JP2002219674A - Device and method for calibrating position of arm finger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a model error to precisely calibrate a position of an arm finger in a real time. SOLUTION: A representative point angle correction amount table 12 comprising positions of respective points within an arm operation range dispersed with optional fixed lengths, and the optimum angle correction values corresponding to the respective positions is prepared to extract, based on the table 12, plural angle correction amount data in the vicinity of a target position and an attitude by a neighboring angle correction amount extracting means 11, and the angle correction amount for the target position and the attitude is calculated by an interpolation operation using the extracted angle amount correction data. The calculated correction amount is added to a target joint angle to calibrate the arm figer position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arm tip position calibration apparatus and method applied to arm tip position control.

[0002]

2. Description of the Related Art FIG. 5 shows only a portion related to the present invention in a configuration of a conventional arm tip position calibration device. In FIG. 5, reference numeral 50 denotes a calibration device. The calibration device 50 inputs an arm target position / posture S51 to the arm simulator 51. The arm simulator 51 gives the input arm target position / posture S51 to the internal arm model, and obtains a joint angle of the arm model. The calculated joint angle is output to the adder 53 and the gravitational torque deflection angle deriving unit 52 as a joint angle command S52. The gravitational torque deflection angle derivation unit 52 calculates the gravitational torque applied to each joint angle, and calculates and outputs a deflection angle S53 (angle correction amount) from the gravitational torque and a rigidity constant corresponding thereto. The adder 53 in the calibration device 50 adds the joint angle command S52 and the gravitational torque deflection angle S53 (angle correction amount), and outputs a corrected joint angle command S54 (Japanese Patent Laid-Open No. 09-174466).

[0003]

A conventional arm tip position calibration apparatus obtains a deflection angle using model parameters such as the rigidity constant of each joint, the arm link length, the link center of gravity length, and the link weight. The correction amount is calculated. However, since the model parameters and the joint stiffness constant tend to include a model error, there is a problem that calibration cannot be performed with high accuracy. Further, there is another problem that it is difficult to perform real-time calibration because a dynamics operation including a combination of a plurality of matrix calculations must be calculated.

Accordingly, an object of the present invention is to provide a device and a method for calibrating an arm hand position which realizes calibration in real time with high accuracy.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, the position of each point in an arm operating range discretized by an arbitrary fixed length and the optimum angle correction amount corresponding to each position are set. A representative point angle correction amount data table is prepared, and a plurality of angle correction amount data in the vicinity of the target position and the posture are extracted from the data table. The target position is calculated by interpolation using the extracted angle correction amount data. , And calculates the amount of posture angle correction. The correction amount calculated in this way is added to the target joint angle to perform calibration of the arm tip position.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an arm hand position calibration device according to an embodiment of the present invention. In FIG. 1, reference numeral 6 denotes a calibration device. The calibration device 6 includes a target position / posture generation unit 1, a target joint angle generation unit 2, an angle correction amount generation unit 3, and an adder 7. The calibration device 6 is connected to the arm 5 via the joint drive amplifier 4.

FIG. 2 is a diagram showing the configuration of the angle correction amount generating means 3. In FIG. 2, reference numeral 11 denotes a neighboring angle correction amount extracting means which is connected to the representative point angle correction amount data table 12 and the interpolation calculating means 13.

FIGS. 3 and 4 show details of the data table of the representative point angle correction amount data table 13. FIG. In FIG. 3, the operation range of the arm 5 is previously discretized in a lattice shape with a width of a fixed length Δd. Pi, k, and m are joint angle correction amount data arrays 22 of grid point coordinates (△ d × i, △ d × k, △ d × m), each of which is obtained by measurement using a sensor or the like. This is the optimum correction data at the lattice points. As shown in FIG. 4, the representative point angle correction amount data table 12 is a data table composed of a plurality of joint angle correction amount data arrays 22.

Hereinafter, the operation of the arm hand position calibration apparatus will be described with reference to FIGS. 1, 2, 3 and 4.

The arm target position / posture S1 (Xre) is a target of the arm hand position generated by the target position / posture generating means.
f, Yref, Zref) are input to the target joint angle generation means 2 and the angle correction amount generation means 3. The target joint angle generation means 2 converts the target joint angle S2 (ang1, an
g2,. . . ang6) is output. Angle correction amount generation means 3
Then, the arm target position / posture S1 and the joint angle correction amount data array S12 of the representative point angle correction amount data table 12 are input to the neighboring angle correction amount extracting means 11 (FIG. 2).

(Equation 1) From the conditional expression

(Equation 2) The eight adjacent joint angle correction amount data arrays S13 near the arm target position / posture S1 are extracted. The eight joint angle correction amount data arrays S13 thus extracted are input to the interpolation calculating means 13,

(Equation 3) Using the linear interpolation equation shown in FIG.
3 (△ θ1, △ θ2,... △ θ6), and S3 is output to the adder 7 (FIG. 1).

The target command joint angle S4 (angRef1, angRef2,... AngRef6) angle-corrected by the angle correction amount S3.
Is input to the joint drive amplifier 4, and the joint drive current S5 is output to drive each joint of the arm 5.

[0013]

As described above, according to the present invention, the position of each point in the arm operating range discretized at an arbitrary fixed length and the optimum angle obtained by actual measurement corresponding to each position. From the representative point angle correction amount data table consisting of the correction amount, the neighboring angle correction amount is obtained, the optimum angle correction amount for the target point position and orientation is obtained by interpolation calculation, and the conventional rigidity constant of each joint is used to correct the deflection angle. , Arm link length,
It does not include errors caused by model parameters such as link center-of-gravity and link weight, allows highly accurate calibration of the arm hand position, and does not include complicated matrix calculations. The arm target position / posture can be accurately positioned in real time.

[Brief description of the drawings]

FIG. 1 shows a configuration of an arm hand position calibration device according to an embodiment of the present invention.

FIG. 2 shows a configuration of an angle correction amount generation unit.

FIG. 3 shows details of a representative point angle correction amount data table.

FIG. 4 shows details of a representative point angle correction amount data table.

FIG. 5 shows a configuration of a conventional calibration device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 target position and orientation generation means 2 target joint angle generation means 3 angle correction amount generation means 4 joint drive amplifier 5 arm 6 calibration device 7 adder 11 proximity angle correction amount extraction means 12 representative point angle correction amount data table 13 interpolation calculation means 22 Joint angle correction amount data array 50 Calibration device 51 Arm simulator 52 Gravity torque deflection angle deriving unit 53 Adder S1 Arm target position and orientation S2 Target joint angle S3 Angle correction amount S4 Target command joint angle S5 Joint drive current S12 Joint angle correction Amount data array S13 Neighboring joint angle correction amount data array S51 Arm target position / posture S52 Joint angle command S53 Deflection angle S54 Corrected joint angle command

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Goto 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka F-term (reference) 3F059 FB17 FC14

Claims (3)

[Claims] 1. An arm tip position calibration apparatus for accurately positioning an arm target position and orientation, which is a target of an arm tip position, wherein a target position and orientation generation unit generates a target position and orientation of the arm tip position. Means, a representative point angle correction amount data table including positions of respective points in an arm operation range discretized by an arbitrary fixed length and an optimum angle correction amount corresponding to each position, and the target position generation. Means for extracting a plurality of angle correction amount data near the target position and posture from the representative point angle correction amount data table using the position and posture data generated by the means; and a target position and posture. The target position is calculated by interpolation using a plurality of nearby angle correction amount data.
Interpolation calculating means for calculating an angle correction amount of the posture; target joint angle generating means for generating a joint angle command using the position and posture data generated by the target position generating means; An arm adder for adding a correction amount and outputting a correction joint angle command. 2. A method for calibrating an arm tip position for accurately positioning an arm target position and orientation, which is a target of a hand position of an arm, comprises the steps of: A representative point angle correction amount data table including a position and an optimum angle correction amount corresponding to each position is prepared, and a plurality of angle correction amount data near a target position and a posture are extracted from the representative point angle correction amount data table. Then, an angle correction amount of a target position and a posture is calculated by interpolation using these angle correction amount data, and the joint angle command and the angle correction amount generated using the position and posture data are added. A method of calibrating an arm tip position, comprising adjusting an arm joint. 3. An arm tip position calibration, comprising: a position of each point in an arm operating range discretized by an arbitrary fixed length; and an optimum angle correction amount corresponding to each position. A representative point angle correction amount data table to be used.