Vibration control device, vibration control method, and vibration control program

Abstract

The present invention provides a vibration control device, a vibration control method, and a vibration control program that compensate for rotational non-uniformity caused by the effects of angular transmission errors in the reduction mechanism. [Solution] The vibration damping control device is applied to a servo control system equipped with a reduction mechanism and is a vibration damping control device that compensates for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, and includes an angular transmission error compensator that has a predetermined compensation order, amplitude and phase and generates a sinusoidal compensation signal based on position information, and an adder that adds the compensation signal to a position command, speed command, current command, or a control signal related thereto, wherein the angular transmission error compensator corrects the compensation signal by referring to a compensation model that corrects the amplitude and phase based on speed information.

Description

Technical Field

[0001] The present disclosure relates to a vibration control device, a vibration control method, and a vibration control program, and particularly relates to a technique for compensating for an angular transmission error of a speed reduction mechanism.

Background Art

[0002] In recent years, in high-precision servo control systems such as robots and machine tools, actuators using motors and small and high-precision speed reduction mechanisms, particularly harmonic gear devices and planetary gear mechanisms, have been adopted. These speed reduction mechanisms achieve both a high reduction ratio and miniaturization. However, it is known that due to structural tooth profile errors, assembly errors, etc., a deviation in the rotation angle called an angular transmission error occurs. The angular transmission error is the difference between the theoretically calculated rotation output angle and the actual rotation output angle when a rotational input is applied to the speed reduction mechanism, and it is periodically repeated with respect to the rotational input. In particular, an angular transmission error including a periodic vibration component accompanying the rotation of the motor appears as rotational non-uniformity (rotation unevenness, undulation, speed fluctuation, etc.) on the output shaft, causing deterioration in the motion accuracy, trajectory accuracy, etc. of the robot or device. Such a phenomenon is known as a vibration phenomenon caused by the angular transmission error. In compensating for rotational non-uniformity (vibration phenomenon), generally, a compensation signal is used to adjust the rotational input to the speed reduction mechanism so as to cancel the periodic angular transmission error with respect to the motor rotation position (that is, to make the error of the rotational output of the speed reduction mechanism approach zero) (see, for example, Patent Document 1). Also, as in Patent Document 2, there are known methods of adding correction to the motor speed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technologies described in Patent Documents 1 and 2, various factors can make it difficult to determine (or identify, estimate) appropriate parameters or to achieve sufficient compensation.

[0005] This disclosure is made in view of the above circumstances and aims to provide a vibration control device, a vibration control method, and a vibration control program that compensate for rotational non-uniformity caused by the influence of angular transmission errors in the reduction mechanism. [Means for solving the problem]

[0006] A first aspect of this disclosure is a vibration control device applied to a servo control system equipped with a reduction mechanism, which compensates for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, comprising: an angular transmission error compensator that generates a sinusoidal compensation signal based on position information having a predetermined compensation order, amplitude, and phase; and an adder that adds the compensation signal to a position command, speed command, current command, or a control signal related thereto, wherein the angular transmission error compensator corrects the compensation signal by referring to a compensation model that corrects the amplitude and phase based on speed information.

[0007] A second aspect of the present disclosure is a vibration damping control method applied to a servo control system equipped with a reduction mechanism, for compensating for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, wherein a computer performs the following actions: generates a sinusoidal compensation signal having a predetermined compensation order, amplitude, and phase based on position information; adds the compensation signal to a position command, speed command, current command, or a control signal related thereto; and corrects the compensation signal by referring to a compensation model that corrects the amplitude and phase based on speed information.

[0008] A third aspect of this disclosure is a vibration damping control program applied to a servo control system equipped with a reduction mechanism, which compensates for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, and which causes a computer to perform the following actions: generate a sinusoidal compensation signal having a predetermined compensation order, amplitude and phase based on position information, add the compensation signal to a position command, speed command, current command, or a control signal related thereto, and correct the compensation signal by referring to a compensation model that corrects the amplitude and phase based on speed information. [Effects of the Invention]

[0009] According to this disclosure, it is possible to compensate for rotational non-uniformity caused by the angular transmission error of the reduction mechanism, and to efficiently design and realize comprehensive suppression of rotational output errors that take various factors into consideration in a variety of systems. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows a schematic diagram of the vibration control system. [Figure 2] Figure 2 shows a first example of the configuration of the control block for dynamic angle transmission error compensation of a vibration control device according to the present disclosure. [Figure 3] Figure 3 shows a second example of the configuration of the control block for dynamic angle transmission error compensation of the vibration control device according to the present disclosure. [Figure 4] Figure 4 shows a third configuration example of the control block for dynamic angle transmission error compensation of the vibration control device according to the present disclosure. [Figure 5] Figure 5 is a control block diagram when the compensator input is used as command information. [Figure 6] Figure 6 shows the response data of the motor speed in a constant speed interval when the motor is operated at a constant speed at multiple operating speeds. [Figure 7] Figure 7 shows the response data of the load speed in a constant speed interval when the system is operated at a constant speed at multiple operating speeds. [Figure 8]Figure 8 shows the order analysis results of the motor speed when the operating speed is 1600 r / min. [Figure 9] Figure 9 shows the order analysis results of the load speed when the operating speed is 1600 r / min. [Figure 10] Figure 10 shows the results of extracting the quadratic component of motor speed at multiple operating speeds. [Figure 11] Figure 11 shows the extraction results of the second-order component of the load velocity at multiple operating speeds. [Figure 12] Figure 12 shows the quadratic component of the motor position under condition A. [Figure 13] Figure 13 shows the second-order component of the load position under condition A. [Figure 14] Figure 14 shows the quadratic component of the motor speed under condition A. [Figure 15] Figure 15 shows the quadratic component of the load velocity under condition A. [Figure 16] Figure 16 shows the quadratic component of the motor position under condition B. [Figure 17] Figure 17 shows the second-order component of the load position under condition B. [Figure 18] Figure 18 shows the quadratic component of the motor speed under condition B. [Figure 19] Figure 19 shows the second-order component of the load velocity under condition B. [Figure 20] Figure 20 shows the quadratic component of the motor position under condition C. [Figure 21] Figure 21 shows the quadratic component of the load position under condition C. [Figure 22] Figure 22 shows the quadratic component of the motor speed under condition C. [Figure 23] Figure 23 shows the quadratic component of the load velocity under condition C. [Figure 24] Figure 24 shows the amplitude characteristics in the frequency response characteristics from angular transmission error to compensation current, and the compensation parameters corresponding to the motor speeds for the number of lookup table values. [Figure 25]Figure 25 shows the phase characteristics in the frequency response characteristics from angular transmission error to compensation current, and the compensation parameters corresponding to the motor speeds for the number of lookup table values. [Figure 26] Figure 26 shows the motor speed under condition D. [Figure 27] Figure 27 shows the load speed under condition D. [Figure 28] Figure 28 shows the motor speed vibration components under condition D. [Figure 29] Figure 29 shows the load velocity oscillation component under condition D. [Figure 30] Figure 30 shows the motor position vibration component under condition D. [Figure 31] Figure 31 shows the load position vibration component under condition D. [Figure 32] Figure 32 shows the motor speed under condition E. [Figure 33] Figure 33 shows the load speed under condition E. [Figure 34] Figure 34 shows the motor speed vibration components under condition E. [Figure 35] Figure 35 shows the load velocity oscillation component under condition E. [Figure 36] Figure 36 shows the motor position vibration component under condition E. [Figure 37] Figure 37 shows the load position vibration component under condition E. [Figure 38] Figure 38 shows the motor speed under condition F. [Figure 39] Figure 39 shows the load speed under condition F. [Figure 40] Figure 40 shows the motor speed vibration components under condition F. [Figure 41] Figure 41 shows the load velocity oscillation component under condition F. [Figure 42] Figure 42 shows the motor position vibration component under condition F. [Figure 43] Figure 43 shows the load position vibration component under condition F. [Figure 44] Figure 44 shows the motor speed under condition G. [Figure 45] Figure 45 shows the load speed under condition G. [Figure 46] Figure 46 shows the motor speed vibration components under condition G. [Figure 47] Figure 47 shows the load velocity vibration component under condition G. [Figure 48] Figure 48 shows the motor position vibration component under condition G. [Figure 49] Figure 49 shows the load position vibration component under condition G. [Figure 50] Figure 50 shows the motor speed under condition H. [Figure 51] Figure 51 shows the load speed under condition H. [Figure 52] Figure 52 shows the motor speed vibration components under condition H. [Figure 53] Figure 53 shows the load velocity vibration component under condition H. [Figure 54] Figure 54 shows the motor position vibration component under condition H. [Figure 55] Figure 55 shows the load position vibration component under condition H. [Figure 56] Figure 56 shows the amplitude characteristics and corresponding compensation parameters in the frequency response characteristics from the angular transmission error to the compensation position. [Figure 57] Figure 57 shows the phase characteristics and corresponding compensation parameters in the frequency response characteristics from the angular transmission error to the compensation position. [Figure 58] Figure 58 shows the motor speed under condition I. [Figure 59] Figure 59 shows the load speed under condition I. [Figure 60] Figure 60 shows the motor speed vibration components under condition I. [Figure 61] Figure 61 shows the load velocity oscillation component under condition I. [Figure 62]Figure 62 shows the motor position vibration component under condition I. [Figure 63] Figure 63 shows the load position vibration component under condition I. [Figure 64] Figure 64 shows the motor speed under condition J. [Figure 65] Figure 65 shows the load speed under condition J. [Figure 66] Figure 66 shows the motor speed vibration components under condition J. [Figure 67] Figure 67 shows the load velocity oscillation component under condition J. [Figure 68] Figure 68 shows the motor position vibration component under condition J. [Figure 69] Figure 69 shows the load position vibration component under condition J. [Figure 70] Figure 70 shows the motor speed under condition K. [Figure 71] Figure 71 shows the load speed under condition K. [Figure 72] Figure 72 shows the motor speed vibration components under condition K. [Figure 73] Figure 73 shows the load velocity oscillation component under condition K. [Figure 74] Figure 74 shows the motor position vibration component under condition K. [Figure 75] Figure 75 shows the load position vibration component under condition K. [Figure 76] Figure 76 shows the error between the motor position and the position command under condition K. [Figure 77] Figure 77 shows the error between the motor position and the approximate motor position under condition K. [Figure 78] Figure 78 shows the load position vibration component when the compensator input is command information and the servo control approximation characteristic is the dead time element. [Figure 79] Figure 79 shows the error between the motor position and the approximate motor position when the compensator input is command information and the servo control approximation characteristic is the dead time element. [Figure 80] Figure 80 shows the motor speed under condition L. [Figure 81] Figure 81 shows the load speed under condition L. [Figure 82] Figure 82 shows the motor speed vibration components under condition L. [Figure 83] Figure 83 shows the load velocity oscillation component under condition L. [Figure 84] Figure 84 shows the motor position vibration component under condition L. [Figure 85] Figure 85 shows the load position vibration component under condition L. [Figure 86] Figure 86 shows the motor speed under condition M. [Figure 87] Figure 87 shows the load speed under condition M. [Figure 88] Figure 88 shows the motor speed vibration components under condition M. [Figure 89] Figure 89 shows the load velocity vibration component under condition M. [Figure 90] Figure 90 shows the motor position vibration component under condition M. [Figure 91] Figure 91 shows the load position vibration component under condition M. [Figure 92] Figure 92 shows the motor speed under condition N. [Figure 93] Figure 93 shows the load speed under condition N. [Figure 94] Figure 94 shows the motor speed vibration components under condition N. [Figure 95] Figure 95 shows the load velocity oscillation component under condition N. [Figure 96] Figure 96 shows the motor position vibration component under condition N. [Figure 97] Figure 97 shows the load position vibration component under condition N. [Figure 98] Figure 98 shows the load moment of inertia fluctuation ratio. [Figure 99]Figure 99 shows the motor speed under condition O. [Figure 100] Figure 100 shows the load speed under condition O. [Figure 101] Figure 101 shows the motor speed vibration components under condition O. [Figure 102] Figure 102 shows the load velocity oscillation component under condition O. [Figure 103] Figure 103 shows the motor position vibration component under condition O. [Figure 104] Figure 104 shows the load position vibration component under condition O. [Figure 105] Figure 105 shows the motor speed under condition P. [Figure 106] Figure 106 shows the load speed under condition P. [Figure 107] Figure 107 shows the motor speed vibration components under condition P. [Figure 108] Figure 108 shows the load velocity oscillation component under condition P. [Figure 109] Figure 109 shows the motor position vibration component under condition P. [Figure 110] Figure 110 shows the load position vibration component under condition P. [Figure 111] Figure 111 shows the motor position vibration component under condition Q. [Figure 112] Figure 112 shows the load position vibration component under condition Q. [Figure 113] Figure 113 shows the motor position vibration component under condition R. [Figure 114] Figure 114 shows the load position vibration component under condition R. [Figure 115] Figure 115 shows the motor position vibration component under condition S. [Figure 116] Figure 116 shows the load position vibration component under condition S. [Figure 117] Figure 117 shows the motor position vibration component under condition T. [Figure 118]Figure 118 shows the load position vibration component under condition T. [Figure 119] Figure 119 shows the motor position vibration component under condition U. [Figure 120] Figure 120 shows the load position vibration component under condition U. [Figure 121] Figure 121 shows the motor position vibration component under condition V. [Figure 122] Figure 122 shows the load position vibration component under condition V. [Figure 123] Figure 123 is a magnified view of a portion of the motor speed vibration components shown in Figure 28. [Figure 124] Figure 124 is a flowchart of a vibration damping control program in a servo control system equipped with a reduction mechanism. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the drawings.

[0012] [Vibration damping control system configuration and the effect of angular transmission error] (Vibration control system configuration) Figure 1 shows a schematic diagram of the vibration damping control system. The vibration damping control system 1000 includes, for example, a vibration damping control device 100_1, a motor 200, a reduction mechanism 300, a load 400, and an encoder 500. The vibration damping control device 100_1 is a computer device equipped with one or more processors, memory, etc. The vibration damping control system 1000 may also include vibration damping control devices 100_2, 100_3, or 100_4, which will be described later, instead of vibration damping control device 100_1. Hereafter, when vibration damping control devices 100_1, 100_2, 100_3, and 100_4 are not distinguished, they may be referred to as vibration damping control devices or simply as control devices. Also below, the motor 200, reduction mechanism 300, load 400, encoder 500, and vibration damping control system 1000 may be referred to simply as the motor, reduction mechanism, load, encoder, and vibration damping control system. A vibration control device may consist of a single control unit or two or more control units (for example, a combination of a PLC (Programmable Logic Controller) and, for example, a servo driver and a servo control unit). The control device performs target trajectory calculations for the load to generate position commands, generates speed commands, torque commands or drive currents based on the position commands, and supplies drive currents to the motor. The control device generates position commands, speed commands, and torque commands or drive currents as command values ​​(target values). Depending on the purpose of the control device, the command values ​​may be position commands, speed commands or torque commands. Since many control devices are so-called embedded systems, the computer resources of the control device, such as processing power (e.g., CPU performance) and memory resource usage (e.g., ROM capacity or RAM capacity), may be limited.

[0013] The motor rotates its motor shaft using a drive current supplied from the control device. The motor (e.g., a servo motor) may be equipped with a position detector (e.g., an encoder) that detects the rotational position of the motor shaft. The position detector outputs a rotational position signal (motor position) of the motor shaft to the control device. It may also be equipped with a speed detector (e.g., a tachogenerator) that detects the rotational speed of the motor shaft, and the speed detector outputs a rotational speed signal to the control device.

[0014] The reduction gear mechanism has a motor rotation shaft connected to its input shaft, reduces the motor rotation at a predetermined reduction ratio, and drives the load via the output shaft of the reduction gear mechanism. The motor rotation shaft may also be connected to the input shaft of the reduction gear mechanism via, for example, a belt mechanism. The load is a robot arm or the like connected to the output shaft of the reduction gear mechanism. The output shaft of the reduction gear mechanism may also be equipped with a position sensor. The position information of the output shaft of the reduction gear mechanism is sometimes called the load position. The reduction gear mechanism may also be equipped with a torque sensor to detect the load torque for driving the load. The torque sensor can output a load torque signal representing the load torque to a control device. The reduction gear mechanism may be, for example, a harmonic drive gear, a belt pulley mechanism, an RV reducer, or a planetary gear mechanism.

[0015] A servo control system is a system for precisely controlling the output (position, speed, or torque (current)) in relation to a command value, and may be a control system using a servo motor. The controlled variable is a state variable of the controlled object 1 to be controlled, and may be observed by various detectors (e.g., position detectors) and used in feedback control. Position control controls the position with the command value as the target position (angle) and the controlled variable as the position. Speed ​​control controls the speed with the command value as the target speed (rotational speed) and the controlled variable as the speed. Torque control controls the torque with the command as the target torque (current) and the controlled variable as the torque. Note that the output torque of the motor is controlled in proportion to the current flowing through the motor, so this is sometimes called current control.

[0016] Position control, speed control, and torque control (current control) may be configured in a multi-loop structure. In a multi-loop structure, the trade-off between the responsiveness (control performance) and computational load of each loop may be considered, and the processing cycle of the outer loop (speed control or position control) may be changed compared to the inner loop (current control), or the processing cycle of the target trajectory calculation (e.g., command unit, command generation unit) may be further slowed down.

[0017] Semi-closed control refers to a method where the control amount is the output shaft of the reduction gear mechanism, a position detector is installed on the motor side, and feedback control is performed using the rotational position of the motor. In this method, the actual position of the output shaft of the reduction gear mechanism is not directly detected, but control is performed based on information from the motor side.

[0018] (Effect of angular transmission error) This section summarizes the definition of angular transmission error and its impact on servo control systems.

[0019] Angular transmission error is defined as the difference between the theoretical rotation angle of the output and the actual rotation angle of the output. The characteristics of angular transmission error are mainly determined by machining errors in the reduction mechanism (e.g., dimensional errors of the reduction mechanism components and gear errors) and assembly errors (e.g., deformation of parts). Therefore, there are individual differences in the product, and the angular transmission error characteristics differ depending on the rotation direction of the reduction mechanism.

[0020] The effects of angular transmission errors can be broadly categorized into the following two types. Static: Deterioration of positioning accuracy Dynamic: Fluctuations in rotational speed (operating speed) during operation (non-uniformity of rotation)

[0021] As can be seen from the definition of angular transmission error, static effects do not result in the rotation angle of the theoretically rotating output, leading to a deterioration in positioning accuracy.

[0022] Regarding dynamic effects, for example, the technical documentation concerning harmonic drive gears (Harmonic Drive®) explains it as follows: When the natural frequency of the vibration system including the harmonic drive gear matches the natural frequency caused by the inertia of the housing or load, a resonance state occurs, and the angular transmission error component in the harmonic drive gear is amplified. In this case, the rotational non-uniformity behaves as a vibration phenomenon caused by the angular transmission error.

[0023] For example, in a harmonic drive gear, due to its structural characteristics, two main angular error components are generated for each rotation of the input shaft. Therefore, the frequency of the main component of the angular error corresponds to twice the input frequency. Consequently, if resonance occurs in the frequency range corresponding to twice the input frequency, the angular transmission error may be significantly amplified.

[0024] Furthermore, the actual vibration frequency is affected by servo control and is not the natural frequency mentioned above, but rather the vibration frequency of the entire system including the servo control, amplifying the effect of angular transmission error. As a result, the effect of angular transmission error behaves differently depending on the motor speed (input frequency).

[0025] Static effects tend to be a problem mainly during PTP (Point-to-Point) operation, while dynamic effects tend to be a problem during CP (Continuous Path) operation. For example, in the configuration shown in Figure 1, the angular transmission error can be understood as the difference between the load position and the motor position divided by the reduction ratio. The angular transmission error can be expressed by equation (1), taking into account the harmonic order with respect to the motor position.

number

[0026] (1) The symbols in the equation are as follows: θ Sync :Angular transmission error, unit is angular-second (arc-sec). θ m Motor position, unit is radians (rad). k: harmonic order O C : A coefficient determined by the structure of the reduction mechanism (a real number, not limited to integers) A k :Each order amplitude, in arc-seconds (arc-sec). φ k Each phase is expressed in radians (rad). The arc-sec is a unit of angle equivalent to 1 / 3600th of a degree (°), and is used to express very small angles.

[0027] Note that, with respect to the actual angular transmission error, there may be components that cannot be expressed by equation (1). However, it is known that such components are often dominant and are often reproducible. Therefore, hereinafter, the angular transmission error will be treated as θ Sync . Note that, for the purpose of distinguishing from the definition of the angular transmission error, it is expressed as synchronous (Sync) with respect to the motor position.

[0028] In addition, the vibration component with two cycles per one rotation of the input shaft (motor position) is referred to as a "secondary component", and the vibration with n cycles per one rotation of the input shaft is expressed as an nth-order component. Note that, depending on the structure of the speed reduction mechanism, it may be other than integer-order components.

[0029] [Vibration control method (dynamic angular transmission error compensation)] (Dynamic angular transmission error compensation) Hereinafter, a vibration control system according to an embodiment of the present disclosure will be described with reference to the drawings. In addition, the effect of suppressing the non-uniformity of rotation (vibration suppression effect) possessed by the present disclosure will be quantitatively shown by a numerical simulation described later.

[0030] Fig. 2 shows a control block diagram of dynamic angular transmission error compensation. The control system configuration here is a multi-loop configuration composed of position control, speed control, and current control, and the control device constitutes position control.

[0031] Each symbol in Fig. 2 is as follows. θ * m : Position command θ m : Motor position ω m : Motor speed θ l : Load position K p : Position loop gain K v : Speed loop gain T v : Speed loop integration time constant Tt Torque filter time constant V Fil : Speed ​​feedback filter Delay: Delay elements in current control systems, etc. C ATE :Angle transmission error compensator i ATEComp :Compensation signal (compensation current) R: Reduction ratio J m :Motor moment of inertia K t Torque constant J l : Load moment of inertia K g : Spring constant of the reduction mechanism θ Sync :Angular transmission error Delay=e -Tds As a second-order Padé approximation Represented as JPEG0007870026000003.jpg1742 T d : Delay time JPEG0007870026000004.jpg1126 T V : Speed ​​feedback filter time constant

[0032] The control device outputs a drive current to the motor based on the position command generated by the command generation unit (not shown) and the motor position acquired from the position detector (not shown). The control device comprises a position control unit (not shown), a speed control unit (not shown), a torque control unit (not shown), and an angle transmission error compensator. The position control unit generates a speed command by performing proportional control (P control) on the position deviation between the position command and the motor position. The speed control unit generates a current command (torque command) by performing proportional-integral control (PI control) and a torque filter on the speed deviation between the speed command and the motor speed. The torque control unit generates a drive current based on a command obtained by adding the current command and the compensation signal (compensation current) output from the angle transmission error compensator. The motor speed is obtained by passing the motor speed information, which is the result of a differential calculation with respect to the motor position, through a speed feedback filter.

[0033] The motor is driven based on a drive current from the control device. When torque is applied to the motor via a torque constant from the drive current, the rotational position of the motor changes with acceleration corresponding to the motor's moment of inertia, and this is integrated over time and converted into the motor's position.

[0034] The reduction mechanism reduces the motor's rotation by a predetermined reduction ratio and drives the load via the output shaft of the reduction mechanism. In this case, an angular transmission error is added to the difference between the motor position and the load position, and this is converted into torque that drives the load via the reduction mechanism's spring constant (stiffness). The torque that drives the load acts as a reaction force on the motor.

[0035] The load is driven by torque applied from the reduction gear mechanism, and, similar to a motor, the load position is determined according to the load's moment of inertia.

[0036] The drive system, including the motor, reduction gear, and load, can be modeled as a so-called two-inertia frame of reference.

[0037] The angular transmission error compensator generates a sinusoidal compensation signal, including compensation model 3, which will be described later. This compensation signal suppresses vibration phenomena caused by angular transmission errors. Hereafter, compensation model 3 may be simply referred to as the compensation model.

[0038] The terms used in this disclosure are defined as follows:

[0039] The control system configuration refers to the configuration of the control method in a control device. For example, in Figure 2, it shows the configuration of a feedback control system consisting of position proportional control, velocity proportional-integral control, and a filter.

[0040] Control parameters refer to parameters used to determine the response characteristics of various controls in a control system configuration. For example, in Figure 2, these include the position loop gain, velocity loop gain, velocity loop integral time constant, torque filter time constant, velocity feedback filter time constant, and delay time. Note that the content, type, and set values ​​of control parameters may differ depending on the control system configuration.

[0041] Motor characteristics refer to the characteristics that determine the dynamic characteristics of a motor. For example, in the case of Figure 2, these characteristics include the torque constant and the characteristics of a second-order integral system including the motor moment of inertia. Furthermore, if the motor is connected to a reduction mechanism, for example via a belt mechanism, these characteristics are treated as part of the dynamic characteristics.

[0042] Dynamic angular transmission error compensation refers to a vibration control method that compensates for the dynamic effects of angular transmission errors (vibration phenomena caused by angular transmission errors).

[0043] Position information refers to the motor position or position command, and speed information refers to the motor speed or position command speed.

[0044] Frequency response characteristics refer to the changes in amplitude and phase of the output signal for each frequency when sinusoidal waves of various frequencies are input to a given transfer function or system.

[0045] (Dynamic angle transmission error compensation, automatic setting of compensation parameters) This section describes the compensation method for the dynamic effects of angular transmission error shown in equation (1). In particular, it describes the angular transmission error compensator in the dynamic angular transmission error compensation, whose configuration is shown in Figure 2. In Figure 2, reference numeral 1 denotes the controlled object, reference numeral 200 denotes the motor, reference numeral 300 denotes the reduction mechanism, reference numeral 400 denotes the load, and reference numeral 100_1 denotes the vibration control device.

[0046] [composition] In this configuration, the compensation signal generated by the angle transmission error compensator is the compensation current i ATEComp This is shown in equations (2) through (5).

number

number

number

number

[0047] The symbols in equations (2) through (5) are as follows: i: Compensation order A i Each compensation order amplitude is expressed in arcseconds (arc-sec). φ i Each compensation order phase is expressed in radians (rad). A Ci :Angle transmission error compensator amplitude at each compensation order, in units of amperes per angle-second (A / arc-sec). φ Ci :Angle transmission error compensator phase at each compensation order, in radians (rad). ω m Motor speed, in revolutions per minute (r / min). ω mi : Motor speed angular frequency relative to i The image is JPEG0007870026000009.jpg927, and the unit is radians per second (rad / s). j: Imaginary unit

[0048] Furthermore, the formula takes into account the comparison with the angular transmission error shown in equation (1), and also considers the handling of multiple compensation orders described later.

[0049] Hereafter, A corresponds to the angular transmission error in the controlled object 1. i , φ i This is called the angular transmission error characteristic. This characteristic uses values ​​that have been measured in advance or measured or identified on the system.

[0050] The angular transmission error compensator amplitude and phase at each compensation order are given by the transfer function from the angular transmission error to the compensation current. Using JPEG0007870026000010.jpg923, the frequency response characteristics at frequencies corresponding to the system's operating speed range are calculated and constructed as a compensation model. In equation (4), π corresponds to compensation in reverse phase, and equation (3) may be multiplied by "-1". This configures the system to automatically set the parameters of the compensation model and register them in the compensation model.

[0051] Hereafter, the information necessary for the angular transmission error characteristics and compensation model, which are parameters in an angular transmission error compensator, will be collectively referred to as compensation parameters. For example, if the reduction mechanism is a harmonic drive gear, the coefficient O is determined by the structure of the reduction mechanism. c This is shown by equation (5).

[0052] In this configuration, the summing unit 2 adds the compensation signal to the current command. Hereafter, the summing unit 2 may be simply referred to as the summing unit. Here, the current command is the target of the compensation signal addition, and in this disclosure, this is called the compensation addition point. In this configuration, in order to unify the compensation addition point regardless of the control mode (position control, speed control, or torque control selected), the compensation addition point is set to the current command.

[0053] The dynamic effects of the angular transmission error in the reduction mechanism are influenced by various structural and control factors in addition to the motor position. Therefore, the angular transmission error compensator generates a sinusoidal compensation signal, or compensation current, based on the angular transmission error characteristics of a separately determined compensation order and the motor position. In this process, to compensate for the effects of control factors, the amplitude and phase used to generate the compensation signal are corrected using a compensation model that has the amplitude and phase calculated from the frequency response characteristics at the frequency corresponding to the motor speed using the transfer function from the angular transmission error to the compensation current as the angular transmission error compensator amplitude and the angular transmission error compensator phase for each compensation order. The sinusoidal wave during compensation signal generation can be realized, for example, by using a sinusoidal function or a table reference to the position.

[0054] The transfer function from the angular transmission error to the compensation current is given by equation (6).

number

[0055] The symbols in equation (6) are as in equations (7) and (8).

number

number

[0056] As shown in equation (6), the transfer function from the angular transmission error to the compensation current is not proper, and generally requires properization for implementation. However, in this case, the effect of suppressing rotational non-uniformity was limited due to the influence of properization.

[0057] This disclosure utilizes the fact that angular transmission error can be expressed as a sum of sinusoidal waves, and uses a compensation model that has amplitude and phase calculated from frequency response characteristics. By correcting the amplitude and phase used to generate sinusoidal compensation signals of each compensation order using this compensation model, a desired compensation signal is generated. As a result, by correcting the amplitude and phase from frequency response characteristics rather than as a transfer function, properization is not required, and rotational non-uniformity can be suppressed.

[0058] An angle transmission error compensator compensates for the effects of angle transmission errors based on the control system configuration and angle transmission error characteristics, and thus has aspects of feedforward control. It is described as feedforward control because it calculates the compensation signal using motor position and motor speed.

[0059] Furthermore, since this is a feedforward control, the compensation is for the reproducible component of the angular transmission error.

[0060] For the sake of explanation, we are using a transfer function G(s) in the continuous-time domain, but this is not the only way to explain it; it also includes cases where the transfer function G[z] is in the discrete-time domain.

[0061] [effect] As mentioned above, in an angle transmission error compensator, rotational non-uniformity can be suppressed by utilizing frequency response characteristics rather than transfer functions to account for the influence of control system characteristics (characteristics from angle transmission error to compensation current).

[0062] The transfer function from angular transmission error to compensation current can be calculated from the control system configuration, control parameters, and motor characteristics, and can be set based on a clear mathematical formula derived theoretically. Therefore, the optimal parameters can be uniquely derived without the need for trial-and-error adjustments. This streamlines the design process, reduces variability and judgment errors by eliminating reliance on the designer's experience and subjectivity, and enables the construction of a highly reliable angular transmission error compensator in a short period of time.

[0063] Furthermore, it clearly distinguishes between angular transmission error characteristics, which vary from product to product, and control system characteristics, which do not. As a result, the design content and its operation are systematically structured and logically consistent, making it easy to handle at each stage of design, analysis, and maintenance, and resulting in excellent designability and implementability of the control device.

[0064] (Flexibility of control system configuration) [composition] The angle transmission error compensator can accommodate various control system configurations, not just the one shown in Figure 2. Figure 3 is a control block diagram where the compensation addition point is a position command (the compensation signal is added to the position command), and Figure 4 is a control block diagram where the compensation addition point is a speed feedback signal (motor speed) (the compensation signal is added to the speed feedback signal). In each case, the compensation signal is the compensation position command θ. ATEComp , compensation speed feedback signal ω ATEComp In addition, in Figures 3 to 5, including Figure 5 which will be described later, reference numeral 1 represents the controlled object, reference numeral 200 represents the motor, reference numeral 300 represents the reduction mechanism, and reference numeral 400 represents the load, while reference numerals 100_2, 100_3, and 100_4 represent the vibration control devices, respectively. The transfer function used when constructing the compensation model is, in the case of Figure 3, the transfer function from the angular transmission error to the position command. In the case of JPEG0007870026000014.jpg1022, Figure 4, the transfer function from the angular transmission error to the velocity feedback signal. You should use the filename JPEG0007870026000015.jpg925.

[0065] For example, the transfer function from the angular transmission error to the position command is given by equation (9).

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[0066] The symbols in equation (9) are as follows:

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number

[0067] In the case where the compensation signal is added to the current command, the transfer function is not proper, as in equation (6), and it has the same problems as described above, but compensation is possible in the same way. The same applies when the compensation addition point is the speed feedback signal.

[0068] Although the above concerns the control system structure for position control, this disclosure can also be applied to speed control and torque control, taking into account the control system configuration and compensation addition points, thereby enabling the configuration of dynamic angular transmission error compensation. Furthermore, it is applicable not only to feedback control system configurations but also to control system configurations that combine feedback control and feedforward control.

[0069] [effect] Because systems or devices using reduction mechanisms have a variety of applications, the preferred control system configurations for such systems or devices also vary. For example, in addition to general PID control, various feedback control algorithms can be cited, such as I-PD control with a modified differential term structure, P-PI control, P-IP control, state variable feedback control based on optimal regulator theory, and even H∞ control that considers robustness.

[0070] According to this disclosure, vibration damping control (suppression of rotational non-uniformity) can be added to the aforementioned existing feedback control system based on feedforward control that adds a compensation signal, without making any structural changes to the system. As mentioned above, the compensation parameters can be set based on clear mathematical formulas derived theoretically, making it easily applicable to a variety of systems. From an industrial application perspective, it may be difficult to modify the structure of existing control systems from the standpoint of performance and reliability, and this has the excellent effect of obtaining vibration damping control functionality while maintaining the existing control system structure.

[0071] (Compensation model based on speed information) [composition] The angle transmission error compensator is configured as a compensation model in which the angle transmission error compensator amplitude and the angle transmission error compensator amplitude phase for each compensation order are set as a linear interpolation lookup table (hereinafter referred to as LUT) based on speed information. For compensation order i, the compensation model has angle transmission error compensator amplitude and angle transmission error compensator phase corresponding to multiple discrete motor speeds.

[0072] The angular transmission error compensator amplitude for each compensation order is shown in equation (12). The same applies to the angular transmission error compensator phase for each compensation order.

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[0073] The symbols in equation (12) are as follows: n i : Number of LUTs for compensation order i ω mil :ith LUT input is the lth motor speed A cil :Angle transmission error compensator amplitude at each l-th compensation order, which is the i-th LUT output.

[0074] For example, it can be set in increments of 200 r / min within the range of 0 to 3000 r / min to match the operating speed range of the system (0, 200, 400, ..., 3000). In this case, n i =16 corresponds to this. In this case, for example, ω m =ω mi2 In the case of A ci (ω m )=A ci2 This is the result. Note that the motor speeds do not need to be at equal intervals. Also, the angular transmission error compensator amplitude and the angular transmission error compensator phase at each compensation order are different n i This may also be done. For example, the number of amplitude LUTs n for compensation order i. iA =20, number of phase LUTs n for compensation order i iφ n can also be set to =10. iThis involves a trade-off between the amount of memory resources needed to store the necessary data and the compensation performance, so the balance between the two can be flexibly adjusted based on the requirements of the control device.

[0075] Specifically, in speed ranges where the corresponding frequency response characteristics change steeply, a balance between compensation performance and computing resources can be considered by setting more closely spaced (or more) motor speeds, and in speed ranges where the corresponding frequency response characteristics change gradually, a looser (or less) motor speed setting can be considered.

[0076] Furthermore, various algorithms exist for LUTs, including not only linear interpolation but also nearest neighbor interpolation, polynomial interpolation, and spline interpolation, so the choice should be made considering implementation constraints. From the viewpoint of the continuity of the compensation signal, it is preferable that the output of the LUT be a continuous output obtained by linear interpolation, but a discrete output method is also acceptable. In addition, if the operating speed exceeds the LUT consideration range (corresponding to extrapolation), the speed may be set to the maximum speed value set in the LUT (corresponding to clipping), or a warning may be issued from a display device or the like to prompt the user to reset the operating speed range.

[0077] Alternatively, another method for realizing the compensation model is to create a regression function (approximation function) for the amplitude and phase of the frequency response characteristics and use it to calculate the angular transmission error compensator amplitude and phase. Alternatively, the frequency response characteristics may be calculated sequentially to calculate the angular transmission error compensator amplitude and phase for each compensation order.

[0078] While the frequency response characteristics are calculated using the control system configuration, control parameters, and motor characteristics, if some or all of these are unknown, compensation parameters may be identified and set experimentally. For example, compensation parameters capable of reducing vibration when operating at a certain constant speed can be identified at multiple operating speeds. In this case, however, the compensation parameters will need to be identified again as the control parameters are adjusted.

[0079] [effect] In this disclosure, multiple configurations or computation methods can be selected as implementation methods for the compensation model, such as LUTs, regression functions, and sequential calculation of frequency response characteristics. The optimal implementation method can be flexibly selected according to the constraints of computing resources and design requirements of the control device. Therefore, this disclosure offers excellent industrial applicability, is easily applicable to various control devices in diverse industrial fields, and provides a compensation method with excellent versatility and scalability.

[0080] (Setting of compensation speed range) [Background and Challenges] Compensation is necessary depending on the operating speed at which rotational non-uniformity becomes a problem due to the effects of angular transmission errors. Furthermore, since the operating speed at which rotational non-uniformity becomes a problem differs depending on the compensation order, compensation that considers a wide range of operating speeds for various situations is preferable. Moreover, while rotational non-uniformity decreases above the operating speed at which resonance occurs, the frequency of the compensation signal becomes high and the amplitude also becomes large, resulting in a large power load relative to the compensation performance, which is undesirable from an energy saving perspective.

[0081] [composition] In an angular transmission error compensator, compensation speed bands may be additionally set to achieve compensation according to the operating speed at which rotational non-uniformity becomes a problem. Specifically, the degree of compensation influence can be set according to the operating speed by multiplying the angular transmission error compensator amplitude at each compensation order of the compensation model by a weighting coefficient. This is equivalent to adjusting (controlling) the effectiveness of the compensation signal according to a predetermined speed range. An example of setting the compensation speed band is shown in equation (13). In this case, for example, ω m =ω mi2 In the case of A ci (ω m )=W ci2 *A ci2 This is the result.

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[0082] The symbols in equation (13) are as follows: W cil: Weighting coefficients for angular transmission error compensator amplitude at each l-th compensation order

[0083] As for the weighting coefficient, for example, it is conceivable to set it to "1" near the operating speed assumed to be in the frequency band where the resonance state occurs, and to "0" everywhere else. Note that the weighting coefficient may be a value other than 1 or 0, and by appropriately setting the weighting coefficient according to the characteristics of the system, it is possible to handle various situations. To avoid compensation at low speeds, for example, the weighting coefficient may be set to "0" below 100 r / min. Similarly, to avoid compensation at high speeds, for example, the weighting coefficient may be set to "0" above the operating speed where vibration becomes a problem. In addition to multiplying the compensation model by the weighting coefficient, a weighting coefficient for the compensation speed band may also be constructed. Note that from the viewpoint of the continuity of the compensation signal, it is preferable for the weighting coefficient to be continuous, but a discrete method is also acceptable.

[0084] [effect] With this configuration, at low speeds, processing is performed that takes into account quantization errors in position detectors such as encoders, discretization errors associated with digital control, and the processing cycle of compensation processing. This makes it possible to prevent minute positioning movements, instability of control in the low-speed range, and excessive effects of compensation.

[0085] Furthermore, by configuring the system to suppress or stop the compensation operation under conditions where rotational non-uniformity is not a problem at high speeds, it is possible to avoid overloading the control device due to excessive compensation signals. This reduces unnecessary calculations and power consumption, enabling high efficiency and stability for the control device as a whole.

[0086] In particular, in a configuration where the compensation model is multiplied by a weighting coefficient, the compensation model based on velocity information and the consideration of the compensation velocity range can be implemented in a single process, making it simple and allowing for efficient use of computing resources.

[0087] (Information used for compensation) [composition] In the example shown in Figure 2, the inputs to the angle transmission error compensator (hereinafter referred to as compensator inputs) are motor position and motor speed, which are actual information derived from measured values ​​from the position detector. However, depending on the configuration of the control device, it may not be possible to use actual information. In such cases, the angle transmission error compensator may use command information (position command, position command speed) instead of actual information in the compensation calculation.

[0088] Figure 5 is a control block diagram when the compensator input is used as command information. In this case, the servo control approximate characteristics are Approximate motor position calculated via JPEG0007870026000021.jpg722 JPEG0007870026000022.jpg716 and approximate motor speed JPEG0007870026000023.jpg718 will be used as the compensator input.

[0089] The following describes in detail the case where position commands are used as position information. To derive an approximate motor position, which is information equivalent to the motor position, we use characteristics that approximate the servo control characteristics of the control device. The servo control approximation characteristics can be, for example, the first-order lag in equation (14) or the dead time element in equation (15). The approximate motor position can be calculated using equation (16) with the respective transfer functions.

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[0090] The symbols in equations (14) through (16) are as follows: ω approx : Estimated angular frequency for servo control, unit is radians per second (rad / s). Lapprox : Estimated dead time for servo control, in seconds (s).

[0091] The P-PI control system, which has the control system configuration shown in Figure 2, can approximate the response globally with the position loop gain, so ω approx =K p It can be done in the same way. The file can be named JPEG0007870026000027.jpg634. The approximate motor speed, which is the speed information, may also be the derivative (difference) of the approximate motor position.

[0092] Servo control characteristics vary depending on the system, and approximation requires consideration of servo control characteristics, operating speed range, control parameter settings, and management. To approximate the characteristics from position command to motor position, it is generally sufficient to determine the configuration of the servo control approximation characteristics and their parameters. For example, the objective function can be the sum of the squared errors or the mean squared error between the motor position and the position command. Alternatively, a curve fitting process of the frequency response characteristics may be used. This curve fitting can be achieved, for example, by estimating parameters using regression methods such as the least squares method based on a predefined transfer function model for the gain characteristics and phase characteristics on the Bode plot. The same applies to speed control and torque control.

[0093] Furthermore, it is necessary to consider the approximation accuracy of the position information and velocity information, which are inputs to the compensator. Errors in position information have a significant impact because they directly affect the period and phase of the sinusoidal compensation signal, while errors in velocity information affect the amplitude and phase values ​​of the compensation parameters, but the impact of errors is smaller compared to that of position information. Therefore, as an approximation characteristic that prioritizes the error of position information, the approximate motor speed may be calculated from the approximate motor position.

[0094] [effect] Depending on the configuration of the control device, it may be difficult to use real information due to physical wiring constraints, or it may be difficult to achieve the desired accuracy due to factors such as the resolution and processing cycle of the obtained information. In this disclosure, the information used for compensation can be flexibly selected according to the control device's requirements, enabling optimal compensation processing according to the system configuration and operating conditions. This makes it possible to apply to a variety of systems with different configuration requirements, improving the design flexibility of the system and expanding its scope of application and practicality.

[0095] (Non-interference with static components) [Background and Challenges] When compensating for rotational non-uniformity, which is a dynamic effect of angular transmission error, there is a problem in that, especially when adding a compensation signal to the position command, if the compensation signal is not set to zero when the system stops, it directly affects the static characteristics of the angular transmission error, leading to a deterioration in positioning accuracy. A similar problem exists when adding a compensation signal to something other than the position command, as it affects the behavior during operation start and positioning.

[0096] [composition] To achieve non-interference with static components, the angle transmission error compensator is configured to correct the compensation signal to zero when the velocity information is zero, i.e., when the system is stopped. Even when the compensation signal is added to components other than the position command, a similar configuration is preferable if it affects the static characteristics. Alternatively, the compensation model may be set so that the compensation signal is zero when the velocity information is zero.

[0097] Specifically, for example, by utilizing the compensation speed range setting, the weighting coefficient corresponding to the case where the motor speed is 0 can be set to 0, or each compensation order amplitude can be multiplied by the sign function sgn(x) (for details of the sign function, see the definition in the part that reflects the rotational direction characteristics).

[0098] [effect] In particular, when a compensation signal is added to a position command, it can lead to a deterioration of positioning accuracy. Therefore, this configuration allows for compensation of the dynamic effects of angular transmission error without affecting the static characteristics of the angular transmission error. Furthermore, by considering this in conjunction with the setting of the compensation speed band using a LUT, multiple functions can be implemented at once, making it simple and efficient use of computer resources. This makes it possible to achieve compensation that clearly distinguishes between dynamic and static compensation. Note that the dynamic compensation described in this disclosure may be used in combination with other static compensation methods.

[0099] (Reflection of rotational direction characteristics) [composition] In the angular transmission error compensator, the amplitude and phase of each compensation order, taking into account the direction of rotation, and the angular transmission error compensator phase at each compensation order are as shown in equations (17), (18), and (19).

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[0100] The symbols in equations (17) through (19) are as follows: A F i : The amplitude of each compensation order during forward rotation; the unit is arcseconds (arc-sec). A R i : The amplitude of each compensation order during reversal, in arc-sec units. φ F i : The phase of each compensation order during forward rotation; the unit is radians (rad). φ R i : The phase of each compensation order during reversal, in units of radians (rad). sgn(x): This is a sign function, defined as +1 when x > 0, 0 when x = 0, and -1 when x < 0. Alternatively, it may be defined as +1 when x = 0. This is to suppress the effects of chattering when the sign of x changes and to clearly correspond to the two values ​​of forward and reverse rotation. The superscript F indicates the characteristic of forward rotation, and the superscript R indicates the characteristic of reverse rotation.

[0101] [effect] Because angular transmission errors have different characteristics depending on the direction of rotation due to their generation principle, effective compensation is possible by considering the direction of rotation. In particular, when considering operation in which the direction of rotation reverses, by configuring it in conjunction with the non-interference with the static component mentioned above, the compensation signal changes continuously and smoothly without requiring complex processing even when the direction of rotation reverses, thus enabling stable operation. Furthermore, since the characteristics of the direction of rotation can be set separately in advance, parameters can be determined easily and efficiently, simplifying adjustment work in the design process, improving the efficiency of the design process, and suppressing rotational non-uniformity.

[0102] (Multiple compensation orders) [composition] As shown in equations (2) to (4), the angle transmission error compensator can support multiple compensation orders, and a compensation model corresponding to each compensation order is constructed. Alternatively, the following configuration, which is a modification of equation (2), may also be used.

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[0103] The symbols in equations (20) through (23) are as follows: ω mCi :ith motor speed, unit is radians per second (rad / s). ω m1 : The motor speed angular frequency relative to the primary, in units of radians per second (rad / s).

[0104] As a single compensation model (corresponding to a compensation model with a first-order compensation), the compensation model is referenced using motor speed and compensation order as equation (23). In contrast to the aforementioned pre-calculation configuration (equation (2)) in which the effect of the compensation order is calculated and stored in advance, this is a sequential calculation configuration (equation (20)) in which the effect of the compensation order is calculated sequentially. Furthermore, the compensation speed band may be set based on speed or based on (angular) frequency. When dealing with multiple compensation orders, the configuration can be simplified by using frequency as the basis.

[0105] [effect] When there are multiple components that dynamically influence the angular transmission error determined by the structure of the reduction mechanism, the configuration of the angular transmission error compensator can be designed according to certain rules without becoming overly complex.

[0106] Furthermore, when the compensation order and the number of lookup tables are large, a flexible configuration can be selected to suit the computing resources available. For example, if there is ample memory resources, a pre-calculation configuration can be used to reduce the sequential calculation process for compensation signal generation. Conversely, if the control unit has sufficient processing power, a sequential calculation configuration can be used to reduce the amount of memory resources used.

[0107] Multiple configurations or calculation methods are available, allowing for flexible selection of the optimal implementation method according to the design requirements and computing resource constraints of the control device.

[0108] Therefore, the present disclosure can provide a compensation method that is excellent in industrial applicability, easy to apply to various control devices in diverse industrial fields, and excellent in versatility and expandability.

[0109] (Load inertia moment) [Configuration] In the angular transmission error compensator, for example, the frequency response characteristics from the angular transmission error to the compensation current can be calculated from the control system configuration, control parameters, and motor characteristics, and it is configured without requiring information on the load inertia moment. When the control parameters are changed in accordance with changes in the load inertia moment (for example, gain scheduling), compensation can be achieved by also changing the compensation parameters.

[0110] (Reducer spring constant) [Configuration] In the angular transmission error compensator, for example, the frequency response characteristics from the angular transmission error to the compensation current can be calculated from the control system configuration, control parameters, and motor characteristics, and it is configured without requiring information on the reducer spring constant.

[0111] [Effect] In a two-inertia system, the vibration phenomenon is determined by the inertia moment and the (reducer) spring constant in terms of its vibration frequency and influence degree. However, in the present disclosure, the compensation parameters can be determined without requiring information on both. Regarding the load inertia moment, for example, when the load inertia moment is unknown, or in a vertical articulated robot or a horizontal articulated robot system where the load inertia moment changes depending on the posture and the vibration frequency changes, compensation can be achieved without being affected. Also, the reducer spring constant often has product-to-product differences, and various measures have been taken to address this. However, in the present disclosure, vibration suppression control can be realized without being affected by differences in the spring constant or its variations.

[0112] As described above, in the present disclosure, an angular transmission error compensator can be designed regardless of the load inertia moment and the reducer spring constant, thereby improving the efficiency of the design process and suppressing rotational non-uniformity regardless of these characteristics.

[0113] (Load torque response) [Background and problems] The angular transmission error characteristic may change depending on the load torque (gravitational torque, acceleration / deceleration torque (torque for driving the load)) applied to the reduction mechanism. For example, in a robot system, the influence of the load torque due to the gravitational torque may be large.

[0114] [Configuration] To consider the influence of the load torque, the angular transmission error compensator is configured to correct each compensation order amplitude and each compensation order phase according to the load torque τ l Specifically, equations (24) and (25) are used for equations (3) and (4). [Equation] ···(24) [Equation] ···(25) Note that as a compensation model, correction values for the amplitude of the angular transmission error compensator at each compensation order and the phase of the angular transmission error compensator at each compensation order may be set according to the load torque. The load torque may be estimated using the dynamic model of the robot based on a torque sensor, the configuration, and the operation of the system.

[0115] [Effect] Compensation considering the influence of the load torque on the angular transmission error can be easily configured. It is possible to compensate for the influence of the variation in the angular transmission error characteristic due to the influence of the load torque and suppress the non-uniformity of rotation.

[0116] (Temperature variation response) [Background and problems] The angular transmission error characteristic may vary depending on the temperature characteristic of the components of the reduction mechanism, the temperature of the reduction mechanism, and the temperature around the reduction mechanism (ambient temperature).

[0117] [Configuration] To consider the influence of temperature, the angular transmission error compensator is configured to correct each compensation order amplitude and each compensation order phase according to the temperature information T. Specifically, for equations (3) and (4), equations (26) and (27) are as follows.

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[0118] [Effect] Compensation considering the influence of temperature on the angular transmission error can be easily configured. The influence of fluctuations in the angular transmission error characteristics due to the influence of temperature can be compensated, and the non-uniformity of rotation can be suppressed.

[0119] (Compensation Model Configuration) [Configuration] Here, a different configuration of the angular transmission error compensator in the above-mentioned dynamic angular transmission error compensation and automatic setting of compensation parameters will be described.

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[0120] Each symbol in equations (28) to (30) is as follows. A Mi : Integrated amplitude of each compensation order, unit is Ampere (A). φ Mi : The integrated compensation order phases, in units of radians (rad).

[0121] This configuration uses a merged (integrated) compensation model that combines the angular transfer error characteristics and the angular transfer error compensator characteristics. By considering the angular transfer error characteristics when creating the compensation model, the compensation signal calculation can be simplified. This is based on the same concept as the pre-calculation configuration described above.

[0122] [effect] In this disclosure, the implementation method of the compensation model allows for flexible configuration by selecting a configuration according to the available computing resources. For example, if there is sufficient memory resource usage, a pre-calculation configuration can be used to reduce the sequential calculation process for generating compensation signals, and if the control device has sufficient processing power, a sequential calculation configuration can be used to reduce the amount of memory resource usage.

[0123] (Combination of functions) As mentioned above, various factors can be considered when designing an angle transmission error compensator. For example, by appropriately selecting and combining configurations that consider setting the compensation speed band and non-interference with static components, or configurations that consider non-interference with static components, rotational direction characteristics, and support for multiple compensation orders, it is possible to easily configure embodiments that support a variety of functions. Furthermore, multiple functions can be considered collectively as a compensation model, reducing the redundancy of computational processing and enabling efficient use of computing resources.

[0124] These combinations of functions are not mutually exclusive; by appropriately selecting and combining them according to the purpose and constraints of each system, it is possible to efficiently design and implement comprehensive suppression of rotational output errors that take various factors into account in a variety of systems.

[0125] [Numerical example] (Simulation conditions) To verify the operation and effects of this disclosure, a numerical simulation is performed using the configuration shown in Figure 2. The various parameters used in the numerical example are shown in Table 1.

[0126] [Table 1]

[0127] Furthermore, in order to convert the control parameter units from SI units to the processing unit system, a normalization coefficient is considered for the velocity loop gain. JPEG0007870026000043.jpg743, JPEG0007870026000044.jpg736 is the nominal load inertia value, K tn This is the nominal torque constant.

[0128] The compensation parameters were designed under the following conditions: Compensation order i:2 Lookup table count n i :16 Lookup table for a number of minutes Motor speed ω m2l [r / min]: 0, 200, 400, 600, ..., 2800, 3000 (16 equally spaced data points)

[0129] The load speed is expressed as a value multiplied by the reduction ratio, taking into consideration comparison with the motor speed. In this case, the unit is expressed as "Mr / min". The motor position and load position are both values ​​on the load side, expressed in "arc-sec" units. Here, in order to consider the responsiveness of the servo control, the control parameters are evaluated in two ways: "low" and "high" (corresponding to "low" and "high" in Table 1). Hereafter, the low case will be referred to as "low gain setting" and the high case as "high gain setting". In general, control parameters are set according to the rigidity of the device (for example, the spring constant of the reduction mechanism). The higher the responsiveness, the better the tracking of commands and the shorter the settling time, but the more likely vibrations are to occur. Therefore, for example, the parameters are set so that the desired responsiveness is obtained within a range where vibrations do not occur.

[0130] (Constant speed operation) To evaluate the dynamic effects of angular transmission error and the effects of this disclosure, the vibration characteristics during constant-speed operation are evaluated. In constant-speed operation, the vibration characteristics are evaluated by performing an order analysis on the response data of the section in which constant-speed operation is performed after a time has elapsed during which the effects of transient response can be ignored. Hereafter, for example, the second-order component of the order analysis result for the constant-speed section of the motor speed will be referred to as the "second-order component of the motor speed." Here, the characteristics at an operating speed equal to the motor speed set in the LUT are evaluated.

[0131] As a vibration characteristic analysis, the motor is operated at a constant speed at multiple operating speeds (e.g., 1000, 1200, ..., 2400 r / min), and the quadratic components of the motor speed and load speed at each operating speed are extracted from the response data within the constant speed interval. Furthermore, position information is calculated by integral calculation of the speed information within the constant speed interval, and the quadratic components of the motor position and load position are also extracted.

[0132] (Explanation of order analysis content under constant speed operation) Figures 6 and 7 show the motor speed response data and load speed response data in the constant speed section when the motor is operated at a constant speed at multiple operating speeds, while Figures 8 and 9 show the order analysis results of the motor speed and load speed when the operating speed is 1600 r / min, respectively, with a low gain setting and no compensation.

[0133] Figures 6 to 11 show the case with a low gain setting and no compensation. In Figure 6, the horizontal axis represents time and the vertical axis represents motor speed. In Figure 7, the horizontal axis represents time and the vertical axis represents load speed.

[0134] Figures 6 and 7 show that although the operation command is set to a constant speed, periodic speed fluctuations are superimposed on the motor speed and load speed due to the effect of angular transmission errors. In particular, when the operating speed is set to 1600 r / min, the amplitude of the vibration component is shown to be larger compared to other speeds.

[0135] Figure 8 shows the order of the motor speed on the horizontal axis and the order of the motor speed on the vertical axis. Figure 9 shows the order of the load speed on the horizontal axis and the order of the load speed on the vertical axis. Figures 8 and 9 show that the effect is due to the second-order component of the angular transmission error, which was considered in the simulation model.

[0136] In Figures 10 and 11, the horizontal axis represents the operating speed, and the vertical axis represents the extraction results of the second-order component of the motor speed and the extraction results of the second-order component of the load speed at multiple operating speeds, respectively. Figures 10 and 11 show that the degree of influence of equal angular transmission error differs depending on the operating speed, and that the influence of angular transmission error on load speed is significant.

[0137] (Vibration characteristics due to differences in control parameters) Figures 12 to 15 show the characteristics of the motor position quadratic component, load position quadratic component, motor speed quadratic component, and load speed quadratic component under low gain setting, high gain setting, and no compensation (hereinafter referred to as condition A). The solid lines represent the characteristics under low gain setting, the dashed lines represent the characteristics under high gain setting, the horizontal axis represents operating speed, and the vertical axis represents each quadratic component.

[0138] Figures 12 to 15 show that differences occur in each of the secondary components depending on the control parameters, indicating that they are affected by servo control. In particular, when the operating speed is 1600 r / min, the load position is 35.8 arc-sec with low gain setting and 59.0 arc-sec with high gain setting, and the load speed is 27.8 Mr / min with low gain setting and 45.7 Mr / min with high gain setting, showing a difference of 1.6 times and 1.7 times depending on the control parameters.

[0139] (Vibration characteristics with and without compensation (low gain setting)) Figures 16 to 19 show the characteristics of the motor position quadratic component, load position quadratic component, motor speed quadratic component, and load speed quadratic component, respectively, under low gain settings and with or without compensation (hereinafter referred to as Condition B). The solid lines represent the characteristics with compensation, the dashed lines represent the characteristics without compensation, the horizontal axis represents the operating speed, and the vertical axis represents each quadratic component.

[0140] Figures 16 to 19 show that the second-order component of the load position and load speed is reduced to zero by compensation. Furthermore, the motor position and motor speed are shown to have characteristics with a predetermined amplitude due to the compensation. Figure 16 shows that the motor position oscillates at 10 arc-sec, corresponding to the amplitude of the second-order component of the angular transmission error, regardless of the operating speed. This cancels out (compensates for) the effects of the second-order component of the angular transmission error in the load position and load speed. From the second-order components of the load position and load speed shown in Figures 17 and 19, it is clear that this disclosure can effectively compensate for the effects of angular transmission error.

[0141] (Vibration characteristics with and without compensation (high gain setting)) Figures 20 to 23 show the characteristics of the motor position quadratic component, load position quadratic component, motor speed quadratic component, and load speed quadratic component, respectively, under high gain settings and with and without compensation (hereinafter referred to as condition C). The solid lines represent the characteristics with compensation, the dashed lines represent the characteristics without compensation, the horizontal axis represents the operating speed, and the vertical axis represents each quadratic component.

[0142] Figures 20 to 23 show that, similar to the low-gain setting, the load position and load speed have their second-order components reduced to zero by compensation. Furthermore, the motor position and motor speed are shown to have characteristics with a predetermined amplitude due to the compensation. Figure 20 shows that the motor position oscillates at 10 arc-sec, which corresponds to the amplitude of the second-order component of the angular transmission error, regardless of the operating speed.

[0143] Simulation results under conditions A to C clearly demonstrate that the influence of the second-order component of angular transmission error, which exhibits different vibration characteristics depending on the control parameters, can be suppressed.

[0144] (Compensation parameters) Figures 24 and 25 show the amplitude and phase characteristics of the frequency response from angular transmission error to compensation current, with solid lines representing low-gain settings and dotted lines representing high-gain settings. The circles represent the compensation parameters for low-gain settings and the crosses represent the compensation parameters for high-gain settings.

[0145] The amplitude at motor speed = 0 indicates that the amplitude is set to 0 to avoid compensation when stopped in order to achieve non-interference with the static component. Figures 24 and 25 show that the amplitude and phase differ depending on the control parameter in order to compensate for the fact that the angular transmission error has different vibration characteristics depending on the control parameter. This means that once the control parameter is determined, the compensation parameter can be uniquely determined without trial and error. The motor speed and the number of compensation tables to be set in the compensation model may be determined from the amplitude and phase characteristics in the frequency response characteristics shown in Figures 24 and 25. Alternatively, as mentioned above, a regression function may be created for these characteristics.

[0146] (Acceleration and deceleration) As mentioned above, the effect of angular transmission error changes depending on the change in motor speed. Here, we examine the effect of angular transmission error and the effectiveness of this disclosure when the motor speed changes continuously due to acceleration and deceleration. During acceleration and deceleration, we evaluate the vibration characteristics when the effect of angular transmission error changes sequentially with the change in speed. Note that, unlike constant speed operation, it is difficult to evaluate vibration characteristics by order analysis during acceleration and deceleration. Therefore, in order to remove components associated with acceleration and deceleration other than the effect of angular transmission error, the output of the high-pass filter (HPF) shown in equation (31) is used as each vibration component.

number

[0147] The symbols in equation (31) are as follows: ω HPF :HPF cutoff angle frequency, in radians per second (rad / s). o HPF :HPF order Here, ω HPF =2π*5, o HPF =6

[0148] Figures 26 to 31 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, and load position vibration component, respectively, under low gain settings and no compensation (hereinafter referred to as condition D). The horizontal axis represents time, and the vertical axis represents each component. Note that in the vibration component graphs such as Figure 28, the graphs are solid-colored because continuous vibration is occurring. As an example, an enlarged view of Figure 28 is shown in Figure 123.

[0149] Figures 32 to 37 show the characteristics under high gain setting with no compensation (hereinafter referred to as condition E), Figures 38 to 43 show the characteristics under low gain setting with compensation (hereinafter referred to as condition F), and Figures 44 to 49 show the characteristics under high gain setting with compensation (hereinafter referred to as condition G).

[0150] Since it is difficult to discuss the magnitude of vibration from the motor speed and load speed shown in Figures 26, 27, 32, 33, 38, 39, and 44, 45, the influence of angular transmission error and the effectiveness of this disclosure will be confirmed from each vibration component using the HPF described above.

[0151] In the uncompensated load speed vibration components and load position vibration components shown in Figures 29, 31 and 35, 37, the vibration characteristics due to the influence of angular transmission error change sequentially with differences in operating speed, and the differences in control parameters show a similar trend to the constant speed operation described above. Note that the components around 0 and 10 s in each vibration component are due to the transient response associated with the start of acceleration and deceleration.

[0152] Figures 41, 43 and 47, 49 show the compensated load speed vibration components and load position vibration components, demonstrating that the vibration characteristics associated with changes in operating speed can be suppressed by this disclosure.

[0153] Figures 28, 30, 34, 36, 40, 42, 45, 48 show the motor speed vibration components and motor position vibration components with and without compensation, demonstrating that, even with different control parameters, the effect of angular transmission error at the load position is reduced by vibrating the motor position, similar to the constant speed operation described above.

[0154] From the simulation results under conditions D to G, it is clear that the present disclosure can suppress the effects of vibration even when the operating speed changes continuously.

[0155] (Compensation due to differences in compensation points) The simulation results for the configuration shown in Figure 3, where the compensation addition point is the position command, are shown. Figures 50 to 55 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, and load position vibration component, respectively, when the compensation addition point is the position command, low gain setting, and compensation is enabled (hereinafter referred to as condition H). The horizontal axis represents time, and the vertical axis represents each component.

[0156] Figures 50 to 55 demonstrate that rotational non-uniformity can be suppressed even when the compensation addition point is a position command.

[0157] Figures 56 and 57 show the amplitude and phase characteristics of the frequency response from the angular transmission error to the compensation position, with the compensation parameters indicated by circles. Note that the amplitude at motor speed = 0 is set to 0 to ensure non-interference with static components and to avoid compensation when stopped.

[0158] Figures 58 to 63 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, and load position vibration component, respectively, under the configuration of Figure 4, with compensation added at the speed feedback, low gain setting, and compensation enabled (hereinafter referred to as Condition I). The horizontal axis represents the operating speed, and the vertical axis represents each component.

[0159] Figures 58 to 63 demonstrate that equivalent compensation can be achieved regardless of compensation bonus points.

[0160] From the simulation results under conditions H to I, it is clear that compensation points can be flexibly set in this disclosure.

[0161] (Setting of compensation speed range) The simulation results when a compensation speed range is set are shown. Low gain setting, and the compensation summation point is the current command. As an example of compensation only in the resonant operating speed range, the weighting coefficient between 1000 and 2000 r / min was set to "1", and the weighting coefficient at other motor speeds was set to "0". The weighting coefficient for the angular transmission error compensator amplitude is shown in equation (32).

number

[0162] Figures 64 to 69 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, and load position vibration component, respectively, when the compensation summation point is set to current command, low gain setting, and compensation is enabled (hereinafter referred to as condition J). The horizontal axis represents time, and the vertical axis represents each component.

[0163] Compared to Figures 26-31, which do not consider weighting coefficients, Figures 67 and 69, in particular, show that the vibration components at the specified operating speed range are compensated for in the load speed vibration components and load position vibration components, demonstrating that rotational non-uniformity can be suppressed only in that specific operating speed range. Similar trends are observed in the other figures as well.

[0164] From the simulation results under condition J, it is clear that rotational non-uniformity can be flexibly suppressed in a configuration with a set compensation speed range.

[0165] (Configuration using compensator input as command information) The simulation results for the configuration shown in Figure 5, where command information is used as the information for compensation, are shown. Figures 70 to 77 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, load position vibration component, error between motor position and position command, and error between motor position and approximate motor position, respectively, for the configuration in Figure 5, with the servo control approximation characteristics set to equation (14), low gain setting, and compensation enabled (hereinafter referred to as condition K). The horizontal axis represents time, and the vertical axis represents each component.

[0166] Compared to Figures 26-31, which use actual information (motor position, motor speed), Figures 74 and 75 show that equivalent compensation performance is obtained for the load speed vibration component and load position vibration component.

[0167] The error between the motor position and the position command shown in Figure 76 has a maximum error of approximately -3.2 rad, which corresponds to half a motor rotation. This indicates that simply using the position command as the compensator input will not generate a proper compensation signal.

[0168] Figure 77 shows that the error between the motor position and the approximate motor position is kept small compared to the actual motor position, demonstrating that vibration reduction at load speed and load position is achievable. A similar trend is observed in other figures.

[0169] Figures 78 and 79 show the servo control approximation characteristics using equation (15), low gain setting, and compensation, as well as the load position vibration component and the error between the motor position and the approximation motor position, respectively, with the configuration of Figure 5. The horizontal axis represents time, and the vertical axis represents each component.

[0170] Figures 78 and 79 demonstrate that even with different approximation methods, rotational non-uniformity can be suppressed if the error between the motor position and the approximate motor position is kept small.

[0171] From the simulation results under condition K, it is clear that even in configurations using command information, the present disclosure can suppress rotational non-uniformity.

[0172] (compensation order) The angular transmission error characteristics were investigated under conditions that considered both the second-order and fourth-order components. The fourth-order angular transmission error characteristics were set to A4 = 5 arc-sec and φ4 = -10 deg. The number of lookup tables and the motor speed for each lookup table were set to be equivalent to those for the second-order component. The fourth-order component resonates at approximately 750 r / min (approximately 2.5 s). Note that the low gain setting and compensation summation point are current commands.

[0173] Figures 80 to 85 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, and load position vibration component for the case without compensation (hereinafter referred to as condition L), Figures 86 to 91 show the case with secondary compensation (hereinafter referred to as condition M), and Figures 92 to 97 show the motor speed, load speed, motor speed vibration component, load speed vibration component, and load position vibration component for the cases of secondary and quaternary compensation (hereinafter referred to as condition N), respectively. The horizontal axis represents time, and the vertical axis represents each component.

[0174] Figures 83 and 85 show that, by considering the fourth-order component, the fourth-order component reaches a resonant state at approximately 750 r / min (approximately 2.5 s), and that the combination of the amplitudes and phases of the second-order and fourth-order angular transmission errors results in a complex vibration waveform. Similar trends are observed in other figures as well.

[0175] Figures 89 and 91 show that even if a fourth-order component exists, the second-order component can be compensated for by the second-order compensation. A similar trend is observed in the other figures as well.

[0176] Figures 95 and 97 demonstrate that non-uniformity of rotation due to both order components can be suppressed by second-order and fourth-order compensation. Similar trends are observed in other figures.

[0177] From the simulation results under conditions L to N, it is clear that even when multiple orders of angular transmission error exist, rotational non-uniformity can be suppressed by compensating for only the second-order component, or for multiple order components such as the second-order and fourth-order components.

[0178] (Load moment of inertia fluctuation) The vibration characteristics during load moment of inertia fluctuations are evaluated. Figure 98 shows the load moment of inertia fluctuation ratio, which is set to decrease in accordance with the acceleration and deceleration operations described above. Note that the low gain setting and compensation addition point are current commands.

[0179] Figures 99 to 104 show the motor speed, load speed, motor speed vibration component, load speed vibration component, motor position vibration component, and load position vibration component, respectively, under the case without compensation (hereinafter referred to as condition O), while Figures 105 to 110 show the motor speed, load speed, motor speed vibration component, load position vibration component, and load position vibration component under the case with compensation (hereinafter referred to as condition P). The horizontal axis represents time, and the vertical axis represents each component.

[0180] Figures 102 and 104 show that the resonant frequency changes due to fluctuations in the load moment of inertia, resulting in a lower operating speed at which resonance occurs. This corresponds to a change in the time period when the vibration reaches its maximum value. Similar trends are observed in the other figures as well.

[0181] Figures 108 and 110 demonstrate that the vibration characteristics associated with load moment of inertia fluctuations can be suppressed by this disclosure, thereby reducing rotational non-uniformity. Similar trends are observed in the other figures as well.

[0182] From the simulation results under conditions O to P, it is clear that even when the load moment of inertia fluctuates, the non-uniformity of rotation can be suppressed by this disclosure without changing the compensation parameters.

[0183] Furthermore, in a configuration where the compensator input is used as command information, when load moment of inertia fluctuations occur, the characteristics from the position command to the motor position change. Therefore, if the effect of load moment of inertia fluctuations is significant, it is necessary to consider load moment of inertia fluctuations in the approximation characteristics. In this case, for example, the approximation characteristics can be changed to match the load moment of inertia fluctuations, or the characteristics can be made to minimize the objective function when the expected load moment of inertia fluctuations occur, or the approximation error in the operating speed range where resonance occurs can be minimized.

[0184] (Difference in reduction mechanism spring constant) To evaluate the vibration characteristics when the reduction gear spring constant differs, the vibration characteristics are evaluated using three different values: nominal, 0.8 times the nominal, and 1.2 times the nominal. Here, the case where the reduction gear spring constant differs is assumed to be due to individual differences in the reduction gear. Note that the low gain setting and compensation addition point are current commands.

[0185] Figures 111 and 112 show the case where the reduction mechanism spring constant is nominal and there is no compensation (hereinafter referred to as condition Q). Figures 113 and 114 show the case where the reduction mechanism spring constant is 0.8 times the nominal and there is no compensation (hereinafter referred to as condition R). Figures 115 and 116 show the case where the reduction mechanism spring constant is 1.2 times the nominal and there is no compensation (hereinafter referred to as condition S). Figures 117 and 118 show the case where the reduction mechanism spring constant is nominal and there is compensation (hereinafter referred to as condition T). Figures 119 and 120 show the case where the reduction mechanism spring constant is 0.8 times the nominal and there is compensation (hereinafter referred to as condition U). Figures 121 and 122 show the case where the reduction mechanism spring constant is 1.2 times the nominal and there is compensation (hereinafter referred to as condition V). Each figure shows the motor position vibration component and the load position vibration component, respectively, with the horizontal axis representing time and the vertical axis representing each component.

[0186] Figures 111 to 116 show that the resonant frequency changes due to the different spring constants of the reduction gear mechanism, resulting in different operating speeds at which resonance occurs. This corresponds to a change in the time period when the vibration reaches its maximum value. Furthermore, the peak value also changes along with the change in vibration frequency.

[0187] Figures 117 to 122 demonstrate that the vibration characteristics resulting from different spring constants in the reduction gear mechanism can be suppressed by this disclosure.

[0188] From the simulation results under conditions Q to V, it is clear that even when the spring constants of the reduction mechanism differ, the non-uniformity of rotation can be suppressed by this disclosure without changing the compensation parameters.

[0189] Furthermore, in configurations where the compensator input is used as command information, if the fluctuation in the reduction mechanism spring constant has a significant impact, the same measures as those for load inertia moment fluctuations will be necessary.

[0190] Figure 124 is a flowchart of a vibration damping control program in a servo control system equipped with a reduction mechanism.

[0191] Step S1: Initial setup. Initial settings necessary for executing the vibration damping control program are performed. This includes initial settings for predetermined compensation order, amplitude, and phase for generating compensation signals. Amplitude and phase information corresponding to each compensation order and rotation direction is loaded into the compensation model (e.g., lookup table) referenced by the dynamic angular transmission error compensator. These compensation parameters may be configured to automatically set the amplitude and phase according to the frequency or compensation order corresponding to a predetermined speed range, based on the servo control system configuration, control parameters, and motor characteristics for at least one of the motor's position, speed, and current, and to be registered in the compensation model.

[0192] Step S2: Information acquisition. The system acquires the current position information of the controlled object (e.g., motor position or position command) and the current speed information of the controlled object (e.g., motor speed or position command speed). This information can be used by selecting either real-world information (motor position / motor speed) or command information (position command / position command speed).

[0193] Step S3: Amplitude and phase correction. Based on the speed information acquired in step S2, the amplitude and phase of the compensation signal are determined and corrected by referring to the compensation model. The dynamic angular transmission error compensator is configured so that the compensation signal is 0 when the speed information is 0, so adjustments are made so that the compensation signal is 0 when stopped (when the speed information is 0). The compensation model may be set to correct the compensation signal using a weighting coefficient that controls the effectiveness of the compensation signal according to a predetermined range of speed information. Consideration is given to generating the compensation signal from a preset amplitude and phase according to the rotation direction of the motor. If necessary, sinusoidal compensation signals are generated for each compensation order based on preset amplitude and phase for each different compensation order, and these are added together to generate a compensation signal. The compensation signal is corrected by referring to the compensation model regardless of the inertia of the load connected to the output shaft of the reduction mechanism with respect to rotation. The compensation signal is also corrected by referring to the compensation model regardless of the spring constant of the reduction mechanism. It is also possible to correct the compensation signal according to the load torque acting on the reduction mechanism. Furthermore, it is also possible to correct the compensation signal according to the temperature of the reduction mechanism, the temperature around the reduction mechanism, or the temperature assumed based on the operating conditions.

[0194] Step S4: Compensation signal generation. A sinusoidal compensation signal is generated based on the compensation order set in step S1, the amplitude and phase corrected in step S3, and the position information acquired in step S2. The sinusoidal wave can be realized as a sinusoidal function or by using a table reference to the position.

[0195] Step S5: Signal addition. The compensation signal generated in step S4 is added to either the position command, speed command, current command, or a control signal associated with these. According to the source, the compensation addition point is often the current command value because compensation is performed regardless of the control mode (position control, speed control, torque control). However, this compensation method can be implemented with any control system configuration, and the compensation addition point does not have an essential meaning; it is an element that can be designed according to the characteristics of the system. It has been confirmed that adding to the position command or speed feedback also yields a similar compensation effect.

[0196] Step S6: Servo control. A servo control system equipped with a reduction mechanism performs its operation based on a control signal to which a compensation signal has been added. This compensates for rotational non-uniformity caused by the angular transmission error of the reduction mechanism, resulting in a vibration damping effect.

[0197] [Summary of effects] As described above, this disclosure shows that when compensating for rotational non-uniformity due to the effects of angular transmission errors, the influence of various factors such as motor speed and parameter settings within the control device (e.g., various gains in feedback control) can be taken into consideration. This makes it possible to compensate for individual differences in the reduction mechanism and variations in operating conditions. Furthermore, even if the configuration and control method of the control device that implements the compensation are diverse, flexible compensation suitable for each configuration is possible, and adjustments can also be made according to the constraints of computer resources. Moreover, it is clear that the design and adjustment of control parameters of the control device that take various factors into consideration are easy.

[0198] In this embodiment, each process is executed on any computer. Furthermore, any computer may execute these processes using a processor as hardware, a program as software, or a combination thereof. In that case, the processor is configured to work in cooperation with the program to execute the various processes in this embodiment, and can function as a unit or means in this embodiment. Also, the execution order of the processes by the processor is not limited to the order described and may be changed as appropriate. Any computer may be a general-purpose computer, a computer designed for a specific purpose, a workstation, or any other system capable of executing each process.

[0199] A processor may consist of one or more hardware components, and the type of hardware is not limited. For example, a processor may consist of hardware such as a CPU, MPU (Micro Processing Unit), FPGA (Field Programmable Gate Array) or other programmable logic devices, ASIC (Application Specific Integrated Circuit) or other dedicated circuits for executing specific processes, GPU (Graphic Processing Unit), or NPU (Neural Processing Unit). Furthermore, the type of hardware may be a combination of different types of hardware. When multiple hardware components are configured to execute one or more processes of a given processor, these multiple hardware components may reside in physically separate devices or in the same device. Also, in any embodiment, the order of each process performed by the processor is not limited to the order described above and may be changed as appropriate. Hardware is composed of electrical circuits (circuitry) that combine circuit elements such as semiconductor elements.

[0200] Furthermore, the program may be firmware or software such as microcode. Alternatively, the program may be, for example, a group of program modules, each function of which may be implemented by a processor configured to perform its respective function. The program may be program code or multiple code segments stored on one or more non-temporary computer-readable media (e.g., storage media or other storage devices). The program may be divided and stored on multiple non-temporary computer-readable media located on physically separate devices. The program code or code segments may represent any combination of procedures, functions, subprograms, routines, subroutines, modules, software packages, classes, or instructions, data structures, or program statements. The program code or code segments may be connected to other code segments or hardware circuits by sending and receiving information, data, arguments, parameters, or memory contents. The program of this application may also be provided as a program product.

[0201] The vibration control method and vibration control program of this disclosure include steps or instructions to be executed by a computer that realize the functions of the main components of the vibration control device of this disclosure (angle transmission error compensator, adder, etc.). Therefore, the vibration control method and vibration control program can be configured in an embodiment that includes all of the additional features of the vibration control device (e.g., automatic setting of the compensation model) as steps of the method or instructions of the program, respectively.

[0202] (Note) The following is an addendum regarding the nature of this disclosure. (Note 1) A vibration control device applied to a servo control system equipped with a reduction mechanism, for compensating for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, comprising: an angular transmission error compensator that generates a sinusoidal compensation signal based on position information having a predetermined compensation order, amplitude, and phase; and an adder that adds the compensation signal to a position command, speed command, current command, or a control signal related thereto, wherein the angular transmission error compensator corrects the compensation signal by referring to a compensation model that corrects the amplitude and phase based on speed information. (Note 2) The vibration control device described in Appendix 1, wherein the angle transmission error compensator is configured to automatically set the amplitude and phase at frequencies corresponding to a predetermined speed range based on a control system configuration in which one of the motor position, motor speed, or current is the control variable, the control parameters, and the frequency response characteristics derived from the motor characteristics, and register these settings in the compensation model. (Note 3) The vibration control device according to Appendix 1 or Appendix 2, wherein the compensation model is a lookup table that references the amplitude and phase based on the velocity information. (Note 4) The vibration control device according to any one of the appendices 1 to 3, wherein the compensation model is set to correct the amplitude using a weighting coefficient that controls the effectiveness of the compensation signal according to a predetermined speed range of the speed information. (Note 5) The vibration control device according to any one of Appendix 1 to Appendix 4, wherein the position information is a position command or motor position, and the speed information is a position command speed or motor speed. (Note 6) The vibration control device according to any one of the appendices 1 to 5, wherein the angle transmission error compensator is configured such that the compensation signal becomes 0 when the speed information is 0. (Note 7) The vibration control device according to any one of Appendix 1 to Appendix 6, wherein the angle transmission error compensator generates the compensation signal from the pre-set amplitude and phase according to the rotation direction of the reduction mechanism. (Note 8) The vibration control device according to any one of Appendix 1 to Appendix 7, wherein the angle transmission error compensator generates sinusoidal compensation signals for each compensation order based on the amplitude and phase set in advance for each compensation order, and generates the compensation signal by adding these together. (Note 9) The vibration control device according to any one of Appendix 1 to Appendix 8, wherein the angle transmission error compensator designs the compensation model and corrects the compensation signal regardless of the rotational inertia of the load connected to the output shaft of the reduction mechanism. (Note 10) The vibration control device according to any one of the appendices 1 to 9, wherein the angle transmission error compensator designs the compensation model and corrects the compensation signal regardless of the spring constant of the reduction mechanism. (Note 11) The vibration control device according to any one of Appendix 1 to Appendix 10, wherein the angle transmission error compensator corrects the amplitude and phase for generating the compensation signal based on the load torque acting on the reduction mechanism. (Note 12) The vibration control device according to any one of Appendix 1 to Appendix 11, wherein the angle transmission error compensator corrects the amplitude and phase for generating the compensation signal based on the temperature of the reduction mechanism, the temperature around the reduction mechanism, or a temperature assumed based on the operating conditions.

[0203] All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference. [Explanation of symbols]

[0204] 1. Controlled object 2 Addition section 3. Compensation Models 100_1, 100_2, 100_3, 100_4 Vibration control device 200 motor 300 Reduction mechanism 400 load 500 encoders 1000 Vibration Control System

Claims

1. A vibration damping control device applied to a servo control system equipped with a reduction mechanism, which compensates for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, An angle transmission error compensator having a predetermined compensation order, amplitude, and phase, and generating a sinusoidal compensation signal based on position information, An adder that adds the compensation signal to a position command, speed command, current command, or a control signal related thereto, Includes, The angle transmission error compensator is a vibration control device that corrects the compensation signal by referring to a compensation model that corrects the amplitude and phase based on velocity information.

2. The vibration control device according to claim 1, wherein the angle transmission error compensator is configured to automatically set the amplitude and phase at frequencies corresponding to a predetermined speed range based on a control system configuration in which one of the motor position, motor speed, or current is the control variable, the control parameters, and the frequency response characteristics derived from the motor characteristics, and register these settings in the compensation model.

3. The vibration control device according to claim 1, wherein the compensation model is a lookup table that references the amplitude and phase based on the velocity information.

4. The vibration control device according to claim 1, wherein the compensation model is set to correct the amplitude using a weighting coefficient that controls the effectiveness of the compensation signal according to a predetermined speed range of the speed information.

5. The position information is a position command or motor position. The vibration control device according to claim 1, wherein the speed information is a position command speed or motor speed.

6. The vibration control device according to claim 1, wherein the angle transmission error compensator is configured such that the compensation signal becomes 0 when the speed information is 0.

7. The vibration control device according to claim 1, wherein the angle transmission error compensator generates the compensation signal from the amplitude and phase set in advance according to the rotation direction of the reduction mechanism.

8. The vibration control device according to claim 1, wherein the angle transmission error compensator generates sinusoidal compensation signals for each compensation order based on the amplitude and phase set in advance for each compensation order, and generates the compensation signal by adding these together.

9. The vibration control device according to claim 1, wherein the angle transmission error compensator designs the compensation model and corrects the compensation signal regardless of the rotational inertia of the load connected to the output shaft of the reduction mechanism.

10. The vibration control device according to claim 1, wherein the angle transmission error compensator designs the compensation model and corrects the compensation signal regardless of the spring constant of the reduction mechanism.

11. The vibration control device according to claim 1, wherein the angle transmission error compensator corrects the amplitude and phase for generating the compensation signal based on the load torque acting on the reduction mechanism.

12. The vibration control device according to claim 1, wherein the angle transmission error compensator corrects the amplitude and phase for generating the compensation signal based on the temperature of the reduction mechanism, the temperature around the reduction mechanism, or a temperature assumed based on the operating conditions.

13. A vibration damping control method applied to a servo control system equipped with a reduction mechanism, which compensates for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, It generates a sinusoidal compensation signal with a predetermined compensation order, amplitude, and phase, based on position information. The compensation signal is added to a position command, speed command, current command, or a control signal related thereto. The compensation signal is corrected by referring to a compensation model that corrects the amplitude and phase based on velocity information. A vibration control method in which a computer performs the action.

14. A vibration damping control program applied to a servo control system equipped with a reduction mechanism, which compensates for rotational non-uniformity caused by the influence of angular transmission error of the reduction mechanism, It generates a sinusoidal compensation signal with a predetermined compensation order, amplitude, and phase, based on position information. The compensation signal is added to a position command, speed command, current command, or a control signal related thereto. The compensation signal is corrected by referring to a compensation model that corrects the amplitude and phase based on velocity information. A vibration control program that instructs a computer to perform this action.

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