Control system, control device, control method, and control program

Abstract

To provide a control system, a control device, a control method, and a control program that can perform stable control so that an offset does not occur with respect to a target value even when dead time is relatively long.SOLUTION: A control system 100 comprises: a target device 20 that is controlled based on a control signal; a sensor 30 that measures the physical quantity of the target device 20; and a control device 10 that sends the control signal to the target device 20 on the basis of a command value and the physical quantity and performs feedback control. The control device 10 includes a calculation unit 14 that calculates a compensation amount of the control signal on the basis of a set value of dead time and a model of the target device 20. The calculation unit 14 calculates the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past, and changes a coefficient of the second term from a predetermined value to a value less than the predetermined value when a predetermined condition is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control system, a control device, a control method, and a control program. [Background technology]

[0002] In the field of factory automation, feedback control of target devices such as servo motors is performed based on values ​​measured by sensors. If there is a time lag between when an input is given to the target device and when an output corresponding to that input appears, the feedback control loop is said to have dead time. For example, dead time can occur when devices are connected via relatively slow wired or wireless communication, or when a sensor performs measurement at the end of a conveyor belt or other transport device.

[0003] When the dead time is large compared to the response time of the controlled object, feedback control may not be performed appropriately. Regarding this point, for example, Patent Document 1 describes a remote control system that includes a communication disturbance estimation means composed of a disturbance observer and compensates for communication delays based on the estimated communication disturbance.

[0004] Furthermore, Patent Document 2 describes a conveyance system that reduces the compensation amount corresponding to the dead time when an object reaches a specific position determined upstream in the conveyance direction from a target stop position. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4930938 [Patent Document 2] Patent No. 6213071 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the configuration described in Patent Document 1, compensation is performed to obtain a feedback value (for example, velocity or position obtained by integrating velocity) assuming there is no dead time. Therefore, this type of control becomes open-loop control in which feedback information is canceled, and an offset may occur in the controlled variable (for example, position) from the target value due to an inertia modeling error.

[0007] Furthermore, although the configuration described in Patent Document 2 can stop the motor at the target position without offset, if the dead time is relatively long, the stopped state cannot be maintained stably, and the control amount may diverge. This problem will be described in detail later in comparison with the configuration of the present invention.

[0008] Therefore, the present invention provides a control system, a control device, a control method, and a control program that can perform stable control so that no offset occurs with respect to the target value even when the dead time is relatively long. [Means for solving the problem]

[0009] A control system according to one aspect of the present invention includes a target device that is controlled based on a control signal, a sensor that measures a physical quantity of the target device, and a control device that sends a control signal to the target device based on a command value and the physical quantity and performs feedback control. The control device has a calculation unit that calculates a compensation amount for the control signal based on a set value for dead time and a model of the target device. The calculation unit calculates the compensation amount including a first term based on the control signal and a second term based on a compensation amount calculated in the past, and changes the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied.

[0010] According to this aspect, by changing the coefficient of the second term, which is based on the compensation amount calculated in the past, to less than a predetermined value, it is possible to make the second term converge to zero more quickly while continuing compensation by the first term. Therefore, stable control can be achieved so that no offset occurs with respect to the target value even when the dead time is relatively long or when a modeling error is included.

[0011] In the above aspect, when the command value reaches the target value, the calculation unit may change the coefficient of the second term from a predetermined value to a value less than the predetermined value.

[0012] According to this aspect, it is possible to prevent the controlled variable from stabilizing in a state where it is deviated from the target value.

[0013] In the above aspect, the calculation unit may change the coefficient of the second term from a predetermined value to less than the predetermined value when the command value reaches the target value and the absolute value of the compensation amount is equal to or greater than a first reference value.

[0014] According to this aspect, even when a disturbance is applied, it is possible to prevent the command value from stabilizing in a state where it is deviated from the target value.

[0015] In the above aspect, when the calculation unit changes the coefficient of the second term from a predetermined value to less than the predetermined value and then updates the target value, the calculation unit may change the coefficient of the second term from less than the predetermined value to the predetermined value.

[0016] According to this aspect, even when the target value is updated, it is possible to control the target value so as to follow the updated value appropriately.

[0017] In the above aspect, the calculation unit may change the coefficient of the second term from the predetermined value to less than the predetermined value when the absolute value of the difference between the command value and the target value becomes equal to or less than a second reference value.

[0018] According to this aspect, it is possible to prevent the controlled variable from stabilizing in a state where it is deviated from the target value.

[0019] In the above aspect, the calculation unit may change the coefficient of the second term from a predetermined value to a value less than the predetermined value when the elapsed time from the start of the control is equal to or greater than a third reference value.

[0020] According to this aspect, it is possible to prevent the controlled variable from stabilizing in a state where it is deviated from the target value.

[0021] In the above aspect, the calculation section may change the coefficient of the second term from a predetermined value to a value less than the predetermined value when a disturbance is applied.

[0022] According to this aspect, even when a disturbance is applied, it is possible to prevent the controlled variable from stabilizing in a state where it is deviated from the target value.

[0023] In the above aspect, the control device controls the position of the target device, and the calculation unit calculates compensation amounts for each of the position and velocity, and when predetermined conditions are satisfied, the coefficients of the second terms for each of the position and velocity may be changed from predetermined values ​​to less than the predetermined values.

[0024] According to this aspect, even when the dead time is relatively long or when a modeling error is included, stable position and speed control can be performed so that an offset does not occur with respect to the target value.

[0025] A control device according to another aspect of the present invention is a control device that performs feedback control by sending a control signal to a target device based on a physical quantity and a command value of the target device measured by a sensor, and has a calculation unit that calculates a compensation amount for the control signal based on a set value for dead time and a model of the target device, and the calculation unit calculates a compensation amount including a first term based on the control signal and a second term based on a compensation amount calculated in the past, and changes the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied.

[0026] According to this aspect, by changing the coefficient of the second term, which is based on the compensation amount calculated in the past, to less than a predetermined value, it is possible to make the second term converge to zero more quickly while continuing compensation by the first term. Therefore, stable control can be achieved so that no offset occurs with respect to the target value even when the dead time is relatively long or when a modeling error is included.

[0027] A control method according to another aspect of the present invention is a control method for performing feedback control by sending a control signal to a target device based on a physical quantity and a command value of the target device measured by a sensor, the control method including: calculating a compensation amount for the control signal based on a set value of a dead time and a model of the target device, the compensation amount including a first term based on the control signal and a second term based on a compensation amount calculated in the past; and changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied.

[0028] According to this aspect, by changing the coefficient of the second term, which is based on the compensation amount calculated in the past, to less than a predetermined value, it is possible to make the second term converge to zero more quickly while continuing compensation by the first term. Therefore, stable control can be achieved so that no offset occurs with respect to the target value even when the dead time is relatively long or when a modeling error is included.

[0029] A control program according to another aspect of the present invention causes a control device that sends a control signal to a target device and performs feedback control based on a physical quantity and a command value of the target device measured by a sensor to calculate a compensation amount for the control signal based on a set value of dead time and a model of the target device, the compensation amount including a first term based on the control signal and a second term based on a compensation amount calculated in the past, and changing the coefficient of the second term from a predetermined value to less than the predetermined value when predetermined conditions are satisfied.

[0030] According to this aspect, by changing the coefficient of the second term, which is based on the compensation amount calculated in the past, to less than a predetermined value, it is possible to make the second term converge to zero more quickly while continuing compensation by the first term. Therefore, stable control can be achieved so that no offset occurs with respect to the target value even when the dead time is relatively long or when a modeling error is included. [Effects of the Invention]

[0031] According to the present invention, it is possible to provide a control system, a control device, a control method, and a control program that can perform stable control so that no offset occurs with respect to a target value even when the dead time is relatively long. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a diagram showing a network configuration of a control system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing functional blocks of a control device according to the present embodiment. [Figure 3] FIG. 2 is a control block diagram of a control device according to the present embodiment. [Figure 4] FIG. 2 is a diagram illustrating details of a control block of the control device according to the present embodiment. [Figure 5] FIG. 2 is a diagram illustrating a physical configuration of a control device according to the present embodiment. [Figure 6a] FIG. 10 is a diagram showing a command position in a first simulation example. [Figure 6b] FIG. 10 is a diagram illustrating disturbances in a first simulation example. [Figure 7a] FIG. 4 is a diagram showing the position of a target device controlled by a control device according to the present embodiment in a first simulation example. [Figure 7b] 10 is a diagram showing an error between a position controlled by the control device according to the present embodiment and a command position in a first simulation example. FIG. [Figure 7c] FIG. 4 is a diagram showing a thrust force controlled by the control device according to the present embodiment in a first simulation example. [Figure 7d] 5 is a diagram showing a speed compensation amount calculated by the control device according to the present embodiment in a first simulation example. FIG. [Figure 7e] FIG. 4 is a diagram showing a position compensation amount calculated by the control device according to the present embodiment in a first simulation example. [Figure 7f] FIG. 10 is a diagram showing the coefficient of the second term of the compensation amount used by the control device according to the present embodiment in the first simulation example. [Figure 8a] FIG. 4 is a diagram showing the position of a target device controlled by a control device according to a first comparative example in a first simulation example. [Figure 8b]FIG. 10 is a diagram showing an error between a position controlled by a control device according to a first comparative example and a command position in a first simulation example. [Figure 8c] FIG. 4 is a diagram showing a thrust force controlled by a control device according to a first comparative example in a first simulation example. [Figure 9a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to a second comparative example in a first simulation example. [Figure 9b] FIG. 10 is a diagram showing an error between a position controlled by a control device according to a second comparative example and a command position in a first simulation example. [Figure 9c] FIG. 10 is a diagram showing the thrust force controlled by the control device according to the second comparative example in the first simulation example. [Figure 9d] FIG. 10 is a diagram showing a position compensation amount calculated by a control device according to a second comparative example in a first simulation example. [Figure 9e] FIG. 10 is a diagram showing a position compensation amount reduction adjustment coefficient used by the control device according to the second comparative example in the first simulation example. [Figure 10a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to a third comparative example in a first simulation example. [Figure 10b] FIG. 10 is a diagram showing an error between a position controlled by a control device according to a third comparative example and a command position in a first simulation example. [Figure 10c] FIG. 10 is a diagram showing the thrust force controlled by the control device according to the third comparative example in the first simulation example. [Figure 10d] FIG. 10 is a diagram showing a speed compensation amount calculated by a control device according to a third comparative example in a first simulation example. [Figure 10e] FIG. 10 is a diagram showing a position compensation amount calculated by a control device according to a third comparative example in a first simulation example. [Figure 10f] FIG. 10 is a diagram showing the coefficient of the second term of the position compensation amount used by the control device according to the third comparative example in the first simulation example. [Figure 11]FIG. 10 is a diagram illustrating disturbances in a second simulation example. [Figure 12a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to the present embodiment in a second simulation example. [Figure 12b] FIG. 10 is a diagram showing an error between a position controlled by the control device according to the present embodiment and a command position in a second simulation example. [Figure 12c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the present embodiment in a second simulation example. [Figure 12d] FIG. 10 is a diagram showing a speed compensation amount calculated by the control device according to the present embodiment in a second simulation example. [Figure 12e] FIG. 10 is a diagram showing the amount of position compensation calculated by the control device according to the present embodiment in a second simulation example. [Figure 12f] FIG. 10 is a diagram showing the coefficient of the second term of the compensation amount used by the control device according to the present embodiment in the second simulation example. [Figure 13a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to a first comparative example in a second simulation example. [Figure 13b] FIG. 10 is a diagram showing an error between a position controlled by the control device according to the first comparative example and a command position in a second simulation example. [Figure 13c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the first comparative example in the second simulation example. [Figure 14a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to a second comparative example in a second simulation example. [Figure 14b] FIG. 10 is a diagram showing an error between a position controlled by a control device according to a second comparative example and a command position in a second simulation example. [Figure 14c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the second comparative example in the second simulation example. [Figure 14d]FIG. 10 is a diagram showing a position compensation amount calculated by a control device according to a second comparative example in a second simulation example. [Figure 14e] FIG. 10 is a diagram showing a position compensation amount reduction adjustment coefficient used by the control device according to the second comparative example in the second simulation example. [Figure 15a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to the present embodiment in a third simulation example. [Figure 15b] FIG. 11 is a diagram showing the error between the position controlled by the control device according to the present embodiment and the command position in a third simulation example. [Figure 15c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the present embodiment in a third simulation example. [Figure 15d] FIG. 10 is a diagram showing a speed compensation amount calculated by the control device according to the present embodiment in a third simulation example. [Figure 15e] FIG. 10 is a diagram showing the amount of position compensation calculated by the control device according to the present embodiment in a third simulation example. [Figure 15f] FIG. 11 is a diagram showing the coefficient of the second term of the compensation amount used by the control device according to the present embodiment in the third simulation example. [Figure 16a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to a first comparative example in a third simulation example. [Figure 16b] FIG. 10 is a diagram showing an error between a position controlled by the control device according to the first comparative example and a command position in a third simulation example. [Figure 16c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the first comparative example in a third simulation example. [Figure 17] FIG. 10 is a diagram illustrating disturbances in a fourth simulation example. [Figure 18a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to the present embodiment in a fourth simulation example. [Figure 18b]FIG. 11 is a diagram showing the error between the position controlled by the control device according to the present embodiment and the command position in the fourth simulation example. [Figure 18c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the present embodiment in a fourth simulation example. [Figure 18d] FIG. 10 is a diagram showing a speed compensation amount calculated by the control device according to the present embodiment in a fourth simulation example. [Figure 18e] FIG. 10 is a diagram showing the amount of position compensation calculated by the control device according to the present embodiment in a fourth simulation example. [Figure 18f] FIG. 11 is a diagram showing the coefficient of the second term of the compensation amount used by the control device according to the present embodiment in the fourth simulation example. [Figure 19a] FIG. 10 is a diagram showing the position of a target device controlled by a control device according to a first comparative example in a fourth simulation example. [Figure 19b] FIG. 10 is a diagram showing the error between the position controlled by the control device according to the first comparative example and the command position in the fourth simulation example. [Figure 19c] FIG. 10 is a diagram showing the thrust controlled by the control device according to the first comparative example in a fourth simulation example. [Figure 20] 4 is a flowchart of a control process executed by the control device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same or similar components.

[0034] 1 is a diagram showing the network configuration of a control system 100 according to an embodiment of the present invention. The control system 100 includes a target device 20 that is controlled based on a control signal, a sensor 30 that measures a physical quantity of the target device 20, and a control device 10 that performs feedback control by sending a control signal to the target device 20 based on a command value and the physical quantity measured by the sensor 30.

[0035] The target device 20 may be any device that is controlled based on a control signal. For the sake of concreteness, the following description will be based on a device that controls the position of a moving part using a servo motor. In this case, the command value is a target value for the position of the moving part, and the control signal is the thrust (torque) of the servo motor.

[0036] The sensor 30 may measure any physical quantity related to the target device 20. For example, if the target device 20 is a device that controls the position of a movable part, the sensor 30 may measure the position of the movable part.

[0037] The control device 10, the target device 20, and the sensor 30 are communicatively connected to each other via a communication network N. The communication network N may be a wired or wireless communication network, for example, a communication network conforming to standards such as EtherNet / IP or EtherCAT (registered trademark), or a local 5G network.

[0038] 2 is a diagram showing functional blocks of the control device 10 according to this embodiment. The control device 10 includes a command value generating unit 11, a control signal generating unit 12, an acquiring unit 13, and a calculating unit .

[0039] The command value generator 11 generates a command value according to set values ​​such as a target position, a moving time, a maximum allowable speed, and a maximum allowable acceleration. When the control target of the control device 10 is the position of a movable part of the target device 20, the final value of the command value becomes a target value for the position. The command value generator 11 may be a part of the configuration of the control device 10, or may be a separate configuration. For example, the command value generator 11 may be realized as a functional part of a so-called controller. In that case, the control device 10 may be a device that includes a so-called controller and a so-called driver (e.g., a servo driver) as separate entities.

[0040] The control signal generator 12 generates a control signal for controlling the target device 20 based on the command value and the physical quantity of the target device 20 measured by the sensor 30, and transmits the control signal to the target device 20. If the target device 20 is a device that controls the position of a moving part by a servo motor, the control signal may be a signal for controlling the thrust (torque) of the servo motor.

[0041] The acquisition unit 13 acquires the physical quantity of the target device 20 measured by the sensor 30. The acquired physical quantity is used by the control signal generation unit 12.

[0042] The calculation unit 14 calculates the amount of compensation for the control signal based on the set value of the dead time and the model of the target device 20. The calculation unit 14 calculates the amount of compensation including a first term based on the control signal and a second term based on a compensation amount calculated in the past, and changes the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied.

[0043] The set value of the dead time may be a value set based on an actual measurement value of the dead time, or a value estimated by any method. The model of the target device 20 is a model of the equation of motion that the moving part of the target device 20 follows, and may be, for example, a model derived based on the equation of motion that holds between the thrust applied to the moving part and the inertial force and the friction force.

[0044] Let the model value of the inertia coefficient be represented as Jm, the model value of the viscous friction coefficient be represented as Cm, Tm = Jm / Cm, Km = 1 / Cm, the control period be represented as Ts, the number of cycles of the dead time Lm be represented as Dm = round(Lm / Ts) (where round is a function that rounds off the decimal part), the control signal (thrust) for the current cycle be represented as U(1), the control signal (thrust) before the dead time cycle be represented as U(1 + Dm). When a1m = exp(-Ts / Tm) and b1m = Km×(1 - a1m) are defined, the calculation unit 14 may calculate the velocity compensation amount Vc by Vc = b1m×(U(1) - U(1 + Dm)) + Adj×a1m×Vc. Here, b1m×(U(1) - U(1 + Dm)) is the first term based on the control signal, Adj×a1m×Vc is the second term based on the compensation amount calculated in the past, and Adj is the coefficient of the second term. When the calculation unit 14 satisfies a predetermined condition, it changes the coefficient Adj of the second term from a predetermined value Adj0 to a value less than the predetermined value Adj1 (Adj1 < Adj0). When the calculation unit 14 satisfies a predetermined condition, for example, it may change the coefficient Adj of the second term from a predetermined value Adj0 = 1 to a value less than the predetermined value Adj1 = 0.99.

[0045] Also, the calculation unit 14 may calculate the position compensation amount Pc by Pc = Vc×Ts + Adj×Pc. Here, Vc×Ts is the first term based on the velocity compensation amount, Adj×Pc is the second term based on the compensation amount calculated in the past, and Adj is the coefficient of the second term.

[0046] By changing the coefficient of the second term based on the compensation amount calculated in the past to a value less than the predetermined value, the control device 10 can continue the compensation by the first term while making the second term converge to zero more quickly. Therefore, stable control can be achieved so that no offset occurs with respect to the target value even when the dead time is relatively long or when modeling errors are included.

[0047] When the command value reaches the target value, the calculation unit 14 may change the coefficient of the second term from a predetermined value to less than the predetermined value. That is, the predetermined condition for changing the coefficient of the second term may be that the command value has reached the target value. Here, the command value reaching the target value includes not only the command value being equal to the target value but also the absolute value of the difference between the command value and the target value being equal to or less than a second reference value.

[0048] By changing the coefficient of the second term from a predetermined value to a value less than the predetermined value when the command value reaches the target value, it is possible to prevent the controlled variable from stabilizing in a state where it deviates from the target value.

[0049] The calculation unit 14 may change the coefficient of the second term from a predetermined value to less than the predetermined value when the command value reaches the target value and the absolute value of the compensation amount is equal to or greater than a first reference value. More specifically, the predetermined condition for changing the coefficient of the second term may be that the command value reaches the target value and abs(Pc)>AdjChg is satisfied. Here, abs(Pc) is the absolute value of the position compensation amount, and AdjChg is the first reference value, which may be set to, for example, AdjChg=0.2.

[0050] When the command value reaches the target value and the absolute value of the compensation amount becomes equal to or greater than the first reference value, the coefficient of the second term is changed from a predetermined value to a value less than the predetermined value, thereby preventing the control amount from stabilizing in a state where it deviates from the target value even when an external disturbance is applied.

[0051] When the target value is updated after the calculation unit 14 changes the coefficient of the second term from a predetermined value to less than the predetermined value, the calculation unit 14 may change the coefficient of the second term from less than the predetermined value to the predetermined value. In other words, when the target value is updated, the calculation unit 14 may return the coefficient of the second term to its initial value even after decreasing the coefficient of the second term.

[0052] When the target value is updated, the coefficient of the second term is changed from less than a predetermined value to a predetermined value, thereby enabling control to ensure appropriate tracking even when the target value is updated.

[0053] When the absolute value of the difference between the command value and the target value becomes equal to or smaller than a second reference value, the calculation unit 14 may change the coefficient of the second term from a predetermined value to a value less than the predetermined value. More specifically, the predetermined condition for changing the coefficient of the second term may be that abs(rR)≦Δy is satisfied, where abs(rR) is the absolute value of the difference between the command value r and the target value R, and Δy is the second reference value.

[0054] When the absolute value of the difference between the command value and the target value becomes equal to or less than the second reference value, the coefficient of the second term is changed from a predetermined value to a value less than the predetermined value, thereby preventing the controlled variable from stabilizing in a state where it deviates from the target value.

[0055] The calculation unit 14 may change the coefficient of the second term from a predetermined value to less than the predetermined value when the elapsed time from the start of control is equal to or greater than a third reference value. More specifically, the predetermined condition for changing the coefficient of the second term may be that t≧ΔT is satisfied, where t is the elapsed time from the start of control and ΔT is the third reference value. The third reference value ΔT may be determined based on the command value.

[0056] When the elapsed time from the start of control is equal to or greater than the third reference value, the coefficient of the second term is changed from a predetermined value to a value less than the predetermined value, thereby preventing the controlled variable from stabilizing in a state where it deviates from the target value.

[0057] When a disturbance is applied, the calculation unit 14 may change the coefficient of the second term from a predetermined value to less than the predetermined value. When the timing of the application of the disturbance is known, the calculation unit 14 may change the coefficient of the second term from a predetermined value to less than the predetermined value at the timing of the application of the disturbance, may change the coefficient of the second term from a predetermined value to less than the predetermined value a predetermined time before the timing of the application of the disturbance, or may change the coefficient of the second term from a predetermined value to less than the predetermined value a predetermined time after the timing of the application of the disturbance. Furthermore, when the timing of the application of the disturbance is unknown, the calculation unit 14 may statistically estimate the timing of the application of the disturbance and change the coefficient of the second term from a predetermined value to less than the predetermined value at the estimated timing.

[0058] When a disturbance is applied, by changing the coefficient of the second term from a predetermined value to a value less than the predetermined value, it is possible to prevent the control variable from stabilizing in a state where it deviates from the target value even when a disturbance is applied.

[0059] When the control device 10 controls the position of the target device 20, the calculation unit 14 may calculate the compensation amount for each of the position and velocity of the target device 20, and, if a predetermined condition is satisfied, may change the coefficient of the second term related to each of the position and velocity of the target device 20 from a predetermined value to less than the predetermined value. That is, the control device 10 may not only change the coefficient of the second term related to the position compensation amount of the target device 20 from a predetermined value to less than the predetermined value, but also change the coefficient of the second term related to the velocity compensation amount from a predetermined value to less than the predetermined value.

[0060] By changing the coefficients of the second terms for the position and velocity of the target device 20 from a predetermined value to a value less than the predetermined value, stable position and velocity control can be achieved so that no offset occurs with respect to the target value even when the dead time is relatively long or when modeling errors are included.

[0061] 3 is a control block diagram of the control device 10 according to this embodiment. Below, a case will be described in which the control device 10 controls the position of the movable part of the target device 20. In addition, as a model of the equation of motion that the movable part follows, an equation of motion that holds between a thrust force applied to the movable part and an inertial force and a frictional force is considered.

[0062] First, the control device 10 generates a command value r (S40). In this example, the command value r is a value related to position, and the final value of the command value r is a target value. The command value r is input to the PID control G(s), and a control signal u representing thrust is output (S41). Note that although the feedforward control block is omitted in the figure, the control block may include a feedforward control block, and for example, a model following type two-degree-of-freedom control may be applied.

[0063] The control device 10 calculates the delay time Lm by using the factor (1-e -Lms) is multiplied by the control signal u (S42) to calculate the compensation amount (S43). The calculated speed compensation amount Vc and position compensation amount Pc are fed back to the PID control G(s).

[0064] And there is a time delay of L. -Ls After this occurs (S44), a control signal u is input to the control object P(s) (S45). Here, the control object is a part (for example, a moving part) or the whole of the control device 20. If the dead time is a communication delay, a delay of L1 may occur in the transmission of the control signal u, and a delay of L2 may occur in the transmission of the position y, which is a physical quantity of the control object P(s), but in this example, these are collectively expressed as L = L1 + L2. If the delay time does not vary with time, such a substitution can be made.

[0065] Then, the position y, which is a physical quantity of the controlled object P(s), is read and fed back to the PID control G(s). The control device 10 repeats this control at a predetermined cycle to control the position y so that it follows the command value r.

[0066] 4 is a diagram showing details of the control blocks of the control device 10 according to this embodiment, which shows the feedback of the compensation amount in more detail than FIG.

[0067] First, the control device 10 generates a command value r (S40). The command value r is combined with the measured position y and position compensation amount Pc, and then input to P control (S41a). Furthermore, the time derivative of the measured position y (S41b) and the velocity compensation amount Vc are combined with the output of P control, and the combined result is input to PI control, and a control signal u representing thrust is output (S41c). Note that a feedforward control block may be included, as in FIG. 3.

[0068] As in FIG. 3, the control device 10 calculates the delay time setting value Lm by using the element (1-e -Lms ) is multiplied by the control signal u (S42) to calculate the compensation amount (S43). The calculated speed compensation amount Vc and position compensation amount Pc are fed back to the PI control and P control, respectively.

[0069] And there is a time delay of L. -Ls After this occurs (S44), a control signal u is input to the control object P(s) (S45). Thereafter, the position y, which is a physical quantity of the control object P(s), is read and fed back to the PID control G(s). The control device 10 repeats this control at a predetermined cycle to control the position y so that it follows the command value r.

[0070] FIG. 5 is a diagram showing the physical configuration of the control device 10 according to this embodiment. The control device 10 includes a central processing unit (CPU) 10a corresponding to a calculation unit, a random access memory (RAM) 10b corresponding to a storage unit, a read-only memory (ROM) 10c corresponding to a storage unit, a communication unit 10d, an input unit 10e, and a display unit 10f. These components are connected via a bus so that they can transmit and receive data to and from each other. While this example describes a case in which the control device 10 is configured by a single computer, the control device 10 may also be realized by combining multiple computers. The configuration shown in FIG. 5 is merely an example, and the control device 10 may include other components or may not include some of these components.

[0071] The CPU 10a is a control unit that controls the execution of programs stored in the RAM 10b or the ROM 10c and performs data calculations and processing. The CPU 10a is a calculation unit that executes a program (control program) that calculates the amount of compensation and controls the target device 20 based on the amount of compensation. The CPU 10a receives various data from the input unit 10e and the communication unit 10d, and displays the results of calculations on the data on the display unit 10f or stores the results in the RAM 10b.

[0072] The RAM 10b is a rewritable storage unit and may be implemented, for example, by a semiconductor memory device. The RAM 10b may store data such as programs executed by the CPU 10a, initial values ​​used in calculating the compensation amount, and coefficients for the second term. Note that these are merely examples, and the RAM 10b may store data other than these, or may not store some of these data.

[0073] The ROM 10c is a storage unit from which data can be read, and may be configured, for example, with a semiconductor memory element. The ROM 10c may store, for example, control programs and data that is not rewritten.

[0074] The communication unit 10d is an interface that connects the device 10 to other devices, and may be connected to a communication network such as a LAN.

[0075] The input unit 10e receives data input from a user, and may include, for example, a keyboard and a touch panel.

[0076] The display unit 10f visually displays the results of calculations performed by the CPU 10a and may be configured with, for example, an LCD (Liquid Crystal Display). The display unit 10f may display, for example, the control signal and the calculated compensation amount in chronological order.

[0077] The control program may be provided by being stored in a computer-readable storage medium such as RAM 10b or ROM 10c, or may be provided via a communication network connected by communication unit 10d. In control device 10, CPU 10a executes the control program to realize the various operations described with reference to FIG. 2. Note that these physical configurations are merely examples and do not necessarily have to be independent configurations. For example, control device 10 may include an LSI (Large-Scale Integration) in which CPU 10a is integrated with RAM 10b and ROM 10c.

[0078] Figure 6a shows the command position in the first simulation example. In this simulation example, the command position increases monotonically from the origin to 100 mm between 10 ms and 250 ms. The maximum acceleration during movement is 10,000 mm / s. 2 ].

[0079] 6b is a diagram showing a disturbance in the first simulation example, in which a disturbance of −10 [N] is applied in a stepwise manner starting from time 50 [ms].

[0080] Other conditions for the first simulation example are as follows: inertial mass J is 10 kg, viscous friction coefficient C is 0 [Ns / m], control period Ts is 0.25 [ms], and number of dead time periods D is 20. It is assumed that no modeling error occurs in this simulation example.

[0081] 7a is a diagram showing the position y1 of the target device 20 controlled by the control device 10 according to this embodiment in the first simulation example. In the figure, the position y1 of the target device 20 controlled by the control device 10 according to this embodiment is shown by a solid line, and the command position r is shown by a dashed line. The position y1 of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without offset after the command position r becomes constant at the target value of 100 [mm].

[0082] FIG. 7b shows the error between the position controlled by the control device 10 according to this embodiment and the command position in the first simulation example. This figure shows the difference between r and y1 shown in FIG. 7a. The error increases to about 4 mm while the command position changes, but rapidly converges to zero after the command position reaches the target value and becomes constant. Thus, this figure also confirms that the position of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without any offset.

[0083] 7c is a diagram showing the thrust controlled by the control device 10 according to this embodiment in the first simulation example. The thrust is a control signal transmitted from the control device 10 to the target device 20. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of 10 [N] is generated after time 50 [ms] to cancel out the step disturbance of -10 [N].

[0084] Fig. 7d is a diagram showing the speed compensation amount calculated by the control device 10 according to this embodiment in the first simulation example. The speed compensation amount changes in the same manner as the thrust shown in Fig. 7c, but converges to zero after the coefficient of the second term of the speed compensation amount, which will be described later, changes from 1 to 0.99.

[0085] Fig. 7e is a diagram showing the position compensation amount calculated by the control device 10 according to this embodiment in the first simulation example. The position compensation amount changes in the same manner as the error shown in Fig. 7b, but converges to zero after the coefficient of the second term of the position compensation amount, which will be described later, changes from 1 to 0.99.

[0086] FIG. 7F shows the coefficient of the second term of the compensation amount used by the control device 10 according to this embodiment in the first simulation example. The coefficient of the second term shown in this figure is used for both the velocity compensation amount and the position compensation amount. The coefficient of the second term of the compensation amount changes from 1 to 0.99 at 250 ms, when the command position reaches the target value of 100 mm and the position compensation amount is greater than or equal to 0.2 mm. After the coefficient of the second term changes to 0.99, the second terms of the velocity compensation amount and the position compensation amount rapidly converge to zero. Furthermore, because the first terms of the velocity compensation amount and the position compensation amount are proportional to the difference between the thrust force in the current cycle and the thrust force before the dead time cycle, they converge to zero after the thrust force becomes constant. In this way, the velocity compensation amount and the position compensation amount become zero after the command position becomes constant.

[0087] FIG. 8a is a diagram showing the position of the target device 20 controlled by the control device according to the first comparative example in the first simulation example. The control device according to the first comparative example is an example in which the position of the target device 20 is controlled using PID control and a conventional Smith compensator. In the figure, the position y1a of the target device 20 controlled by the control device according to the first comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y1a of the target device 20 controlled by the control device according to the first comparative example gradually decreases after 250 [ms] when the command position r becomes constant at the target value of 100 [mm], and does not converge to the same position as the target value.

[0088] 8b is a diagram showing the error between the command position and the position controlled by the control device according to the first comparative example in the first simulation example. The error begins to increase and diverge after 250 ms, when the command position r becomes constant at 100 mm.

[0089] 8c is a diagram showing the thrust controlled by the control device according to Comparative Example 1 in Simulation Example 1. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of 10 N is generated after time 50 ms to cancel out the -10 N step disturbance.

[0090] 9a is a diagram showing the position of the target device controlled by the control device according to the second comparative example in the first simulation example. The control device according to the second comparative example is an example of controlling the position of the target device 20 using the configuration described in Patent Document 2. In the figure, the position y1b of the target device 20 controlled by the control device according to the second comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y1b of the target device 20 controlled by the control device according to the second comparative example vibrates after 250 ms when the command position r becomes constant at the target value of 100 mm, and the amplitude of the vibration gradually increases and does not converge to the target position.

[0091] 9b is a diagram showing the error between the command position and the position controlled by the control device according to the second comparative example in the first simulation example. The error oscillates after the command position r becomes constant at 100 mm, and the amplitude of the oscillation gradually increases and diverges.

[0092] 9c is a diagram showing the thrust force controlled by the control device according to Comparative Example 2 in Simulation Example 1. The thrust force is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, but it oscillates after 250 ms, indicating that the control is not being performed appropriately.

[0093] 9d is a diagram showing the position compensation amount calculated by the control device according to the second comparative example in the first simulation example. The position compensation amount oscillates and gradually converges to zero after 250 ms when the command position r becomes constant at 100 mm.

[0094] FIG. 9e shows the position compensation amount reduction adjustment coefficient used by the control device according to the second comparative example in the first simulation example. The position compensation amount reduction adjustment coefficient changes from 1 to 0 at 250 ms, when the command position r becomes constant at 100 mm. The position compensation amount reduction adjustment coefficient is a coefficient multiplied by the entire position compensation amount. The reduction in the position compensation amount shown in FIG. 9d is achieved as the position compensation amount reduction adjustment coefficient decreases. However, as is clear from FIGS. 9a, 9b, and 9c, when a relatively long dead time exists, appropriate control cannot be achieved even with the use of such a position compensation amount reduction adjustment coefficient. Even if a step disturbance does not exist in the first simulation example, when a relatively long dead time exists, the control device according to the second comparative example will oscillate the position of the target device 20, preventing appropriate control.

[0095] FIG. 10a shows the position of the target device controlled by the control device according to the third comparative example in the first simulation example. The control device according to the third comparative example differs from the control device 10 according to the present embodiment in that the coefficient of the second term of the position compensation amount is changed from 1 to 0.99 while the coefficient of the second term of the velocity compensation amount remains at 1. However, the other configurations are the same as those of the control device 10 according to the present embodiment. In FIG. 10a, the position y1c of the target device 20 controlled by the control device according to the third comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y1c of the target device 20 controlled by the control device according to the third comparative example converges to almost the same position 250 ms after the command position r becomes constant at the target value of 100 mm, but a slight offset remains.

[0096] 10b is a diagram showing the error between the command position and the position controlled by the control device according to the third comparative example in the first simulation example. The error remains constant even after 250 ms when the command position r becomes constant at 100 mm, and does not converge to zero.

[0097] 10c is a diagram showing the thrust controlled by the control device according to the third comparative example in the first simulation example. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of 10 N is generated after time 50 ms to cancel out the -10 N step disturbance.

[0098] 10d is a diagram showing the velocity compensation amount calculated by the control device according to the third comparative example in the first simulation example. The velocity compensation amount changes in the same manner as the thrust shown in FIG. 10c. However, unlike the case of the control device 10 according to the present embodiment shown in FIG. 7d, the coefficient of the second term of the position compensation amount does not converge to zero but remains a constant value even after it changes from 1 to 0.99. This is because, in the control device according to the third comparative example, the coefficient of the second term of the velocity compensation amount remains 1, so the second term of the velocity compensation amount does not become zero but remains.

[0099] Fig. 10e is a diagram showing the position compensation amount calculated by the control device according to the third comparative example in the first simulation example. The position compensation amount changes in the same way as the error shown in Fig. 10b, but unlike the case of the control device 10 according to the present embodiment shown in Fig. 7e, the coefficient of the second term of the position compensation amount does not converge to zero but remains a constant value even after it changes from 1 to 0.99.

[0100] 10f is a diagram showing the coefficient of the second term of the position compensation amount used by the control device of the third comparative example in the first simulation example. The coefficient of the second term shown in this figure is used for the position compensation amount, but not for the speed compensation amount. In this way, if only the coefficient of the second term of the position compensation amount is changed from a predetermined value to a value less than the predetermined value and the coefficient of the second term of the speed compensation amount is maintained at the predetermined value, the effects of disturbances cannot be completely eliminated, and an error will remain even after the command position reaches the target value and becomes constant.

[0101] FIG. 11 is a diagram showing the disturbance in the second simulation example. In this simulation example, the disturbance is applied in a stepwise manner of +10 [N] from time 400 [ms]. The command position in this simulation example is the same as in the first simulation example. That is, in this simulation example, the command position monotonically increases from the origin to 100 [mm] between time 10 [ms] and 250 [ms]. The maximum acceleration during movement is 10,000 [mm / s 2 In this simulation example, the disturbance is added after the command position has stabilized at 100 mm.

[0102] Other conditions for the second simulation example are as follows: inertial mass J is 10 kg, viscous friction coefficient C is 0 [Ns / m], control period Ts is 0.25 [ms], and number of dead time periods D is 20. It is assumed that no modeling error occurs in this simulation example.

[0103] 12a is a diagram showing the position y2 of the target device 20 controlled by the control device 10 according to this embodiment in the second simulation example. In the figure, the position y2 of the target device 20 controlled by the control device 10 according to this embodiment is shown by a solid line, and the command position r is shown by a dashed line. The position y2 of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without any offset after the command position r becomes constant at the target value of 100 [mm].

[0104] FIG. 12b shows the error between the position controlled by the control device 10 according to this embodiment and the command position in the second simulation example. This figure shows the difference between r and y2 shown in FIG. 12a. The error increases to approximately 3.5 mm while the command position changes, but rapidly converges to zero after the command position reaches the target value and becomes constant. Furthermore, a slight error occurs at 400 ms when a step disturbance is applied, but quickly converges to zero. Thus, this figure also confirms that the position of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without any offset.

[0105] 12c is a diagram showing the thrust controlled by the control device 10 according to this embodiment in the second simulation example. The thrust is a control signal transmitted from the control device 10 to the target device 20. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of −10 [N] is generated after time 400 [ms] to cancel out the step disturbance of +10 [N].

[0106] Fig. 12d is a diagram showing the speed compensation amount calculated by the control device 10 according to this embodiment in the second simulation example. The speed compensation amount changes in the same manner as the thrust shown in Fig. 12c, but converges to zero after the coefficient of the second term of the speed compensation amount, which will be described later, changes from 1 to 0.99.

[0107] Fig. 12e is a diagram showing the position compensation amount calculated by the control device 10 according to this embodiment in the second simulation example. The position compensation amount changes in the same manner as the error shown in Fig. 12b, but converges to zero after the coefficient of the second term of the position compensation amount, which will be described later, changes from 1 to 0.99.

[0108] FIG. 12F shows the coefficient of the second term of the compensation amount used by the control device 10 according to this embodiment in the second simulation example. The coefficient of the second term shown in this figure is used for both the speed compensation amount and the position compensation amount. The coefficient of the second term of the compensation amount changes from 1 to 0.99 at approximately 450 ms, when the command position reaches the target value of 100 mm and position compensation is generated due to a step disturbance. After the coefficient of the second term changes to 0.99, the second terms of the speed compensation amount and position compensation amount rapidly converge to zero. Furthermore, because the first terms of the speed compensation amount and position compensation amount are proportional to the difference between the thrust force in the current cycle and the thrust force before the dead time cycle, they converge to zero after the thrust force becomes constant.

[0109] FIG. 13a is a diagram showing the position of the target device 20 controlled by the control device according to the first comparative example in the second simulation example. The control device according to the first comparative example is an example in which the position of the target device 20 is controlled using PID control and a conventional Smith compensator. In the figure, the position y2a of the target device 20 controlled by the control device according to the first comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y2a of the target device 20 controlled by the control device according to the first comparative example gradually increases after 250 [ms] when the command position r becomes constant at the target value of 100 [mm], and does not converge to the same position as the target value.

[0110] 13b is a diagram showing the error between the command position and the position controlled by the control device of Comparative Example 1 in Simulation Example 2. After the command position r becomes constant at 100 [mm], the error turns negative and diverges at 400 [ms] when a step disturbance is applied.

[0111] 13c is a diagram showing the thrust controlled by the control device of Comparative Example 1 in Simulation Example 2. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of −10 N is generated after time 400 ms to cancel out the +10 N step disturbance.

[0112] 14a is a diagram showing the position of the target device 20 controlled by the control device according to the second comparative example in the second simulation example. The control device according to the second comparative example is an example of controlling the position of the target device 20 using the configuration described in Patent Document 2. In the figure, the position y2b of the target device 20 controlled by the control device according to the second comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y2b of the target device 20 controlled by the control device according to the second comparative example has been vibrating since before the step disturbance was applied, after 250 ms when the command position r became constant at the target value of 100 mm, and the amplitude of the vibration gradually increased, so that it did not converge to the target position.

[0113] 14b is a diagram showing the error between the command position and the position controlled by the control device according to the second comparative example in the second simulation example. After the command position r becomes constant at 100 mm, the error oscillates even before the step disturbance is applied, and the amplitude of the oscillation gradually increases and diverges.

[0114] 14c is a diagram showing the thrust force controlled by the control device according to Comparative Example 2 in Simulation Example 2. The thrust force is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, but it oscillates after 250 ms, indicating that the control is not being performed appropriately.

[0115] 14d is a diagram showing the position compensation amount calculated by the control device according to the second comparative example in the second simulation example. The position compensation amount oscillates and gradually converges to zero after 250 [ms] when the command position r becomes constant at 100 [mm].

[0116] FIG. 14e is a diagram showing the position compensation amount reduction adjustment coefficient used by the control device according to the second comparative example in the second simulation example. The position compensation amount reduction adjustment coefficient changes from 1 to 0 at 250 ms, when the command position r becomes constant at 100 mm. The position compensation amount reduction adjustment coefficient is a coefficient by which the entire position compensation amount is multiplied. As the position compensation amount reduction adjustment coefficient decreases, the position compensation amount shown in FIG. 14d decreases. However, as is clear from FIGS. 14a, 14b, and 14c, when a relatively long dead time and disturbances exist, appropriate control cannot be achieved even if such a position compensation amount reduction adjustment coefficient is used.

[0117] FIG. 15a is a diagram showing the position y3 of the target device controlled by the control device 10 according to this embodiment in the third simulation example. In this simulation example, the command position is the same as in the first simulation example, and increases monotonically from the origin to 100 mm between times 10 ms and 250 ms. The maximum acceleration during movement is 10,000 mm / s. 2 ]. No disturbances are added in this simulation example.

[0118] In this simulation example, unlike the first simulation example, the viscous friction coefficient C should be 0 [Ns / m], but the viscous friction coefficient model value Cm is set to 40 [Ns / m]. In other words, this simulation example includes a modeling error for the viscous friction coefficient. Other conditions for this simulation example are as follows: inertia mass J is 10 kg, control period Ts is 0.25 [ms], and dead time period count D is 20.

[0119] 15a, the position y3 of the target device 20 controlled by the control device 10 according to this embodiment is indicated by a solid line, and the command position r is indicated by a dashed line. The position y3 of the target device 20 controlled by the control device 10 according to this embodiment accurately follows the change in the command position r, and after the command position r becomes constant at the target value of 100 [mm], it converges to the target value without any offset.

[0120] FIG. 15b shows the error between the position controlled by the control device 10 according to this embodiment and the command position in the third simulation example. This figure shows the difference between r and y4 shown in FIG. 15a. The error increases to about 3 mm while the command position changes, but rapidly converges to zero after the command position reaches the target value and becomes constant. Thus, this figure also confirms that the position of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without any offset.

[0121] 15c is a diagram showing the thrust controlled by the control device 10 according to this embodiment in the third simulation example. The thrust is a control signal transmitted from the control device 10 to the target device 20. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs.

[0122] Fig. 15d is a diagram showing the speed compensation amount calculated by the control device 10 according to this embodiment in the third simulation example. The speed compensation amount changes in the same manner as the thrust shown in Fig. 15c, but converges to zero after the coefficient of the second term of the speed compensation amount, which will be described later, changes from 1 to 0.99.

[0123] Fig. 15e is a diagram showing the position compensation amount calculated by the control device 10 according to this embodiment in the third simulation example. The position compensation amount changes in the same manner as the error shown in Fig. 15b, but converges to zero after the coefficient of the second term of the position compensation amount, which will be described later, changes from 1 to 0.99.

[0124] FIG. 15F shows the coefficient of the second term of the compensation amount used by the control device 10 according to this embodiment in the third simulation example. The coefficient of the second term shown in this figure is used for both the velocity compensation amount and the position compensation amount. The coefficient of the second term of the compensation amount changes from 1 to 0.99 at 250 ms, when the command position reaches the target value of 100 mm and the absolute value of the position compensation amount is greater than or equal to 0.2 mm. After the coefficient of the second term changes to 0.99, the second terms of the velocity compensation amount and the position compensation amount rapidly converge to zero. Furthermore, because the first terms of the velocity compensation amount and the position compensation amount are proportional to the difference between the thrust force in the current cycle and the thrust force before the dead time cycle, they converge to zero after the thrust force becomes constant. In this way, the velocity compensation amount and the position compensation amount become zero after the command position becomes constant.

[0125] FIG. 16a is a diagram showing the position of the target device 20 controlled by the control device according to the first comparative example in the third simulation example. The control device according to the first comparative example controls the position of the target device 20 using PID control and a conventional Smith compensator. In the figure, the position y3a of the target device 20 controlled by the control device according to the first comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y3a of the target device 20 controlled by the control device according to the first comparative example converges to the same position 250 ms after the command position r becomes constant at the target value of 100 mm, but the time to converge is longer than that of the control device 10 according to this embodiment.

[0126] 16b is a diagram showing the error between the position controlled by the control device according to Comparative Example 1 and the command position in Simulation Example 3. The error slowly approaches zero after 250 ms when the command position r becomes constant at 100 mm, but the convergence is slower than in the case of the control device 10 according to this embodiment.

[0127] 16c is a diagram showing the thrust force controlled by the control device according to Comparative Example 1 in Simulation Example 3. The thrust force is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs.

[0128] In this way, when the control device according to the first comparative example is used, the convergence to the target position is slow due to the influence of the modeling error. In contrast, the control device 10 according to the present embodiment achieves relatively fast convergence to the target position even when the control device includes the modeling error.

[0129] FIG. 17 is a diagram showing the disturbance in the fourth simulation example. In this simulation example, the disturbance is applied in a pulse of +50 [N] at time 100 [ms]. The command position in this simulation example is the same as in the first simulation example. That is, in this simulation example, the command position monotonically increases from the origin to 100 [mm] between time 10 [ms] and 250 [ms]. The maximum acceleration during movement is 10,000 [mm / s 2 ].

[0130] Other conditions for the fourth simulation example are as follows: inertial mass J is 10 kg, viscous friction coefficient C is 0 [Ns / m], control period Ts is 0.25 [ms], and number of dead time periods D is 20. It is assumed that no modeling error occurs in this simulation example.

[0131] 18a is a diagram showing the position y4 of the target device 20 controlled by the control device 10 according to this embodiment in the fourth simulation example. In the figure, the position y4 of the target device 20 controlled by the control device 10 according to this embodiment is shown by a solid line, and the command position r is shown by a dashed line. The position y4 of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without any offset after the command position r becomes constant at the target value of 100 [mm].

[0132] FIG. 18b is a diagram showing the error between the position controlled by the control device 10 according to this embodiment and the command position in the fourth simulation example. This diagram shows the difference between r and y4 shown in FIG. 18a. Due to the influence of pulse disturbance, an error of approximately -1.3 mm occurs when the command value reaches the target value, but then converges to zero. Thus, this diagram also confirms that the position of the target device 20 controlled by the control device 10 according to this embodiment converges to the target value without any offset.

[0133] 18c is a diagram showing thrust forces controlled by the control device 10 according to this embodiment in the fourth simulation example. The thrust forces are control signals transmitted from the control device 10 to the target device 20. The thrust forces are generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of −50 [N] is generated at time 100 [ms] to cancel out the pulse disturbance of +50 [N].

[0134] Fig. 18d is a diagram showing the speed compensation amount calculated by the control device 10 according to this embodiment in the fourth simulation example. The speed compensation amount changes in the same manner as the thrust shown in Fig. 18c, but converges to zero after the coefficient of the second term of the speed compensation amount, which will be described later, changes from 1 to 0.99.

[0135] Fig. 18e is a diagram showing the position compensation amount calculated by the control device 10 according to this embodiment in the fourth simulation example. The position compensation amount changes in the same manner as the error shown in Fig. 18b, but converges to zero after the coefficient of the second term of the position compensation amount, which will be described later, changes from 1 to 0.99.

[0136] FIG. 18f shows the coefficient of the second term of the compensation amount used by the control device 10 according to this embodiment in the fourth simulation example. The coefficient of the second term shown in this figure is used for both the velocity compensation amount and the position compensation amount. The coefficient of the second term of the compensation amount changes from 1 to 0.99 at 250 ms, when the command position reaches the target value of 100 mm and the absolute value of the position compensation amount is approximately 0.2 mm or greater. After the coefficient of the second term changes to 0.99, the second terms of the velocity compensation amount and the position compensation amount rapidly converge to zero. Furthermore, because the first terms of the velocity compensation amount and the position compensation amount are proportional to the difference between the thrust force in the current cycle and the thrust force before the dead time cycle, they converge to zero after the thrust force becomes constant. In this way, the velocity compensation amount and the position compensation amount become zero after the command position becomes constant.

[0137] FIG. 19a is a diagram showing the position of the target device 20 controlled by the control device according to the first comparative example in the fourth simulation example. The control device according to the first comparative example is an example in which the position of the target device 20 is controlled using PID control and a conventional Smith compensator. In the figure, the position y4a of the target device 20 controlled by the control device according to the first comparative example is shown by a solid line, and the command position r is shown by a dashed line. The position y4a of the target device 20 controlled by the control device according to the first comparative example still has an error even after 250 ms, at which the command position r becomes constant at the target value of 100 mm, and does not converge to the same position as the target value.

[0138] 19b is a diagram showing the error between the position controlled by the control device according to the first comparative example and the command position in the fourth simulation example. The error does not become zero even 250 [ms] after the command position r becomes constant at 100 [mm], and remains constant.

[0139] 19c is a diagram showing the thrust controlled by the control device according to Comparative Example 1 in Simulation Example 4. The thrust is generated with opposite signs during periods when positive acceleration occurs and periods when negative acceleration occurs, and a thrust of −50 N is generated at time 100 ms to cancel out the +50 N pulse disturbance.

[0140] 20 is a flowchart of a control process executed by the control device 10 according to this embodiment. First, the control device 10 sets initial values ​​(S10). The setting of the initial values ​​may include, for example, setting a model value of the target device 20, initializing the thrust force, which is the control signal, to zero, setting the coefficient of the second term to 1, setting the changed value of the coefficient of the second term to 0.99, and setting the first reference value AdjChg to 0.2.

[0141] Thereafter, the control device 10 starts a control loop process. The control loop is repeatedly executed at a predetermined control period. Here, the control period may be set to, for example, 0.25 [ms].

[0142] In the control loop, the control device 10 performs a compensation amount calculation (S11). The compensation amount calculation may include determining whether the command value reaches the target value and the absolute value of the compensation amount is equal to or greater than a first reference value. If the command value does not reach the target value or the absolute value of the compensation amount is not equal to or greater than the first reference value, the control device 10 calculates the speed compensation amount and the position compensation amount while leaving the coefficient of the second term at its initial value (1). The method of calculating the speed compensation amount and the position compensation amount is as described above. On the other hand, if the command value reaches the target value and the absolute value of the compensation amount is equal to or greater than the first reference value, the control device 10 changes the coefficient of the second term to a value less than the initial value (for example, to 0.99) and calculates the speed compensation amount and the position compensation amount.

[0143] When the coefficient of the second term is changed to be less than the initial value, the control device 10 maintains the coefficient of the second term less than the initial value as long as the command value reaches the target value. However, if the command value starts to move again and deviates from the target value, the control device 10 may return the coefficient of the second term to the initial value.

[0144] Thereafter, the control device 10 performs a PID control calculation based on the command position, the position of the target device 20 measured by the sensor 30, and the calculated velocity compensation amount and position compensation amount (S12). A thrust force, which is a control signal, is calculated by the PID control calculation. The control device 10 controls the target device 20 based on the calculated thrust force.

[0145] The control device 10 determines whether to end the control loop process and terminate the control (S13). If the control is to be continued (S13: NO), the compensation amount calculation (S11) and the PID control calculation (S12) are executed again. If the control is to be terminated (S13: YES), the control loop is exited and the process is terminated.

[0146] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those illustrated and can be modified as appropriate. Furthermore, configurations shown in different embodiments can be partially substituted or combined with each other.

[0147] [Appendix 1] a target device (20) to be controlled based on the control signal; a sensor (30) for measuring a physical quantity of the target device (20); a control device (10) that sends the control signal to the target device (20) based on the command value and the physical quantity and performs feedback control; The control device (10) a calculation unit (14) that calculates a compensation amount for the control signal based on a set value of a dead time and a model of the target device (20); the calculation unit (14) calculates the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; A control system (100).

[0148] [Appendix 2] A control device (10) that performs feedback control by sending a control signal to a target device (20) based on a physical quantity of the target device (20) measured by a sensor (30) and a command value, a calculation unit (14) that calculates a compensation amount for the control signal based on a set value of a dead time and a model of the target device (20); the calculation unit (14) calculates the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; Control device (10).

[0149] [Appendix 3] A control method for performing feedback control by sending a control signal to a target device (20) based on a physical quantity of the target device (20) measured by a sensor (30) and a command value, comprising: calculating a compensation amount for the control signal based on a set value of a dead time and a model of the target device (20), the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; A control method comprising:

[0150] [Appendix 4] a control device (10) that performs feedback control by sending a control signal to a target device (20) based on a physical quantity of the target device (20) measured by a sensor (30) and a command value; calculating a compensation amount for the control signal based on a set value of a dead time and a model of the target device (20), the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; A control program that executes the above. [Explanation of symbols]

[0151] 10...control device, 10a...CPU, 10b...RAM, 10c...ROM, 10d...communication unit, 10e...input unit, 10f...display unit, 11...command value generation unit, 12...control signal generation unit, 13...acquisition unit, 14...calculation unit, 20...target device, 30...sensor, 100...control system

Claims

1. a target device to be controlled based on the control signal; a sensor for measuring a physical quantity of the target device; a control device that performs feedback control by sending the control signal to the target device based on the command value and the physical quantity, The control device a calculation unit that calculates a compensation amount for the control signal based on a set value of a dead time and a model of the target device; the calculation unit calculates the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; Control system.

2. the calculation unit changes the coefficient of the second term from the predetermined value to a value less than the predetermined value when the command value reaches a target value. The control system of claim 1 .

3. the calculation unit changes the coefficient of the second term from the predetermined value to a value less than the predetermined value when the command value reaches a target value and the absolute value of the compensation amount is equal to or greater than a first reference value. The control system of claim 1 .

4. the calculation unit changes the coefficient of the second term from less than the predetermined value to the predetermined value when the target value is updated after changing the coefficient of the second term from the predetermined value to less than the predetermined value; The control system of claim 1 .

5. the calculation unit changes the coefficient of the second term from the predetermined value to less than the predetermined value when an absolute value of the difference between the command value and the target value becomes equal to or less than a second reference value; The control system of claim 1 .

6. the calculation unit changes the coefficient of the second term from the predetermined value to less than the predetermined value when the elapsed time from the start of the control becomes equal to or greater than a third reference value. The control system of claim 1 .

7. the calculation unit changes the coefficient of the second term from the predetermined value to a value less than the predetermined value when a disturbance is applied; The control system of claim 1 .

8. The control device controls the position of the target device; the calculation unit calculates the compensation amount for each of the position and the velocity; changing the coefficients of the second terms relating to the position and the velocity from predetermined values ​​to values ​​less than the predetermined values ​​when the predetermined condition is satisfied; A control system according to any one of claims 1 to 7.

9. A control device that performs feedback control by sending a control signal to a target device based on a physical quantity of the target device measured by a sensor and a command value, a calculation unit that calculates a compensation amount for the control signal based on a set value of a dead time and a model of the target device; the calculation unit calculates the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; Control device.

10. A control method for performing feedback control by sending a control signal to a target device based on a physical quantity of the target device measured by a sensor and a command value, comprising: calculating a compensation amount for the control signal based on a set value of a dead time and a model of the target device, the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; A control method comprising:

11. a control device that performs feedback control by sending a control signal to the target device based on a physical quantity and a command value of the target device measured by a sensor; calculating a compensation amount for the control signal based on a set value of a dead time and a model of the target device, the compensation amount including a first term based on the control signal and a second term based on the compensation amount calculated in the past; changing the coefficient of the second term from a predetermined value to less than the predetermined value when a predetermined condition is satisfied; A control program that executes the above.

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