JP2011224662A - Correction parameter identification device of robot control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct waviness by a reduction gear angle transmission error.SOLUTION: This correction parameter identification device of a robot control device includes: a means for determining amplitude of the waviness generated in a finger part of a robot; a means for determining an amplitude value Di of the waviness corresponding to a predetermined joint Ji of a plurality of joints; a means for measuring a position feedback signal Bi appearing on a shaft of the joint when operating the predetermined joint Ji in a single shaft by a position command θrefi of a motor; a means for superimposably adding the waviness of the amplitude C to the position command value θrefi to the joint Ji and calculating waviness C'i generated in a finger position when assuming that a position command θrefx is added to the other shaft Jx; a means for determining Ai corresponding to Bi according to an expression such as Ai=(Ci/C'i)×Di; and a means for determining the Ai corresponding to the Bi by using the respective means to a plurality of robots.

Description

  An embodiment of the present invention relates to a correction parameter identification device of a robot control device, for example.

  For example, in a robot control device used for arc welding and laser cutting robots, the robot's hand position oscillates in the direction of gravity during operation, resulting in a phenomenon in which machining accuracy deteriorates (for example, Patent Document 1). reference). This swell is considered to be caused by the angle transmission error of the speed reducer attached to each axis of the robot.

In order to cope with the angle transmission error of the speed reducer, a normal robot controller corrects the position of the work object by giving a sine wave command that cancels the swell of each axis.
FIG. 9 shows a position correction technique for a robot control apparatus in the prior art. Here, the swell of the speed reducer is canceled by a sine wave correction signal θcom. The amplitude A and phase Δθ of the sine wave θcom are adjusted in advance to obtain an appropriate value.

  This appropriate value is set by the amplitude setting unit 19 and the phase setting unit 20. The sine wave generator 24 calculates the correction signal θcom based on the set amplitude A, phase Δθ, and the position command base signal θrb output from the command generator 53.

  The calculated correction signal θcom is added to the position command base signal θrb to become a corrected position command signal θref. This position command signal θref is compared with the rotation angle θfb of the motor detected by the angle detection unit 51, the servo control unit 52 drives the motor 11 based on the deviation of the comparison result, and the robot arm 14 is positioned and controlled.

  A conventional reduction parameter identification method for a reduction gear angle transmission error uses a robot external sensor and adjusts and identifies the correction parameter amplitude and phase so as to minimize the waviness of the hand (for example, Patent Document 1). , See Patent Document 2).

  In addition, by considering the reduction ratio in the reaction force to the motor due to torsional torque, it is possible to identify a more accurate model to be controlled, and some that have improved robot hand position trajectory accuracy through the introduction of modern control theory. is there. In this case, the phase, which is a correction parameter, is identified using data acquired by a robot internal sensor (current that drives the motor, motor rotation speed) (see, for example, Patent Document 3).

  As described above, in the conventional robot control device, the procedure for identifying the amplitude and phase, which are parameters of the correction signal for correcting the reduction gear angle transmission error, by the robot external sensor, or the procedure for identifying only the phase by the robot internal sensor. It was taken. That is, there has been no technique for identifying the amplitude, which is a parameter of the correction signal, with the internal sensor.

Japanese Patent No. 2577713 Japanese Unexamined Patent Publication No. 7-129251 Japanese Patent No. 3239789

The correction parameter for the angle transmission error of the speed reducer has individual differences even for the speed reducers of the same frame number, and it is necessary to identify each individual speed reducer. In other words, correction parameter identification is required each time the robot is adjusted at the time of shipment or when the reduction gear is replaced due to a failure after shipment.
However, as described above, in the conventional correction parameter identification method, both the amplitude and phase, which are correction parameters, cannot be identified only by the robot internal sensor, and the robot external sensor and peripheral devices must be installed near the robot. I must. Furthermore, when the speed reducer is replaced after shipment, it may take time to transport the robot external sensor and peripheral devices to the robot operation site.
As described above, the conventional correction parameter identification method has a problem that the correction parameter cannot be easily identified (note that the non-simple identification method means that a robot external sensor or peripheral device is required at the time of identification). .

In order to solve the above problems, the present invention at the time of filing provides the following inventions.
Of course, the description of the scope of claims can be amended based on the description of the specification at the time of filing the application, but at that time, the contents of the following “inventions” are not scheduled to be corrected. (Each "invention" below has the meaning as a gist of disclosure in the present specification).
[Invention 1]
A robot in which a plurality of joints J1-n are driven by a motor via a reduction gear;
An angle detector for detecting an angle B1-n [rad] of the motor at each joint 1-n;
A command generator for generating the motor position commands θref1 to n [rad] for each joint J1-n (1 to n is an integer);
A reduction gear angle transmission error, which is an error between the position commands θref1 to n [rad] and the motor angles θfb1 to n [rad] actually detected with respect to the position commands θref1 to n [rad], is corrected. A correction signal generation unit that generates correction signals A1 to n [rad] for performing correction, and the correction signals A1 to n [rad] are added to the position designations θref1 to n [rad]. rad] to eliminate the reduction gear angle transmission error,
A correction parameter identification device for a robot control device comprising:
The Z-axis direction, that is, perpendicular to the ground surface, generated at the hand portion due to the transmission error of at least two speed reducers of the plurality of joints that occurs when the hand portion of the robot is orthogonally moved. Means for determining the direction and the amplitude of the swell Z [mm];
Means for Fourier-transforming the swell amplitude Z [mm] to obtain a swell amplitude value Di [mm] (i is a predetermined number from 1 to n) corresponding to a predetermined joint Ji of the plurality of joints. When,
When the predetermined joint Ji (i is a predetermined number from 1 to n) is uniaxially operated with a motor position command θrefi [rad], a position feedback signal Bi [rad that appears on the axis of the predetermined joint ] Means for measuring
It is assumed that the position command value θrefi for the predetermined joint Ji is further superimposed with a wave of amplitude C [rad] from the outside, and in addition to these, another axis Jx (x is a predetermined number other than i) ), A virtual swell C′i [mm] that is generated in the Z direction at the hand position by forward kinematics, assuming that a position command θrefx [rad] is added to
Ai [rad] = (Ci [rad] / C′i [mm]) × Di [mm]
Means for obtaining Ai [rad] corresponding to Bi [rad] according to the equation:
For a plurality of robots of the same model but having different operable weights, means for obtaining Ai [rad] corresponding to Bi [rad] for each robot using each of the above means;
A correction parameter identification device for a robot control device, comprising:

With this configuration, it is possible to identify the amplitude that is a parameter of the correction signal with the internal sensor.
[Invention 2]
In the correction parameter identification device, a device for compensating for a reduction gear angle transmission error,
Means for uniaxially moving a predetermined joint Jj (j is an arbitrary number from 1 to n);
Means for providing a predetermined position command θrefj [rad] for the single-axis operation;
Means for obtaining a position feedback θfbj [rad] measured at the single-axis operated joint Jj;
Means for obtaining a delay time ΔTdj [sec] of the position feedback θfbj [rad] from the position command θrefj [rad];
Means for obtaining a signal θfb′j [rad] obtained by advancing the position feedback θfbj [rad] by ΔTdj [sec];
Means for obtaining a difference Difj [rad] between the signal θfb ′ j [rad] and the position command θrefj [rad];
Means for obtaining the amplitude Bj [rad] of the Difj [rad];
Means for obtaining Aj [rad] corresponding to the amplitude Bj [rad] by each means described in the invention 1,
A device comprising:

With this configuration, it is possible to compensate for the angular transmission error of the speed reducer that differs for each robot.
The meanings of terms used in the present specification are listed below.
-Robot → A device that performs some work on behalf of a person. In the present invention, an industrial robot that performs automatic work continuously autonomously to some extent is a representative example, but the present invention is not limited to this. It is a “robot (an apparatus that performs some work on behalf of a person)” to be developed in the future, and includes all “robots” that can use the invention included in the technical scope of the claims of the present application.
・ Sensor for measuring the position (rotation angle) of encoder → motor. Differentiating the encoder output gives the motor rotational (angular) speed.
・ For forward kinematics → robot control, the motor that drives each axis is equipped with an encoder. From the position (rotation angle) of each axis measured by the encoder and the length (known) of each link of the robot The position and orientation of the hand of the robot can be obtained. Obtaining the position and orientation of the hand of the robot is called forward kinematics (forward transformation).
・ Inverse kinematics (reverse transformation) → Refers to finding out the position (rotation angle) of each axis of a robot in order to realize the position and orientation of a robot's hand.
External sensor → A sensor that is provided outside the original robot control system and measures the movement of the robot (in the embodiment of the present invention, the undulation of the hand) from the outside. The vibration detector of Patent Document 2 corresponds to this.
・ Inside sensor → A sensor installed inside the robot control system, such as an encoder that measures the position of the robot's motor and a sensor that measures the current and voltage values flowing through the motor.
・ Identify → Calculate. Meaning to obtain parameters to determine the model of the control system or mechanism system.
・ PC → PC ・ Single-axis operation → Operation with only one axis (Move one axis of the robot joint)
・ Orthogonal motion → For example, move the hand of the robot in the X-axis direction.
・ Harmonic reducer → A type of reducer used in combination with a motor that drives each joint of the robot. A typical example of a reduction gear is a gear.

  The embodiment of the present invention has an effect that, for example, an amplitude that is a parameter of a correction signal necessary for correcting waviness due to a reduction gear angle transmission error can be identified by a robot internal sensor.

1 is a general description of an embodiment of the present invention. The flowchart which shows the technique of the Example of this invention The figure which shows the structure of the robot control apparatus to which the technique of the Example of this invention is applied. System diagram used to derive the relationship between corrected amplitude and position feedback Flow chart showing a procedure for deriving a relational expression between correction amplitude and position feedback Figure supplementing the procedure for deriving the relational expression between the correction amplitude and position feedback Graph showing the relationship between the correction amplitude and position feedback Flow chart showing the procedure for identifying the correction amplitude Figure supplementing the procedure for identifying the correction amplitude The figure which shows the robot control device of the prior art

  In the embodiment of the present invention, when the position of the hand of the robot undulates in the direction of gravity, a device that provides a position command A (amplitude value: rad) for correction in the direction opposite to the undulation is used. A novel technique for determining the value A is disclosed.

In this technique, referring to FIG.
(1) First, orthogonal operation is performed, and for each robot of each model, the position command θref [rad] for each axis and the hand position Z actually obtained (including undulation) for the command [Mm] is measured (FIG. 4: S42).
(2) Next, the hand position Z [mm] is Fourier-transformed, and the amplitude D [mm] at the frequency corresponding to each axis of the robot (for example, axis Ji) on the frequency axis (swelling amplitude on the time axis) (The reason why the value for each axis can be obtained at once by one Fourier transform is described later). (Figure 4: S44)
(3) A single axis operation is performed, and the amplitude B [rad] of the position feedback θfb [rad] of each axis (for example, axis Ji) is obtained from the encoder values of each axis of the robot (FIG. 4: S45).
(4) Next, assuming that an amplitude swell of amplitude C [rad] is artificially given to the axis Ji for which the position command A for correction is to be obtained (FIG. 4: S46),
(4-1) A signal (C + θref) [rad] @Ji [data “3” of S46 in FIG. 4] in which the C [rad] is superimposed on the position command value to the axis Ji, and
(4-2) Position command θref [rad] @ Jy on the other axis Jy,
Assuming that the two are given as command values, a virtual undulation C ′ [mm] of the hand position in the Z direction obtained using forward kinematics is calculated (FIG. 4: S47).
(5) The ratio of C [rad] assumed to be artificially applied to the axis Ji and the virtual undulation C ′ [mm] of the hand position in the Z direction is a correction amplitude A [rad] to be applied to the axis Ji; From C [rad], C ′ [mm], and D [mm], which have become known, using the fact that the amplitude is equal to the ratio of the amplitude D [mm] of the undulation of the hand position in the Z direction, A [rad] (FIG. 4: S48).
In the following description, the amplitude that is a parameter of the correction signal is described as “correction amplitude”.

By executing the above procedure for a plurality of robots having the same specifications, the relationship between B and A [rad] corresponding to FIG. 6 is obtained. In this robot, the amplitude B [rad] of the undulation of the hand position θfb is obtained. ] And the required correction amplitude A [rad] corresponding to B, A = f (B) (formula 5) (described later).
Here, “execution of the above procedure for a plurality of robots having the same specification” means that a relationship of A = f (B) is obtained by measuring several robots of the same model. Next, at the shipping stage, the following process is performed to compensate for the reduction gear angle transmission error that differs for each robot while utilizing the relationship of A = f (B) thus obtained.

In other words,
(6) The influence of the time difference existing between the position command θref for each axis and the hand position θfb actually obtained (including waviness) with respect to the command is removed and actually given. When the position command to be obtained is θref and the hand position actually obtained is θfb, the influence of the time difference is removed to obtain an accurate correction amplitude A (described later with reference to FIG. 8).
Hereinafter, specific examples of the robot control apparatus of the present invention will be described with reference to FIGS.

FIG. 1B is a flowchart illustrating a correction parameter identification method according to the embodiment of the present invention.
First, in a plurality of robots, a position command and position feedback are measured by a single axis operation, and a hand position and a position command are measured by an orthogonal operation (S11) (corresponding to (1) to (3) above).
Next, a relational expression between the amplitude of the position feedback and the amplitude that is a parameter of the correction signal is derived (S12) (corresponding to (4) to (5) above).
Then, the correction amplitude for each individual is adjusted (S13) (corresponding to (6) above). (S11) and (S12) are procedures for deriving a relational expression between the amplitude of the position feedback and the amplitude which is a parameter of the correction signal. This is a preliminary preparation and only needs to be performed once per model. One time for one model means that if the size of the robot changes, it must be measured with that model. (For example, if there are 10kg, 20kg, and 30kg portable robots, it is necessary to measure the three models)

Step S13 is a procedure for identifying the correction parameter for each individual, and is performed at the time of shipment or at the time of adjustment accompanying replacement of the reduction gear at the robot operation site. Since the relational expression between the amplitude of the position feedback and the correction amplitude is derived in advance, it can be easily identified without a robot external sensor.

FIG. 2 is a system diagram showing a configuration of a robot control apparatus that implements the technique of the embodiment of the present invention.
The robot 1 is a general 6-axis industrial robot. However, the embodiment of the present invention is not limited to a general 6-axis industrial robot, but can be applied to any robot. In this embodiment, as shown in FIG. 2, each axis of the robot is called an S axis, an L axis, a U axis, an R axis, a B axis, and a T axis.

The robot control device 5 includes an angle detection unit 51, a servo control unit 52, a command generation unit 53, a correction signal generation unit 54, an amplitude identification unit 55, and a phase identification unit 56.
The angle detector 51 detects the angle of each axis motor of the robot 1. The servo control unit 52 controls the motor of each axis. The command generator 53 generates a command to the motor of each axis. The correction signal generation unit 54 generates a correction signal for correcting the waviness of each axis. The amplitude identification unit 55 and the phase identification unit 56 identify the amplitude and phase of the correction signal, respectively. The amplitude identification unit 55 can use the technology of the present invention described later, and the phase identification unit 56 can use the technology used for identification by a robot internal field sensor of the prior art (for example, Patent Document 1).

  The correction signal generation unit 54 includes an amplitude setting unit 19, a phase setting unit 20, and a sine wave generation unit 24. The sine wave generation unit 24 generates a sine wave serving as a correction signal. The amplitude setting unit 19 and the phase setting unit 20 set the amplitude and phase of the sine wave generated by the sine wave generation unit 24. The values identified by the amplitude identification unit 55 and the phase identification unit 56 are set in the amplitude setting unit 19 and the phase setting unit 20.

  FIG. 3 is used in the embodiment of the present invention to derive a relational expression between the correction amplitude A [rad] and the amplitude B [rad] of the position feedback θfb as described in (1) to (5) above. It is a system diagram.

The laser distance measurement sensor 2 is a reflection type laser distance measurement sensor for measuring the position of the hand of the robot 1 relative to the reflection plate 3 by measuring a distance from the reflection plate 3 described later.
The reflector 3 is a member that reflects the laser output from the reflective laser distance measurement sensor and measures the hand position in the Z direction (perpendicular to the ground surface).

  The robot coordinate system 6 is a coordinate system fixed to the robot body, and is a reference coordinate system when the robot is operated. In the robot coordinate system 6, an X axis is provided in the front-rear direction of the robot 1, a Y axis in the left-right direction, and a Z axis in the up-down direction.

  The relational expression deriving unit 4 acquires the Z-direction hand position Z, the position command value θref of each axis, and the position feedback θfb. Using these pieces of information, a relational expression between the correction amplitude A and the amplitude B of the position feedback θfb is derived. The relational expression deriving unit 4 is composed of, for example, a PC.

  The flowchart of FIG. 4 corresponds to steps S11 and S12 of FIG. 1-B (corresponding to (1) to (5) above), and is a procedure for deriving a relational expression of formula (5) described later. It is a flowchart which shows (advance preparation).

Steps S41 to S48 are performed on several robots of the same specification (at least 3 or more, for example, 5), and the relational expression (relationship between the correction amplitude A and the amplitude B of the position feedback) is expressed by Expression (5). Ask.
Here, the system of FIG. 3 is used.
First, the robot is operated orthogonally (S41).
Next, the following two data are measured (S42).

(i) Z direction hand position
(ii) Position command θref [rad] for each axis
Wait for the robot to stop (S43).
Next, the amplitude D [mm] of the Z-direction hand position of each axis is obtained from the data (i) by Fourier transform (S44).

By performing Fourier transform, for example, the amplitude at the L-axis frequency and the amplitude at the U-axis frequency in FIG. 5 are obtained on the frequency axis in a direction increasing from a low frequency. (Note that this “amplitude” is not the “amplitude” [rad] in the rotation direction of the shaft, but the amplitude [rad] in the rotation direction of each axis corresponding to the vibration amplitude [mm] at the hand. (It corresponds to physical quantity converted to vibration amplitude [mm])
Here, it is possible to know which axis of the robot each of the plurality of peak values appearing on the frequency axis after Fourier transform corresponds to the vibration (swell) of the robot as follows.

  The frequency of the undulation appearing at the hand due to the reduction gear angle transmission error of each axis depends on the motor speed and the structure of the reduction gear. For example, it is assumed that N undulations appear in one turn due to the structure of the L-axis speed reducer. It is assumed that the motor speed of the L axis is ω and the L axis reduction ratio d. Then, the frequency of the swell is known as (ω × N) / (2π × d) (refer to “How to obtain D of the Z-direction hand position of each axis” in S44 of FIG. 4 described later with reference to FIG. 5). ).

  In the position feedback, undulation caused by a reduction gear angle transmission error appears. For example, in the case of an RV reducer, the frequency of this swell is proportional to twice the number of meshing pins because two RV gears are attached to one reducer in reverse phase. Further, for example, in the case of a harmonic reduction gear, it is known that there are two cycles per motor rotation. Thus, the swell cycle is determined by the structure of the reduction gear.

In this way, by using the Fourier transform, it is possible to obtain the amplitudes of vibrations of all related axes in one measurement.
Subsequently, the amplitude B [rad] of the position feedback θfb of each axis is obtained using the method outlined in FIG. 3 (S45).

(Note that B obtained in S45 is used in the following processing as follows. That is, as a preliminary preparation, a plurality of robots are used, and in S11 and S12, a relational expression of A and B (A = f (B) [Expression 5 Then, if B is obtained in S13, A can be obtained (if there is an encoder that is an internal sensor, A can be obtained. After the preparation is completed, it is necessary to measure the hand position. (In other words, by obtaining B, the value of B is used to obtain A corresponding to B.)
Further, data (iii) is created by adding a sine wave of amplitude C [rad] to the data of (ii) of the axis to be identified (S46).

Then, the amplitude C ′ [mm] of the hand position in the Z direction is calculated by forward kinematics from the data of (iii) and the data of (ii) other than the axis to be identified (S47).
Finally, a correction amplitude A [rad] is obtained from the relationship of C: C ′ = A: D (S48).

FIG. 5 schematically shows the procedure of step S44, step S46, and step S47 of FIG.
A supplementary description will be given of how to determine the amplitude D of the Z-direction hand position of each axis in step S44 of FIG. 4 using FIG.

Let the Z-direction hand position measured by the laser distance measuring sensor 2 be P (t). Then, the amplitude D of the Z-direction hand position of each axis can be obtained from the equations (1) to (4).
Where T ₀ [sec] is the swell period of each axis, Δt is the sampling period in which the Z-direction hand position data is measured, d is the reduction ratio, ω is the angular velocity, and An and Bn are Fourier coefficients. The angular velocity is calculated from time series data of the measured position feedback θfb.

  FIG. 6 shows the correction amplitude A and position feedback by performing the pre-preparation procedure of FIG. 4 for several robots of the same specification (at least three or more) in order to derive a relational expression of the following expression (5). It is the graph which plotted the amplitude B of (theta) fb. Relational expression (5) is derived from this graph. For example, the relational expression is obtained by the method of least squares, but is not limited to the method of least squares.

FIG. 7 is a flowchart showing a processing procedure for identifying the correction amplitude A in the robot control apparatus at the time of shipment according to step S13 in FIG. 1-B. The technique in the embodiment of the present invention will be described in order with reference to this figure. As the hardware, the system of FIG. 2 is used.
First, the axis to be identified is operated in a single axis (S71).
Next, the position command θref and the position feedback θfb are measured (S72).
Wait for the robot to stop (S73).
Next, a delay ΔTd from the position feedback θfb and the position command θref is obtained (S74).
Then, the position feedback θfb is advanced by the delay ΔTd obtained in (S74) (the obtained data is set as θfb ′) (S75).
Next, a difference between the position command θref and the data θfb ′ obtained in (S75) is obtained (S76).
In this way, it is possible to compensate for a reduction gear angle transmission error that differs for each robot.
Subsequently, the amplitude B [rad] of the data obtained in step S76 is obtained (S77).
The correction amplitude A [rad] is calculated from the equation (5) (S78). The relational expression of Expression (5) has already been obtained as described above (see the flowchart of FIG. 4).

The amplitude identification unit 55 identifies the correction amplitude A from the position feedback amplitude B obtained from the angle detection unit 51 and the equation (5) by the above procedure, and the amplitude setting unit 19 sets the value.
FIG. 8 is a schematic diagram of steps S74 to S77 in FIG.

  In this way, the axis that the robot wants to identify is operated in a single axis, the amplitude of the undulation caused by the speed reducer angle transmission error of the position feedback signal is obtained by the encoder that is the robot internal sensor, and the speed reducer angle transmission error of each joint axis The correction amplitude is identified from the amplitude of the position feedback signal using the relational expression obtained in advance between the correction amplitude for correcting the amplitude and the amplitude of the position feedback signal. A correction parameter can be easily identified in a short time without requiring a new peripheral device.

Even if the correction amplitude changes due to secular change, if the amplitude of the position feedback signal is measured again, the correction amplitude after the secular change can be identified.
Particular embodiments described herein have been described. Other embodiments are within the scope of the claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. By way of example, the processes shown in the accompanying drawings do not necessarily require the particular order shown or sequential order to achieve desirable results.

  Moreover, the function which one component has may be implement | achieved by two or more physical structures, and the function which two or more component elements have may be implement | achieved by one physical structure. The invention of the system can be grasped as an invention of a method in which the functions of each component are sequentially executed, and vice versa. In the method invention, the steps are not limited to being performed in the order described, but can be performed in any order as long as the overall function can be performed consistently. . These inventions are also established as a program that realizes a predetermined function in cooperation with predetermined hardware, and also as a recording medium that records the program. The present invention can also be realized as a computer data signal embodied on a carrier wave and having a program code.

Other embodiments of the present aspect include corresponding systems, apparatuses, devices, computer program products, and computer readable media.
The present invention can be corrected to the various aspects described above by amendment of procedures during examination and within the scope of legal restrictions in a trial for correction or a request for correction after patent.

  In addition, the judgment of “substantially change the scope of claims” in a trial for correction after a patent or a request for correction is based on whether or not a new component has been added to the claims at the time of patent (that is, because of so-called external addition). Or whether it further restricts any one or more components of the claims at the time of the patent (ie, so-called internal additions have been made) Therefore, it should be made from the viewpoint of whether the effects of the claimed invention before and after the correction are similar.

  This specification includes a number of specifics, which should not be construed as a limitation on the scope of what is claimed or can be claimed, but a description of features specific to a particular embodiment. Should be interpreted as

In the context of separate embodiments, certain features described herein can be further implemented in combination in a single embodiment.
In contrast, the various features described in the context of a single embodiment can be further implemented in a number of embodiments or in any suitable subcombination.

  Further, features are described above to act in a particular combination and may be initially so claimed, but one or more features from the claimed combination may be several In that case, it can be carried out from that combination, and the claimed combination can be directed to a small coupling or various small couplings.

  Similarly, operations are illustrated in a particular order, which means that such operations are performed in the particular order shown or in sequential order to achieve the desired results, or their It should not be understood as requiring that all illustrated operations be performed.

DESCRIPTION OF SYMBOLS 1 Robot 11 Motor 12 Encoder 13 Reduction gear 14 Robot arm 15 Load 19 Amplitude setting part 2 Laser distance measurement sensor 20 Phase setting part 24 Sine wave generation part 3 Reflecting plate 4 Relational expression derivation part 5 Robot controller 51 Angle detection part 52 Servo Control unit 53 Command generation unit 54 Correction signal generation unit 55 Amplitude identification unit 56 Phase identification unit 6 Robot coordinate system 7 Amplitude calculation unit

Claims (2)

A robot in which a plurality of joints J1-n are driven by a motor via a reduction gear;
An angle detector for detecting an angle B1-n [rad] of the motor at each joint 1-n;
A command generator for generating the motor position commands θref1 to n [rad] for each joint J1-n (1 to n is an integer);
A reduction gear angle transmission error, which is an error between the position commands θref1 to n [rad] and the motor angles θfb1 to n [rad] actually detected with respect to the position commands θref1 to n [rad], is corrected. A correction signal generation unit that generates correction signals A1 to n [rad] for performing correction, and the correction signals A1 to n [rad] are added to the position designations θref1 to n [rad]. rad] to eliminate the reduction gear angle transmission error,
A correction parameter identification device for a robot control device comprising:
The Z-axis direction, that is, perpendicular to the ground surface, generated at the hand portion due to the transmission error of at least two speed reducers of the plurality of joints that occurs when the hand portion of the robot is orthogonally moved. Means for determining the direction and the amplitude of the swell Z [mm];
Means for Fourier-transforming the swell amplitude Z [mm] to obtain a swell amplitude value Di [mm] (i is a predetermined number from 1 to n) corresponding to a predetermined joint Ji of the plurality of joints. When,
When the predetermined joint Ji (i is a predetermined number from 1 to n) is uniaxially operated with a motor position command θrefi [rad], a position feedback signal Bi [rad that appears on the axis of the predetermined joint ] Means for measuring
It is assumed that the position command value θrefi for the predetermined joint Ji is further superimposed with a wave of amplitude C [rad] from the outside, and in addition to these, another axis Jx (x is a predetermined number other than i) ), A virtual swell C′i [mm] that is generated in the Z direction at the hand position by forward kinematics, assuming that a position command θrefx [rad] is added to
Ai [rad] = (Ci [rad] / C′i [mm]) × Di [mm]
Means for obtaining Ai [rad] corresponding to Bi [rad] according to the equation:
For a plurality of robots of the same model but having different operable weights, means for obtaining Ai [rad] corresponding to Bi [rad] for each robot using each of the above means;
A correction parameter identification device for a robot control device, comprising: In the correction parameter identification device, a device for compensating for a reduction gear angle transmission error,
Means for uniaxially moving a predetermined joint Jj (j is an arbitrary number from 1 to n);
Means for providing a predetermined position command θrefj [rad] for the single-axis operation;
Means for obtaining a position feedback θfbj [rad] measured at the single-axis operated joint Jj;
Means for obtaining a delay time ΔTdj [sec] of the position feedback θfbj [rad] from the position command θrefj [rad];
Means for obtaining a signal θfb′j [rad] obtained by advancing the position feedback θfbj [rad] by ΔTdj [sec];
Means for obtaining a difference Difj [rad] between the signal θfb ′ j [rad] and the position command θrefj [rad];
Means for obtaining the amplitude Bj [rad] of the Difj [rad];
Means for determining Aj [rad] corresponding to the amplitude Bj [rad] by each means according to claim 1;
A device comprising: