates the upper limit and lower limit of the correction amount Udob at time t=k, k+1, . . . using these equations (1).

[0082] Then, the correction unit 5 corrects the interference amount d^(k+i / N) (which has the same absolute value as the modification amount Udob(k+i / N) but has an opposite sign to the modification amount Udob(k+i / N)) (where i=0, 1, ..., and N-1) so that the modification amount Udob(k+i / N) at time t=k+i / N satisfies the following formula (2) to meet the constraint condition: 0≤Umin≤u'≤Umax. Figure 3B In the example shown, N is 4 in the following formula (2).

[0083] [Mathematical expression 3]

[0084]

[0085] Note that the correction unit 5 includes, for example, a storage device (e.g., an electrically programmable nonvolatile semiconductor memory such as a flash memory) and stores information related to the constraint conditions (e.g., the upper limit value Umax and the lower limit value Umin) in the storage device. In addition, for correction, the correction unit 5 directly obtains information related to the second manipulated variable Umpc (e.g., in the above example, information related to the second manipulated variable Umpc(k) at time t=k) from the model predictive controller 3.

[0086] In this way, correction unit 5 corrects the disturbance variable while taking into account constraints imposed on the plant and constraints imposed on the plant controller. By having model predictive controller 3 provide constraints imposed on the plant or the plant controller with respect to the second manipulated variable, the need to calculate the second manipulated variable is eliminated. This can reduce the amount of MPC calculations and contribute to further acceleration of MPC.

[0087] As described above, the "value related to the first manipulated variable" may also be the amount of change in the first manipulated variable. In this case, the correction unit 5 calculates the upper limit value ΔUdobmax and the lower limit value ΔUdobmin of the amount of change in the modification amount Udob at time t=k, k+1, ..., etc. by the following formula (3). In the following formula (3), the amount of change ΔUmpc(k) of the second manipulated variable at time t=k in the following formula (3) is the difference between the second manipulated variable at time t=k and the second manipulated variable at time t=k-1, and is calculated by the formula ΔUmpc(k)=Umpc(k)-Umpc(k-1). The amount of change ΔUmpc(k) of the second manipulated variable at time t=k will be constant until time t=k+1, so the upper limit value ΔUdobmax(k) and the lower limit value ΔUdobmin(k) will also be constant until time t=k+1.

[0088] [Mathematical expression 4]

[0089] Δu dobMax (k)=Δu Max -Δu mpc (k)

[0090] Δu dobmin (k)=Δu min -Δu mpc (k) …Equation (3)

[0091] Assuming that the change amount of the first manipulated variable is Δu', the upper limit value of the change amount is ΔUmax, and the lower limit value of the change amount is ΔUmin, the correction unit 5 corrects the change amount of the interference amount Δd^(k+i / N) (which has the same absolute value as the change amount of the modification amount ΔUdob(k+i / N), but has an opposite sign to the change amount of the modification amount ΔUdob(k+i / N)) (where i=0, 1, ... and N-1) so that the change amount of the modification amount ΔUdob(k+i / N) at time t=k+i / N satisfies the following formula (4) to meet the constraint condition: ΔUmin≤Δu'≤ΔUmax. Figure 3B In the example shown, N is 4 in the following formula (4).

[0092] [Mathematical expression 5]

[0093]

[0094] As can be seen, a constraint is provided for the amount of change of the first manipulated variable, which allows the vibration of the controlled object Ob1 to be suppressed.

[0095] The D / A converter 6 converts the output signal provided by the modification unit 4 into an analog signal and outputs the analog signal to the controlled object Ob1. The output terminal of the D / A converter 6 is electrically connected to the control input terminal of the controlled object Ob1. The output signal of the modification unit 4, including the modified second manipulated variable (i.e., the first manipulated variable), is a digital signal having discrete values. The D / A converter 6 converts the digital signal into a continuously changing analog signal and outputs the analog signal to the controlled object Ob1.

[0096] (2) Control system operation

[0097] Next, refer to Figure 4 To illustrate the process of controlling the operation of the control system 1. Note that Figure 4 The flowchart shown is merely an exemplary process for controlling the operation of the system 1 and should not be construed as limiting. Figure 4 The processing steps shown may be performed in an order different from that illustrated and may be omitted as appropriate. Figure 4 Some of the processing steps are shown, and / or additional processing steps may be performed as needed.

[0098] First, the control system 1 sets the first manipulated variable u'(t) at the current time t to the first manipulated variable u'(t-Tdob) at a previous time that is one cycle earlier than the current time, corresponding to the sampling cycle Tdob of the disturbance estimation unit 2, using the following equation (5). Then, the control system 1 sets the first manipulated variable u'(0) at the current time t=0 to u'(t) (in step ST1). As used herein, the phrase "one cycle earlier than the current time" refers to a time that is one sampling cycle Tdob earlier than the current time t.

[0099] [Mathematical expression 6]

[0100] u′(t)=u′(t-Tdob),u′(0)=u′(t),t=0,

[0101] Where, if t<0, then u′(t)=0,

[0102] Next, the control system 1 advances the current time t by Tdob to a future time that is one cycle later than the current time t (ie, one sampling cycle Tdob later) (ie, in step ST2 , t=t+Tdob).

[0103] If the current moment t is simultaneous with or later than the sampling period Tmpc of the model predictive controller 3 when it has advanced by X cycles (if the answer is "no" in step ST3), the control system 1 causes the model predictive controller 3 to perform MPC (i.e., perform the model predictive control step in step ST4). As used herein, "X" corresponds to the number of times (or the number of rounds) that the processing step ST2 has been performed. Specifically, when the processing is completed for the first round, the current moment t will have advanced by one round (i.e., X=1Tdob). When the processing is completed for the second round, the current moment t will have advanced by two rounds (i.e., X=2Tdob). In addition, the control system 1 causes the interference estimation unit 2 to predict the amount of interference (i.e., perform the interference estimation step in step ST5).

[0104] On the other hand, if the current time t does not reach the sampling period Tmpc of the model predictive controller 3 after advancing X periods (if the answer is "yes" in step ST3), the control system 1 causes the disturbance estimation unit 2 to estimate the disturbance amount without performing MPC (i.e., performing the disturbance estimation step in step ST5). In other words, MPC is performed every sampling period Tmpc.

[0105] The control system 1 causes the correction unit 5 to correct the disturbance amount predicted by the disturbance estimation unit 2 (in step ST6). In addition, the control system 1 also modifies the second manipulated variable output by the model predictive controller 3 based on the corrected disturbance amount (i.e., performs a modification step in step ST7).

[0106] If the current time t does not reach the sampling period Tmpc of the model predictive controller 3 when it advances by X cycles (if the answer is "No" in step ST8), the control system 1 returns to processing step ST2, in which the control system 1 further advances the current time t by another cycle (i.e., by one Tdob) and performs the processing from processing step ST3 onward. On the other hand, if the current time t is simultaneous with or later than the sampling period Tmpc of the model predictive controller 3 when it advances by X cycles (if the answer is "Yes" in step ST8), the control system 1 causes the model predictive controller 3 to determine whether the controlled variable of the control object Ob1 has reached the end point of the target trajectory (in step ST9).

[0107] If the model predictive controller 3 has determined that the controlled variable of the control object Ob1 has reached the end point of the target trajectory (if the answer is "Yes" in step ST9), the control system 1 ends the processing. On the other hand, if the model predictive controller 3 has determined that the controlled variable of the control object Ob1 has not reached the end point of the target trajectory (if the answer is "No" in step ST9), the control system 1 returns to the processing step ST1.

[0108] (3) Exemplary Application of Control System

[0109] Will refer to Figure 5 and Figure 6 An exemplary application of the control system 1 according to the present embodiment will be described.

[0110] Figure 5 The block structure according to the first exemplary application of the control system 1 is illustrated. Figure 5 , a programmable logic controller (PLC) 100 , a servo driver 200 , a motor (servo motor) 300 , and a load device 400 are shown.

[0111] The load device 400 corresponds to a portion of the control object Ob1. The load device 400 may include, for example, a mechanical mechanism such as a ball screw mechanism, a gear mechanism, or a belt mechanism. The load device 400 is driven by power supplied from the motor 300. The motor 300 is not limited to any particular type and may be a rotary motor or a linear motor, whichever is appropriate. The motor 300 corresponds to another portion of the control object Ob1. For example, the motor 300 may be a three-phase brushless motor.

[0112] The servo drive 200 includes a processing unit 201. The processing unit 201 includes a computer system including one or more processors and a memory. At least a portion of the functions of the processing unit 201 is performed by causing the processor of the computer system to execute a program stored in the memory of the computer system. The program can be pre-stored in the memory. Alternatively, the program can also be downloaded via a telecommunication line such as the Internet, or distributed after being stored in a non-transitory storage medium such as a memory card. The processing unit 201 performs feedback control for determining a control value based on a control signal supplied from the PLC 100 and a detection signal supplied from a detection unit for detecting the state of the motor 300 (such as position, speed or any other parameter), thereby driving and controlling the motor 300 so that a predetermined type of operation is performed. Examples of control values ​​include a command value related to the position of the motor 300, a command value related to the torque (or thrust) of the motor 300, and a command value related to the speed of the motor 300. Examples of predetermined types of operations include operations of assembling electronic components and operations of transporting products.

[0113] The servo driver 200 further includes an inverter circuit. The processing unit 201 controls the inverter circuit based on the control value thus determined, thereby adjusting the power (drive current) to be supplied to the motor 300.

[0114] The PLC 100 is a high-level controller and is connected to a plurality of servo drives 200 (in Figure 5 The PLC 100 is configured to be ready for bidirectional communication with the plurality of servo drives 200 (only one of which is shown). The PLC 100 includes a processing unit 101. The processing unit 101 generates a control signal including an operation command related to a predetermined type of operation and transmits the control signal to each of the plurality of servo drives 200 to control the servo drives 200.

[0115] In the first exemplary application, among the multiple functions of the control system 1, the function of the model predictive controller 3 (serving as the first processor P1) is installed in the PLC 100, and the functions of the interference estimator 2, the correction unit 5, the modification unit 4, the D / A converter 6, the upsampler Up1 and other components (serving as the second processor P2) are installed in the servo drive 200.

[0116] The PLC 100 (functioning as the model predictive controller 3) acquires a controlled variable (i.e., a quantity indicating the state of the motor 300) from each of the plurality of servo drives 200, performs MPC, and individually transmits a control signal including a second manipulated variable to each of the plurality of servo drives 200. Each of the plurality of servo drives 200 performs disturbance estimation, corrects the disturbance amount, modifies the second manipulated variable that the servo drive 200 has received from the PLC 100, and controls the inverter circuit to supply the first manipulated variable (i.e., drive current) to the motor 300.

[0117] According to the first exemplary application, the functions of the model predictive controller 3 and the functions of the disturbance estimation unit 2 and other components are decentralized, thereby achieving the advantage of suppressing the concentration of computational load on the processing units 101 and 201. In particular, in this embodiment, the model predictive control function (i.e., the first processor P1) and the disturbance estimation function (i.e., the second processor P2) are performed by two different processors. This makes it easier to provide the model predictive control function for the PLC 100 including a (relatively expensive) high-performance processor, as in the first exemplary application, and to provide the disturbance estimation function for each servo drive 200 including a (relatively inexpensive) processor (whose processing performance is lower than that of the processor of the PLC 100).

[0118] In other words, according to the first exemplary application, one or more (e.g., one in this example) first processors P1 are installed in the first device (PLC 100), and one or more (e.g., one in this example) second processors P2 are installed in the second device (servo drive 200). The second device is preferably arranged so that the communication distance between the second device and the controlled object Ob1 is shorter than the communication distance between the first device and the controlled object Ob1 (via the servo drive 200 in the first exemplary application). For example, the second device (each servo drive 200) can be configured closer to the controlled object Ob1 than the first device (PLC 100) to shorten the cable length (i.e., the communication distance) of the connection cable connecting the second device to the controlled object Ob1. This reduces communication delays and reduces the possibility of causing a degradation in interference suppression functionality.

[0119] Figure 6 The block structure of the control system 1 according to the second exemplary application is illustrated. Figure 6 , there is shown a servo driver 200, a motor (servo motor) 300, and a load device 400. The servo driver 200, the motor (servo motor) 300, and the load device 400 are the same as their counterparts in the first exemplary application described above, and therefore their description will be omitted herein.

[0120] However, in the second exemplary application, all of the functions of the control system 1 are incorporated into each servo drive 200. Each servo drive 200 (control system 1) acquires a controlled variable indicating the state of the motor 300 from the detection unit to perform MPC and disturbance estimation. Each servo drive 200 (control system 1) corrects the disturbance amount, modifies the second manipulated variable, and controls the inverter circuit to supply the first manipulated variable (i.e., drive current) to the motor 300.

[0121] According to the second exemplary application, multiple functions of the control system 1 are all installed at components closer to the control object Ob1 than in the first exemplary application to perform MPC and disturbance estimation, thereby achieving the advantage of reduced communication delay.

[0122] (4) Advantages

[0123] As can be seen from the foregoing description, in the control system 1 according to the present embodiment, the model predictive controller 3 includes one or more first processors P1 (refer to Figure 2A The interference estimation unit 2 includes one or more second processors P2 (refer to Figure 2B). The second output period of the interference estimator 2 and the third output period of the modification unit 4 are both shorter than the first output period of the model predictive controller 3. That is, the second output period of the interference estimator 2 and the third output period of the modification unit 4 are set independently of the first output period of the model predictive controller 3. This reduces the possibility of causing a decline in the function of removing or suppressing interference (i.e., the interference suppression function) compared to, for example, a situation where the processing of the interference estimator 2 is delayed synchronously with the MPC. In addition, this allows for a structure that makes it easier to set the second output period of the interference estimator 2 and the third output period of the modification unit 4 independently of the first output period of the model predictive controller 3 with good stability. In particular, this makes it easier to provide the model predictive control function for a first device including a processor with relatively high processing performance (i.e., a relatively expensive processor) and to provide the interference estimation function for a second device including a processor with lower processing performance than the processor of the first device (i.e., a relatively inexpensive processor). For example, the second device can be configured closer to the controlled object Ob1 than the first device to shorten the cable length of the connection cable used to connect the second device to the controlled object Ob1. This reduces communication delay and reduces the possibility of causing a decline in the interference suppression function. Therefore, the control system 1 achieves an advantage of contributing to improved usability in terms of the model predictive control function and the disturbance suppression function.

[0124] Furthermore, in the control system 1 , the disturbance amount estimated by the disturbance estimating section 2 is corrected so as to satisfy predetermined constraints, thereby further improving practicality in terms of the model predictive control function and the disturbance suppression function.

[0125] Specifically, the predetermined constraint condition is that the value associated with the first manipulated variable based on the corrected disturbance amount falls within a predetermined constraint range having a lower limit and an upper limit. This can reduce the possibility that the first manipulated variable exceeding the constraints imposed on the device (i.e., the controlled object Ob1) or the constraints imposed by the controller of the device (in terms of maximum voltage, maximum current, or permissible torque of the motor) will be sent to the device, thereby causing a saturated state (e.g., generating saturated torque).

[0126] (5) Modification

[0127] Next, modifications of the exemplary embodiment will be listed one by one. Note that the modifications to be described below can be appropriately combined and adopted.

[0128] The functions of the control system 1 according to the above-described exemplary embodiment may be implemented as, for example, a control method, a computer program, or a non-transitory storage medium storing the computer program.

[0129] The control system 1 according to the present disclosure includes a computer system. The computer system may include a processor and a memory as its main hardware components. The computer system performs the functions of the control system 1 according to the present disclosure by causing the processor to execute a program stored in the memory of the computer system. The program may be pre-stored in the memory of the computer system. Alternatively, the program may also be downloaded via a telecommunications line, or distributed after being recorded in a non-transient storage medium (such as a memory card, an optical disc or a hard disk drive (any of which is readable by the computer system)). The processor of the computer system may be composed of a single or multiple electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). As used herein, "integrated circuits" such as IC or LSI are referred to by different names depending on the degree of their integration. Examples of integrated circuits such as IC and LSI include integrated circuits referred to as "system LSI", "very large-scale integrated circuit (VLSI)" and "ultra-large-scale integrated circuit (ULSI)". Alternatively, a field programmable gate array (FPGA) to be programmed after the LSI is manufactured or a logic device that allows the reconfiguration of the connections or circuit segments inside the LSI may also be used as a processor. These electronic circuits can be integrated together on a single chip or distributed across multiple chips, whichever is appropriate. These multiple chips can be aggregated together in a single device or distributed across multiple devices, without limitation. As used herein, a "computer system" includes a microcontroller comprising one or more processors and one or more memories. Therefore, a microcontroller can also be implemented as one or more electronic circuits comprising a semiconductor integrated circuit or a large-scale integrated circuit.

[0130] In the above embodiment, the multiple functions of the control system 1 are integrated together in a single housing. However, this is not a necessary structure of the control system 1. Alternatively, these constituent elements of the control system 1 may be dispersed in a plurality of different devices.

[0131] Instead, multiple functions of the control system 1 may be aggregated together in a single housing. Still alternatively, at least a portion of the functions of the control system 1 (eg, a portion of the functions of the control system 1 ) may also be implemented as a cloud computing system.

[0132] (5-1) First Modification

[0133] Next, refer to Figure 7 A control system 1 according to a first modification will be described below. In the following description, any constituent element in the control system 1 according to the first modification that has substantially the same function as a corresponding portion of the control system 1 according to the above-described embodiment will be designated by the same reference numerals as those of the corresponding portion, and detailed description thereof will be omitted herein.

[0134] In the control system 1 according to the first modification, the disturbance amount estimated by the disturbance estimating section 2 is also input to the model predictive controller 3, and the control system 1 further includes a delay element 7 (refer to Figure 7 ), which is different from the control system 1 according to the above-mentioned first embodiment.

[0135] In the first modification, if Figure 7 As shown, the model predictive controller 3 is electrically connected to the disturbance estimator 2 so as to be able to obtain disturbance information related to the disturbance amount estimated by the disturbance estimator 2. In a first variation, the model predictive controller 3 calculates a second manipulated variable based on the controlled variable and the disturbance information, and outputs a control signal including the second manipulated variable. In the following description, it is assumed that the disturbance information is a value representing the disturbance amount. However, this is merely an example and should not be construed as limiting. Alternatively, the disturbance information may also be a change in the disturbance amount.

[0136] In the first modification, as described above, the control system 1 further includes a delay element 7. The delay element 7 is provided between the disturbance estimating unit 2 and the connection node N1 (node). The delay element 7 outputs data acquired about the first manipulated variable included in the output signal at a previous moment that is one cycle earlier than a certain point in time (e.g., the current moment) to the disturbance estimating unit 2. That is, the delay element 7 outputs data acquired about the first manipulated variable at a moment that is one sampling cycle earlier to the disturbance estimating unit 2. In the first modification, the disturbance estimating unit 2 estimates a disturbance amount corresponding to the data acquired in the previous cycle based on the first manipulated variable and the controlled variable, and outputs the estimation result as disturbance information to the model predictive controller 3. That is, in the first modification, the disturbance estimating unit 2 compares the controlled variable at the current moment with the data acquired about the first manipulated variable at a moment that is one sampling cycle earlier than the current moment to estimate the disturbance amount, and outputs an estimation signal including the disturbance amount thus estimated to the model predictive controller 3 and the correction unit 5.

[0137] The data acquired about the first manipulated variable one sampling period ago is used for the following reasons. Specifically, even if the model predictive controller 3 needs the disturbance amount d^(k) to calculate the second manipulated variable Umpc(k) at time t=k, the second manipulated variable Umpc(k) to be used by the disturbance estimation unit 2 to calculate the disturbance amount d^(k) has not yet been output and is still unavailable. Therefore, the disturbance estimation unit 2 uses the second manipulated variable Umpc(k-1) to calculate the disturbance amount d^(k). More specifically, the disturbance estimation unit 2 uses the second manipulated variable Umpc(k-1) to calculate the disturbance amount d^(k+1 / N) (where i=0, 1, ..., and N-1 and Tmpc=N·Tdob (where N>1)).

[0138] In the first modified example, the first sampler 32 of the model predictive controller 3 downsamples not only the controlled variable but also the disturbance amount toward the first operating cycle (sampling cycle Tmpc). That is, the period Tdob of the estimation signal including the disturbance amount output by the disturbance estimator 2 is shorter than the first operating cycle. Therefore, the first processor P1 causes the first sampler 32 to perform period conversion to convert the period of the disturbance amount to the first operating cycle (i.e., sampling cycle Tmpc) for data sampling.

[0139] In a first variant, the model predictive controller 3 uses, for example, a state space model of the control object Ob1 to define a state variable when a disturbance quantity (which may also be a change in the disturbance quantity) is set as a state quantity, thereby calculating a second manipulated variable for optimizing (for example, minimizing) the deviation of the disturbance quantity (i.e., the difference between the preset value and the estimated value).

[0140] If it is assumed that the controlled object Ob1 is linear time-invariant and the state space model of the controlled object Ob1 is transformed into a discrete system with a control period (for example, Tdob, which is as long as the sampling period of the disturbance estimator 2), the state equation and the output equation will be the following equation (6).

[0141] [Mathematical expression 7]

[0142] x(k+1)=A d x(k)+B d u(k)

[0143] y(k)=C d x(k) …(6)

[0144] Note that the input u, output y, and state variable x are assumed to be as follows.

[0145] [Mathematical expression 8]

[0146] u∈R m

[0147] y∈R l

[0148] x∈R n …(7)

[0149] The state equation of the extended system in the case of redefining the state variable x-(k)=[x^(k)d^(k)]T using the disturbance amount d^(k) estimated as the state amount is the following equation (8). The following equation (8) has a full-order observer form and enables simultaneous estimation of the original state variable x. Thus, x is expressed as x^.

[0150] [Mathematical expression 9]

[0151]

[0152] The control output Z(k) predicted until the time Hp steps later than time k is expressed by the following equation (9), assuming that z(k) = x-(k). Alternatively, z(k) can also be y^(k) or a constant × x^(k).

[0153] [Mathematical expression 10]

[0154]

[0155] The tracking error E(k) is expressed by the following equation (10).

[0156] [Mathematical expression 11]

[0157]

[0158] The variables in equation (10) are represented by the following equation (11), where the reference trajectory at time k is r(t|k), the change in the control input is Δu^(k|k) (=u^(k|k)-u(k-1), and the control time domain used to indicate the number of steps the input is allowed to change is Hu.

[0159] [Mathematical expression 12]

[0160]

[0161] The optimization problem for determining the amount of change in the control input using MPC is expressed by the following equation (12).

[0162] [Mathematical expression 13]

[0163]

[0164] With the condition ΩΔU(k)≤ω···(12)

[0165] Here, each parameter is represented by the following equation (13): Q and R are weights of the cost function V(k) and can be freely set.

[0166] [Mathematical expression 14]

[0167] Q=diag(Q(k) Q(k+1)…Q(k+H p ))

[0168] R=diag(R(k) R(k+1)…Q(k+H u -1))

[0169] G=2ΘT QE(k),H=Θ T QΘ+R …(13)

[0170] In the above example, the disturbance variable (or the change in the disturbance variable) is assumed to be a state variable. Alternatively, the disturbance variable (or the change in the disturbance variable) can also be used only as a constraint on the output during MPC calculation. As represented by the following inequality (14) representing the state variable constraint x(k+j), the control input constraint u(k+j), and the control input change constraint Δu(k+j), constraints can be calculated for the state variable x, the second manipulated variable Umpc, and the change in the second manipulated variable ΔUmpc.

[0171] [Mathematical expression 15]

[0172] x min ≤x(k+j)≤x Max j=0,…,H p

[0173] u min ≤u(k+j)≤u Max j=0,…,H u

[0174] Δu min ≤Δu(k+j)≤Δu Max j=0,…,H u …(14)

[0175] In the first modification, the model predictive controller 3 is provided with a function to obtain ΔU(k) ​​that minimizes the cost function V(k) under the constraints and output its first value Δu^(k|k). However, since the modification unit 4 subtracts d^(k), it is preferable that the model predictive controller 3 outputs Umpc(k) as Umpc(k) = Δu^(k|k) + d^k.

[0176] In the first modified example, the model predictive controller 3 obtains ΔU(k) ​​by performing the following optimization calculation:

[0177] [Mathematical expression 16]

[0178]

[0179] This equation includes a disturbance deviation relative to the state variable x including the estimated disturbance variable. As a result, a second manipulated variable that achieves a disturbance suppression effect is obtained. From this point on, the modification unit 4 modifies the second manipulated variable at time k+i / N based on the disturbance variable corrected by the correction unit 5 to satisfy the constraints imposed on the controlled object Ob1, thereby obtaining the first manipulated variable.

[0180] As can be seen, according to the first modification, the disturbance amount is used for the MPC to be performed by the model predictive controller 3. This is why, in a situation where the change in the disturbance between time k and time k+1 is so significant that the estimation accuracy of the disturbance estimator 2 decreases, calculating the second manipulated variable obtained by MPC while taking the disturbance amount into account enables further reduction of the average disturbance error during the time period. Consequently, this allows the control system 1 to be provided with an even higher degree of robustness against disturbances.

[0181] (5-2) Second Modification

[0182] Next, refer to Figure 8 A control system 1 according to a second modification will be described below. In the following description, any constituent element in the control system 1 according to the second modification that has substantially the same function as a corresponding portion of the control system 1 according to the above-described embodiment will be designated by the same reference numerals as those of the corresponding portion, and detailed description thereof will be omitted herein.

[0183] The control system 1 according to the second modified example includes a first D / A converter D1 and a second D / A converter D2, instead of the upsampler Up1 and the D / A converter 6 in the control system 1 according to the above exemplary embodiment. This is different from the control system 1 according to the above exemplary embodiment. That is, the control system 1 according to the second modified example performs D / A conversion at a stage before the modification unit 4, which is different from the control system 1 according to the above exemplary embodiment.

[0184] As described above, the control system 1 according to the second modification includes the first D / A converter D1 and the second D / A converter D2. The first D / A converter D1 is provided between the model predictive controller 3 and the modification unit 4. The second D / A converter D2 is provided between the correction unit 5 and the modification unit 4.

[0185] The control signal output by the model predictive controller 3 and the estimation signal output by the disturbance estimation unit 2 are digital signals. The first D / A converter D1 converts the control signal into an analog signal and outputs the analog signal to the modification unit 4. The second D / A converter D2 converts the estimation signal into an analog signal and outputs the analog signal to the modification unit 4. Note that the first D / A converter D1 preferably has an upsampling function, as does the upsampler Up1 of the control system 1 according to the above-described exemplary embodiment.

[0186] In the control system 1 according to the second modification, the modification section 4 modifies the analog signal including the second manipulated variable based on the analog signal including the corrected disturbance amount. This makes it easier for the modification section 4 to synchronize the calculation timing for modifying the manipulated variable.

[0187] (5-3) Third Modification

[0188] Next, refer to Figure 9 A control system 1 according to a third modification will be described. In the following description, any constituent element in the control system 1 according to the third modification having substantially the same function as a corresponding portion of the control system 1 according to the embodiment, the first modification, or the second modification described above will be designated by the same reference numerals as those of the corresponding portion, and detailed description thereof will be omitted herein.

[0189] The control system 1 according to this modification further includes a first D / A converter D1 and a second D / A converter D2, as does the control system 1 according to the second modification. Furthermore, like the control system 1 according to the first modification, the control system 1 according to the third modification also supplies the disturbance amount estimated by the disturbance estimator 2 to the model predictive controller 3 and further includes a delay element 7. However, unlike the control systems 1 according to the exemplary embodiment, the first modification, or the second modification described above, the control system 1 according to the third modification further includes an A / D converter 8.

[0190] In short, according to the third modification, the output signal including the first manipulated variable provided by the modification unit 4 is an analog signal. In order to input the first manipulated variable to the disturbance estimation unit 2 via the delay element 7, the analog signal needs to be converted into a digital signal. For this purpose, an A / D converter 8 is provided.

[0191] An A / D converter 8 is provided between the connection node N1 (node) and the delay element 7. The A / D converter 8 samples the first manipulated variable of the output signal at a specific operation cycle (e.g., Tdob, which is the same length as the sampling cycle of the disturbance estimator 2) to convert the output signal into a digital signal and output the converted digital signal. The delay element 7 is connected to the A / D converter 8 and outputs data regarding the first manipulated variable of the digital signal output by the A / D converter 8 at a time point one cycle earlier than a certain time point (e.g., the current time) to the disturbance estimator 2. The disturbance estimator 2 estimates the disturbance amount corresponding to the data acquired in the previous cycle based on the first manipulated variable and the controlled variable, and outputs the estimation result as disturbance information to the model predictive controller 3.

[0192] The control system 1 according to the third modification makes it easier for the model predictive controller 3 to use the disturbance amount estimated by the disturbance estimating section 2 even if the output signal provided by the modifying section 4 is a simulated signal, thereby ultimately further improving the accuracy of the second manipulated variable.

[0193] (Summary)

[0194] The above-described exemplary embodiments and their modifications are specific implementations of the following aspects of the present disclosure.

[0195] According to a first aspect, a control system (1) provides an output signal including a first manipulated variable to a controlled object (Ob1). The control system (1) includes a disturbance estimating unit (2), a model predictive controller (3), and a modifying unit (4). The disturbance estimating unit (2) estimates a disturbance generated by or applied to the controlled object (Ob1) based on the first manipulated variable and the controlled variable, and outputs an estimated signal including a disturbance amount as a result of the estimation. The controlled object (Ob1) outputs a controlled variable signal including a controlled variable based on the first manipulated variable. The model predictive controller (3) calculates a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable. The modifying unit (4) modifies the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the second manipulated variable thus modified. The model predictive controller (3) includes one or more first processors (P1) for performing processing related to model predictive control. The disturbance estimating unit (2) includes one or more second processors (P2) for performing processing related to disturbance estimation. The model predictive controller (3) outputs a control signal with a first output period. The interference estimation unit (2) outputs an estimation signal with a second output period. The modification unit (4) provides an output signal with a third output period. Both the second output period and the third output period are shorter than the first output period.

[0196] According to this aspect, the model predictive control function and the disturbance estimation function are implemented by different processors, and the second output cycle of the disturbance estimation unit (2) and the third output cycle of the modification unit (4) are both shorter than the first output cycle of the model predictive controller (3). In other words, the second output cycle and the third output cycle are set independently of the first output cycle of the model predictive controller (3). Therefore, the control system (1) achieves an advantage that contributes to improving the practicality of the model predictive control function and the disturbance suppression function.

[0197] The control system (1) according to the second aspect, which can be implemented in combination with the first aspect, further includes a correction unit (5) that corrects the disturbance amount estimated by the disturbance estimation unit (2) so as to satisfy a predetermined constraint condition. The modification unit (4) uses the result of the correction performed by the correction unit (5) as modification information to modify the second manipulated variable.

[0198] According to this aspect, the disturbance amount estimated by the disturbance estimation unit (2) is corrected to satisfy predetermined constraints, thereby further improving the practicality in terms of the model predictive control function and the disturbance suppression function.

[0199] In the control system (1) according to the third aspect which can be implemented in combination with the second aspect, the predetermined constraint condition is that a value related to the first manipulated variable based on the corrected disturbance amount falls within a predetermined constraint range having a lower limit value and an upper limit value.

[0200] This aspect can reduce the possibility that a first manipulated variable that exceeds the constraints imposed on the device (i.e., the control object Ob1) or the constraints imposed on the controller of the device (in terms of maximum voltage, maximum current, or allowable torque of the motor) is sent to the device and produces a saturated state (e.g., produces saturated torque).

[0201] In the control system (1) according to the fourth aspect, which can be implemented in combination with any one of the first to third aspects, the second output cycle is as long as the third output cycle.

[0202] According to this aspect, the third output cycle of the modification section (4) is matched with the second output cycle of the interference estimation section (2), thereby providing a more accurate interference suppression function.

[0203] In the control system (1) according to the fifth aspect, which can be implemented in combination with any one of the first to fourth aspects, the model predictive controller (3) operates in a first operation cycle to perform processing related to the model predictive control. The disturbance estimation unit (2) operates in a second operation cycle to perform processing related to disturbance estimation. The first output cycle is equal to or longer than the first operation cycle. The second output cycle is equal to or longer than the second operation cycle.

[0204] This aspect makes it easier to provide a more accurate interference suppression function.

[0205] In the control system (1) according to the sixth aspect that can be implemented in combination with the fifth aspect, one or more first processors (P1) include a first sampler (32) and an operation unit (31). The first sampler (32) performs downsampling of a controlled variable toward a first operation cycle. The operation unit (31) performs operation processing related to model predictive control on the result of the sampling performed by the first sampler (32) by operating in the first operation cycle. One or more second processors (P2) include a second sampler (22) for sampling data related to the controlled variable using the second operation cycle as a sampling cycle.

[0206] This aspect makes it easier to provide a more accurate interference suppression function.

[0207] In the control system (1) according to the seventh aspect, which can be implemented in combination with the fifth aspect or the sixth aspect, one or more first processors (P1) include a timer (33) operating at a constant cycle, and an operation unit (31). The operation unit (31) performs operation processing related to model predictive control by operating at a first operation cycle based on the constant cycle of the timer (33). The control system (1) satisfies Tmpc>Tdob≥Ts, where Ts is the constant cycle, Tmpc is the first operation cycle, and Tdob is the second operation cycle.

[0208] This aspect makes it easier to provide a more accurate interference suppression function.

[0209] In the control system (1) according to the eighth aspect, which can be implemented in combination with any one of the first to seventh aspects, the output signal provided by the modification unit (4) is a digital signal. The control system (1) further includes an upsampler (Up1) and a D / A converter (6). The upsampler (Up1) performs period conversion to convert the control signal output by the model predictive controller (3) with a first output period into a signal with a second output period, and outputs the signal with the second output period to the modification unit (4). The D / A converter (6) converts the output signal provided by the modification unit (4) into an analog signal, and outputs the analog signal to the control object (Ob1).

[0210] This aspect makes it easier to provide a more accurate interference suppression function.

[0211] In the control system (1) according to the ninth aspect, which can be implemented in combination with any one of the first to eighth aspects, each of the control signal output by the model predictive controller (3) and the estimation signal output by the disturbance estimation unit (2) is a digital signal. The control system (1) further includes: a first D / A converter (D1) for converting the control signal into an analog signal and outputting the analog signal to the modification unit (4); and a second D / A converter (D2) for converting the estimation signal into an analog signal and outputting the analog signal to the modification unit (4).

[0212] This aspect makes it easier to provide a more accurate interference suppression function.

[0213] In a control system (1) according to the tenth aspect that can be implemented in combination with any one of the first to ninth aspects, a model predictive controller (3) calculates a second manipulated variable based on a controlled variable and disturbance information related to a disturbance amount estimated by a disturbance estimation unit (2) to output a control signal including the second manipulated variable.

[0214] According to this aspect, the disturbance amount estimated by the disturbance estimating section (2) is also applied to the model predictive controller (3), thereby improving the accuracy of the second manipulated variable.

[0215] The control system (1) according to the eleventh aspect, which can be implemented in combination with the tenth aspect, further includes a delay element (7) that outputs data related to a first manipulated variable included in the output signal to the disturbance estimation unit (2). The data is acquired in a cycle before a certain time point. The disturbance estimation unit (2) estimates a disturbance amount corresponding to the data acquired in the previous cycle based on the first manipulated variable and the controlled variable, and outputs the estimation result as disturbance information to the model predictive controller (3).

[0216] This aspect makes it easier for the model predictive controller (3) to use the disturbance amount estimated by the disturbance estimating section (2), thereby ultimately further improving the accuracy of the second manipulated variable.

[0217] In the control system (1) according to the twelfth aspect that can be implemented in combination with the tenth aspect or the eleventh aspect, the disturbance estimation unit (2) includes one or more second processors (P2) for operating in a specific operation cycle to perform processing related to disturbance estimation. The output signal provided by the modification unit (4) is an analog signal. The control system (1) also includes an A / D converter (8) and a delay element (7). The A / D converter (8) samples the first manipulated variable included in the output signal in a specific operation cycle to convert the output signal into a digital signal and output the digital signal. The delay element (7) is connected to the A / D converter (8) and outputs data related to the first manipulated variable included in the digital signal output by the A / D converter (8) to the disturbance estimation unit (2). The data is acquired in a cycle before a certain time point. The disturbance estimation unit (2) estimates the disturbance amount corresponding to the data acquired in the previous cycle based on the first manipulated variable and the controlled variable to output the estimation result as disturbance information to the model predictive controller (3).

[0218] This structure makes it easier for the model predictive controller (3) to use the disturbance amount estimated by the disturbance estimating section (2) even if the output signal provided by the modifying section (4) is an analog signal, thereby ultimately further improving the accuracy of the second manipulated variable.

[0219] In the control system (1) according to the thirteenth aspect which can be implemented in combination with any one of the first to twelfth aspects, the disturbance estimating section (2) is implemented as a disturbance observer for calculating the disturbance amount based on the first manipulated variable and the controlled variable.

[0220] This aspect makes it easier to provide a more accurate interference suppression function.

[0221] In the control system (1) according to the fourteenth aspect, which can be implemented in combination with any one of the first to thirteenth aspects, one or more first processors (P1) are installed in a first device (such as a PLC 100). One or more second processors (P2) are installed in a second device (such as a servo drive 200). The second device is arranged so that a communication distance between the second device and the controlled object (Ob1) is shorter than a communication distance between the first device and the controlled object (Ob1).

[0222] This aspect enables reduction of communication delay caused by the second device, thereby making it easier to provide a more accurate interference suppression function.

[0223] A control method according to a fifteenth aspect is a control method of a control system (1) that provides an output signal including a first manipulated variable to a controlled object (Ob1). The control method includes a disturbance estimation step, a model predictive control step, and a modification step. The disturbance estimation step includes estimating a disturbance generated by or applied to the controlled object (Ob1) based on the first manipulated variable and a controlled variable, and outputting an estimated signal including a disturbance amount as a result of the estimation. The controlled object (Ob1) outputs a controlled variable signal including a controlled variable based on the first manipulated variable. The model predictive control step includes calculating a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable. The modification step includes modifying the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the second manipulated variable thus modified. The model predictive control step is performed by one or more first processors (P1) for performing processing related to model predictive control. The disturbance estimation step is performed by one or more second processors (P2) for performing processing related to disturbance estimation. The model predictive control step includes outputting a control signal with a first output period. The interference estimation step includes outputting an estimated signal with a second output period. The modification step includes providing an output signal with a third output period. Both the second output period and the third output period are shorter than the first output period.

[0224] This aspect can provide a control method that helps improve practicality in terms of model predictive control function and disturbance suppression function.

[0225] The program according to the sixteenth aspect is designed to cause one or more processors to perform the control method according to the fifteenth aspect.

[0226] This aspect can provide functionality that helps improve practicality in terms of model predictive control functionality and disturbance rejection functionality.

[0227] Note that the constituent elements according to the second aspect to the fourteenth aspect are not essential constituent elements of the control system (1) and may be omitted as appropriate.

[0228] Industrial applicability

[0229] The control system, control method, and program according to the present disclosure can help improve the practicality of model predictive control functions and disturbance suppression functions, thereby further improving the practicality of controlling motors and equipment, for example. Therefore, the control system, control method, and program according to the present disclosure are applicable to various industrial-based fields.

[0230] Description of Reference Numerals

[0231] 1 Control System

[0232] 2 Interference Estimation Unit

[0233] 22 Second Sampler

[0234] 3 Model Predictive Controller

[0235] 31 Arithmetic Units

[0236] 32 First Sampler

[0237] 33 Timer

[0238] 4. Revision Department

[0239] 5 Correction Department

[0240] 6 D / A converter

[0241] 7 Delay Elements

[0242] 8 A / D converters

[0243] D1 First D / A converter

[0244] D2 Second D / A converter

[0245] Ob1 control object

[0246] P1 first processor

[0247] P2 Second Processor

[0248] Up1 Upsampler

Claims

1. A control system configured to provide an output signal including a first manipulated variable to a controlled object, the control system comprising: a disturbance estimating section configured to estimate a disturbance generated by or applied to the controlled object based on the first manipulated variable and a controlled variable, the controlled object outputting a controlled variable signal including the controlled variable according to the first manipulated variable, and output an estimation signal including an amount of the disturbance as a result of the estimation; a model predictive controller configured to calculate a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable; as well as a modification section configured to modify the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the second manipulated variable thus modified, wherein the model predictive controller comprises one or more first processors configured to perform processing related to model predictive control, The interference estimation unit includes one or more second processors configured to perform processing related to interference estimation, The model predictive controller is configured to output the control signal in a first output period, The interference estimation unit is configured to output the estimation signal with a second output period, The modifying section is configured to provide the output signal in a third output cycle, and The second output period and the third output period are both shorter than the first output period.

2. The control system according to claim 1, further comprising a correction unit configured to correct the disturbance amount estimated by the disturbance estimation unit so as to satisfy a predetermined constraint condition. in, The modification section is configured to modify the second manipulated variable using a result of correction performed by the correction section as the modification information.

3. The control system according to claim 2, wherein: The predetermined constraint condition is that a value related to the first manipulated variable based on the corrected disturbance quantity falls within a predetermined constraint range having a lower limit value and an upper limit value.

4. The control system according to any one of claims 1 to 3, wherein: The second output period is as long as the third output period.

5. The control system according to any one of claims 1 to 4, wherein: The model predictive controller is configured to operate in a first operation cycle to perform processing related to the model predictive control, The interference estimation section is configured to operate in a second operation cycle to perform processing related to the interference estimation, The first output period is equal to or longer than the first operation period, and The second output period is equal to or longer than the second operation period.

6. The control system according to claim 5, wherein: The one or more first processors include: a first sampler configured to downsample the controlled variable toward the first operating period, and an operation unit configured to perform operation processing related to the model predictive control on a result of sampling performed by the first sampler by operating in the first operation cycle, and The one or more second processors include a second sampler configured to sample data related to the controlled variable using the second operation period as a sampling period.

7. The control system according to claim 5 or 6, wherein: The one or more first processors include: a timer that is configured to operate with a constant period, and an arithmetic unit configured to perform arithmetic processing related to the model predictive control by operating in a first operation cycle having a constant cycle based on the timer, and The control system satisfies Tmpc>Tdob≥Ts, where Ts is the constant period, Tmpc is the first operation period, and Tdob is the second operation period.

8. The control system according to any one of claims 1 to 7, wherein: The output signal provided by the modification unit is a digital signal, and The control system further comprises: an upsampler configured to perform cycle conversion to convert the control signal output by the model predictive controller with the first output cycle into a signal with the second output cycle, and output the signal with the second output cycle to the modification section; and A D / A converter is configured to convert the output signal provided by the modification section into an analog signal and output the analog signal to the control object.

9. The control system according to any one of claims 1 to 8, wherein: The control signal output by the model predictive controller and the estimation signal output by the disturbance estimation unit are each a digital signal, and The control system further comprises: a first D / A converter configured to convert the control signal into an analog signal and output the analog signal to the modifying section, and A second D / A converter is configured to convert the estimated signal into an analog signal and output the analog signal to the modifying section.

10. The control system according to any one of claims 1 to 9, wherein: The model predictive controller is configured to calculate the second manipulated variable based on the controlled variable and disturbance information related to the disturbance amount estimated by the disturbance estimating section to output a control signal including the second manipulated variable.

11. The control system according to claim 10 , further comprising a delay element configured to output data related to the first manipulated variable included in the output signal to the disturbance estimation unit, the data having been acquired one cycle before a certain time point. in, The disturbance estimating section is configured to estimate a disturbance amount corresponding to data acquired in the previous one cycle based on the first manipulated variable and the controlled variable to output an estimation result as the disturbance information to the model predictive controller.

12. The control system according to claim 10 or 11, wherein: The interference estimation unit includes one or more second processors, wherein the one or more second processors are configured to operate in a specific operation cycle to perform processing related to the interference estimation. The output signal provided by the modification unit is an analog signal, The control system further comprises: an A / D converter configured to data-sample a first manipulated variable included in the output signal in the specific operation cycle to convert the output signal into a digital signal and output the digital signal; and a delay element connected to the A / D converter and configured to output, to the disturbance estimating section, data related to a first manipulated variable included in a digital signal output by the A / D converter, the data having been acquired one cycle before a certain time point; and The disturbance estimating section is configured to estimate a disturbance amount corresponding to data acquired in the previous one cycle based on the first manipulated variable and the controlled variable to output an estimation result as the disturbance information to the model predictive controller.

13. The control system according to any one of claims 1 to 12, wherein: The disturbance estimating section is implemented as a disturbance observer configured to calculate the disturbance amount based on the first manipulated variable and the controlled variable.

14. The control system according to any one of claims 1 to 13, wherein: The one or more first processors are installed in the first device, The one or more second processors are installed in the second device, and The second device is arranged so that a communication distance between the second device and the control object is shorter than a communication distance between the first device and the control object.

15. A control method for controlling a control system, the control system being configured to provide an output signal including a first manipulated variable to a controlled object, the control method comprising: a disturbance estimating step for estimating a disturbance generated by or applied to the controlled object based on the first manipulated variable and a controlled variable, and outputting an estimation signal including an amount of the disturbance as a result of the estimation, the controlled object outputting a controlled variable signal including a controlled variable according to the first manipulated variable; a model predictive control step for calculating a second manipulated variable based on the controlled variable to output a control signal including the second manipulated variable; as well as a modifying step for modifying the second manipulated variable by referring to modification information based on the disturbance amount, thereby providing an output signal including the first manipulated variable as the second manipulated variable thus modified, wherein the model predictive control step is performed by one or more first processors configured to perform processing related to model predictive control, The interference estimation step is performed by one or more second processors configured to perform processing related to interference estimation, The model predictive control step is used to output the control signal in a first output period, The interference estimation step is used to output the estimated signal with a second output period, The modifying step is for providing the output signal with a third output period, and The second output period and the third output period are both shorter than the first output period. 16 . A program designed to cause one or more processors to perform the control method according to claim 15 .

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