External force estimation device, method, and non-transitory computer-readable recording medium

Abstract

An external force estimation device, method, and non-transitory computer-readable recording medium estimate an external force acting on a motor. The external force estimation device includes a processor. The processor is configured to calculate an output torque of the motor using a current value supplied to the motor, estimate an inertial torque of the motor using rotational position information of the motor, estimate a first friction torque of the motor using the rotational position information of the motor, temperature-correct the first friction torque using temperature information of the motor, and estimate the external force by subtracting the inertial torque and the temperature-corrected first friction torque from the output torque.

Description

Technical Field

[0001] This invention relates to an external force estimation device, an external force estimation method, and a non-transient computer-readable recording medium. Background Technology

[0002] In feedback control systems, disturbance observers are used to suppress the effects of disturbances and stabilize the control system. For example, Japanese Patent Application Publication No. 2020-035394 discloses a disturbance observer that calculates the torque constant based on the motor's temperature information and estimates the frictional torque and inertial torque generated by Coulomb friction and viscous resistance based on the motor's position information, thereby estimating the disturbance. Summary of the Invention

[0003] To ensure smooth load operation via a motor, improved motor control precision is required. This necessitates accurately estimating the external force acting on the motor. Furthermore, accurate estimation of the external force is crucial for achieving adaptive and gentle control that responds to the external force. However, the value of frictional torque generated by Coulomb friction, viscous friction, etc., varies with temperature, making it difficult to accurately estimate the external force using the method described in Japanese Patent Application Laid-Open No. 2020-035394, which relies solely on temperature information in the calculation of the torque constant.

[0004] The present invention provides an external force estimation device, an external force estimation method, and a non-transient computer-readable recording medium that can reduce the error of the estimated external force.

[0005] One technical solution of the present invention relates to an external force estimation device that estimates the external force acting on a motor.

[0006] The external force estimation device includes a processor.

[0007] The processor is configured as follows:

[0008] The output torque of the motor is calculated using the current value supplied to the motor.

[0009] The rotational position information of the motor is used to estimate the inertial torque of the motor.

[0010] The first frictional torque of the motor is estimated using the rotational position information of the motor.

[0011] The temperature information of the motor is used to perform temperature correction on the first friction torque.

[0012] The external force is estimated by subtracting the inertial torque and the temperature-corrected first frictional torque from the output torque.

[0013] One technical solution of the present invention relates to a method for estimating external forces acting on a motor, the method comprising:

[0014] The output torque of the motor is calculated using the current value supplied to the motor;

[0015] The rotational position information of the motor is used to estimate the inertial torque and the frictional torque of the motor.

[0016] The estimated friction torque is corrected using the motor's temperature information; and

[0017] The external force is estimated by subtracting the inertial torque and the temperature-corrected frictional torque from the output torque.

[0018] One technical solution of the present invention relates to a non-transitory computer-readable recording medium storing a program.

[0019] When the program is executed by the processor of the external force estimation device, which is estimated to act on the motor, the external force estimation device performs the following processing:

[0020] The output torque of the motor is calculated using the current value supplied to the motor.

[0021] The rotational position information of the motor is used to estimate the inertial torque and the frictional torque of the motor.

[0022] The estimated friction torque is corrected using the temperature information of the motor.

[0023] The external force is estimated by subtracting the inertial torque and the temperature-corrected frictional torque from the calculated output torque.

[0024] One technical solution of the present invention relates to an external force estimation device that uses the motor's temperature information to perform temperature correction on the friction torque. Therefore, the external force estimation device according to one technical solution of the present invention can correct for variations in friction torque associated with temperature changes, and can reduce the error in the estimated external force.

[0025] According to the present invention, an external force estimation device, an external force estimation method, and a non-transient computer-readable recording medium are provided that can reduce the error of the estimated external force. Attached Figure Description

[0026] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and wherein:

[0027] Figure 1This is a schematic diagram showing the configuration of the motor and load according to the first embodiment.

[0028] Figure 2 This is a diagram illustrating an example of the overall configuration of the control system according to the first embodiment.

[0029] Figure 3 This is a diagram illustrating an example of the overall configuration of the control system according to the first embodiment.

[0030] Figure 4 This is a diagram showing the configuration of the external force estimation device according to the first embodiment.

[0031] Figure 5 This is a flowchart illustrating the operation of the external force estimation device according to the first embodiment.

[0032] Figure 6 This is a schematic diagram showing the configuration of the motor and load according to the second embodiment.

[0033] Figure 7 This is a diagram showing the configuration of the external force estimation device according to the second embodiment.

[0034] Figure 8 This is a flowchart illustrating the operation of the external force estimation device according to the second embodiment.

[0035] Figure 9 This is a diagram illustrating examples of the hardware configuration of the control unit according to the first and second embodiments. Detailed Implementation

[0036] Hereinafter, specific embodiments in which the present invention is applied will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. Furthermore, for clarity of description, the following description and drawings have been appropriately simplified. Figure 1 , Figure 6 The right-handed xyz orthogonal coordinate system shown is a suitable coordinate system for illustrating the positional relationships of the constituent elements. Typically, the positive z-axis points vertically upwards, and the xy plane is horizontal.

[0037] <First Embodiment>

[0038] Figure 1 This is a schematic diagram illustrating the configuration of the motor and load according to the first embodiment. The configuration of the motor and load is, for example, used in the joints of a robot. Figure 1 Motor 1 is connected to load 3 via gear 2. Motor 1 can actuate load 3 via gear 2. In addition, motor 1 is mounted on fixed part 4.

[0039] The load 3 and the fixing part 4 are, for example, frames that constitute the robot's arms, legs, etc. The load 3 is, for example, a frame provided on the front end side of the robot, and the fixing part 4 is, for example, a frame connected to the main body side of the robot. The motor 1 operates based on the control of the control unit 21 of the control unit 20, which will be described later. The motor 1 is, for example, a servo motor.

[0040] The rotational motion of motor 1 is transmitted to load 3 via gear 2. For simplicity, the following explanation will focus on the case where the position of the fixing part 4 is fixed. However, the position of the fixing part 4 can also be changed in conjunction with the robot's movements.

[0041] Load 3 rotates in the yz plane. When the rotation direction of motor 1 is changed, the direction of movement (rotation direction) of load 3 is changed. Furthermore, by changing the number and size of gears 2, load 3 can move in any direction and at any rotational speed (angular velocity). The speed of load 3 changes according to the rotational speed of motor 1. Specifically, as the rotational speed of motor 1 increases, the speed of load 3 also increases. Similarly, as the rotational speed of motor 1 decreases, the speed of load 3 also decreases.

[0042] Figure 2 This is a diagram showing the overall configuration of the control system 100 according to the first embodiment. To control the motor 1, the following is used... Figure 2 The control system 100 shown has an instruction unit 10 and a control unit 20. The instruction unit 10 and the control unit 20 are, for example, computer devices. Furthermore, each process related to the instruction unit 10 and the control unit 20 can also be executed by its own independent computer device. Figure 1 As described above, the motor 1 actuates the load 3 via the gear 2. The motor 1 is equipped with a current detection unit 11, a position detection unit 12, and a temperature detection unit 13. Furthermore, the control system 100 may also have other components necessary for operation.

[0043] The command unit 10 sends commands to the control unit 20 to control the motor 1. The control unit 20 controls the motor 1 based on the commands from the command unit 10. There can be multiple control units 20, for example, they can be individually installed on the joints of the robot, such as arms or legs. That is, the control unit 20 can also be installed on each motor that moves each joint. In this case, the command unit 10 can control the movement of multiple joints of the robot individually by sending motor control commands to multiple control units 20.

[0044] The control unit 20 includes a control unit 21 and an external force estimation device 22. The control unit 21 controls the motor 1 based on control commands from the command unit 10. The external force estimation device 22 is a device for estimating the external force acting on the motor. The control unit 21 and the external force estimation device 22 are, for example, computer devices. Furthermore, each process related to the control unit 21 and the external force estimation device 22 can also be executed by its own independent computer device.

[0045] The external force estimation device 22 is connected to the current detection unit 11, the position detection unit 12, and the temperature detection unit 13, respectively. The external force estimation device 22 uses the current value of the motor 1 obtained by the current detection unit 11, the rotational position information of the motor 1 obtained by the position detection unit 12, and the temperature information of the motor 1 obtained by the temperature detection unit 13 to estimate the external force acting on the motor 1. Here, the external force is a force (reaction force) related to the load 3, which acts on the motor 1 via the load 3. The external force estimation device 22 outputs the estimated external force to the command unit 10. In the case where multiple control units 20 are provided, multiple external force estimation devices 22 output their respective estimated external forces to the command unit 10. The detailed configuration of the external force estimation device 22 will be described later.

[0046] The current detection unit 11 is a device that detects the value of the current supplied to the motor 1. The current detection unit 11 is, for example, a current sensor. The current detection unit 11 can be installed at any position that can detect the current of the motor 1. The current value obtained by the current detection unit 11 is input to the external force estimation device 22.

[0047] The position detection unit 12 is a device for detecting the rotational position of the motor 1. The position detection unit 12 is, for example, an encoder installed on the motor 1. It can calculate the angular velocity, angular acceleration, and rotation angle of the motor 1 based on the rotational position information of the motor 1. The rotational position information obtained by the position detection unit 12 is input to the external force estimation device 22.

[0048] Temperature detection unit 13 is a device for detecting the temperature of motor 1. Temperature detection unit 13 is, for example, a temperature sensor. Temperature detection unit 13 can be installed at any location where the temperature of motor 1 can be detected. The temperature information obtained by temperature detection unit 13 is input to external force estimation device 22.

[0049] The command unit 10 controls the motor 1 via the control unit 21 using the external force estimated by the external force estimation device 22. This improves the accuracy of motor control and enables the load 3 to operate smoothly. For example, the command unit 10 uses the direction of the external force estimated by the external force estimation device 22 to move the load 3 in a direction that eliminates the effect of the external force, thereby achieving smooth operation of the load 3. Furthermore, the command unit 10 increases the moving speed or acceleration of the load 3 in the direction of the external force estimated by the external force estimation device 22 based on the magnitude of the external force, thereby achieving a smooth and adaptive movement corresponding to the external force on the load 3. The command unit 10 can also control multiple motors using multiple external forces estimated by multiple external force estimation devices 22 provided in multiple control units 20 to ensure smooth operation of the entire load.

[0050] In addition, such as Figure 3 As shown, the external force estimation device 22 can also output the estimated external force to the control unit 21. The control unit 21 can also obtain the external force estimated by the external force estimation device 22, and based on the command of the command unit 10, use the direction of the obtained external force to move the load 3 in the direction that eliminates the influence of the external force, thereby realizing the smooth operation of the load 3. In addition, the control unit 21 can also increase the moving speed or moving acceleration of the load 3 in the direction of the external force based on the magnitude of the external force obtained by the external force estimation device 22, thereby realizing a smooth operation that is adaptive to the external force of the load 3.

[0051] In addition, the external force estimation device 22 can also output the estimated external force to both the command unit 10 and the control unit 21.

[0052] <Composition of the External Force Estimation Device>

[0053] Figure 4 This is a block diagram showing the configuration of the external force estimation device 22 according to the first embodiment. The external force estimation device 22 includes a torque calculation unit 23, an inertial torque estimation unit 24, a friction torque estimation unit 25, a temperature correction unit 26, and an external force estimation unit 27. In addition, the external force estimation device 22 may also have other components required for operation.

[0054] The torque calculation unit 23 calculates the output torque of the motor 1 using the current value supplied to the motor 1. The torque calculation unit 23 obtains the current value detected by the current detection unit 11 and calculates the product of the current value and the torque constant of the motor 1, thereby calculating the output torque of the motor 1.

[0055] The inertial torque estimation unit 24 uses the rotational position information of the motor 1 to estimate the inertial torque of the motor 1. Specifically, the inertial torque estimation unit 24 derives the angular acceleration of the motor 1 based on the rotational position information of the motor 1, and calculates the product of this angular acceleration and the moment of inertia of the motor 1, thereby estimating the inertial torque. Furthermore, by measuring the output torque of the motor 1 when it rotates at a constant angular acceleration for multiple angular accelerations, and deriving the proportional relationship between the angular acceleration and the output torque, the moment of inertia can be calculated. Alternatively, the moment of inertia can also be calculated using values ​​derived from the load design drawing.

[0056] The inertial torque estimation unit 24 can also use the results of inverse dynamics calculations to estimate the inertial torque of the motor 1. Inverse dynamics calculations are methods for calculating the torque required to actuate the load based on angular velocity and angular acceleration.

[0057] The friction torque estimation unit 25 uses the rotational position information of the motor 1 to estimate the friction torque of the motor 1. The method for estimating the friction torque will be explained below. First, when the angular velocity of the motor 1 is constant, the motor output torque is equal to the friction torque when no external force is applied. Furthermore, the friction torque varies depending on the rotational speed of the motor 1. Therefore, by calculating the average current value of the load 3 rotating at a constant speed for one revolution and multiplying the current value by a torque constant, the motor output torque at a predetermined motor speed, i.e., the friction torque, can be derived. By changing the rotational speed of the motor 1 while obtaining the current value, a friction torque value corresponding to the speed change can be obtained. The friction torque estimation unit 25 can estimate the friction torque at the rotational speed of the motor 1 based on the rotational speed calculated from the rotational position information of the motor 1 and the pre-derived correspondence between the rotational speed of the motor 1 and the friction torque.

[0058] Friction torque can include at least one of Coulomb friction torque and viscous friction torque. The friction torque estimation unit 25 can estimate the Coulomb friction torque and viscous friction torque using the angular velocity calculated based on the rotational position information of the motor 1. Specifically, the friction torque estimation unit 25 derives the Coulomb friction torque and the viscous friction coefficient from two steady states, and multiplies the viscous friction coefficient by the angular velocity of the motor 1, thereby deriving the Coulomb friction torque and viscous friction torque respectively. Here, the steady state is the state where the angular velocity of the motor 1 is constant.

[0059] The temperature correction unit 26 uses the temperature information from the motor 1 to perform temperature correction on the friction torque. The temperature correction unit 26 derives a predetermined correspondence between temperature and friction torque. Using this correspondence and the temperature represented by the temperature information obtained by the temperature detection unit 13, the temperature correction unit 26 performs temperature correction on the friction torque estimated by the friction torque estimation unit 25.

[0060] For example, by rotating motor 1 at a first speed under no-load conditions and measuring the current value while changing the temperature, the correspondence between the current value at the first speed and the temperature change can be derived. Then, by rotating motor 1 at a second speed different from the first speed and measuring the current value while changing the temperature, the correspondence between the current value at the second speed and the temperature change can be derived.

[0061] By determining the relationship between the first rotational speed and the current value at a predetermined temperature, and the relationship between the second rotational speed and the current value, the corresponding relationship between the rotational speed and the current value of motor 1 at the predetermined temperature can be determined. Here, the friction torque estimation unit 25 can estimate the friction torque before temperature correction based on the rotational speed of motor 1. In addition, the product of the current value at the predetermined temperature and the torque constant of motor 1 becomes the value of the friction torque based on temperature changes.

[0062] Based on the above, the temperature correction unit 26 can perform temperature correction using the following formula, which is a linear approximation of the relationship between the friction torque before temperature correction and the friction torque after temperature correction at a predetermined temperature.

[0063] [Number 1]

[0064] y = ax + b

[0065] y: Friction torque after temperature correction

[0066] x: Friction torque before temperature correction

[0067] a: Coefficient at the predetermined temperature

[0068] b: Coefficient at the predetermined temperature

[0069] For example, when the temperature detected by the temperature detection unit 13 is the first temperature, the temperature correction unit 26 can estimate the friction torque after temperature correction by substituting the friction torque before temperature correction estimated by the friction torque estimation unit 25 into x for the equation y = a1x + b1 (where a1 and b1 are coefficients at the first temperature).

[0070] Similarly, when the temperature detected by the temperature detection unit 13 is the second temperature, the temperature correction unit 26 can estimate the friction torque after temperature correction by substituting the friction torque before temperature correction estimated by the friction torque estimation unit 25 into x, based on the corresponding relationship y = a2x + b2 (where a2 and b2 are coefficients at the second temperature). At temperatures other than the first and second temperatures described above, the coefficients can also be obtained, for example, by polynomial interpolation, based on the previously explained relationship between the current value measured while changing the temperature and the temperature change. Furthermore, although the temperature correction unit 26 corrects the friction torque based on temperature as described above, the effect of temperature-based correction can also be included in the friction torque estimation unit 25, calculating and utilizing the friction torque that changes according to temperature. This is because, when the friction torque is expressed in terms of Coulomb friction torque and viscous friction torque, the Coulomb friction coefficient and viscosity coefficient change according to temperature.

[0071] As described above, the temperature correction unit 26 can use the temperature information obtained by the temperature detection unit 13 to perform temperature correction of the friction torque.

[0072] The external force estimation unit 27 estimates the external force by subtracting the inertial torque and the temperature-corrected friction torque from the output torque calculated by the torque calculation unit 23. The external force estimation unit 27 outputs the estimated external force to the command unit 10.

[0073] Based on the above, the external force estimation device 22 according to the first embodiment can correct for variations in frictional torque based on temperature changes, and can reduce the error of the estimated external force. The external force estimation device 22 according to the first embodiment can improve the accuracy of motor control.

[0074] exist Figure 2 In the external force estimation device 22 shown in the first embodiment, the estimated external force is output to the command unit 10, which is located above the control unit 21. The command unit 10 can control the motor 1 via the control unit 20 according to the direction and magnitude of the external force, so that the load 3 can operate smoothly.

[0075] Furthermore, when the acceleration of load 3 is close to zero and the inertia of load 3 is sufficiently small, the influence of the inertial torque becomes extremely small, so the external force estimation unit 27 can also set the value of the inertial torque to zero to estimate the external force.

[0076] <External Force Estimation Method>

[0077] use Figure 5 The method for estimating external forces according to the first embodiment will be described. Figure 5 This is a flowchart illustrating the operation of the external force estimation device 22 according to the first embodiment.

[0078] The torque calculation unit 23 calculates the output torque of the motor 1 using the current value of the motor 1 obtained by the current detection unit 11 (step S1). The inertial torque estimation unit 24 estimates the inertial torque of the motor 1 using the rotational position information of the motor 1 obtained by the position detection unit 12 (step S2). Furthermore, as described above, the inertial torque estimation unit 24 can also estimate the inertial torque of the motor 1 using the results of inverse dynamics calculations. As a result, the effects of gravity, centrifugal force, and Coriolis force can also be taken into account, further improving the accuracy.

[0079] The friction torque estimation unit 25 estimates the friction torque based on the rotational position information obtained by the position detection unit 12 (step S3). The temperature correction unit 26 uses the temperature information obtained by the temperature detection unit 13 to perform temperature correction on the friction torque estimated by the friction torque estimation unit 25 (step S4). Furthermore, the temperature correction method can be performed using the method described above.

[0080] The external force estimation unit 27 estimates the external force by subtracting the inertial torque estimated by the inertial torque estimation unit 24 and the temperature-corrected frictional torque from the output torque calculated by the torque calculation unit 23 (step S5). Then, the external force estimation unit 27 outputs the estimated external force to the command unit 10. Furthermore, the order of steps S1 to S3 is not limited to this and can be arbitrary.

[0081] As described above, the external force estimation device 22 according to the first embodiment can correct for variations in frictional torque based on temperature changes, and can reduce the error of the estimated external force. The external force estimation device 22 according to the first embodiment can improve the accuracy of motor control and enable smooth load operation.

[0082] <Second Implementation>

[0083] Figure 6 This is a schematic diagram illustrating the configuration of the motor and load according to the second embodiment. Figure 1 The gear configuration is shown in more detail. Motor 1 actuates load 3 via gears 5 and 6. Furthermore, although in Figure 6 For the sake of simplicity, the number of gears is set to 2, but for gears 5 and 6, any number and any size can be set.

[0084] The rotation angle Θ1 of motor 1 is the angle of motor 1 in the rotation direction. The rotation angle Θ2 of load 3 is the angle of load 3 in the rotation direction. The rotation angle Θ1 of motor 1 is detected by the position detection unit 12 provided on motor 1. The rotation angle Θ2 of load 3 can be calculated based on the rotation angle Θ1 of motor 1 detected by the position detection unit 12 and the gear ratio. Alternatively, a position detection unit can be further provided on the load 3 side to detect the rotation angle Θ2 of load 3.

[0085] <Composition of the External Force Estimation Device>

[0086] Figure 7 This is a block diagram showing the configuration of the external force estimation device 30 according to the second embodiment. The external force estimation device 30 according to the second embodiment includes a torque calculation unit 23, an inertial torque estimation unit 24, a friction torque estimation unit 25, a temperature correction unit 26, an external force estimation unit 27, a motor angle-friction variation table 28, and a load angle-friction variation table 29. Compared to the external force estimation device 22 according to the first embodiment, the external force estimation device 30 according to the second embodiment adds the motor angle-friction variation table 28 and the load angle-friction variation table 29. Furthermore, in the external force estimation device 30 according to the second embodiment, the same reference numerals are used for the same components as in the external force estimation device 22 according to the first embodiment, and detailed descriptions are appropriately omitted.

[0087] Motor angle-friction variation table 28 is a table that stores the correspondence between the rotation angle Θ1 of motor 1 and the friction torque that varies according to that rotation angle Θ1. In other words, motor angle-friction variation table 28 stores the value of the amount of friction torque variation corresponding to the rotation angle Θ1 of motor 1.

[0088] The motor angle-friction variation table 28 can be made by the following steps: obtaining the current value when the motor 1 rotates 1 revolution, dividing the interval according to the rotation angle Θ1 of the motor 1, averaging the current values ​​of the divided intervals and averaging the current values ​​of 1 revolution, and multiplying the result obtained by subtracting the average value of 1 revolution from the average current value of the divided intervals by the torque constant, thereby making the motor angle-friction variation table 28.

[0089] Table 1 is an example of motor angle-friction variation table 28.

[0090] Table 1

[0091]

[0092] The friction torque corresponding to the rotation angle Θ1 of the motor 1 is estimated using the motor angle-friction variation table 28. The external force estimation unit 27 can estimate the external force by subtracting the inertial torque, the temperature-corrected friction torque, and the friction torque estimated using the motor angle-friction variation table 28 from the output torque calculated by the torque calculation unit 23. The external force estimation device 30 can compensate for the influence of the friction torque corresponding to the rotation angle Θ1 of the motor 1 by using the motor angle-friction variation table 28, thereby reducing the estimation error of the external force.

[0093] Load Angle-Friction Variation Table 29 is a table that stores the correspondence between the rotation angle Θ2 of the load 3 and the frictional torque that varies according to that rotation angle Θ2. In other words, the load angle-friction variation table 29 stores the value of the amount of frictional torque variation corresponding to the rotation angle Θ2 of the load 3.

[0094] The load angle-friction variation table 29 can be made by the following steps: obtaining the current value when the load 3 rotates 1 revolution, dividing the load 3 into intervals according to the rotation angle Θ2, averaging the current values ​​of the divided intervals and averaging the current values ​​of 1 revolution, and multiplying the result obtained by subtracting the average value of 1 revolution from the average current value of the divided intervals by the torque constant, thereby making the load angle-friction variation table 29.

[0095] Table 2 is an example of load angle-friction variation table 29.

[0096] Table 2

[0097]

[0098] The external force estimation device 30 can estimate the friction torque corresponding to the rotation angle Θ2 of the load 3 using the load angle-friction variation table 29. The external force estimation unit 27 can estimate the external force by subtracting the inertial torque, the temperature-corrected friction torque, and the friction torque estimated using the load angle-friction variation table 29 from the output torque calculated by the torque calculation unit 23. By using the load angle-friction variation table 29, the external force estimation device 30 can compensate for the influence of the friction torque corresponding to the rotation angle Θ2 of the load 3, thereby reducing the estimation error of the external force.

[0099] Furthermore, the external force estimation unit 27 can also estimate the external force by subtracting the inertial torque, the temperature-corrected friction torque, the friction torque estimated using the motor angle-friction variation table 28, and the friction torque estimated using the load angle-friction variation table 29 from the output torque calculated by the torque calculation unit 23. By using the motor angle-friction variation table 28 and the load angle-friction variation table 29, the external force estimation device 30 can compensate for the influence of the friction torque corresponding to the rotation angle Θ1 of the motor 1 and the friction torque corresponding to the rotation angle Θ2 of the load 3, and can further reduce the estimation error of the external force.

[0100] <External Force Estimation Method>

[0101] use Figure 8 The method for estimating external forces involved in the second embodiment will be described. Figure 8 This is a flowchart illustrating the operation of the external force estimation device 30 according to the second embodiment. Furthermore, Figure 8 Steps S11 to S14 and Figure 5Steps S1 to S4 are the same, so the explanation is omitted.

[0102] The friction torque is estimated using the rotation angle Θ1 of the motor 1 obtained by the position detection unit 12 and the motor angle-friction variation table 28 (step S15). The friction torque is estimated using the rotation angle Θ2 of the load 3 calculated based on the rotation angle Θ1 of the motor 1 and the gear ratio, and the load angle-friction variation table 29 (step S16). Furthermore, the order of steps S15 and S16 is not limited to this and can be any order.

[0103] The external force estimation unit 27 estimates the external force by subtracting the inertial torque, the temperature-corrected friction torque, the friction torque estimated using the motor angle-friction variation table 28, and the friction torque estimated using the load angle-friction variation table 29 from the output torque calculated by the torque calculation unit 23 (step S17). The external force estimation unit 27 outputs the estimated external force to the command unit 10.

[0104] As described above, the external force estimation device 30 according to the second embodiment can not only correct for variations in frictional torque based on temperature changes, but also estimate the external force based on the influence of frictional torque corresponding to the rotation angle Θ1 of the motor 1 and the rotation angle Θ2 of the load 3. Therefore, the external force estimation device 30 according to the second embodiment can reduce the error in the estimated external force and improve the accuracy of the estimated value of the external force acting on the motor 1. The external force estimation device 30 according to the second embodiment can improve the accuracy of motor control and enable smooth load operation.

[0105] Furthermore, the external force estimation device 30 according to the second embodiment can reduce the influence of the cogging torque generated based on the rotation angle Θ1 of the motor 1 by using the motor angle-friction variation table 28, and thus can compensate for the cogging torque that usually exists at about 5% relative to the rated output torque of the motor.

[0106] use Figure 9 Examples of the hardware configuration of the control unit 20 according to the first and second embodiments will be described. Furthermore, the instruction unit 10 may also have the same hardware configuration as the control unit 20. Additionally, the control unit 21, the external force estimation device 22, and the external force estimation device 30 may also be... Figure 9 The hardware configuration is shown. In Figure 9In this configuration, the control unit 20 includes a processor 101 and a memory 102. The processor 101 may be, for example, a microprocessor, an MPU (Micro Processing Unit), or a CPU (Central Processing Unit). The processor 101 may also include multiple processors. The memory 102 consists of a combination of volatile and non-volatile memory. The memory 102 may also include a storage device configured separately from the processor 101. In this case, the processor 101 can access the memory 102 via an input / output interface (not shown).

[0107] Furthermore, the devices in the above embodiments are composed of hardware or software, or both hardware and software; they can be composed of one piece of hardware or software, or multiple pieces of hardware or software. The functions (processing) of the devices in the above embodiments can also be implemented by a computer. For example, the functions can be implemented by storing a program for performing the actions in the embodiments in memory 102, and by having the processor 101 execute the program stored in memory 102.

[0108] The program involved in this embodiment is an external force estimation program for estimating the external force acting on a motor. The external force estimation program is used to enable a computer to perform the following processes: calculate the output torque of the motor using the current value supplied to the motor, estimate the inertial torque and friction torque of the motor using the rotational position information of the motor, perform temperature correction on the estimated friction torque using the temperature information of the motor, and estimate the external force by subtracting the inertial torque and the temperature-corrected friction torque from the calculated output torque.

[0109] The program includes a set of commands (or software code) for causing the computer to perform one or more functions described in the embodiments, when read by the computer. The program may also be stored on a non-transitory computer-readable medium or a physical storage medium. Examples, not intended to be limiting, of computer-readable media or physical storage media include random access memory (RAM), read-only memory (ROM), flash memory, solid-state drives (SSDs) or other storage technologies, CD-ROMs, digital video optical discs (DVDs), Blu-ray discs or other optical disc storage devices, magnetic tape cassettes, magnetic tapes, disk storage devices, or other magnetic storage devices. The program may also be transmitted on a transient computer-readable medium or communication medium. Examples, not intended to be limiting, of transient computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0110] The external force estimation device 22 and external force estimation device 30 involved in this embodiment can be applied not only to robots such as partner robots, collaborative robots, auxiliary robots, and service robots, but also to sensorless power steering technology and automatic door opening and closing technology in automobiles.

[0111] Furthermore, the present invention is not limited to the above-described embodiments, and appropriate modifications can be made without departing from the spirit of the invention.

Claims

1. An external force estimation device for estimating an external force acting on a motor, characterized in that, Equipped with a processor The processor is configured such that, The output torque of the motor is calculated using the current value supplied to the motor. The rotational position information of the motor is used to estimate the inertial torque of the motor. The first frictional torque of the motor is estimated using the rotational position information of the motor. The temperature information of the motor is used to perform temperature correction on the first friction torque. The motor actuates the load via gears. The processor is configured such that, The second friction torque is estimated based on the correspondence between the motor's rotation angle and the second friction torque that varies according to the rotation angle. The third friction torque is estimated based on the correspondence between the rotation angle of the load and the third friction torque that varies according to the rotation angle. The external force is estimated by subtracting the inertial torque, the temperature-corrected first friction torque, the second friction torque, and the third friction torque from the output torque.

2. The external force estimation device according to claim 1, characterized in that, The first frictional torque includes at least one of Coulomb frictional torque and viscous frictional torque.

3. The external force estimation device according to claim 1 or 2, characterized in that, The processor is configured to use the results of inverse dynamics calculations to estimate the inertial torque of the motor.

4. A method for estimating an external force, wherein the external force acting on a motor is estimated, the motor causing a load to move via gears, the method being characterized by comprising: The output torque of the motor is calculated using the current value supplied to the motor; The rotational position information of the motor is used to estimate the inertial torque of the motor and the first frictional torque of the motor. The temperature information of the motor is used to perform temperature correction on the first frictional torque; The second friction torque is estimated based on the correspondence between the rotation angle of the motor and the second friction torque that varies according to the rotation angle; The third friction torque is estimated based on the correspondence between the rotation angle of the load and the third friction torque that varies according to the rotation angle; and The external force is estimated by subtracting the inertial torque, the temperature-corrected first friction torque, the second friction torque, and the third friction torque from the output torque.

5. A non-transient computer-readable recording medium storing a program that, when executed by a processor of an external force estimation device assuming an external force acting on a motor, causes the external force estimation device to perform processing, wherein the motor actuates a load via gears. The process includes: The output torque of the motor is calculated using the current value supplied to the motor; The rotational position information of the motor is used to estimate the inertial torque of the motor and the first frictional torque of the motor. The temperature information of the motor is used to perform temperature correction on the first frictional torque; The second friction torque is estimated based on the correspondence between the rotation angle of the motor and the second friction torque that varies according to the rotation angle; The third friction torque is estimated based on the correspondence between the rotation angle of the load and the third friction torque that varies according to the rotation angle; and The external force is estimated by subtracting the inertial torque, the temperature-corrected first friction torque, the second friction torque, and the third friction torque from the output torque.

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