Control system, control method, and program

Abstract

This control system is provided with a speed control unit, a disturbance compensation unit, an adjustment unit, and a drive control unit. The speed control unit controls the speed of a motor. The disturbance compensation unit outputs a compensation signal for compensating for a disturbance relating to the motor side. The adjustment unit is connected in series to the disturbance compensation unit, and performs adjustment relating to the disturbance compensation unit. The drive control unit receives input of a command signal based on a result of the adjustment by the adjustment unit, and performs drive control of the motor on the basis of the command signal. The adjustment unit performs a first adjustment for adjusting the output of the compensation signal so as to approach zero or a second adjustment for blocking the output of the compensation signal in response to stopping of the operation of an object under control including the motor.

Description

Control system, control method, and program

[0001] The present disclosure generally relates to a control system, a control method, and a program, and more particularly to a control system, a control method, and a program having a disturbance compensation function.

[0002] Patent Document 1 discloses a motor control device. The motor control device includes a position controller, a speed controller, a servo amplifier, and a friction compensator. According to Patent Document 1, when the motion direction of the table reverses, i.e., when the rotation direction of the ball screw reverses, the friction force in the table drive mechanism changes suddenly, and the control system cannot respond to this change, resulting in the occurrence of a quadrant projection. The friction compensator corrects the effect of the friction force when the motion direction of the table reverses. The friction compensator generates a friction compensation signal that compensates for the friction force. The friction compensation signal is added to a torque command signal from the speed controller. As a result, a friction-compensated torque command signal is applied to the servo amplifier.

[0003] Japanese Patent Application Laid-Open No. 2008-210273

[0004] Depending on the compensation model used, a compensator (disturbance compensation unit) that compensates for disturbances such as friction may continue to output a compensation command even when the operation of a controlled object, including a motor, is stopped. As a result, a situation may arise that is not intended by the user, in which unnecessary energy is consumed even when the motor is stopped (for example, a drive current may continue to flow to the motor), which is undesirable from the viewpoint of energy conservation.

[0005] A control system according to one aspect of the present disclosure includes a speed control unit, a disturbance compensation unit, an adjustment unit, and a drive control unit. The speed control unit controls the speed of a motor. The disturbance compensation unit outputs a compensation signal that compensates for disturbances related to the motor. The adjustment unit is connected in series to the disturbance compensation unit and performs adjustments related to the disturbance compensation unit. The drive control unit receives a command signal based on the adjustment result by the adjustment unit and controls the drive of the motor based on the command signal. The adjustment unit performs a first adjustment to adjust the output of the compensation signal so that it approaches zero, or a second adjustment to cut off the output of the compensation signal, in response to a stop of operation of a controlled object including the motor.

[0006] A control method according to one aspect of the present disclosure includes a speed control step, a disturbance compensation step, an adjustment step, and a drive control step. In the speed control step, the speed of a motor is controlled. In the disturbance compensation step, a disturbance compensation unit outputs a compensation signal that compensates for disturbances related to the motor. In the adjustment step, an adjustment unit connected in series to the disturbance compensation unit performs adjustments related to the disturbance compensation step. In the drive control step, a command signal based on the adjustment result in the adjustment step is input, and drive control of the motor is performed based on the command signal. In the adjustment step, in response to a stop of operation of a controlled object including the motor, a first adjustment is performed to adjust the output of the compensation signal so that it approaches zero, or a second adjustment is performed to cut off the output of the compensation signal.

[0007] A program according to one aspect of the present disclosure is a program for causing one or more processors to execute the above-described control method.

[0008] The present disclosure has the advantage of being able to conserve energy in motor control.

[0009] FIG. 1 is a block diagram of an overall system including a control system according to one embodiment. FIG. 2 is a block diagram of the control system. FIG. 3 is a block diagram of a friction compensation unit and an adjustment unit (high-pass filter) in the control system. FIG. 4A is a comparative waveform diagram relating to friction torque and compensation torque. FIG. 4B is a waveform diagram relating to friction torque and compensation torque in the control system. FIG. 5 is a flowchart for explaining the operation of the control system. FIG. 6 is a block diagram of an overall system including a control system according to Modification 1. FIG. 7 is a block diagram of a main part of a control system according to Modification 2. FIG. 8 is a block diagram of an overall system including a control system according to Modification 3. FIG. 9 is a block diagram of an overall system including a control system according to Modification 4. FIG. 10 is a block diagram of an overall system including a control system according to Modification 5. FIG. 11 is a block diagram of an overall system including a control system according to Modification 6. FIG. 12 is a block diagram of a main part of a control system according to Modification 7.

[0010] (Summary) Below, a control system, a control method, and a program according to embodiments and modifications will be described with reference to the drawings. Note that the following embodiment and modifications are merely one of various embodiments of the present disclosure. Furthermore, the following embodiment and modifications can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, the configuration of each of the modifications can be appropriately combined with the following embodiment or other modifications.

[0011] A control system 1 according to one embodiment (see FIGS. 1 and 2 ) provides a control input to a plant 2, which is a control target. The control system 1 outputs an output signal including a manipulated variable to the plant 2. In particular, the control system 1 is a system having a function related to disturbance compensation for the plant 2 including a motor M1.

[0012] The type of plant 2 (controlled object) referred to here is not particularly limited. For example, the plant 2 may include a load device (load L1), a servo motor (motor M1) that drives the load L1, and a detector (encoder, current detector, etc.) that detects the position, speed, (drive) current, etc. of the motor M1 and the load L1. The plant 2 may be, for example, a machining machine. The load L1 may include, for example, a ball screw and a stage (table) that operate using the motor M1 as a drive source.

[0013] The manipulated variable for the plant 2 is defined as a control value for the motor M1. Here, the manipulated variable for the plant 2 is the drive current of the motor M1. The plant 2 outputs a controlled variable signal including a controlled variable according to the manipulated variable. The controlled variable is a quantity indicating the state of the plant 2, and may include the position, speed, etc. of the motor M1 and the load L1 detected by a detection unit. The control system 1 performs feedback control using the controlled variable (position, speed, etc.) detected by the detection unit.

[0014] As shown in FIGS. 1 and 2, the control system 1 includes a speed control unit 11, an external disturbance compensation unit 7, an adjustment unit 13, and a drive control unit 10 (see FIG. 2).

[0015] The speed control unit 11 controls the speed of the motor M1. The disturbance compensation unit 7 outputs a compensation signal that compensates for disturbances related to the motor M1. The adjustment unit 13 is connected in series to the disturbance compensation unit 7 and performs adjustments related to the disturbance compensation unit 7. The drive control unit 10 receives a command signal based on the adjustment result by the adjustment unit 13 and performs drive control of the motor M1 based on the command signal. The adjustment unit 13 performs a first adjustment to adjust the output of the compensation signal so that it approaches zero, or a second adjustment to cut off the output of the compensation signal, in response to a stop of operation of the controlled object (plant 2) including the motor M1. As an example, the drive control unit 10 includes a current control unit 15 (see FIG. 1) that controls the drive current of the motor M1 based on the command signal.

[0016] According to the above-described configuration of the control system 1, the adjustment unit 13 connected in series to the disturbance compensation unit 7 performs the first adjustment or the second adjustment in response to the stoppage of the operation of the controlled object (the plant 2) including the motor M1. This reduces the possibility of unnecessary energy consumption (for example, the possibility that the drive current continues to flow to the motor M1) due to the compensation signal that compensates for the disturbance even when the motor M1 is stopped. As a result, there is an advantage in that energy savings in motor control can be achieved.

[0017] In the following description, it is assumed, as an example, that the disturbance is friction occurring on the motor M1 side, and that the disturbance compensation unit 7 is the friction compensation unit 12.

[0018] A control method according to one aspect includes a speed control step, a disturbance compensation step, an adjustment step, and a drive control step. In the speed control step, the speed of the motor M1 is controlled. In the disturbance compensation step, a compensation signal that compensates for disturbances related to the motor M1 is output by the disturbance compensation unit. In the adjustment step, an adjustment unit 13 connected in series to the disturbance compensation unit 7 performs adjustments related to the disturbance compensation step. In the drive control step, a command signal based on the adjustment result in the adjustment step is input, and drive control of the motor M1 is performed based on the command signal. In the adjustment step, a first adjustment is performed to adjust the output of the compensation signal so that it approaches zero, or a second adjustment is performed to cut off the output of the compensation signal, in response to a stop of operation of the controlled object (plant 2) including the motor M1. The above control method has the advantage of being able to achieve energy savings in motor control.

[0019] This control method is used on a computer system (control system 1). That is, this control method can also be embodied as a computer program. A program according to one aspect is a program for causing one or more processors to execute the above control method. The program may be recorded on a computer-readable non-transitory recording medium.

[0020] (Details) (1) Overall Configuration Hereinafter, the overall system including the control system 1 according to this embodiment and its peripheral configuration will be described in detail with reference to FIG.

[0021] Note that "zero" referred to in the description of the speed command, the output of the compensation signal, the detected speed (angular velocity), etc. in this disclosure does not necessarily mean that the signal output level is strictly zero. For example, due to the influence of bias, noise, etc., the signal output level may not be instantaneously zero. If the average value of the signal output level over a predetermined period of time is approximately zero, it may be considered "zero" in this disclosure.

[0022] The control system 1 is electrically connected to a plant 2, which is the object of control, and is configured to output an output signal (electrical signal) including a manipulated variable (control input) to the plant 2. The manipulated variable may be a manipulated variable related to a drive current for driving and controlling a motor M1. As shown in FIG. 1 , a disturbance may be added to the output signal from the control system 1. As described above, the disturbance is assumed to be friction generated on the motor M1 side. In addition to friction generated on the motor M1, the disturbance may also include friction generated on the load L1 side, such as a stage. The disturbance friction can be canceled out by a compensation signal, which will be described later.

[0023] In the following, as an example, it is assumed that the object of friction compensation (i.e., friction occurring on the motor M1 side) includes both friction in the motor M1 and friction in the load L1. However, if the load L1 is negligible in the system, the object of friction compensation (friction occurring on the motor M1 side) may be friction in the motor M1 only.

[0024] As described above, the plant 2 (control target) may include the load L1, the motor M1 that drives the load L1, and a detector (encoder, current detector, etc.) that detects the position, speed, (drive) current, etc. of the motor M1 and the load L1. The load L1 may include, for example, a ball screw and a stage (table) that operate using the motor M1 as a drive source.

[0025] The motor M1 is, for example, a servo motor. The motor M1 is, for example, a rotary motor, but may also be a linear motor. The motor M1 includes, for example, a stator around which three-phase (U-phase, V-phase, and W-phase) windings are wound. The control system 1 is configured to drive and control the operation (rotational operation) of the motor M1.

[0026] The plant 2 outputs a control amount signal including a control amount (plant output) according to the input operation amount. The control amount (plant output) is a quantity that indicates the state of the plant 2. Specifically, in the plant 2, the motor M1 is driven according to the operation amount, and the detection unit outputs a control amount signal including control amounts such as the speed, position, and drive current of the motor M1 to the outside (control system 1). In FIG. 1, a "position" (for example, the coordinate position of the stage) is illustrated as the output of the load L1.

[0027] Dynamic friction models for motor friction compensation include the LuGre model and the GMS model. These models are speed-input / friction-output friction models that, when a motor speed command is input, return a function that represents the friction of the motor or load (e.g., a value converted into friction torque). However, even when the input speed is zero, such functions return a constant amount of friction torque equivalent to the static friction of the motor or load. Therefore, even when the operation of a controlled object, including the motor, is stopped, a compensation command may continue to be output to compensate for static friction. As a result, an unintended situation may occur in which a drive current continues to flow through the motor (although not large enough to start the motor) even when the motor is stopped. This situation is undesirable from the perspective of energy conservation. Therefore, the control system 1 of this embodiment has functions related to friction compensation (disturbance compensation) as well as the function of an adjustment unit 13 that adjusts the friction compensation (disturbance compensation).

[0028] The control system 1 includes a computer system having one or more processors and a memory. At least some of the functions of the control system 1 are realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in the memory, or may be provided via a telecommunications line such as the Internet, or may be provided by being recorded on a non-transitory recording medium such as a memory card.

[0029] 1, the control system 1 includes a speed control unit 11, a friction compensation unit 12 (disturbance compensation unit 7), an adjustment unit 13, and a drive control unit 10 (see FIG. 2). In other words, the control system 1 has the functions of the speed control unit 11, the friction compensation unit 12, the adjustment unit 13, and the drive control unit 10.

[0030] As shown in FIG. 1 , the control system 1 further includes a differentiator 5, a velocity feedforward (hereinafter sometimes abbreviated as “FF”) unit 4, a position control unit 3 (position control system), an adder 6, and a calculation unit 14.

[0031] These multiple functions of the control system 1 may be housed in a single housing or may be housed separately in multiple housings. As an example, all of these multiple functions of the control system 1 may be implemented in a servo amplifier. However, at least some of these multiple functions of the control system 1 may be implemented outside the servo amplifier, for example, in a host controller.

[0032] As shown in FIG. 1, the control system 1 acquires (receives) a position command (represented as a "command" in FIG. 1) for the motor M1 from the outside. The "external" here may be, for example, a host controller. The host controller is configured, for example, by a programmable logic controller, and is communicatively connected to the control system 1. The position command from the outside is input to each of the position control unit 3, the speed FF unit 4, and the differentiator 5.

[0033] The position control unit 3 (position control system) controls the position of the motor M1 based on a position command for the motor M1 (e.g., the angle of the motor M1) and the position (e.g., the angle of the motor M1) that is the control result of the motor M1. That is, as shown in FIG. 1 , the position control unit 3 receives an external position command and the control result (position) of the motor M1. The control result (position) of the motor M1 is, for example, a control amount related to the position of the motor M1 detected by a detection unit of the plant 2. Note that the external position command may be a position command related to a load L1 such as a stage, and in that case, the control system 1 can convert the position command related to the load L1 into a position command related to the motor M1.

[0034] The position control unit 3 performs position feedback (hereinafter, sometimes abbreviated as "FB") control. The position control unit 3 determines a speed command (e.g., angular velocity of the motor M1) and outputs a signal including the speed command so that an external position command (angle of the motor M1) matches the control result of the motor M1 (angle of the motor M1). The position control unit 3 may include a differentiator that time-differentiates the position (angle) of the motor M1 detected by a detection unit of the plant 2.

[0035] The speed FF unit 4 determines a speed feedforward command for the speed (angular velocity) of the motor M1 based on an external position command (angle of the motor M1) and outputs a signal including the speed feedforward command. The speed feedforward control of the speed FF unit 4 improves the responsiveness of the motor M1. The speed FF unit 4 may include a differentiator that time-differentiates the external position command.

[0036] The differentiator 5 time-differentiates the external position command (angle) and outputs the time-differentiated result (angular velocity) to the friction compensation unit 12 .

[0037] The speed command from the position control unit 3 and the speed feedforward command from the speed FF unit 4 are input to the adder 6 and summed up by the adder 6. The summation result by the adder 6 is then input to the speed control unit 11.

[0038] The speed control unit 11 controls the speed of the motor M1. In other words, the speed control step of the control method according to this embodiment controls the speed of the motor M1. A signal based on the output result from the position control system (position control unit 3) is input to the speed control unit 11. The speed control unit 11 controls the speed of the motor M1 based on the output result from the position control system (position control unit 3). However, in this embodiment, as an example, the output result from the position control unit 3 is input to the speed control unit 11 via the adder 6.

[0039] The speed control unit 11 performs feedback control of the speed. Specifically, the speed control unit 11 controls the speed of the motor M1 based on the summation result from the adder 6 and the speed (e.g., angular velocity) that is the control result of the motor M1. That is, as shown in FIG. 1 , the speed control unit 11 receives the summation result from the adder 6 and the control result (angular velocity) of the motor M1. The control result (angular velocity) of the motor M1 is a control amount related to the speed (angular velocity) of the motor M1 detected, for example, by a detection unit of the plant 2.

[0040] The speed control unit 11 determines the torque command for the motor M1 so that the summation result from the adder 6 matches the speed (angular velocity) that is the control result of the motor M1, and outputs a torque command signal that includes the torque command.

[0041] The friction compensation unit 12 (disturbance compensation unit 7) calculates a compensation amount for friction (disturbance) occurring on the motor M1 side. Here, as an example, it is assumed that the "friction occurring on the motor M1 side" is the friction torque of the motor M1 and the friction in the load L1 (e.g., rolling friction of a ball screw), as described above. In other words, the friction compensation unit 12 calculates a compensation amount for friction of the entire plant 2, including the friction torque of the motor M1 and the friction of the load L1.

[0042] However, if the load L1 is negligible in the system, the "friction occurring on the motor M1 side" may be the friction torque of the motor M1 alone.

[0043] The friction torque of the motor M1 and the friction generated by the load L1 (e.g., rolling friction of a ball screw) can become significant, for example, when the rotation direction of the motor M1 is reversed. In this embodiment, as shown in Fig. 1, the friction compensation unit 12 calculates a compensation amount for the friction of the plant 2, including the friction torque of the motor M1, based on the time differentiation result (e.g., angular velocity) from the differentiator 5.

[0044] The friction compensation unit 12 has a friction model that uses, for example, a speed-dependent function. Typical examples of friction models include the LuGre model and the GMS model. The friction model is a speed input / friction output friction model, and is a function that returns the friction of the entire plant 2 when a speed command (angular speed of the motor M1) is input. Note that in a system where the load L1 can be ignored, the friction model may also be a function that returns the friction torque of the motor M1 when a speed command is input.

[0045] The friction compensation unit 12 calculates a friction compensation amount for the friction of the plant 2 output from the friction model, and outputs a compensation signal (i.e., a torque compensation command) including the friction compensation amount. In other words, in the disturbance compensation step of the control method according to this embodiment, a compensation signal that compensates for disturbance (friction) related to the motor M1 is output. The friction of the plant 2 can be canceled out by the friction compensation amount of the compensation signal output from the friction compensation unit 12.

[0046] In this way, the velocity (angular velocity) input to the friction compensation unit 12 is the result of time differentiation of the position command, and the friction compensation unit 12 calculates the friction compensation amount using a friction model, thereby performing friction compensation by FF control. In other words, the friction compensation unit 12 is a feedforward type that receives as input a velocity-dimensional command (velocity command) obtained by time differentiation of the position command.

[0047] Here, the friction model of the friction compensation unit 12 is a function that returns a constant amount of friction torque as static friction of the controlled object (plant 2) even when the input speed command is zero. Therefore, even when the speed command is zero, the friction compensation unit 12 calculates a friction compensation amount for the constant amount of friction torque and outputs a compensation signal. In other words, due to the characteristics of the friction model, the friction compensation unit 12 may operate to compensate for static friction of the plant 2. In other words, the friction compensation unit 12 receives a speed-dimension command as input and outputs a compensation signal including a friction compensation amount for friction generated on the motor M1 side. However, even when a zero command is input as the speed-dimension command, it outputs a compensation signal including a non-zero friction compensation amount. The zero command corresponds to a command to stop the operation of the controlled object (plant 2).

[0048] The adjustment unit 13 is connected in series to the friction compensation unit 12 (disturbance compensation unit 7) (see FIG. 1 ) and performs adjustments related to the friction compensation unit 12 (disturbance compensation unit 7). In other words, in the adjustment step of the control method according to this embodiment, adjustments related to the disturbance compensation step are performed by the adjustment unit 13 connected in series to the disturbance compensation unit 7.

[0049] Specifically, the adjustment unit 13 performs a first adjustment to adjust the output (signal level) of the compensation signal from the friction compensation unit 12 so that it approaches zero, or a second adjustment to cut off the output of the compensation signal, in response to the stop of operation of the controlled object (plant 2). As long as the adjustment unit 13 can perform the first adjustment or the second adjustment, it may be connected in series before the friction compensation unit 12, or may be connected in series after the friction compensation unit 12. In response to the stop of operation of the plant 2, the adjustment unit 13 performs the first adjustment or the second adjustment so that the drive current of the motor M1 is reduced. In other words, in the adjustment step of the control method according to this embodiment, the first adjustment or the second adjustment is performed in response to the stop of operation of the plant 2.

[0050] In the present embodiment, as an example, the adjustment unit 13 is connected in series to the friction compensation unit 12 at a stage subsequent to the friction compensation unit 12 (see FIG. 1 ). The adjustment unit 13 performs the first adjustment or the second adjustment at a stage subsequent to the friction compensation unit 12 in response to the stop of the operation of the plant 2.

[0051] In particular, in this embodiment, as an example, the adjustment unit 13 includes a high-pass filter 130 (abbreviated as "HPF" in FIG. 3) connected in series to the disturbance compensation unit 7 (friction compensation unit 12) at a stage subsequent to the disturbance compensation unit 7 (here, friction compensation unit 12), as shown in FIG. 3. The adjustment unit 13 performs a first adjustment through the high-pass filter 130 in response to a stop of operation of the plant 2. Note that FIG. 3 is a block configuration diagram of main parts showing only the friction compensation unit 12 and the adjustment unit 13 in the control system 1.

[0052] Specifically, even in response to a zero command input, the friction compensation unit 12 outputs a compensation signal containing a non-zero friction compensation amount for a certain amount of friction torque. However, this compensation signal is a signal that indicates a substantially constant output value (signal level) and is a relatively low-frequency signal. Therefore, the output value of this compensation signal is attenuated by the high-pass filter 130 and can become substantially zero after a predetermined time has elapsed. In other words, the "stop of operation of the controlled object (plant 2)" can be automatically detected by the high-pass filter 130 when a low-frequency compensation signal is input to the adjustment unit 13.

[0053] The shorter the time constant of the high-pass filter 130, for example, 100 ms, the more quickly the output value of the compensation signal can become zero when a zero command is input. However, according to the results of a simulation conducted by the present inventors, it was found that a short time constant makes it more likely that a gap will form between the friction compensation amount and the actual amount of friction during operation of the motor M1. Therefore, from the viewpoint of suppressing a decrease in the accuracy of the friction compensation amount, it is preferable to set the time constant of the high-pass filter 130 long, for example, within the range of 1 second to 10 seconds.

[0054] The calculation unit 14 calculates a command for driving the motor M1 based on the output results of the speed control unit 11 and the friction compensation unit 12 (via the adjustment unit 13). That is, the calculation unit 14 receives the compensation signal (torque compensation command) from the friction compensation unit 12 and the torque command signal (torque command) from the speed control unit 11.

[0055] In this embodiment, as an example, the calculation unit 14 converts the output results of the speed control unit 11 and the friction compensation unit 12 into signals corresponding to current commands, adds them up, and outputs an electrical signal based on the summation result.

[0056] Specifically, the calculation unit 14 has a function of converting the torque command signal from the speed control unit 11 into a signal corresponding to, for example, a current command for the motor M1. This conversion function may be provided in the speed control unit 11. The calculation unit 14 also has a function of converting the compensation signal (torque compensation command) from the friction compensation unit 12 into a signal corresponding to, for example, a current command for the motor M1. This conversion function may be provided in the friction compensation unit 12.

[0057] In this way, the two torque commands are converted into a current command by the calculation unit 14 and added together by the adder 141. The result of the addition by the adder 141 is then input to the current control unit 15 of the drive control unit 10. Note that the calculation unit 14 may add together the compensation signal (torque compensation command) and the torque command signal (torque command) directly in the adder 141 without converting them, and the result of the addition may be input to the current control unit 15. The current control unit 15 may then convert the result of the addition into a signal corresponding to the current command.

[0058] The drive control unit 10 (see FIG. 2) controls the drive of the motor M1 based on commands from the calculation unit 14. The drive control unit 10 includes a current control unit 15 (see FIG. 1) and an inverter circuit. The current control unit 15 controls the drive current of the motor M1 based on commands from the calculation unit 14. Specifically, the current control unit 15 receives an addition result (current command) from the adder 141 of the calculation unit 14. The current control unit 15 also receives a detected value of the drive current of the motor M1 detected by a detection unit of the plant 2.

[0059] The current control unit 15 performs feedback control of the current. Based on the summation result (current command) from the adder 141 and the detection result of the drive current of the motor M1, the current control unit 15 performs feedback control (determination of the manipulated variable) so that the drive current of the motor M1 coincides with the current command. The current control unit 15 controls the inverter circuit so that the determined manipulated variable (drive current) is supplied to the motor M1.

[0060] In particular, in this embodiment, since the adjustment unit 13 is connected in series to the friction compensation unit 12, the drive control unit 10 (current control unit 15) receives a command signal (current command) based on the adjustment result by the adjustment unit 13 and controls the drive of the motor M1 based on the command signal. In other words, in the drive control step of the control method according to this embodiment, a command signal based on the adjustment result in the adjustment step is received and the drive of the motor M1 is controlled based on the command signal.

[0061] (2) Operation of the Control System A series of operational flows in the control system 1 will be described below with reference to Fig. 5. The flowchart shown in Fig. 5 is merely an example of an operational flow related to the control system 1, and the order of processes may be changed as appropriate, and processes may be added or omitted as appropriate. Note that the flowchart shown in Fig. 5 shows, as an example, an operational flow mainly related to the functions of the friction compensation unit 12 and the adjustment unit 13.

[0062] For example, suppose that a position command corresponding to stopping the plant 2 (i.e., stopping the motor M1) is input to the control system 1 while the controlled object (plant 2) is in operation. In response to this position command, the torque command signal output from the speed control unit 11 begins to approach zero. Meanwhile, the speed command resulting from time differentiation by the differentiator 5 is input to the friction compensation unit 12 as a zero command (step ST1: obtain zero command). In response to the input of the zero command, the friction torque output from the friction model gradually decreases, and the friction compensation amount also begins to approach zero. However, the friction model still outputs a constant (non-zero) amount of friction torque equivalent to the static friction of the motor M1 and the load L1. To compensate for this constant amount of friction torque, the friction compensation unit 12 begins to output a compensation signal indicating a substantially constant output value (signal level) (step ST2).

[0063] Here, the adjustment unit 13 (high-pass filter 130) is connected downstream of the friction compensation unit 12, so the output value is cut (the output value approaches zero). In other words, the adjustment unit 13 performs a first adjustment, which is to "adjust the output of the compensation signal from the friction compensation unit 12 so that it approaches zero" (step ST3: cut the output).

[0064] Therefore, the output of the compensation signal input to the adder 141 gradually becomes zero or a value close to zero (for example, the value before the operation of the motor M1 starts) based on the time constant of the high-pass filter 130. A current command of zero or a value close to zero is input to the drive control unit 10 (current control unit 15) as a result of adding the torque command signal and the compensation signal from the speed control unit 11. As a result, the possibility that the drive current will continue to flow to the motor M1 due to the compensation signal that compensates for friction torque even when the motor M1 is stopped is reduced (step ST4: reduce drive current).

[0065] When a position command for restarting the operation of the stopped plant 2 (in other words, the operation of the motor M1) is input to the control system 1, a compensation signal containing high frequency components may be output from the friction compensation unit 12. Therefore, the compensation signal is input to the adder 141 without being cut off by the high-pass filter 130. As a result, the first adjustment is (automatically) canceled, and the original friction compensation function is restored.

[0066] (3) Advantages As described above, according to the control system 1 of this embodiment, the adjustment unit 13, which is connected in series to the friction compensation unit 12 (disturbance compensation unit 7), performs the first adjustment in response to the stop of operation of the plant 2 including the motor M1 (for example, in response to input of a zero command). This reduces the possibility of unnecessary energy consumption due to a compensation signal that compensates for friction torque (for example, the possibility that drive current continues to flow to the motor M1) even when the motor M1 is stopped. As a result, there is an advantage in that energy savings in motor control can be achieved.

[0067] The adjustment unit 13 also includes a high-pass filter 130 connected in series to the friction compensation unit 12 (disturbance compensation unit 7) at a stage subsequent to the friction compensation unit 12 (disturbance compensation unit 7), and performs the first adjustment through the high-pass filter 130 in response to a stop of operation of the plant 2 (for example, in response to input of a zero command). Therefore, the first adjustment can be performed without requiring a configuration for controlling the adjustment unit 13, and the first adjustment can be executed with a simple configuration. Furthermore, the first adjustment can be canceled without requiring a configuration for controlling the adjustment unit 13, and the original friction compensation function can be easily restored.

[0068] 4A and 4B, the advantages of the control system 1 according to this embodiment will be described in more detail.

[0069] FIG. 4A is a signal waveform diagram (simulation result) of the compensation torque A1 (friction compensation amount from the friction compensation unit 12) and the actual friction torque B1 in a comparative control system that does not have the function of the adjustment unit 13. That is, FIG. 4A shows the simulation result of the friction compensation amount and the actual friction torque in a comparative control system that has the function of the friction compensation unit 12 but does not have the function of the adjustment unit 13. The horizontal axis of FIG. 4A represents time, and the vertical axis represents torque. "T1" in FIG. 4A indicates a period during which the position of the plant 2 is intermittently changing (i.e., a period during which the motor M1 is operating). "T2" in FIG. 4A indicates a period during which the position of the plant 2 is not changing (i.e., a period during which the motor M1 is stopped). Note that in FIG. 4A, the signal waveforms of the compensation torque A1 and the friction torque B1 are approximately the same.

[0070] Fig. 4A shows that, during period T1 when motor M1 is operating, friction compensation is performed almost accurately in accordance with actual friction torque B1. Furthermore, Fig. 4A shows that, during period T2 when motor M1 is stopped, the signal waveform of actual friction torque B1 exhibits a (non-zero) constant negative value corresponding to static friction of plant 2. Fig. 4A also shows that, even during period T2 when motor M1 is stopped, friction compensation is performed almost accurately in accordance with actual friction torque B1, and a compensation signal including a (non-zero) friction compensation amount continues to be output from friction compensation unit 12. As a result, unnecessary drive current continues to flow to motor M1 even during period T2 when motor M1 is stopped.

[0071] On the other hand, Fig. 4B is a signal waveform diagram (simulation result) of the compensation torque A2 (friction compensation amount from the friction compensation unit 12) to which adjustment by the adjustment unit 13 has been applied, and the actual friction torque B2 in the control system 1 according to this embodiment. That is, Fig. 4B shows the simulation result of the friction compensation amount and the actual friction torque in the control system 1 including the friction compensation unit 12 and the adjustment unit 13. The horizontal axis of Fig. 4B represents time, and the vertical axis represents torque. "T1" in Fig. 4B indicates a period during which the position of the plant 2 is intermittently changing (i.e., a period during which the motor M1 is operating). "T2" in Fig. 4B indicates a period during which the position of the plant 2 is not changing (i.e., a period during which the motor M1 is stopped).

[0072] Like FIG. 4A , FIG. 4B also shows that friction compensation is performed almost accurately in accordance with friction torque B2 during period T1 when motor M1 is operating. Furthermore, like FIG. 4A , during period T2 when motor M1 is stopped, the signal waveform of actual friction torque B2 exhibits a constant (non-zero) negative value corresponding to static friction of plant 2. FIG. 4B also shows that for a while after the start of period T2 when motor M1 is stopped, friction compensation is performed in accordance with friction torque B1, and a compensation signal including a (non-zero) friction compensation amount is output from friction compensation unit 12. However, FIG. 4B also shows that, due to adjustment by adjustment unit 13, compensation torque A2 begins to approach zero after a few seconds without following friction torque B1, and then becomes zero. As a result, unnecessary drive current is prevented from continuing to flow to motor M1 during period T2 when motor M1 is stopped. In this way, control system 1 can achieve energy savings in motor control.

[0073] (4) Modifications Modifications of the above embodiment are listed below. The configuration of each of the following modifications can be appropriately combined with the above embodiment or other modifications.

[0074] The same functions as those of the control system 1 according to the above embodiment may be realized as a control method, a computer program, or a non-transitory recording medium on which a computer program is recorded.

[0075] The control system 1 in the present disclosure includes a computer system. The computer system is primarily composed of a processor and memory as hardware. The processor executes a program stored in the memory of the computer system to realize the functions of the control system 1 in the present disclosure. The program may be pre-recorded in the memory of the computer system, provided via a telecommunications line, or provided in a non-transitory recording medium such as a memory card, optical disk, or hard disk drive that is readable by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI). The integrated circuits, such as ICs or LSIs, are referred to by different names depending on the degree of integration, and include integrated circuits called system LSIs, very large-scale integrations (VLSIs), or ultra-large-scale integrations (ULSIs). Furthermore, field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or logic devices that allow the reconfiguration of internal connections or internal circuit partitions of the LSI, can also be used as processors. The electronic circuits may be integrated into one chip or distributed across multiple chips. The chips may be integrated into one device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0076] Furthermore, it is not essential that the multiple functions of the control system 1 be concentrated in one housing. For example, the components of the control system 1 may be distributed across multiple housings.

[0077] Conversely, multiple functions of the control system 1 may be integrated into one housing. Furthermore, at least some of the functions of the control system 1, for example, some of the functions of the control system 1 may be realized by the cloud (cloud computing) or the like.

[0078] (4.1) Modification 1 A control system 1 according to Modification 1 will be described below with reference to Fig. 6. Note that, in the control system 1 according to Modification 1, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0079] Fig. 6 is a block diagram of an overall system including a control system 1 according to Modification 1. As shown in Fig. 6, the control system 1 according to Modification 1 includes a position control unit 3, a speed FF unit 4, an adder 6, a speed control unit 11, a friction compensation unit 12 (disturbance compensation unit 7), an adjustment unit 13, a calculation unit 14, and a drive control unit 10 (current control unit 15). In Modification 1 as well, the adjustment unit 13 is connected in series to the friction compensation unit 12 at a stage subsequent to the friction compensation unit 12.

[0080] However, the control system 1 according to the first modification does not have the differentiator 5 of the control system 1 according to the above embodiment, and instead differs from the control system 1 according to the above embodiment in that a signal based on the output result (speed command) of the position control unit 3 is input to the friction compensation unit 12.

[0081] That is, in the control system 1 according to the first modification, a signal based on the output result from the position control system (position control unit 3) is input to the friction compensation unit 12 and the speed control unit 11. The friction compensation unit 12 calculates a friction compensation amount based on the output result from the position control system. The speed control unit 11 controls the speed of the motor M1 based on the output result (speed command) from the position control system and the speed resulting from the control of the motor M1. In other words, the output result (speed command) from the position control system input to the friction compensation unit 12 is a signal that occurs before the speed resulting from the control of the motor M1 is input. Note that in the example of FIG. 6 , the output result from the position control unit 3 is added by the speed feedforward command from the speed FF unit 4 in the adder 6, and then input to the friction compensation unit 12 and the speed control unit 11.

[0082] According to the control system 1 of the first modification, the friction compensation unit 12 performs friction compensation based on a speed command based on the position FB in the position control unit 3. Therefore, the accuracy of the compensation amount in the friction compensation unit 12 is improved compared to the case where a speed command obtained by time-differentiating the position command in the differentiator 5 is used as in the control system 1 of the above embodiment.

[0083] (4.2) Modification 2 A control system 1 according to Modification 2 will be described below with reference to Fig. 7. Note that, in the control system 1 according to Modification 2, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0084] Fig. 7 is a block diagram of the main parts of a control system 1 according to Modification 2. As shown in Fig. 7, the control system 1 according to Modification 2 includes a friction compensation unit 12 (disturbance compensation unit 7) and an adjustment unit 13 connected in series downstream of the friction compensation unit 12. The control system 1 according to Modification 2 also includes a position control unit 3, a speed FF unit 4, a differentiator 5, an adder 6, a speed control unit 11, a calculation unit 14, and a drive control unit 10 (current control unit 15) (see Fig. 1).

[0085] However, in Modification 2, the adjustment unit 13 differs from the control system 1 according to the above embodiment in that it includes a switch 131 (see FIG. 7 ) that switches the electrical path between a conductive state and a non-conductive state. Also, in Modification 2, the control system 1 differs from the control system 1 according to the above embodiment in that it further includes a switch control unit (determination unit 8) that controls the switch 131.

[0086] The switch 131 is inserted in an electric path between the friction compensation unit 12 and the calculation unit 14 (adder 141), for example, and is configured to be able to switch the electric path between a conductive state and a non-conductive state, and performs the second adjustment by switching the electric path to a non-conductive state. The switch 131 is configured by a semiconductor switch that closes / opens (turns on / off) a contact provided in the electric path.

[0087] The switch 131 is normally on when friction compensation is required, and the electrical path between the friction compensation unit 12 and the calculation unit 14 (adder 141) is in a conductive state. When the semiconductor switch is turned off (open), the adjustment unit 13 puts the electrical path between the friction compensation unit 12 and the calculation unit 14 (adder 141) in a non-conductive state, thereby cutting off the output of the compensation signal from the friction compensation unit 12. Note that the switch 131 is not limited to a semiconductor switch and may be configured, for example, by a relay.

[0088] The switching control unit (determination unit 8) controls the switch 131 to switch the electrically conductive path to a non-conductive state in response to the stop of operation of the controlled object (plant 2), whereby the adjustment unit 13 performs the second adjustment. The determination unit 8 is connected to be able to control the switch 131, and sends a control signal to the switch 131 to switch the electrically conductive state or the non-conductive state of the electrically conductive path.

[0089] In the second modification, the determination unit 8 determines whether or not a zero command has been input, and if a zero command has been input, controls the switch 131 to switch the above-mentioned electrical path to a non-conductive state. That is, in the second modification, if a zero command has been input, the determination unit 8 determines that the operation of the controlled object (plant 2) has been stopped, and switches the switch 131 off.

[0090] According to the second modification, the adjustment unit 13 includes a switch 131 and performs the second adjustment through the switch 131 in response to the stoppage of operation of the plant 2. Therefore, the execution of the second adjustment can be realized with a simple configuration. Furthermore, the cancellation of the second adjustment can also be realized with a simple configuration, and the original friction compensation function can be easily restored. Note that, in response to the resumption of operation of the plant 2 (for example, in response to the input of the zero command changing from "present" to "absent"), the switching control unit (determination unit 8) controls the switch 131 to switch the above-mentioned electrical path that was in a non-conductive state to a conductive state, thereby causing the adjustment unit 13 to cancel the second adjustment.

[0091] (4.3) Modification 3 A control system 1 according to Modification 3 will be described below with reference to Fig. 8. Note that, in the control system 1 according to Modification 3, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0092] Fig. 8 is a block diagram of an entire system including a control system 1 according to Modification 3. As shown in Fig. 8, the control system 1 according to Modification 3 includes a position control unit 3, a speed FF unit 4, a differentiator 5, an adder 6, a speed control unit 11, a friction compensation unit 12 (disturbance compensation unit 7), an adjustment unit 13, a calculation unit 14, and a drive control unit 10 (current control unit 15).

[0093] However, in variant example 3, the adjustment unit 13 differs from the control system 1 according to the above embodiment in that it is connected in series to the friction compensation unit 12 (external disturbance compensation unit 7) at a stage before the friction compensation unit 12 (external disturbance compensation unit 7).

[0094] The adjustment unit 13 according to the third modification performs the second adjustment at a stage upstream of the friction compensation unit 12 in response to the stoppage of the operation of the controlled object (plant 2). That is, the adjustment unit 13 cuts off the output of the compensation signal from the friction compensation unit 12 at a stage upstream of the friction compensation unit 12 in response to the stoppage of the operation of the plant 2. Specifically, for example, the adjustment unit 13 is configured to be able to switch the electrical path between the differentiator 5 and the friction compensation unit 12 between a conductive state and a non-conductive state, and performs the second adjustment by switching the electrical path to a non-conductive state.

[0095] The adjustment unit 13 may include, for example, a switch 131 (see FIG. 7 of Modification 2) that switches the electrical path between the differentiator 5 and the friction compensation unit 12 between a conductive state and a non-conductive state. The switch 131 is configured by a semiconductor switch that closes / opens (on / off) a contact. The switch 131 is normally in an on state when friction compensation is required, and the electrical path between the differentiator 5 and the friction compensation unit 12 is in a conductive state. By turning off (opening) the semiconductor switch, the adjustment unit 13 brings the electrical path between the differentiator 5 and the friction compensation unit 12 into a non-conductive state and cuts off the output of the compensation signal from the friction compensation unit 12. Note that the switch 131 is not limited to a semiconductor switch and may be configured by, for example, a relay.

[0096] When the adjustment unit 13 includes the switch 131 as in Modification 3, it is preferable that the control system 1 further includes a switching control unit (determination unit 8: see FIG. 7 of Modification 2) that controls the switching of the switch 131. The switching control unit (determination unit 8) controls the switch 131 to switch the above-mentioned electric circuit to a non-conductive state in response to a stop of operation of the plant 2, thereby causing the adjustment unit 13 to perform the second adjustment. The switching control unit (determination unit 8) determines whether or not a zero command has been input, and if a zero command has been input, controls the switch 131 to switch the above-mentioned electric circuit to a non-conductive state. In other words, also in Modification 3, when a zero command has been input, the determination unit 8 considers this to be a "stop of operation of the controlled object (plant 2)" and switches the switch 131 off.

[0097] Even in a configuration in which the adjustment unit 13 is disposed before the friction compensation unit 12 (disturbance compensation unit 7) as in the third modification, the possibility of unnecessary energy consumption due to a compensation signal that compensates for friction torque (for example, the possibility that drive current continues to flow to the motor M1) even when the motor M1 is stopped is reduced, thereby achieving energy savings in motor control.

[0098] (4.4) Modification 4 A control system 1 according to Modification 4 will be described below with reference to Fig. 9. Note that, in the control system 1 according to Modification 4, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0099] 9 is a block diagram of an entire system including the control system 1 according to Modification 4. The control system 1 according to Modification 4 has a configuration that further improves the practicality of the switching control unit (determination unit 8) of the control system 1 according to Modification 2.

[0100] The switching control unit (determination unit 8) of Modification 4 determines whether the zero command has continued for a predetermined time. When determining that the zero command has continued for the predetermined time, the determination unit 8 causes the adjustment unit 13 to start the first adjustment or the second adjustment (here, for example, the second adjustment).

[0101] Specifically, the control system 1 according to the fourth modification is configured so that the time differentiation result (speed command) from the differentiator 5 is input not only to the friction compensation unit 12 but also to the determination unit 8. The determination unit 8 monitors the time differentiation result (speed command) from the differentiator 5. Based on the time differentiation result (speed command) from the differentiator 5, the determination unit 8 determines whether or not a zero command has been input, and if it determines that a zero command has been input, it starts timing using a built-in timer.

[0102] The adjustment unit 13 of the fourth modification is connected in series to the friction compensation unit 12 at a stage subsequent to the friction compensation unit 12. Specifically, the adjustment unit 13 of the fourth modification is inserted in the electrical path between the friction compensation unit 12 and the calculation unit 14 (adder 141), similar to the second modification. Also, the adjustment unit 13 of the fourth modification includes, for example, a switch 131, similar to the second modification.

[0103] When the determination unit 8 determines, based on the timing result of the built-in timer, that the state in which the zero command has been input "present" has continued for a predetermined time, it controls the switch 131 to switch the electrical path between the friction compensation unit 12 and the calculation unit 14 (adder 141) from a conductive state to a non-conductive state, causing the adjustment unit 13 to perform the second adjustment. That is, the output of the compensation signal is cut off. In other words, in the fourth modification, when the state in which the zero command has been input "present" has continued for a predetermined time, the determination unit 8 determines that "the operation of the controlled object (plant 2) has stopped," and switches the switch 131 off.

[0104] Immediately after the zero command is input, the motor M1 or the load L1 may still be moving, possibly generating dynamic friction. Therefore, if the first adjustment or the second adjustment (here, the second adjustment) is immediately started, there is a possibility that appropriate friction compensation may not be performed. In contrast, according to the fourth modification, the grace period of a "predetermined time" is provided, thereby reducing such a possibility. Furthermore, it is also possible to reduce the possibility that, due to the influence of noise or the like, the zero command may be momentarily erroneously determined to have been input, resulting in the unintended start of the first adjustment or the second adjustment (here, the second adjustment).

[0105] Furthermore, in the fourth modification, when the determination unit 8 determines that the input of the zero command has changed from "present" to "absent," it causes the adjustment unit 13 to end the first adjustment or second adjustment (here, the second adjustment) that was being performed, and restores friction compensation by the friction compensation unit 12. This allows friction compensation to be restored at a more appropriate timing.

[0106] Note that in the fourth modification, the switch 131 is controlled in accordance with the determination of the determination unit 8, and the adjustment unit 13 performs the second adjustment. However, as in a seventh modification described below, the switch 131 may be controlled in accordance with the determination of the determination unit 8, and the adjustment unit 13 may perform the first adjustment.

[0107] (4.5) Modification 5 A control system 1 according to Modification 5 will be described below with reference to Fig. 10. Note that, in the control system 1 according to Modification 5, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0108] 10 is a block diagram of an overall system including a control system 1 according to Modification 5. The control system 1 according to Modification 5 has a configuration that is yet another example of the control system 1 according to Modification 4.

[0109] The switching control unit (determination unit 8) of Modification 5 determines whether a zero command has been input and whether the speed, which is the control result from the controlled object (plant 2), is zero. When the determination unit 8 determines that a zero command has been input and that the speed, which is the control result from the plant 2, is zero, it causes the adjustment unit 13 to start the first adjustment or the second adjustment (here, for example, the second adjustment).

[0110] Specifically, like the control system 1 according to the modification 4, the control system 1 according to the modification 5 is configured so that the time differentiation result (speed command) from the differentiator 5 is input not only to the friction compensation unit 12 but also to the determination unit 8. However, the control system 1 according to the modification 5 differs from the control system 1 according to the modification 4 in that the speed (angular velocity) of the motor M1 detected by a detection unit of the plant 2 is input to the determination unit 8 as the control result from the plant 2.

[0111] The adjustment unit 13 of the fifth modification is connected in series to the friction compensation unit 12 at a stage subsequent to the friction compensation unit 12. Specifically, the adjustment unit 13 of the fifth modification is inserted in the electrical path between the friction compensation unit 12 and the calculation unit 14 (adder 141), similar to the second modification. Also, the adjustment unit 13 of the fifth modification includes, for example, a switch 131, similar to the second modification.

[0112] The determination unit 8 monitors the time differentiation result (speed command) from the differentiator 5 and the speed (angular velocity) of the motor M1 detected by the detection unit of the plant 2. Based on the speed command and the angular velocity of the motor M1, the determination unit 8 determines whether a zero command has been input and whether the angular velocity of the motor M1 is zero. When the determination unit 8 determines that a zero command has been input and that the angular velocity of the motor M1 is zero, the determination unit 8 controls the switch 131 to switch the conductive electrical path to a non-conductive state, causing the adjustment unit 13 to perform the second adjustment. In other words, the output of the compensation signal is interrupted. In other words, in the fifth modification, when a zero command has been input and the angular velocity of the motor M1 is zero, the determination unit 8 determines that the operation of the controlled object (plant 2) has stopped and switches the switch 131 off.

[0113] Even if the speed of the actual plant 2 (the actual angular velocity of the motor M1) becomes zero, this does not necessarily mean that the plant 2 is stopped. For example, if the stage (load L1) is in a transient state, such as an operation reversal from the positive direction of the Y axis to the negative direction of the Y axis, the detected angular velocity of the motor M1 may momentarily become zero. Furthermore, even if the speed command becomes zero, the control system 1 must continue friction compensation unless the speed of the actual plant 2 becomes zero.

[0114] In contrast, according to Modification 5, the first adjustment or the second adjustment (here, the second adjustment) is performed when the condition that both the speed command and the actual angular velocity of the motor M1 are zero is met, which allows the adjustment unit 13 to start the first adjustment or the second adjustment (here, the second adjustment) at a more appropriate timing.

[0115] Furthermore, in Modification 5, when the determination unit 8 determines that the input of the zero command has changed from "present" to "absent," it causes the adjustment unit 13 to terminate the first adjustment or the second adjustment (here, the second adjustment) that was being performed and restores friction compensation by the friction compensation unit 12. This makes it possible to restore friction compensation at a more appropriate timing. Alternatively, when the determination unit 8 determines that the input of the zero command has changed from "present" to "absent" and determines that the speed of the control result from the plant 2 has changed from zero to a non-zero value, it may cause the adjustment unit 13 to terminate the first adjustment or the second adjustment that was being performed.

[0116] Note that, in the fifth modification, an example is given in which the switch 131 is controlled in accordance with the determination of the determination unit 8, and the adjustment unit 13 performs the second adjustment. However, as in the seventh modification described below, the switch 131 may be controlled in accordance with the determination of the determination unit 8, and the adjustment unit 13 may perform the first adjustment.

[0117] (4.6) Modification 6 A control system 1 according to Modification 6 will be described below with reference to Fig. 11. Note that, in the control system 1 according to Modification 6, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0118] 11 is a block diagram of an overall system including a control system 1 according to Modification 6. The control system 1 according to Modification 6 has a configuration that is yet another example of the control system 1 according to Modification 4.

[0119] The switching control unit (determination unit 8) of Modification 6 determines whether a zero command has been input and whether the amount of change over time in the friction compensation amount is zero. If the determination unit 8 determines that a zero command has been input and that the amount of change over time is zero, it causes the adjustment unit 13 to start the first adjustment or the second adjustment (here, for example, the second adjustment).

[0120] Specifically, like the control system 1 according to the modification 4, the control system 1 according to the modification 6 is configured so that the time differentiation result (speed command) from the differentiator 5 is input not only to the friction compensation unit 12 but also to the determination unit 8. However, the control system 1 according to the modification 6 differs from the control system 1 according to the modification 4 in that the compensation signal output from the friction compensation unit 12 is input also to the determination unit 8.

[0121] The adjustment unit 13 of the sixth modification is connected in series to the friction compensation unit 12 at a stage subsequent to the friction compensation unit 12. Specifically, the adjustment unit 13 of the sixth modification is inserted in the electrical path between the friction compensation unit 12 and the calculation unit 14 (adder 141), similar to the second modification. The adjustment unit 13 of the sixth modification also includes, for example, a switch 131, similar to the second modification. The compensation signal output from the friction compensation unit 12 is input to both the adjustment unit 13 and the determination unit 8.

[0122] The determination unit 8 monitors the time differentiation result (speed command) from the differentiator 5 and the compensation signal from the friction compensation unit 12. Based on the speed command and the time change amount of the friction compensation amount, the determination unit 8 determines whether a zero command has been input and whether the time change amount is zero. When the determination unit 8 determines that a zero command has been input and that the time change amount is zero, it controls the switch 131 to switch the conductive electric circuit to a non-conductive state, causing the adjustment unit 13 to perform the second adjustment. In other words, the output of the compensation signal is cut off. In other words, in the sixth modification, when a zero command has been input and the time change amount is zero, the determination unit 8 determines that the operation of the controlled object (plant 2) has been stopped and switches the switch 131 off.

[0123] The "amount of change over time" referred to here is, for example, the amount of change in the friction compensation amount per sampling period. The sampling period may be a period in which the determination unit 8 acquires data on the friction compensation amount from the friction compensation unit 12. For example, the determination unit 8 determines whether the difference between the value of the friction compensation amount one time before (the previous sampling data) and the value of the data at the current time (the current sampling data) is equal to or greater than a predetermined value (for example, 1×10 －６Alternatively, the determination unit 8 may calculate the "difference between the value one time before and the value at the current time" for 10 sampling periods, calculate the average value of the differences, and determine that the amount of change over time is zero if this average value is smaller than the predetermined value.

[0124] According to variant example 6, even if it is difficult to determine whether the speed of plant 2 (the actual angular velocity of motor M1) is zero due to measurement noise or the like, it is possible to cause adjustment unit 13 to start the first adjustment or the second adjustment at a more appropriate timing.

[0125] Furthermore, in the sixth modification, when the determination unit 8 determines that the input of the zero command has changed from "present" to "absent," it causes the adjustment unit 13 to terminate the first adjustment or the second adjustment (here, the second adjustment) that was being performed, and restores friction compensation by the friction compensation unit 12. This makes it possible to restore friction compensation at a more appropriate timing. Alternatively, when the determination unit 8 determines that the input of the zero command has changed from "present" to "absent" and determines that the amount of change over time has changed from zero to non-zero, it may cause the adjustment unit 13 to terminate the first adjustment or the second adjustment that was being performed.

[0126] Note that in the sixth modification, an example is given in which the switch 131 is controlled in accordance with the determination of the determination unit 8, and the adjustment unit 13 performs the second adjustment. However, as in the seventh modification described below, the switch 131 may be controlled in accordance with the determination of the determination unit 8, and the adjustment unit 13 may perform the first adjustment.

[0127] (4.7) Modification 7 A control system 1 according to Modification 7 will be described below with reference to Fig. 12. Note that, in the control system 1 according to Modification 7, components similar to those of the control system 1 according to the above embodiment will be assigned the same reference numerals, and detailed descriptions thereof may be omitted.

[0128] Fig. 12 is a block configuration diagram of the main parts of a control system 1 according to Modification 7. As shown in Fig. 12, the control system 1 according to Modification 7 includes a friction compensation unit 12 (disturbance compensation unit 7) and an adjustment unit 13 connected in series downstream of the friction compensation unit 12. The control system 1 according to Modification 7 also includes a position control unit 3, a speed FF unit 4, a differentiator 5, an adder 6, a speed control unit 11, a calculation unit 14, and a drive control unit 10 (current control unit 15) (see Fig. 1).

[0129] The control system 1 according to the seventh modification has a configuration different from that of the control systems 1 according to the fourth to sixth modifications. That is, the configuration of the adjustment unit 13 according to the seventh modification is different from that of the adjustment unit 13 according to the fourth to sixth modifications.

[0130] Specifically, as shown in Fig. 12 , the adjustment unit 13 includes a plurality of switches 131 (two switches 131 in Fig. 12 ) that each switch a corresponding electric circuit between a conductive state and a non-conductive state. The control system 1 further includes a switching control unit (determination unit 8) that controls the plurality of switches 131. The switching control unit (determination unit 8) individually controls the plurality of switches 131 to switch the corresponding electric circuits between a conductive state and a non-conductive state in response to a stop of operation of the controlled object (plant 2), whereby the adjustment unit 13 performs the first adjustment or the second adjustment (here, the first adjustment).

[0131] Specifically, the adjustment unit 13 includes a first switch 131A and a second switch 131B that switch the corresponding electrical path between a conductive state and a non-conductive state, and an attenuator 132. The adjustment unit 13 further includes an adder 133.

[0132] The adjustment unit 13 also includes a first electric circuit R1 and a second electric circuit R2 (main electric circuit). The second electric circuit R2 (main electric circuit) is an electric circuit between the friction compensation unit 12 and the calculation unit 14 (adder 141). The first electric circuit R1 branches off from the second electric circuit R2 (main electric circuit) at a connection point P1 and merges with the second electric circuit R2 (main electric circuit) at an adder 133.

[0133] The determination unit 8 controls the first switch 131A and the second switch 131B. The determination unit 8 is connected to the first switch 131A and the second switch 131B so as to be able to control each of them individually.

[0134] The first switch 131A is connected in series with the attenuator 132. In the example of Fig. 12, the first switch 131A is connected in series with the attenuator 132 in a stage subsequent to the attenuator 132 in the first electrical circuit R1, and can switch the first electrical circuit R1 between a conductive state and a non-conductive state. Under normal circumstances when friction compensation is required, the first switch 131A is in an off state with its contacts open, and the first electrical circuit R1 is in a non-conductive state.

[0135] The second switch 131B is connected in parallel to the first switch 131A and the attenuator 132. In the example of Fig. 12, the second switch 131B is inserted in the second electrical circuit R2 and can switch the second electrical circuit R2 between a conductive state and a non-conductive state. Under normal circumstances when friction compensation is required, the second switch 131B is in an on state with its contacts closed, and the second electrical circuit R2 is in a conductive state.

[0136] In response to the stop of operation of the plant 2, the determination unit 8 controls the second switch 131B to switch the second electrical circuit R2 corresponding to the second switch 131B, which was in a conductive state, to a non-conductive state. After switching the second electrical circuit R2 to a non-conductive state, the determination unit 8 controls the first switch 131A to switch the first electrical circuit R1 corresponding to the first switch 131A, which was in a non-conductive state, to a conductive state, whereby the adjustment unit 13 performs the first adjustment via the attenuator 132.

[0137] In other words, during normal operation when friction compensation is required, the compensation signal output from the friction compensation unit 12 passes through the second electrical circuit R2, which is the main electrical circuit, and is input to the calculation unit 14 (adder 141). Then, in response to the stop of operation of the plant 2, which does not require friction compensation, the determination unit 8 first turns off the second switch 131B and then turns on the first switch 131A. As a result, thereafter, the compensation signal output from the friction compensation unit 12 passes through the first electrical circuit R1, and its output (signal level) is attenuated by the attenuator 132 so as to approach zero (first adjustment), and is input to the calculation unit 14 (adder 141).

[0138] Although detailed explanation is omitted, the judgment unit 8 of the modified example 7 controls the first switch 131A and the second switch 131B, regarding the operation of the controlled object (plant 2) as having stopped based on a judgment based on the input of a zero command "present" as described in the modified examples 2 to 6, for example.

[0139] Compared to the case where the first switch 131A is first turned on and then the second switch 131B is turned off, the seventh modification suppresses a situation where both the first switch 131A and the second switch 131B are momentarily turned on, increasing the friction compensation amount output from the adjustment unit 13. As a result, the stability of motor control can be improved.

[0140] In the seventh modification, in response to the recovery of the plant 2 from the shutdown, the switching control unit (determination unit 8) controls the second switch 131B to switch the electrical path (second electrical path R2) corresponding to the second switch 131B, which was in a non-conductive state, to a conductive state. After switching the second electrical path R2 to the conductive state, the adjustment unit 13 cancels the first adjustment by the attenuator 132 by controlling the first switch 131A to switch the electrical path (first electrical path R1) corresponding to the first switch 131A, which was in a conductive state, to a non-conductive state. Note that when the input of the zero command changes from "present" to "absent," the determination unit 8 considers this to mean "the plant 2 has recovered from the shutdown" and cancels the first adjustment.

[0141] This configuration allows the first adjustment to be released (i.e., the compensation function to be restored) with a simple configuration. In particular, when the first adjustment is released, the second switch 131B is switched before the first switch 131A is switched, so that the friction compensation is quickly restored, thereby improving the stability of motor control.

[0142] The attenuator 132 may be replaced with the high-pass filter 130 in the above embodiment. In other words, the compensation signal may be input to the high-pass filter 130 only when friction compensation is not required.

[0143] (4.8) Other Modifications In the above embodiment and modifications 1 to 7, it is assumed that the disturbance is friction generated on the motor M1 side, and the disturbance compensation unit 7 is the friction compensation unit 12.

[0144] However, the disturbance in the present disclosure is not limited to friction and may be the temperature (heat) of the plant 2 including the motor M1. The magnetic force of the motor M1 may change depending on the magnet temperature, etc. As a result, the magnet temperature of the motor M1 is affected by the ambient heat, causing a change in magnetic force, which may result in a change in motor torque. The disturbance compensation unit 7 may be a temperature compensation unit that receives a speed command for the motor M1 as an input and has a model that reproduces changes in motor torque due to temperature (heat). When the plant 2 is stopped, the temperature compensation unit may output a compensation signal to cancel the influence of heat, even though the motor M1 is stopped. This may result in unnecessary energy consumption (e.g., drive current may flow to the motor M1), which is problematic from the perspective of energy conservation. Even in this case, the control system 1 may be provided with an adjustment unit 13 connected in series with the temperature compensation unit, thereby achieving energy conservation in motor control.

[0145] Alternatively, the disturbance may be wind (or air resistance) experienced by the plant 2. For example, when the plant 2 is exposed to wind in an environment where an air conditioner or the like is used, the wind volume (or wind speed) may be a force-dimensional disturbance for the operation of the plant 2. Furthermore, the air resistance experienced by the plant 2 may vary depending on the operating speed of the motor M1 or the stage. Therefore, the disturbance compensator 7 may be a resistance compensator that receives a speed command for the motor M1 as an input and has a model that reproduces changes in motor torque due to wind or air resistance. When the operation of the plant 2 is stopped, the resistance compensator may output a compensation signal to cancel the effect of the wind (or air resistance) even though the motor M1 is stopped. This may result in unnecessary energy consumption (e.g., drive current may flow to the motor M1), which is problematic from the perspective of energy conservation. Even in this case, the control system 1 may be provided with an adjustment unit 13 connected in series with the resistance compensator, thereby achieving energy conservation in motor control.

[0146] In the above embodiment and Modifications 1 to 7, the "speed dimension command" input to the friction compensation unit 12 (disturbance compensation unit 7) has been described as a speed command for the motor M1. However, if the plant 2 includes a linear motion mechanism such as a stage, the "speed dimension command" may be a speed command in a linear motion dimension (mm / s, m / s, etc.) that commands the speed of the linear motion mechanism such as a stage. Alternatively, the "speed dimension command" may be a speed command (angular velocity command) converted into a dimension (rad / s, etc.) for the motor M1 based on a linear motion dimension command that commands the speed of the linear motion mechanism.

[0147] (Summary) The above-described embodiments and the like disclose the following aspects.

[0148] A control system (1) according to a first aspect includes a speed control unit (11), an external disturbance compensation unit (7), an adjustment unit (13), and a drive control unit (10). The speed control unit (11) controls the speed of a motor (M1). The external disturbance compensation unit (7) outputs a compensation signal that compensates for external disturbances related to the motor (M1). The adjustment unit (13) is connected in series to the external disturbance compensation unit (7) and performs adjustments related to the external disturbance compensation unit (7). The drive control unit (10) receives a command signal based on the adjustment result by the adjustment unit (13) and performs drive control of the motor (M1) based on the command signal. The adjustment unit (13) performs a first adjustment to adjust the output of the compensation signal so that it approaches zero, or a second adjustment to shut off the output of the compensation signal, in response to a stop of operation of a controlled object (plant 2) including the motor (M1).

[0149] According to the above aspect, the adjustment unit (13) connected in series to the disturbance compensation unit (7) performs the first adjustment or the second adjustment in response to the stoppage of the operation of the controlled object (plant 2) including the motor (M1). This reduces the possibility of unnecessary energy consumption (for example, the possibility that a drive current continues to flow to the motor (M1)) due to a compensation signal that compensates for the disturbance even when the motor (M1) is stopped. As a result, there is an advantage that energy savings in motor control can be achieved.

[0150] Regarding the control system (1) according to the second aspect, in the first aspect, the disturbance is friction occurring on the motor (M1) side. The disturbance compensation unit (7) is a friction compensation unit (12) that receives a velocity command as input and outputs a compensation signal including a friction compensation amount for friction, and also outputs a compensation signal including a non-zero friction compensation amount even when a zero command is input as the velocity command. The drive control unit (10) includes a current control unit (15) that controls a drive current of the motor (M1) based on the command signal. The zero command corresponds to a command to stop operation of the controlled object (plant 2). The adjustment unit (13) performs a first adjustment or a second adjustment to reduce the drive current in response to the stop of operation of the controlled object (plant 2).

[0151] According to the above aspect, the possibility that a driving current continues to flow to the motor (M1) due to a compensation signal that compensates for friction even when the motor (M1) is stopped is reduced, thereby achieving energy savings in motor control.

[0152] In the second aspect of the control system (1) according to the third aspect, the adjustment unit (13) is connected in series to the friction compensation unit (12) at a stage downstream of the friction compensation unit (12). The adjustment unit (13) performs a first adjustment or a second adjustment at a stage downstream of the friction compensation unit (12) in response to a stop of operation of the controlled object (plant 2).

[0153] According to the above aspect, it is possible to more effectively achieve energy conservation in motor control.

[0154] In the control system (1) according to the fourth aspect, in the second aspect, the adjustment unit (13) is connected in series to the friction compensation unit (12) at a stage preceding the friction compensation unit (12). The adjustment unit (13) performs a second adjustment at a stage preceding the friction compensation unit (12) in response to a stop of operation of the controlled object (plant 2).

[0155] According to the above aspect, it is possible to more effectively achieve energy conservation in motor control.

[0156] Regarding the control system (1) according to the fifth aspect, in any one of the second to fourth aspects, the friction compensation unit (12) is of a feedforward type that receives as input a velocity dimension command obtained by time differentiation of a position command.

[0157] According to the above aspect, energy saving in motor control can be achieved even for a feedforward type friction compensation unit (12).

[0158] The control system (1) according to a sixth aspect is the control system (1) of any one of the second to fifth aspects, further including a determination unit (8) that determines whether the zero command has continued for a predetermined time. When the determination unit (8) determines that the zero command has continued for the predetermined time, the determination unit (8) causes the adjustment unit (13) to start the first adjustment or the second adjustment.

[0159] According to the above aspect, immediately after inputting the zero command, friction may still be occurring on the controlled object side, and therefore, if the first adjustment or the second adjustment is started immediately, there is a possibility that appropriate friction compensation may not be possible, but this possibility can be reduced.

[0160] The control system (1) according to a seventh aspect is the control system (1) of any one of the second to sixth aspects, further including a determination unit (8) that determines whether a zero command has been input and whether the speed, which is the control result from the controlled object (plant 2), is zero. When the determination unit (8) determines that a zero command has been input and that the speed, which is the control result from the controlled object (plant 2), is zero, the determination unit (8) causes the adjustment unit (13) to start the first adjustment or the second adjustment.

[0161] According to the above aspect, even if a zero command is input, it is desirable to continue friction compensation unless the actual speed of the controlled object is zero, and from this perspective, the adjustment unit (13) can be made to start the first adjustment or the second adjustment at a more appropriate timing.

[0162] The control system (1) according to an eighth aspect is any one of the second to seventh aspects, further comprising a determination unit (8) that determines whether a zero command has been input and whether a time change in the friction compensation amount is zero. When the determination unit (8) determines that a zero command has been input and that the time change is zero, the determination unit (8) causes the adjustment unit (13) to start the first adjustment or the second adjustment.

[0163] According to the above aspect, even if it is difficult to determine whether the speed of the plant (2) (the actual angular velocity of the motor M1) is zero due to measurement noise or the like, the adjustment unit (13) can be made to start the first adjustment or the second adjustment at a more appropriate timing.

[0164] With respect to the control system (1) according to the ninth aspect, in any one of the sixth to eighth aspects, when the determination unit (8) determines that the input of the zero command has changed from present to absent, it causes the adjustment unit (13) to terminate the first adjustment or second adjustment that was being performed and restores friction compensation by the friction compensation unit (12).

[0165] According to the above aspect, friction compensation can be restored at a more appropriate timing.

[0166] Regarding the control system (1) according to a tenth aspect, in any one of the first to ninth aspects, the adjustment unit (13) includes a high-pass filter (130) connected in series to the external disturbance compensation unit (7) at a stage subsequent to the external disturbance compensation unit (7). The adjustment unit (13) performs a first adjustment through the high-pass filter (130) in response to a stop of operation of the controlled object (plant 2).

[0167] According to the above aspect, the first adjustment can be achieved with a simple configuration.

[0168] With respect to the control system (1) according to an eleventh aspect, in any one of the first to tenth aspects, the adjustment unit (13) includes a switch (131) that switches the electric circuit between a conductive state and a non-conductive state. The control system (1) further includes a switching control unit (determination unit 8) that controls the switch (131). In response to a stop of operation of the controlled object (plant 2), the switching control unit (determination unit 8) controls the switch (131) to switch the electric circuit that was in a conductive state to a non-conductive state, whereby the adjustment unit (13) performs a second adjustment.

[0169] According to the above aspect, the second adjustment can be achieved with a simple configuration.

[0170] With respect to the control system (1) according to a twelfth aspect, in any one of the first to eleventh aspects, the adjustment unit (13) includes a plurality of switches (131) that each switch a corresponding electric circuit between a conductive state and a non-conductive state. The control system (1) further includes a switching control unit (determination unit 8) that controls the plurality of switches (131). The switching control unit (determination unit 8) individually controls the plurality of switches (131) to switch the corresponding electric circuits between a conductive state and a non-conductive state in response to a stop of operation of the controlled object (plant 2), whereby the adjustment unit (13) performs a first adjustment or a second adjustment.

[0171] According to the above aspect, the first adjustment or the second adjustment can be realized with a simple configuration.

[0172] Regarding the control system (1) according to the thirteenth aspect, in any one of the first to twelfth aspects, the adjustment unit (13) includes a first switch (131A) and a second switch (131B), each of which switches the corresponding electrical path (R1, R2) between a conductive state and a non-conductive state, and an attenuator (132). The control system (1) further includes a switching control unit (determination unit 8) that controls the first switch (131A) and the second switch (131B). The first switch (131A) is connected in series with the attenuator (132). The second switch (131B) is connected in parallel with the first switch (131A) and the attenuator (132). In response to the stop of operation of the controlled object (plant 2), the switching control unit (determination unit 8) controls the second switch (131B) to switch the electrical circuit (second electrical circuit R2) corresponding to the second switch (131B) that was in a conductive state to a non-conductive state, and then controls the first switch (131A) to switch the electrical circuit (first electrical circuit R1) corresponding to the first switch (131A) that was in a non-conductive state to a conductive state, so that the adjustment unit (13) performs a first adjustment through the attenuator (132).

[0173] According to the above-described embodiment, the first adjustment can be realized with a simple configuration. In particular, compared to a case where the first switch (131A) is switched first and then the second switch (131B), it is possible to prevent a situation where both corresponding electric paths (R1, R2) are momentarily brought into a conductive state, thereby improving the stability of motor control.

[0174] With regard to the control system (1) according to the fourteenth aspect, in the thirteenth aspect, the switching control unit (determination unit 8), in response to the return of the controlled object (plant 2) from the stop of operation, controls the second switch (131B) to switch the electrical path corresponding to the second switch (131B) that was in a non-conductive state to a conductive state, and then controls the first switch (131A) to switch the electrical path corresponding to the first switch (131A) that was in a conductive state to a non-conductive state, thereby causing the adjustment unit (13) to cancel the first adjustment by the attenuator (132).

[0175] According to the above aspect, the first adjustment can be released (i.e., the compensation function can be restored) with a simple configuration. In particular, when the first adjustment is released, the second switch (131B) is switched before the first switch (131A) is switched, so that the friction compensation is quickly restored, thereby improving the stability of motor control.

[0176] A control method according to a fifteenth aspect includes a speed control step, a disturbance compensation step, an adjustment step, and a drive control step. In the speed control step, the speed of the motor (M1) is controlled. In the disturbance compensation step, a compensation signal that compensates for disturbances related to the motor (M1) is output by an external disturbance compensation unit. In the adjustment step, an adjustment unit (13) connected in series to the external disturbance compensation unit (7) performs adjustments related to the disturbance compensation step. In the drive control step, a command signal based on the adjustment result in the adjustment step is input, and drive control of the motor (M1) is performed based on the command signal. In the adjustment step, in response to a stop of operation of a controlled object (plant 2) including the motor (M1), a first adjustment is performed to adjust the output of the compensation signal so that it approaches zero, or a second adjustment is performed to cut off the output of the compensation signal.

[0177] According to the above aspect, it is possible to provide a control method that can achieve energy saving in motor control.

[0178] A program according to a sixteenth aspect is a program for causing one or more processors to execute the control method according to the fifteenth aspect.

[0179] According to the above aspect, it is possible to provide a function that can achieve energy saving in motor control.

[0180] The configurations according to the second to fourteenth aspects are not essential for the control system (1) and may be omitted as appropriate.

[0181] REFERENCE SIGNS LIST 1 control system 2 plant (controlled object) 7 disturbance compensation section 8 determination section (switching control section) 10 drive control section 11 speed control section 12 friction compensation section 13 adjustment section 130 high-pass filter 131 switch 132 attenuator 131A first switch 131B second switch 15 current control section M1 motor

Claims

1. A control system comprising: a speed control unit that controls the speed of a motor; a disturbance compensation unit that outputs a compensation signal for compensating for a disturbance related to the motor side; an adjustment unit that is connected in series to the disturbance compensation unit and performs adjustment related to the disturbance compensation unit; and a drive control unit that receives a command signal based on the adjustment result by the adjustment unit and controls the driving of the motor based on the command signal, wherein the adjustment unit performs a first adjustment to adjust the output of the compensation signal to approach zero or a second adjustment to cut off the output of the compensation signal in response to the stop of the operation of the control target including the motor.

2. The disturbance is friction generated on the motor side. The disturbance compensation unit is a friction compensation unit that outputs the compensation signal including a friction compensation amount for the friction with a command in the speed dimension as an input, and also outputs the compensation signal including a non-zero friction compensation amount even for an input of a zero command as the command in the speed dimension. The drive control unit includes a current control unit that controls the drive current of the motor based on the command signal. The zero command corresponds to a command for stopping the operation of the control target. The adjustment unit performs the first adjustment or the second adjustment so that the drive current decreases in response to the stop of the operation of the control target. The control system according to claim 1.

3. The adjustment unit is connected in series to the friction compensation unit after the friction compensation unit. The adjustment unit performs the first adjustment or the second adjustment after the friction compensation unit in response to the stop of the operation of the control target. The control system according to claim 2.

4. The adjustment unit is connected in series to the friction compensation unit before the friction compensation unit. The adjustment unit performs the second adjustment before the friction compensation unit in response to the stop of the operation of the control target. The control system according to claim 2.

5. The friction compensation unit is of a feedforward type that takes, as an input, the command in the speed dimension obtained by time-differentiating a position command. The control system according to any one of claims 2 to 4.

6. The control system further includes a determination unit that determines whether or not the zero command continues for a predetermined time. When the determination unit determines that the zero command continues for the predetermined time, the determination unit causes the adjustment unit to start the first adjustment or the second adjustment. The control system according to any one of claims 2 to 5.

7. The control system further comprises a determination unit that determines whether or not a zero command is input, and determines whether or not the speed, which is a control result from the control target, is zero. When the determination unit determines that the zero command is input and the speed, which is a control result from the control target, is zero, the determination unit causes the adjustment unit to start the first adjustment or the second adjustment. The control system according to any one of claims 2 to 6.

8. The control system further comprises a determination unit that determines whether or not a zero command is input, and determines whether or not the amount of change over time in the friction compensation amount is zero. When the determination unit determines that the zero command is input and the amount of change over time is zero, the determination unit causes the adjustment unit to start the first adjustment or the second adjustment. The control system according to any one of claims 2 to 7.

9. When the determination unit determines that the input of the zero command has changed from being present to absent, the determination unit causes the adjustment unit to end the first adjustment or the second adjustment that was being executed, and causes the friction compensation by the friction compensation unit to return. The control system according to any one of claims 6 to 8.

10. The adjustment unit includes a high-pass filter connected in series to the disturbance compensation unit downstream of the disturbance compensation unit. In response to the stop of the operation of the control target, the adjustment unit performs the first adjustment through the high-pass filter. The control system according to any one of claims 1 to 9.

11. The adjustment unit includes a switch that switches an electric circuit between a conductive state and a non-conductive state. The control system further comprises a switching control unit that controls the switch. In response to the stop of the operation of the control target, the switching control unit controls the switch to switch the electric circuit, which was in the conductive state, to the non-conductive state, whereby the adjustment unit performs the second adjustment. The control system according to any one of claims 1 to 10.

12. The adjustment unit includes a plurality of switches each of which switches a corresponding electric circuit between a conductive state and a non-conductive state. The control system further comprises a switching control unit that controls the plurality of switches. In response to the stop of the operation of the control target, the switching control unit individually controls the plurality of switches to switch the corresponding electric circuits between the conductive state and the non-conductive state, whereby the adjustment unit performs the first adjustment or the second adjustment. The control system according to any one of claims 1 to 10.

13. The adjustment unit includes a first switch and a second switch that each switch a corresponding circuit to a conductive state or a non-conductive state, and an attenuator, and further includes a switching control unit that controls the first switch and the second switch. The first switch is connected in series with the attenuator, and the second switch is connected in parallel with the first switch and the attenuator. In response to the stop of the operation of the control target, the switching control unit controls the second switch to switch the circuit corresponding to the second switch in the conductive state to the non-conductive state, and then controls the first switch to switch the circuit corresponding to the first switch in the non-conductive state to the conductive state, so that the adjustment unit performs the first adjustment through the attenuator. The control system according to any one of claims 1 to 10.

14. In response to the return from the stop of the operation of the control target, the switching control unit controls the second switch to switch the circuit corresponding to the second switch in the non-conductive state to the conductive state, and then controls the first switch to switch the circuit corresponding to the first switch in the conductive state to the non-conductive state, so that the adjustment unit cancels the first adjustment by the attenuator. The control system according to claim 13.

15. A control method including a speed control step of controlling the speed of a motor, a disturbance compensation step of outputting a compensation signal for compensating a disturbance related to the motor side by a disturbance compensation unit, an adjustment step of performing an adjustment related to the disturbance compensation step by an adjustment unit connected in series with the disturbance compensation unit, and a drive control step of inputting a command signal based on the adjustment result of the adjustment step and performing drive control of the motor based on the command signal. In the adjustment step, in response to the stop of the operation of the control target including the motor, a first adjustment for adjusting the output of the compensation signal to approach zero or a second adjustment for blocking the output of the compensation signal is performed.

16. A program for causing one or more processors to execute the control method according to claim 15.

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