JP2002175120A - Method for correcting positioning error of actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the positioning accuracy of an actuator having a wave reduction gear. SOLUTION: In the drive control device 1 for the actuator, a positioning error of the actuator 2 is measured for one rotation of the output shaft 7 of the wave reduction gear 5 based on the absolute position of a motor rotating shaft 4 and this measured error data are averaged, error correction data 10 indicating an error correction value with respect to each rotating position for one rotation of the motor rotating shaft are stored in the error correction data storage portion 11 of the drive control device. During drive control, the rotating position of the motor rotating shaft 4 is detected and the error correction value allocated to the rotating position in the error correction data 10 is added to the detected rotating position information 8 to create rotating position correction information 12, which is then used as position feedback information for controlling the positioning of an actuator output shaft 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting a positioning error of an actuator provided with a wave gear reducer and a drive control device for an actuator for performing a positioning operation by the correcting method.

[0002]

2. Description of the Related Art As an actuator, there is known an actuator having a structure in which a motor output rotation is reduced by a wave gear reducer to move a load-side member to a target position. The wave gear reducer includes an annular rigid internal gear, an annular flexible external gear, and a wave generator.

In a typical configuration, a flexible external gear is bent into an elliptical shape by a wave generator, and external teeth located at both ends in the longitudinal direction of the elliptical shape have corresponding internal teeth of the rigid internal gear. When the wave generator is engaged with the teeth and rotated by the motor, the meshing position of the two gears moves in the circumferential direction, and relative rotation corresponding to the difference in the number of teeth between the two gears is generated in the gears. Generally, a rigid internal gear is fixed, a flexible external gear rotates as a reduced rotation output element, and a load-side member connected to the flexible external gear is driven to rotate at a low speed.

The actuator drive control device having this configuration generally controls the positioning of the actuator by feedback control.

[0005]

Here, there is an angle transmission error in the wave gear reducer, and this error causes the actual positioning position of the actuator output shaft (the output shaft of the wave gear reducer) to be the target positioning position. And an error occurs. If this error can be compensated, the positioning accuracy of the actuator including the wave gear reducer can be improved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive control device for an actuator having a wave gear reducer, which corrects a positioning error caused by an angle transmission error of the wave gear reducer in a feedback control loop for position control. The purpose of the present invention is to improve the positioning accuracy of the drive control device by adding a position correction function for the purpose.

[0007]

In order to solve the above-mentioned problems, a positioning error correction method according to the present invention is directed to an actuator including a motor and a wave gear reducer for reducing the motor output rotation and transmitting the reduced rotation to the load side. Is corrected based on the absolute position of one rotation of the motor rotation shaft.

Here, by measuring the positioning error of the actuator based on the absolute position of one rotation of the motor rotation shaft, error correction data is created, and the rotation position of the motor rotation shaft is detected. Add the error correction value assigned to the rotational position in the error correction data to the detected rotational position information,
Rotational position correction information can be created, and the created rotational position correction information can be used as position feedback information for controlling the positioning of the output shaft.

In this case, the error correction data can be created by measuring the positioning error of the actuator for at least one rotation of the output shaft based on the absolute position of one rotation of the motor rotation shaft.

In addition, the positioning error of the actuator is measured for at least one rotation of the output shaft based on the absolute position of one rotation of the motor rotation shaft, and the measured error data is averaged. Error correction data representing an error correction value for each rotation position for the rotation can be created.

Next, the present invention is a drive control device for an actuator for correcting a positioning error by this method, comprising: an error correction data storage section in which the error correction data is stored; and an absolute position of the motor rotation axis. A rotation position correction information creating unit that creates the rotation position correction information based on the rotation position information supplied from the position detector that detects the error and the error correction data; and the created rotation position correction information as position feedback information. And a feedback control unit that performs feedback control of the actuator so as to be at a target position indicated by the position command information.

Here, the error correction data may be stored and held in the position detector, and downloaded from the position detector to the error correction data storage unit after power is turned on. This makes it possible to generalize the drive control device.

The error correction data may be a data string of correction pulses as error correction information at each rotation position for one rotation of the motor rotation shaft. Instead, a coefficient sequence of an approximate expression representing an error at each rotational position for one rotation of the motor rotation shaft may be used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a drive control device for an actuator to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a drive control device for an actuator according to this embodiment. The actuator 2 of the present example driven by the drive control device 1 includes a motor 3
The wave gear reducer (H) connected to the motor rotation shaft 4
D) 5 and a position detector 6 capable of detecting an absolute rotation position of the motor rotation shaft 4. An output shaft of the wave gear reducer 5, that is, an actuator output shaft 7 is connected to a load (not shown). The position detector 6 is a rotary encoder,
It is a position detector such as a potentiometer that can detect an absolute position.

The drive control device 1 for controlling the driving of the actuator 2 includes an error correction data storage unit 11 storing error correction data 10 for compensating for a positioning error caused by an angle transmission error of the wave gear reducer 5. And the rotational position information 8 and the error correction data 1 supplied from the position detector 6.
0, the rotation position correction information creating unit 13 that creates the rotation position correction information 12, and the created rotation position correction information 1
2 as position feedback information,
Control unit 15 for performing feedback control so that the target position indicated by the position command information 14 becomes the target position.
And The rotation position correction information creating unit 13 can be, for example, an adder or a subtractor.

(Error Correction Data) Here, the error correction data 10 of this embodiment is created as follows.
First, the positioning error of the motor rotation shaft 4 in the actuator 2 is reduced to one-third of the reduction ratio of the speed reducer by the reduction of the wave gear reducer 5 to which the motor rotation shaft 4 is connected. For example, if the speed ratio of the wave gear reducer 5 is 50 or 1
In the case of 00, the positioning error of the motor itself is 1/5.
It is compressed to 0 or 1/100. Therefore, since the positioning error of the actuator 2 is mainly caused by the angle transmission error of the wave gear reducer 5, the one-directional positioning accuracy of the actuator 2 is determined by the angle transmission error of the wave gear reducer 5.

The one-way positioning accuracy means that positioning is performed one after another in a fixed rotation direction, and at each position, the difference between the angle actually rotated from the reference position and the angle to be rotated is determined. It represents the maximum value during one rotation.

In this embodiment, the one-way positioning accuracy of the actuator 2, that is, the positioning error of the actuator 2
One rotation of the actuator output shaft 7 is measured based on the absolute position of the motor rotation shaft 4. For example, when the speed ratio of the wave gear reducer 5 is 1/50, the motor rotating shaft 4
When rotated, the output shaft 7 makes one rotation.

This positioning error is measured every time the motor rotating shaft 5 rotates 3 ° based on the output of the position detector 6, as shown in FIG. 2, for example. In this case, the measurement points are 120 points (360
° / 3 °), and 12
0 points x (speed ratio).

The data to be measured is substantially the same even when the angular transmission accuracy of the wave gear reducer is used instead of the one-way positioning accuracy. The measurement may be performed not only for one rotation of the output shaft 7 but also for one rotation or more.

Next, as shown in the bottom row of the table in FIG. 2, error data at each measurement point, for example, error data at 120 points are respectively averaged to obtain error correction data 10 for one rotation of the motor rotation shaft 4. Create

The format of the created error correction data 10 can be the number of correction pulses for error correction for each rotation angle position in one rotation of the motor rotation shaft 4. For example, as shown in FIG. 3, it is possible to use a correspondence table in which the corrected Hals numbers measured every 3 ° as described above are assigned to the rotation positions of the motor rotation shaft 4 every 3 °.

Instead, Fourier series expansion of the error correction data for one rotation of the motor rotation shaft 4 is performed to obtain an approximate curve, and each coefficient of the Fourier series representing the approximate curve is stored and held as the error correction data 10. It may be.
In this case, in the initialization process after the drive power supply of the drive control device 1 is turned on, the stored data is applied to the approximation formula to calculate the correction data, and the correction pulse as shown in FIG. Just create a data string.

(Positioning Error Correction Operation) Next, correction of a positioning error which is a characteristic part of the drive control operation of the actuator 2 by the drive control device 1 will be described. Based on the feedback pulse (8) for position detection from the position detector 6, based on the absolute position of the motor rotary shaft 4 represented by the feedback pulse, the number of corresponding correction pulses is obtained from the error correction data 10, and the number of correction pulses is calculated. Is added to the feedback pulse (8) in the rotation position correction information creating unit 13, and the addition result is set as a position feedback pulse (12), so that the feedback control unit 1
Return to 5. The feedback control unit 15 performs feedback control of the actuator 2 based on the position feedback pulse (12) so that the target position is indicated by the input position command information 14.

In this embodiment, the error correction data 10 is stored and held in the drive control device 1. Instead, the error correction data 10 may be stored and held in the position detector 6 of the actuator 2. In this case, in the initialization processing immediately after the power is supplied to the drive control device 1, the error correction data 10 held in the actuator position detector 6 is downloaded to the drive control device 1 side. I just need.

[0027]

As described above, in the method of correcting the positioning error of the actuator according to the present invention, the positioning error caused by the angle transmission error of the wave gear reducer is measured in advance, and the positioning error at each rotation position of the motor rotation shaft is measured. Error correction data that can correct the positioning error is created, and at the time of actual error correction, an error correction value of the corresponding rotational position is obtained from the error correction data based on the absolute position of the motor rotation axis,
The position feedback information is corrected. Therefore, according to the present invention, the positioning accuracy of the actuator including the wave gear reducer can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an example of a drive control device for an actuator to which the present invention is applied.

FIG. 2 is a table for explaining a method of generating error correction data used for correcting a positioning error in the drive control device of FIG. 1;

FIG. 3 is a table showing a correspondence table of created error correction data.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Drive control device 2 Actuator 3 Motor 4 Motor rotating shaft 5 Wave gear reducer 6 Position detector 7 Output shaft of wave gear reducer (actuator output shaft) 8 Rotational position information 10 Error correction data 11 Error correction data storage unit 12 Position Feedback information 13 Rotational position correction data creation unit 14 Position command information 15 Feedback control unit

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[Procedure amendment]

[Submission date] December 26, 2000 (200.12.
26)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

Continued on the front page (72) Inventor Naoki Kanayama 1856-1, Maki, Hodaka-cho, Minamiazumi-gun, Nagano Pref. DD28 FF07 GG04 HH05 KK17 LL03

Claims (7)

[Claims] 1. A positioning device that corrects a positioning error of an output shaft in an actuator including a motor and a wave gear reducer that reduces a motor output rotation and transmits the reduced rotation to a load based on an absolute position of one rotation of the motor rotation shaft. Error correction method. 2. The method according to claim 1, wherein an error correction data is created by measuring a positioning error of the actuator based on an absolute position of one rotation of the motor rotation shaft. A position is detected, and an error correction value assigned to the rotational position in the error correction data is added to the detected rotational position information to generate rotational position correction information. A method for correcting a positioning error of an actuator, wherein the position correction information is used as position feedback information for controlling the positioning of the output shaft. 3. The method according to claim 2, wherein the positioning error of the actuator is measured for at least one rotation of the output shaft based on an absolute position of one rotation of the motor rotation shaft, and error correction data is created. Method of correcting positioning error of actuator. 4. The method according to claim 2, wherein the positioning error of the actuator is measured for at least one rotation of the output shaft based on an absolute position of one rotation of the motor rotation shaft, and the measured error data is averaged. A method of correcting an actuator positioning error, comprising creating error correction data representing an error correction value for each rotation position for one rotation of the motor rotation shaft. 5. A drive control device for an actuator for correcting a positioning error by the method according to claim 1, wherein: an error correction data storage unit storing the error correction data; and an absolute position of the motor rotation axis. A rotation position correction information creating unit that creates the rotation position correction information based on the rotation position information and the error correction data supplied from the position detector that detects the rotation position information, and the created rotation position correction information as position feedback information. A drive control unit for feedback-controlling the actuator so as to be at a target position indicated by the position command information. 6. The error correction data according to claim 5, wherein the error correction data is stored and held in the position detector, and is downloaded from the position detector to the error correction data storage unit after power is turned on. Actuator drive control device. 7. The error correction data according to claim 5, wherein the error correction data is a data sequence of a correction pulse as error correction information at each rotation position for one rotation of the motor rotation shaft, and a correction pulse data sequence for one rotation of the motor rotation shaft. The drive control device for an actuator, wherein the drive control device is any one of a series of coefficients of an approximate expression representing an error at each rotational position.