JP2008004007A - Position controller, position control method, robot controller and robot control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of an error in a trajectory of operation caused by phase difference of a band-elimination filter which eliminates resonant frequency components of a position instruction when resonant frequencies are different for each axis constituting a robot in suppression of oscillation by using the band-elimination filter. <P>SOLUTION: This position controller has: a differentiator 30 which differentiates the position instruction; a notch filter 31 which receives output of the differentiator and eliminates components having the resonant frequency of a joint axis as a center frequency; an integrator 32 which integrates output of the notch filter; an amplifier 33 which amplifies the output of the notch filter; and an adder 50 which adds output of the integrator and output of the amplifier together and generates a second position instruction to be output to a position control block. The error in a trajectory operation resulting from phase difference between axes of the notch filter is minimized even when band-elimination frequencies are different for each axis by using a notch filter to which a speed component feed-forward compensation function is added as the band-elimination filter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention mainly relates to a position control device and a position control method for equipment driven by a motor via a speed reducer, and more particularly to a robot control device and a robot control method for suppressing vibrations in a robot. .

  In a robot using a speed reducer, there is resonance due to the spring component of the speed reducer. If the robot is operated in the vicinity of the resonance frequency in a state where no countermeasure is taken, vibration occurs, which adversely affects the trajectory accuracy and stop accuracy.

  As a countermeasure, a resonance frequency component of the detection signal is eliminated in the servo loop, and a control system in which vibration due to resonance is less likely to occur (see, for example, Patent Document 1), or a resonance frequency component from an operation command signal. There is known a method (see, for example, Patent Document 2) that eliminates the operation and avoids an operation at a frequency at which vibration occurs.

  FIG. 7 is a block diagram showing a general position control loop used in a robot. In FIG. 7, the position control block 21 compares the position command θcom 17 with a position feedback (hereinafter abbreviated as FB) signal θfb 20 obtained from the encoder 19 that detects the position of the motor 18, and sends the speed command ωcom 25 to the speed control block 22. Output. The speed control block 22 compares the speed command ωcom 25 with the speed FB signal ωfb 26 obtained by differentiating the position FB signal θfb 20 with the differential element S 24, and outputs a current command icom 27 to the servo amplifier 23. The servo amplifier 23 supplies a current to the motor 18 in accordance with the current command icom 27.

  Here, a method of configuring a control system that eliminates the resonance frequency component of the detection signal in the servo loop described above and hardly generates vibration due to resonance will be described with reference to the drawings. As an example of this method, as shown in FIGS. 8 and 9, it is conceivable to insert a notch filter 31 having a resonance frequency band elimination characteristic in the closed loop shown in FIG. FIG. 10 is an example of the frequency characteristics of the amplitude and phase of the notch filter. The notch filter 31 is a filter that gives a steep attenuation to a specific frequency.

  However, this method can be effective if the resonance frequency can be specified, but for a target whose resonance frequency changes every moment due to a change in the posture of the robot such as a vertical articulated 6-axis robot. It is difficult to accurately erase only the resonance signal.

  If a mismatch occurs between the resonance frequency and the band elimination frequency of the notch filter 31, there is a possibility that a signal necessary for position control is also erased as compared with the case where the resonance elimination is not performed, that is, the case where the notch filter 12 is not inserted. is there. Note that if a signal necessary for position control is deleted, the closed loop characteristic may be deteriorated and position control itself may become unstable, and it is difficult to obtain an effect without causing side effects.

  On the other hand, FIG. 11 shows a method of eliminating the resonance frequency from the operation command signal and avoiding the operation at the frequency at which vibration occurs (see, for example, Patent Document 2). In FIG. 11, the notch filter 31 is inserted after the position command θcom 17 in FIG. 7 and the second position command θcom 2 (29) is output to the position control block 21.

In this method, the notch filter 31 is placed outside the servo loop. Therefore, even if the resonance frequency and the band elimination frequency of the notch filter 31 are deviated, the frequency that tends to resonate remains in the second position command θcom2 (29), and the vibration suppression effect is only weakened. The risk of the conventional position control itself becoming unstable can be avoided.
JP 2004-129416 A JP 2001-293638 A

  However, there is a problem in a method of eliminating the resonance frequency from the conventional operation command signal and avoiding the operation at the frequency at which the vibration is generated.

  In a vertical articulated 6-axis robot, which is an example of a robot, the load inertia of each axis and the spring constant of the speed reducer are different, so that the resonance frequency is different for each axis of the robot.

  That is, the band elimination frequency of the notch filter 31 in FIG. 11 differs for each robot axis. FIG. 12 shows the frequency characteristics of the amplitude and phase of the notch filter 31 when the band elimination frequencies are different. FIG. 12 shows the frequency characteristics of the amplitude 38 and the phase 40 when the band elimination center frequency of the notch filter 31 is 8 Hz, and the frequency characteristics of the amplitude 39 and the phase 41 when the center frequency is 16 Hz. Note that FIG. 12 shows an example in which the robot's first axis resonance frequency is 8 Hz and the robot's second axis resonance frequency is 16 Hz when the load is a certain posture. .

  The problem here is the phase difference between the phase frequency characteristic 40 and the phase frequency characteristic 41. From FIG. 12, it can be seen that when the frequency is 1 Hz (10 0 Hz), a phase difference 42 of about 7 ° is generated. This is because when the position command θcom17 in FIG. 11 is a sine wave of 1 Hz, the second position command θcom2 (29) has a phase difference of about 7 ° between the axes.

  This is not a big problem when operating each axis alone. However, for example, if the robot tip trajectory is to be linearly operated, it is necessary to operate all axes in synchronization. At this time, if a phase difference 42 occurs between the axes of the robot in the second position command θcom2 (29), an error occurs in the locus.

  The above will be described using the following mathematical formula. If the transfer function of the notch filter 31 generally used is G (s), G (s) can be expressed by the following equation.

ここで、図１１における位置指令θｃｏｍ１７と第２の位置指令θｃｏｍ２（２９）間の誤差をｅθとすると、以下の式で表すことが出来る

Here, when an error between the position command θcom17 and the second position command θcom2 (29) in FIG. 11 is eθ, it can be expressed by the following equation.

ノッチフィルタ帯域消去角周波数ωｃ（＝２・π・ｆｃ）より十分に低い周波数域、すなわちｓ＜＜ωｃの場合は、（数２）において、ｓ/ωｃ＝０とすることにより、以下の様に近似することが出来る。

In the frequency range sufficiently lower than the notch filter band elimination angular frequency ωc (= 2 · π · fc), that is, in the case of s << ωc, by setting s / ωc = 0 in (Equation 2), Can be approximated.

つまり、図１１においては、ノッチフィルタ帯域消去周波数ｆｃより十分に低い周波数域では、位置指令を微分した速度成分ｓ・θｃｏｍ(s)に比例した位置指令誤差ｅθが常に発生する。また、ノッチフィルタ帯域消去角周波数ｆｃが異なれば、位置指令誤差ｅθにも差が生じることとなる。

That is, in FIG. 11, a position command error eθ proportional to the speed component s · θcom (s) obtained by differentiating the position command always occurs in a frequency range sufficiently lower than the notch filter band elimination frequency fc. Further, if the notch filter band elimination angular frequency fc is different, a difference also occurs in the position command error eθ.

  That is, FIG. 12 showing the frequency characteristics of the amplitude and phase of the notch filter 31 when the band elimination frequency in FIG. 11 is different can be described by (Equation 3).

  As shown in the above description, in the conventional method, it is possible to suppress the vibration by eliminating the resonance frequency from the operation command signal and avoiding the operation at the frequency at which the vibration is generated. When the resonance frequency is different for each axis, there is a problem that an error occurs in the operation locus due to the phase difference of the band elimination filter.

  Accordingly, an object of the present invention is to solve the above-described problems, and in a method for suppressing vibration of the robot by deleting the resonance frequency from the operation command signal, even if the resonance frequency of each axis constituting the robot is different. Another object of the present invention is to provide a position control device, a position control method, a robot control device, and a robot control method capable of minimizing an error in an operation trajectory.

  In order to achieve the above object, a position control device according to claim 1 of the present invention compares a position command for a device driven by a motor with a position feedback signal obtained by detecting the position of the motor, and outputs a current command. A position control device that includes a control block for outputting, and that causes a current to flow through the motor in response to a current command, a differentiator that differentiates the position command, a band elimination filter that receives an output of the differentiator and eliminates a predetermined frequency component, An integrator that integrates the output of the band elimination filter, an amplifier that amplifies the output of the band elimination filter, and an adder that adds the output of the integrator and the output of the amplifier and outputs a second position command to the position control block It is equipped with.

  The position control method according to claim 2 includes a step of comparing a position command for a device driven by the motor with a position feedback signal obtained by detecting the position of the motor, and outputting a current command. A position control method for flowing current, the step of differentiating a position command, the step of eliminating a predetermined frequency component of the differentiated signal, the step of integrating a signal from which the predetermined frequency component has been deleted, And amplifying the signal from which the frequency component has been eliminated, and adding the integrated signal and the amplified signal to output a second position command for comparison with the position feedback signal.

  The robot control apparatus according to claim 3 is obtained by detecting a position command and a position of the motor with respect to the robot driven by the motor using a reduction gear having a plurality of arms and joint axes and provided in the vicinity of the joint axes. It is a robot controller that compares the position feedback signal and outputs a current command, and sends a current to the motor by the current command. The robot control device differentiates the position command and outputs the joint of the differentiator. A band elimination filter that eliminates a component whose center frequency is the resonance frequency of the shaft, an integrator that integrates the output of the band elimination filter, an amplifier that amplifies the output of the band elimination filter, an output of the integrator, and an output of the amplifier. And an adder that outputs a second position command to the position control block.

  According to a fourth aspect of the present invention, there is provided a robot control method comprising: detecting a position command to a device and a position of a motor in a robot driven by a motor using a reduction gear having a plurality of arms and a joint shaft and provided in the vicinity of the joint shaft. Comparing the obtained position feedback signal and outputting a current command, a robot control method for passing a current to a motor according to the current command, the step of differentiating the position command and the joint axis of the differentiated signal Eliminating a frequency component having a resonance frequency as a center frequency; integrating a signal from which the frequency component has been eliminated; amplifying a signal from which the frequency component has been eliminated; an integrated signal and an amplified signal; And outputting a second position command for comparison with the position feedback signal.

  According to the position control device of the present invention, a differentiator that differentiates a position command, a band elimination filter that receives an output of the differentiator and eliminates a predetermined frequency component, an integrator that integrates the output of the band elimination filter, Since the amplifier for amplifying the output of the band elimination filter and the adder for adding the output of the integrator and the output of the amplifier and outputting the second position command to the position control block, the resonance frequency component of the position command is provided. By using a notch filter to which a velocity component feedforward compensation function is added as a band elimination filter that eliminates the position error, the position command error can be reduced even if the band elimination frequency differs for each element of the device. Thus, when suppressing the vibration by eliminating the resonance frequency from the operation command signal using the band elimination filter and avoiding the operation at the frequency at which the vibration occurs, the locus caused by the phase difference between the elements of the notch filter device Operation errors can be minimized.

  According to the position control method of the present invention, the step of differentiating the position command, the step of eliminating the predetermined frequency component of the differentiated signal, the step of integrating the signal from which the predetermined frequency component has been deleted, A step of amplifying the signal from which the frequency component has been eliminated, and a step of adding the integrated signal and the amplified signal to output a second position command for comparison with the position feedback signal. When canceling the resonance frequency component, by adding the velocity component feedforward compensation function, the position command error can be reduced even if the band cancellation frequency is different for each device element, and the same effect as the above invention can be obtained. It is done.

  According to the robot control device of the present invention, a differentiator that differentiates a position command, a band elimination filter that eliminates a component having an output of the differentiator as an input and a resonance frequency of the joint axis as a center frequency, and an output of the band elimination filter Are integrated, an amplifier that amplifies the output of the band elimination filter, and an adder that adds the output of the integrator and the output of the amplifier and outputs the second position command to the position control block. By using a notch filter with a velocity component feedforward compensation function as a band elimination filter that eliminates the resonance frequency component of the position command, position command errors can be reduced even if the band elimination frequency differs for each joint axis. . As a result, when the vibration is suppressed by canceling the resonance frequency from the operation command signal using the band cancellation filter and avoiding the operation at the frequency at which the vibration occurs, the trajectory operation caused by the phase difference between the joint axes of the notch filter Error can be minimized.

  According to the robot control method of the present invention, the step of differentiating the position command, the step of eliminating the frequency component whose center frequency is the resonance frequency of the joint axis in the differentiated signal, and integrating the signal from which the frequency component has been eliminated And a step of amplifying the signal from which the frequency component has been eliminated, and a step of adding the integrated signal and the amplified signal and outputting a second position command for comparison with the position feedback signal. When the resonance frequency component of the position command is deleted, the velocity command feedforward compensation function is added to reduce the position command error even if the band cancellation frequency is different for each joint axis. An effect is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of a vertical articulated 6-axis robot according to an embodiment of the present invention, which includes a robot mechanism 1 and a robot control device 2. Although not explicitly shown in FIG. 1, the robot mechanism 1 has a plurality of arms and joint axes, and is driven using a speed reducer provided in the vicinity of each joint axis.

  FIG. 2 is a block diagram showing a configuration relating to position control of the vertical articulated robot in the embodiment of the present invention, and shows an outline of the internal configuration of the robot mechanism 1 and the robot control device 2.

  In FIG. 2, the main control unit 4 provided in the robot control device 2 outputs a position command for each of the six axes of the robot in accordance with the trajectory instructed and stored by the operation / teaching unit 3. Then, the first servo control unit 5 to the sixth servo control unit 10 of each axis of the robot are moved from the first motor unit 11 to the sixth motor unit in the robot mechanism 1 so as to follow the position command. 16 are controlled.

  FIG. 3 is a block diagram showing a position control loop of a robot in which a phase compensation band elimination filter is inserted in the motor position command in the embodiment of the present invention.

  As shown in FIG. 3, the robot includes a first servo control unit 5 and a first motor unit 11 for the first axis of the robot. The first motor unit 11 includes a motor 18 and an encoder 19. Similarly, the second to sixth axes of the robot are each independently configured of servo control units 6 to 10 and motor units 12 to 16. Here, in FIG. 3, the same elements as those in FIGS. 7, 8, 9, and 11 described in the prior art are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, the difference from the conventional configuration is that a phase compensation band elimination filter 28 is provided, although the detailed configuration will be described later, instead of the notch filter 31 in FIG. 11 described in the background art.

  In the description of FIG. 11 of the background art, attention is paid to the fact that a position command error eθ proportional to the velocity component s · θcom (s) obtained by differentiating the position command is always generated as shown in (Equation 3). In order to reduce this error, the phase compensation band elimination filter 28 in FIG. 3 adds a velocity component feedforward compensation function to the notch filter. A block diagram of the phase compensation band elimination filter 28 is shown in FIG.

  As shown in FIG. 4, the phase compensation band elimination filter 28 includes a differentiator s30 that receives the position command θcom17, a notch filter 31 that receives the output of the differentiator s30 and eliminates a predetermined frequency component, An integrator 1 / s32 that integrates the output, a feedforward compensation gain Kcomp33 that is an amplifier that amplifies the output of the notch filter 31, and the output of the integrator 1 / s32 and the output of the feedforward compensation gain Kcomp33 are added to obtain a second value. And an adder 50 for outputting the position command θcom2 (29). In this case, the notch filter 31 uses the output of the differentiator s30 as an input and eliminates the component having the center frequency as the resonance frequency of the joint axis of the robot.

  The operation of the position compensation band elimination filter 28 configured as described above will be described. That is, the phase compensation band elimination filter 28 has a differentiator s30 before the notch filter 31, and differentiates the position command θcom17 output to each axis from the main control unit 4 shown in FIG. Is input to the notch filter 31. Next, the output of the notch filter 31 integrated by the integrator 1 / s32 and the output of the notch filter 31 multiplied by the feedforward compensation gain Kcomp33 are added by the adder 50. The adder 50 Output as position command θcom2 (29).

  Here, an example of a method for determining the feedforward gain Kcomp33 will be described.

  In FIG. 4, when the transfer function G (s) of the notch filter 31 is the same as that described in the background art (Formula 1), the position command error eθ between the position command θcom17 and the second position command θcom2 (29) is It can be expressed by the following formula.

そして、ノッチフィルタ帯域消去角周波数ωｃ（＝２・π・ｆｃ）より十分に低い周波数域、すなわちｓ＜＜ωｃの場合は、（数４）において、ｓ/ωｃ＝０とすることにより、以下の様に近似することが出来る。

In the case of a frequency range sufficiently lower than the notch filter band elimination angular frequency ωc (= 2 · π · fc), that is, in the case of s << ωc, by setting s / ωc = 0 in (Equation 4), It can be approximated as follows.

ここで、フィードフォワードゲインＫｃｏｍｐ３３を以下の様に設定すれば、（数５）より求める位置指令誤差ｅθをゼロにすることができる。

Here, if the feedforward gain Kcomp33 is set as follows, the position command error eθ obtained from (Equation 5) can be made zero.

つまり、ノッチフィルタ帯域消去周波数ｆｃより十分に低い周波数域では、位置指令誤差ｅθ≒０であり、以下の式が成り立つ。

That is, in the frequency range sufficiently lower than the notch filter band elimination frequency fc, the position command error eθ≈0, and the following expression is established.

図４で示した位相補償帯域消去フィルタ２８において、帯域消去周波数が異なる場合の振幅および位相の周波数特性を図６に示す。図６は、例として、ロボットがある姿勢である負荷である場合に、ロボットの第１軸の帯域消去中心周波数が８Ｈｚの場合の振幅３４および位相３６の周波数特性、そして、ロボットの第２軸の中心周波数が１６Ｈｚの場合の振幅３５および位相３７の周波数特性を示している。

FIG. 6 shows the frequency characteristics of the amplitude and phase when the band elimination frequency is different in the phase compensation band elimination filter 28 shown in FIG. FIG. 6 shows, as an example, the frequency characteristics of the amplitude 34 and the phase 36 when the band elimination center frequency of the first axis of the robot is 8 Hz when the robot is a load in a certain posture, and the second axis of the robot. The frequency characteristics of the amplitude 35 and the phase 37 when the center frequency is 16 Hz are shown.

  Compared to the frequency characteristics of the amplitudes 38 and 39 and the phases 40 and 41 in FIG. 12 described in the background art, in FIG. 6, the band elimination frequencies of the amplitudes 34 and 35 are not changed from the amplitudes 38 and 39 in FIG. In FIG. 6, the phase difference when the frequency of the phase characteristic 36 and the phase characteristic 37 is 1 Hz (10th power Hz) is the phase difference between the phase characteristic 40 and the phase characteristic 41 shown in FIG. It can be seen that it is much smaller than 42.

  In other words, even when all the axes are operated synchronously so as to move the robot tip locus linearly, for example, the error of the motion locus can be minimized.

  Here, the block diagram constituting the phase compensation band elimination filter 28 shown in FIG. 4 can also be constructed in hardware, but in practice it is often executed by software, so the method is shown in FIG. This will be described with reference to the flowchart shown.

  In the flowchart of FIG. 5, after inputting the position command θcom (step S1), the result of differentiation is stored in the variable a of S2 shown in FIG. 5 (step S2).

次に中間変数ａを、ノッチフィルタ処理し中間変数ｂを求める（ステップＳ３）

Next, the intermediate variable a is subjected to notch filter processing to obtain an intermediate variable b (step S3).

次に、中間変数ｂを積分して中間変数ｃを求める処理（ステップＳ４）と、フィードフォワード補償ゲインＫｃｏｍｐ３３で乗じて中間変数ｄを求める処理（ステップＳ５）を実行する。

Next, a process of obtaining the intermediate variable c by integrating the intermediate variable b (step S4) and a process of obtaining the intermediate variable d by multiplying by the feedforward compensation gain Kcomp33 (step S5) are executed.

最後に、Ｓ４で算出した中間変数ｃとＳ５で算出したｄを加算し、第２の位置指令θｃｏｍ２（２９）として出力する。（ステップＳ６）

Finally, the intermediate variable c calculated in S4 and d calculated in S5 are added and output as the second position command θcom2 (29). (Step S6)

以上により、ソフトウェアにおいてもθｃｏｍ２（２９）を求めることが可能である。

As described above, θcom2 (29) can be obtained also in software.

  In this embodiment, as an example of the position control device and the position control method, an example in which the present invention is applied to a robot has been shown. However, the present invention is not limited to this, and elements corresponding to a plurality of axes having different resonance frequencies are simultaneously used. Alternatively, it goes without saying that the present invention can also be applied to devices other than robots that are individually driven and the phase difference of the band elimination filter for suppressing resonance becomes a problem.

  In this embodiment, as shown in FIG. 3, the current command is generated with the configuration of the position loop and the speed loop. However, the current command may be generated without distinguishing between the position loop speed loop.

  According to the position control device and the control method of the present invention, when suppressing vibration by canceling the resonance frequency from the operation command signal using the band elimination filter and avoiding the operation at the frequency at which the vibration is generated, Since the error of the motion trajectory due to the phase difference can be minimized, the elements corresponding to the multiple axes having different resonance frequencies are driven simultaneously or individually, and the phase difference of the band elimination filter for suppressing the resonance is reduced. It can be applied to problematic equipment and is industrially useful.

It is a figure which shows schematic structure of the vertical articulated robot in embodiment of this invention. It is a block diagram which shows the structure regarding the position control of the vertical articulated robot in embodiment of this invention. It is a block diagram which shows the control loop which inserted the phase compensation zone | band elimination filter in the motor position command in embodiment of this invention. It is a block diagram which shows the structure of the phase compensation band elimination filter in embodiment of this invention. It is a flowchart which shows the flow of a process of the phase compensation band elimination filter in embodiment of this invention. It is a figure which shows the frequency characteristic of an amplitude and a phase in case the notch filter band elimination center frequency in embodiment of this invention differs. It is a block diagram which shows the conventional motor position control loop without the vibration suppression of a resonance. It is a block diagram which shows the example which provided the resonance suppression notch filter in the conventional motor position control loop. It is a block diagram which shows the example which provided the resonance suppression notch filter in the conventional motor position control loop. It is a figure which shows the frequency characteristic of the amplitude and phase of the conventional notch filter. It is a block diagram which shows the example which inserted the resonance suppression notch filter in the conventional motor position command. It is a figure which shows the frequency characteristic of an amplitude and a phase in case the conventional notch filter band elimination center frequency differs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Robot mechanism 2 Robot control apparatus 3 Operation / teaching part 4 Main control parts 5-10 1st servo control part-6th servo control part 11-16 1st motor part-6th motor part 17 Position command (theta) com
18 Motor 19 Encoder 20 Position feedback θfb
21 Position control block 22 Speed control block 23 Servo amplifier 24 Differential element s
25 Speed command ωcom
26 Speed feedback ωfb
27 Motor current command Icom
28 Phase Compensation Band Elimination Filter 29 Second Position Command θcom2
30 differential element s
31 Notch filter 32 Integration element 1 / s
33 Feedforward compensation gain Kcomp
34 Amplitude frequency characteristics of phase compensation band elimination filter (band elimination center frequency 8Hz)
35 Amplitude frequency characteristics of phase compensation band elimination filter (band elimination center frequency 16Hz)
36 Phase frequency characteristics of phase compensation band elimination filter (band elimination center frequency 8Hz)
37 Phase frequency characteristics of phase compensation band elimination filter (band elimination center frequency 16Hz)
38 Amplitude frequency characteristics of notch filter (Band elimination center frequency 8Hz)
39 Amplitude frequency characteristics of notch filter (band elimination center frequency 16Hz)
40 Phase frequency characteristics of notch filter (Band elimination center frequency 8Hz)
41 Phase frequency characteristics of notch filter (band elimination center frequency 16Hz)
42 Notch filter phase difference 43 Notch filter amplitude frequency characteristic 44 Notch filter phase frequency characteristic 45 Position command speed component dθcom
50 adder

Claims (4)

A position control device comprising a control block that compares a position command for a device driven by a motor with a position feedback signal obtained by detecting the position of the motor and outputs a current command, and causes a current to flow to the motor in accordance with the current command Because
A differentiator for differentiating the position command;
A band elimination filter that eliminates a predetermined frequency component using the output of the differentiator as an input,
An integrator for integrating the output of the band elimination filter;
An amplifier for amplifying the output of the band elimination filter;
A position control device comprising: an adder that adds the output of the integrator and the output of the amplifier and outputs a second position command to the position control block. A position control method for comparing a position command for a device driven by a motor with a position feedback signal obtained by detecting the position of the motor and outputting a current command, wherein a current is supplied to the motor by the current command. There,
Differentiating the position command;
Eliminating a predetermined frequency component of the differentiated signal;
Integrating the signal from which the predetermined frequency component has been eliminated;
Amplifying the signal from which the predetermined frequency component has been eliminated;
And a step of outputting a second position command for adding the integrated signal and the amplified signal to compare with the position feedback signal. A position command for a robot driven by a motor using a speed reducer provided with a plurality of arms and a joint shaft in the vicinity of the joint shaft is compared with a position feedback signal obtained by detecting the position of the motor, A robot control device comprising a control block for outputting a current command, and causing a current to flow to the motor in accordance with the current command,
A differentiator for differentiating the position command;
A band elimination filter that eliminates a component having an input of the differentiator as an input and a resonance frequency of the joint axis as a center frequency;
An integrator for integrating the output of the band elimination filter;
An amplifier for amplifying the output of the band elimination filter;
A robot control device comprising: an adder that adds the output of the integrator and the output of the amplifier and outputs a second position command to the position control block. A position command for a device is compared with a position feedback signal obtained by detecting the position of the motor in a robot driven by a motor using a speed reducer provided with a plurality of arms and a joint shaft in the vicinity of the joint shaft. And a step of outputting a current command, and a robot control method for passing a current to the motor by the current command,
Differentiating the position command;
Eliminating the frequency component having the center frequency of the resonance frequency of the joint axis in the differentiated signal;
Integrating the signal from which the frequency component has been eliminated;
Amplifying the signal from which the frequency component has been eliminated;
Adding the integrated signal and the amplified signal and outputting a second position command for comparison with the position feedback signal.

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