TWI847621B - Motor control device, motor control method, motor control program - Google Patents

Abstract

[Topic] A motor control device capable of controlling the speed and torque of a motor at high speed is provided. [Solution] The motor control device (10) comprises: a control unit (12) having a reference speed command generating unit (121) for generating a reference speed command for a motor (4) generating a rotational force; and a drive unit (11) having a speed correction value generating unit (111) for generating a speed correction value for the reference speed command, a speed subtractor (114) for calculating a speed deviation by subtracting the reference speed command corrected by the speed correction value from the measured speed of the motor (4), and a speed converter (114) for converting the speed deviation into A speed deviation conversion unit (115) for a reference torque command of a motor (4), a torque correction value generation unit (116) for generating a torque correction value for the reference torque command, a torque subtractor (118) for calculating a torque deviation by subtracting the reference torque command corrected by the torque correction value from the measured torque of the motor (4), and a torque deviation conversion unit (119) for converting the torque deviation into an applied electric force for the motor (4), wherein the processing cycle is shorter than the processing cycle in the control unit (12).

Description

Motor control device, motor control method, motor control program

The present invention relates to a motor control device, etc.

Patent document 1 discloses a motor control device for compensating the speed and torque of a motor that generates a rotational force. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Application Publication No. 9-161357

[The problem the invention is trying to solve]

When the motor movement must be controlled with high precision in a short time, such as during sudden acceleration or deceleration, there is a risk that the motor control device with a long processing cycle will not be able to compensate for the speed and torque in time.

The present invention was developed in view of such a situation, and its purpose is to provide a motor control device that can control the speed and torque of the motor at high speed. [Technical means to solve the problem]

In order to solve the above-mentioned problem, a motor control device of a certain aspect of the present invention comprises: a control unit, which is a reference speed instruction generating unit for generating a reference speed instruction of a motor generating a rotational force; and a driving unit, which is a speed correction amount generating unit for generating a speed correction amount for the reference speed instruction, and a speed subtractor for calculating a speed deviation by subtracting the reference speed instruction corrected by the speed correction amount from the measured speed of the motor; A speed deviation conversion unit converts the speed deviation into a base torque command of the motor, a torque correction generating unit generates a torque correction for the base torque command, a torque subtractor calculates a torque deviation by subtracting the base torque command corrected by the torque correction from the measured torque of the motor, and a torque deviation conversion unit converts the torque deviation into an applied electric force to the motor, wherein the processing cycle is shorter than the processing cycle in the control unit.

In this aspect, the speed correction amount and the torque correction amount are generated in the driving unit having a processing cycle shorter than that of the control unit, so that the speed and torque of the motor can be controlled at high speed.

Another aspect of the present invention is a motor control method. The method comprises: a reference speed instruction generation step executed in a control unit to generate a reference speed instruction for a motor that generates a rotational force; and a speed correction amount generation step executed in a drive unit having a processing cycle shorter than that in the control unit, namely, generating a speed correction amount for the reference speed instruction, performing a subtraction operation on the reference speed instruction corrected by the speed correction amount and the measured speed of the motor to calculate a speed deviation; A speed subtraction calculation step of the speed difference, a speed deviation conversion step of converting the speed deviation into a reference torque command of the motor, a torque correction amount generation step of generating a torque correction amount for the reference torque command, a torque subtraction step of calculating a torque deviation by subtracting the reference torque command corrected by the torque correction amount and the measured torque of the motor, and a torque deviation conversion step of converting the torque deviation into an applied electric force to the motor.

In addition, any combination of the above components or any expression thereof converted into a method, device, system, recording medium, computer program, etc. is also included in the present invention. [Effect of the invention]

According to the present invention, the speed and torque of the motor can be controlled at high speed.

Hereinafter, a method for implementing the present invention (hereinafter, also referred to as an implementation method) is described in detail with reference to the drawings. In the description and/or drawings, the same or equivalent components, members, processes, etc. are marked with the same symbols and repeated descriptions are omitted. The scale or shape of each part of the diagram is conveniently set for the purpose of simplifying the description and should not be interpreted in a limiting sense unless otherwise mentioned. The implementation method is only an example and does not limit the scope of the present invention in any way. All features or combinations of such features described in the implementation method are not necessarily the essence of the invention.

FIG1 schematically shows the structure of a conveying control device 1 for controlling the conveying action of a conveying device 2 for conveying a conveyed object 3. The conveyed object 3 may be a linear object such as a string or a wire, or a planar object such as paper, cloth, film, foil, rubber, etc. In this embodiment, a conveying device 2 of a roll-to-roll method for conveying a planar substrate 3 in a conveying direction (left-right direction in FIG1) is described. The conveying device 2 can be a device that performs any processing on the conveyed object, such as a coating machine or coating device that applies a coating to the conveyed object, a printing machine that prints on the conveyed object, a stretching device that applies tension to the conveyed object to stretch it, or a part of a box making machine that assembles cardboard boxes, etc., as the conveyed object, into a box shape while conveying it.

The conveying device 2 includes a conveying roller group 20 and a dancer 24. The conveying roller group 20 includes a plurality of conveying rollers as a plurality of conveying parts for conveying the conveyed object 3. The conveying roller group 20 in the example of FIG1 includes three conveying roller pairs arranged in series along the conveying direction of the conveyed object 3. The plurality of conveying rollers are adjacent to each other in the conveying direction. Each conveying roller pair includes driving rollers 211 to 213 that are rotationally driven by driving parts 11A to 11C described later, and driven rollers 221 to 223 that rotate in conjunction with the driving rollers 211 to 213 with the conveyed objects 3 sandwiched between the driving rollers 211 to 213. The three conveying roller pairs 211/221 to 213/223 and the three driving parts 11A to 11C that are respectively corresponding to them and are arranged in the conveying control device 1 can be constructed similarly to each other. Therefore, the first conveying roller pair 211/221 and the first driving unit 11A are described below, and repeated descriptions of other conveying roller pairs 212/222, 213/223 and other driving units 11B and 11C are omitted. In addition, the number of conveying roller pairs provided in the conveying roller group 20 can be arbitrary (an arbitrary integer greater than 1).

The driving roller 211 and the driven roller 221 are conveying rollers of a type as a conveying unit for conveying the conveyed object 3, and can rotate around a rotation axis in a direction orthogonal to the conveying direction (the left-right direction in FIG. 1 ) (a direction perpendicular to the paper surface of FIG. 1 ). The motor (not shown in FIG. 1 ) provided in parallel with the driving roller 211 is rotationally driven by the driving unit 11A according to a reference rotation speed command generated by the control unit 12 described later which constitutes the motor control device 10 of the present embodiment together with the driving units 11A to 11C. When the conveying direction of the conveyed object 3 in FIG. 1 is rightward, the driving roller 211 is rotationally driven by the driving portion 11A in the clockwise direction, and the driven roller 221 rotates counterclockwise in conjunction with the driving roller 211. By using the driving portions 11A to 11C of the conveying control device 1 to individually rotationally drive the driving rollers 211 to 213 constituting the conveying roller group 20, the speed or tension of each part of the conveyed object 3 can be controlled extremely finely, thereby optimizing the conveying action of the conveyed object 3 by the conveying device 2 or the processing of various devices provided with the conveying device 2.

Rollers 24 are provided upstream (left side in FIG. 1 ) and downstream (right side in FIG. 1 ) in the conveying direction of the conveying roller group 20 so as to sandwich the conveying roller group 20 from both sides in the conveying direction. The two rollers 24 shown in the figure may be constructed similarly to each other, so the left roller 24 will be described.

The roller 24 applies tension in the conveying direction to the conveyed object 3. The roller 24 includes a pair of rollers 241, 242 provided on a conveying path of the conveyed object 3 (a path extending in the left and right directions of the conveyed object 3 in FIG. 1 ) and a tension adjusting roller 243 provided between the pair of rollers 241, 242 at a position offset from the conveying path of the conveyed object 3. The tension adjusting roller is also called a tension adjusting roller (dancer roll).

The tension-adjusting roller 243 is arranged to be movable between an upper end 243A and a lower end 243B in a direction perpendicular to the conveying path of the conveyed object 3 (the vertical direction in FIG. 1 ). The air cylinder 244 as a thrust applying unit generates a thrust for applying force or pressurizing the tension-adjusting roller 243 in a direction away from the conveying path of the conveyed object 3 (the downward direction in FIG. 1 ). The thrust is based on the air pressure of the air cylinder 244 connected to the tension-adjusting roller 243 via a piston rod or a connecting rod. The air pressure of the air cylinder 244 is generated by a thrust control unit 17, which is composed of an electro-pneumatic regulator that electrically controls the air pressure. The electro-pneumatic regulator (thrust control unit 17) is generally applied with a substantially constant voltage, and the air pressure of the cylinder 244, that is, the thrust of the tension adjustment roller 243 is controlled to be substantially constant. In addition, a thrust applying unit that applies thrust to the tension adjustment roller 243 based on other principles may be provided instead of the cylinder 244 (for example, a linear motor that applies thrust to the tension adjustment roller 243 based on electricity).

The tension-adjusting roller 243, which is urged or pressurized downward by the thrust from the air cylinder 244, applies tension to the conveyed object 3 by pulling the conveyed object 3 in a direction away from the conveying path. At this time, the tension-adjusting roller 243 is stationary at a position where the downward thrust received from the air cylinder 244 and the upward tension received from the conveyed object 3 are balanced. As described above, the downward thrust received by the tension-adjusting roller 243 from the air cylinder 244 is generally maintained or controlled to be approximately constant, so the position of the tension-adjusting roller 243 in the vertical direction represents the tension of the conveyed object 3.

The position of the tension adjusting roller 243 in the direction of the thrust (the up-down direction in FIG. 1 ) is detected as an electrical signal by the position detecting unit 245 or the position sensor, and is provided to the subtractor 14 of the transport control device 1. In addition, the position command of the tension adjusting roller 243 in the direction of the thrust generated by the position command generating unit 13 of the transport control device 1 is input to the subtractor 14. As described above, the position of the tension adjusting roller 243 is substantially equal to the tension of the transported object 3, so the position command of the tension adjusting roller 243 generated by the position command generating unit 13 is substantially equal to the tension command of the transported object 3. The speed control unit 15 of the transport control device 1 generates a speed command for reducing the deviation of the position of the tension adjusting roller 243 or the tension of the transported object 3 provided by the subtractor 14. The speed command is a command for the conveying speed of the conveyed object 3, and more specifically, is a command for the rotation speed of the driving roller 251 described below.

The driving unit 16 of the conveying control device 1 rotates and drives the driving roller 251 arranged in parallel immediately behind the roller 24 according to the speed command provided by the speed control unit 15. The driving roller 251 is a conveying roller that can rotate around a rotation axis that is orthogonal to the conveying direction of the conveyed object 3. If the driving roller 251 is driven and rotated in the clockwise direction in FIG. 1, the driven roller 252 rotates in the counterclockwise direction in conjunction with the driving roller 251. In addition, a driving roller 231 identical to the driving roller 251 and a driven roller 232 identical to the driven roller 252 are also arranged slightly in front of the roller 24. The driving roller 231 is driven to rotate at a constant rotation speed by a driving unit (not shown), for example. In contrast, the rotation speed of the driving roller 251 is appropriately controlled according to the deviation of the position and/or tension. In this way, the driving roller 251 and the driven roller 252 convey the conveyed object 3 sandwiched therebetween while applying the desired tension corresponding to the position command of the tension adjustment roller 243 generated by the position command generating unit 13, that is, the tension command of the conveyed object 3, to the conveyed object 3. In the example of FIG. 1 , two rollers 24 are provided slightly in front of and immediately behind the conveying roller group 20 in the conveying direction, so that the tension of the conveyed object 3 at the entrance portion (left end in FIG. 1 ) and the exit portion (right end in FIG. 1 ) of the conveying roller group 20 can be controlled to a desired value.

As described above, the conveying device 2 can be installed in various devices such as a coating machine, a printing machine, a stretching device, a box making machine, etc., but in order to optimize various processes, it may be necessary to rapidly accelerate or decelerate the conveyed object 3. In this way, when the movement of the motor must be controlled with high precision in a short time, there is a risk that the speed and torque cannot be compensated in time in the previous motor control device with a long processing cycle. The motor control device 10 of the present embodiment described below is capable of controlling the speed and torque of the motor at high speed. As shown in Figure 1, the motor control device 10 constituting a part of the conveying control device 1 is composed of drive units 11A to 11C (hereinafter, also collectively referred to as the drive unit 11) and a control unit 12.

FIG2 is a functional block diagram of the motor control device 10. The control unit 12 of the motor control device 10 includes a reference speed command generating unit 121. The driving unit 11 of the motor control device 10 includes a speed correction generating unit 111, a speed correction adder 112, a rotation position differentiator 113, a speed subtractor 114, a speed deviation converting unit 115, a torque correction generating unit 116, a torque correction adder 117, a torque subtractor 118, and a torque deviation converting unit 119. These functional blocks are realized by the cooperation of hardware resources such as a central processing unit, a memory, an input device, an output device, and peripheral devices connected to the computer and software executed using these. Regardless of the type of computer or where it is installed, the above-mentioned functional blocks can be implemented by the hardware resources of a single computer or by combining the hardware resources distributed in multiple computers.

The reference speed command generating unit 121 generates a reference speed command for the motor 4 for generating a rotational force for rotating and driving each of the drive rollers 211 to 213. As described in detail below, the drive unit 11 disposed at a later stage than the control unit 12 or at the side of the motor 4 performs speed correction or speed compensation based on a speed correction amount and torque correction or torque compensation based on a torque correction amount on the reference speed command provided from the reference speed command generating unit 121, and then generates a three-phase AC or other applied power to the motor 4.

The processing cycle in the drive unit 11 is shorter than the processing cycle in the control unit 12, so the speed correction and torque correction in the drive unit 11 can be executed at a higher speed than the control unit 12. Specifically, the processing cycle in the drive unit 11 is, for example, several hundred microseconds, and the processing cycle in the control unit 12 is, for example, several milliseconds, and the former is less than about 1/10 of the latter. In this way, by generating the speed correction amount and the torque correction amount at a high speed in the drive unit 11, it is also possible to reliably execute the rapid acceleration and deceleration of the conveyed object 3 required for the conveying device 2 to optimize various processes.

The speed correction generating unit 111 of the drive unit 11 generates a speed correction for the reference speed command generated by the reference speed command generating unit 121 of the control unit 12. A specific example of the speed correction will be described later. The speed correction adder 112 adds the speed correction generated by the speed correction generating unit 111 to the reference speed command generated by the reference speed command generating unit 121 of the control unit 12. The rotational position differentiator 113 differentiates the rotational position of the motor 4 measured by the rotational position detector 41 called PG (Position Generator) to calculate the rotational speed of the motor 4. The speed subtractor 114 calculates the speed deviation by subtracting the reference speed command corrected by the speed correction in the speed correction adder 112 and the speed of the motor 4 measured from the rotational position differentiator 113. The speed deviation conversion unit 115 converts the speed deviation calculated by the speed subtractor 114 into a reference torque command of the motor 4.

The torque correction generating unit 116 generates a torque correction for the base torque command generated by the speed deviation converting unit 115. A specific example of the torque correction will be described later. The torque correction adder 117 adds the torque correction generated by the torque correction generating unit 116 to the base torque command generated by the speed deviation converting unit 115. The torque subtractor 118 calculates the torque deviation by subtracting the base torque command corrected by the torque correction in the torque correction adder 117 from the measured torque of the motor 4. The torque deviation converting unit 119 converts the torque deviation calculated by the torque subtractor 118 into the applied electric force to the motor 4.

FIG3 and FIG4 show specific examples of the speed correction amount for the reference speed command generated by the speed correction amount generating unit 111 of the drive unit 11. In these figures, the horizontal axis represents the rotational position of the motor 4 measured by the rotational position detector 41, and the vertical axis represents the speed correction amount generated by the speed correction amount generating unit 111 added to the reference speed command generated by the reference speed command generating unit 121 in the speed correction amount adder 112. For the reference speed command corresponding to the center or origin of the vertical axis, the upper speed correction amount represents the acceleration amount for the reference speed command, and the lower speed correction amount represents the deceleration amount for the reference speed command. Therefore, in the example of FIG. 3 and FIG. 4, the motor 4, which is controlled to the speed as the reference speed command until the rotation position of "start acceleration/deceleration", is decelerated, accelerated, and decelerated, and is restored to the speed as the reference speed command at the rotation position of "end acceleration/deceleration".

The reference speed command generated by the reference speed command generating unit 121 can be updated with the processing cycle of the control unit 12 (for example, several milliseconds). However, when the motor 4 rotates at a high speed or when the motor 4 is finely accelerated or decelerated in a time shorter than the processing cycle of the control unit 12, the long processing cycle of the control unit 12 cannot cope with it. Therefore, in the present embodiment, in the speed correction amount generating unit 111 of the drive unit 11 with a short processing cycle (for example, several hundred microseconds), a speed correction amount pattern for the reference speed command as shown in FIG. 3 and FIG. 4 is generated at a high speed.

Here, it is preferable to set the acceleration/deceleration pattern of the speed correction amount in advance so that it can also be used in the drive unit 11 having less control resources than the control unit 12. Specifically, as shown in FIG3 and FIG4, it is preferable that the speed correction amount generating unit 111 generates the speed correction amount according to a predetermined pattern corresponding to the rotation position of the motor 4. As shown in FIG3 , the pattern of the speed correction amount can be defined by the rotational position of each change point of the speed correction amount and the coordinates of the acceleration and deceleration amount (X1, Y1), (X2, Y2), (X3, Y3), (X4, Y4), (X5, Y5). As shown in FIG4 , it can also be defined by the parameters of each rotational position interval such as the deceleration interval (DEC1, DEC2), the constant speed interval (CST1, CST2), and the acceleration interval (ACC1, ACC2) (for example, the width of the rotational position interval, the slope of the speed correction amount, etc.). It can also be defined by the gain multiplied by the reference speed command according to the rotational position of the motor 4.

Fig. 5 shows a specific example of the torque correction amount for the reference torque command generated by the torque correction amount generating unit 116 of the drive unit 11. In the figure, the horizontal axis represents the speed of the motor 4 obtained by the rotation position differentiator 113, and the vertical axis represents the torque correction amount generated by the torque correction amount generating unit 116 added to the reference torque command generated by the speed deviation conversion unit 115 in the torque correction amount adder 117. For the reference torque command corresponding to the center or origin of the vertical axis, the upper torque correction amount represents the torque increase amount for the reference torque command, and the lower torque correction amount represents the torque decrease amount for the reference torque command. The torque correction amount generating unit 116 of the driving unit 11, which has a shorter processing cycle (for example, several hundred microseconds) than the control unit 12, generates the pattern of the torque correction amount for the reference torque command as shown in FIG. 5 at high speed.

Here, similarly to the speed correction amount in FIG. 3 and FIG. 4 , it is preferable to set the increase/decrease pattern of the torque correction amount in advance so that it can also be used in the drive unit 11 having less control resources than the control unit 12. Specifically, as shown in FIG. 5 , it is preferable that the torque correction amount generating unit 116 generates the torque correction amount according to a predetermined pattern corresponding to the speed of the motor 4. As shown in FIG. 5 , the pattern of the torque correction amount can be defined by the speed of each change point of the torque correction amount and the coordinates of the torque increase/decrease amount (0, Y0), (X1, Y1), (X2, Y2), (X3, Y3), (X4, Y4), etc., and similarly to FIG. 4 , it can also be defined by the parameters of each speed range (for example, the width of the speed range, the slope of the torque correction amount, etc.), or it can be defined by the gain multiplied by the reference torque command according to the speed of the motor 4.

The present invention has been described above based on the embodiments. It is obvious to those skilled in the art that various modifications can be made to the combinations of the components or processes in the embodiments shown as examples, and such modifications are included in the scope of the present invention.

For example, as shown in FIG6 , the torque correction amount generating unit 116 may also generate a torque correction amount for the reference torque command according to the speed deviation calculated by the speed subtractor 114. Specifically, the torque correction amount generating unit 116 includes a speed deviation differentiator 116A that differentiates the speed deviation calculated by the speed subtractor 114 to calculate an acceleration deviation and an acceleration compensation gain multiplier 116B that multiplies the acceleration deviation by an acceleration compensation gain to calculate a torque correction amount. Here, the acceleration compensation gain of the acceleration compensation gain multiplier 116B is preferably determined according to a predetermined pattern corresponding to the speed of the motor 4 as shown in FIG5 .

In addition, the structure, action, and function of each device or method described in the implementation method can be realized by hardware resources or software resources or the cooperation of hardware resources and software resources. As hardware resources, for example, processors, ROM, RAM, and various integrated circuits can be used. As software resources, for example, programs such as operating systems and applications can be used. This application claims priority based on Japanese patent application No. 2022-047934 filed on March 24, 2022. The entire contents of the Japanese application are cited in this specification by reference.

1: Transport control device 2: Transport device 3: Transported object 4: Motor 10: Motor control device 11: Drive unit 12: Control unit 20: Transport roller group 41: Rotation position detector 111: Speed correction value generation unit 112: Speed correction value adder 113: Rotation position differentiator 114: Speed subtractor 115: Speed deviation conversion unit 116: Torque correction value generation unit 116A: Speed deviation differentiator 116B: Acceleration compensation gain multiplier 117: Torque correction value adder 118: Torque subtractor 119: Torque deviation conversion unit 121: Reference speed command generation unit 211: Drive roller

[Figure 1] schematically shows the structure of the transport control device. [Figure 2] is a functional block diagram of the motor control device. [Figure 3] shows a specific example of the speed correction amount for the reference speed command. [Figure 4] shows a specific example of the speed correction amount for the reference speed command. [Figure 5] shows a specific example of the torque correction amount for the reference torque command. [Figure 6] shows a modified example of the torque correction amount generating unit.

4: Motor

10: Motor control device

11: Drive unit

12: Control Department

41: Rotational position detector

111: Speed correction value generation unit

112: Speed correction adder

113: Rotary position differentiator

114: Speed reducer

115: Speed deviation conversion unit

116: Torque correction amount generation unit

117: Torque correction adder

118: Torque reducer

119: Torque deviation conversion unit

121: Reference speed instruction generation unit

Claims (6)

A motor control device comprises: a control unit having a reference speed command generating unit for generating a reference speed command for a motor generating a rotational force; and a drive unit having a speed correction value generating unit for generating a speed correction value for the reference speed command, a speed subtractor for calculating a speed deviation by subtracting the reference speed command corrected by the speed correction value from the speed of the motor measured, and converting the speed deviation into A speed deviation conversion unit for the base torque command of the motor, a torque correction amount generation unit for generating a torque correction amount for the base torque command, a torque subtractor for calculating a torque deviation by subtracting the base torque command corrected by the torque correction amount and the torque of the motor measured, and a torque deviation conversion unit for converting the torque deviation into an applied electric force for the motor, and the processing cycle is shorter than the processing cycle in the control unit. A motor control device as claimed in claim 1, wherein the speed correction amount generating unit generates the speed correction amount according to a predetermined pattern corresponding to the rotational position of the motor. A motor control device as claimed in claim 1 or 2, wherein the torque correction amount generating unit generates the torque correction amount according to a predetermined pattern corresponding to the speed of the motor. A motor control device as claimed in claim 1 or 2, wherein the torque correction amount generating unit comprises: a speed deviation differentiator for differentiating the speed deviation to calculate the acceleration deviation; and an acceleration compensation gain multiplier for multiplying the acceleration deviation by the acceleration compensation gain to calculate the torque correction amount. A motor control method comprises: a reference speed command generating step executed in a control unit to generate a reference speed command for a motor generating a rotational force; and a speed correction amount generating step executed in a driving unit having a processing cycle shorter than that in the control unit, namely, generating a speed correction amount for the reference speed command, and performing a subtraction operation on the reference speed command corrected by the speed correction amount and the speed of the motor measured to calculate the speed correction amount. A speed subtraction operation step of obtaining a speed deviation, a speed deviation conversion step of converting the speed deviation into a reference torque command of the motor, a torque correction amount generation step of generating a torque correction amount for the reference torque command, a torque subtraction operation step of calculating a torque deviation by subtracting the reference torque command and the torque of the motor measured by correcting the reference torque command with the torque correction amount, and a torque deviation conversion step of converting the torque deviation into an applied electric force for the motor. A motor control program causes a computer to execute: a reference speed command generation step executed in a control unit to generate a reference speed command for a motor that generates a rotational force; and a speed correction amount generation step executed in a drive unit having a processing cycle shorter than that in the control unit, that is, a speed correction amount generation step for generating a speed correction amount for the reference speed command, and a speed correction amount for correcting the reference speed command with the speed correction amount and a speed of the motor measured by performing a subtraction operation. A speed subtraction operation step for calculating a speed deviation, a speed deviation conversion step for converting the speed deviation into a reference torque command of the motor, a torque correction amount generation step for generating a torque correction amount for the reference torque command, a torque subtraction operation step for calculating a torque deviation by subtracting the reference torque command and the torque of the motor measured by correcting the reference torque command with the torque correction amount, and a torque deviation conversion step for converting the torque deviation into an applied electric force for the motor.

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