JPS609687A - Method of calibrating origin of robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to setting the coordinate system of a robot, and in particular relates to a high-precision calibration method for the origin of each joint of an articulated robot. On the orthogonal axis of the sitting body, move each other perpendicularly to the other axes C. Speed up movement control.

This is important from the perspective of making it easier to provide instructions on how to proceed (in the case of remote instruction to the prefecture). Above all, it is no exaggeration to say that this technology is indispensable for 1st (high) concealed articulated robots.

In the multiplex robot, movement in three-dimensional orthogonal coordinates corresponds to rotation of each joint. In this sense, establishing the coordinate system of the robot comes down to the problem of accurately setting the origin of each joint.

(e) Prior art and problems The conventional method for this kind of problem is to set the arm height H constant from one plane substrate so that each joint is perpendicular to all eight points, as shown in Fig. 1, for example. Add the rotation angle at that time to 0. θ′
A method using the origin as the starting point has been considered. However, the quality of the arm H is measured based on the external dimensions of the robot, and with a method that relies on the external dimensions of the robot, the true center of rotation cannot be determined and accuracy cannot be expected. There's a problem.

(d) Purpose of the Invention The purpose of the present invention is to measure the center of rotation of the joint to be calibrated by an optical method, rather than by a method that depends on the external dimensions of the robot, in order to accurately set the origin of each joint of the robot. ,
An object of the present invention is to provide a method for calibrating the origin of a robot in which the angle of the axis of rotation of each joint is set as the origin of each joint when the height of the rotation center of each joint is made equal to the height of the center of rotation.

(e) Structure and object of the invention According to the present invention, in calibrating the origin of a robot, a parallel beam is irradiated onto a mirror attached at a constant angle to a rotation axis that rotates the joint fully at each joint to be calibrated. A light source section having a light source and a height measuring means from the surface plate, and a photodetector arranged in a ring shape for detecting the reflected light from the mirror of the light source, The height of the light source when the reflected light detects a perfect circle on the photodetector based on the deviation between the top and bottom of the light source section is added by 6il1 by the distance measuring means, and that value is determined as the true center of rotation of the joint. 3 of each joint at the same height.
This is achieved by providing an entire robot origin calibration method characterized in that the rotation of each joint when the rotation center heights t are made equal is taken as the origin of each joint.

(f) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a perspective view showing an example of an articulated robot according to the present invention. In the same figure, only the bending type joints related to t, cool point, and battle are shown in all 01 to θ3. Set the rotation center measuring thread at one of these joints, for example θl, as shown in Fig. 3. In Fig. 3, 2 is joint θ, which is the rotation center of the I @ node θ weight that should be claimed. Reference numeral 3 denotes two mirrors mounted at a constant angle with respect to the rotation axis, and are arranged at asymmetric positions with respect to the rotation axis 2' as shown in the figure. A right-angle mirror is used as the mirror 3 as described later, but the most convenient 04 is a collimated light source with an appropriate beam diameter, and 5 is a collimated light source with a suitable beam diameter. This is a corner keep for a laser length measuring instrument for precise measurement.These are attached to a support post 7, and are attached to a fine movement table (not shown) that can move up and down, together with a mirror 8 and a photodetector (not shown). It is posted.

A light beam 9 emitted from a light source 4 is reflected by a mirror 3 and guided to a photodetector surface (not shown) via a half mirror 8. The trajectory of the light beam 9 on the detector plane as the joint 2 rotates is 1 if the light beam 9 and the center of rotation 2' coincide.
0, it becomes a perfect circle, and if they do not match, it becomes an ellipse 11, which deviates from the perfect circle. If a right-angle mirror is used as mirror 3, the incident beam and the output beam are always parallel, so changes in beam deflection due to tilting of the mirror mounting surface due to rotation can be ignored in principle, so high-precision measurements can be expected. Possible 0 The structure of the light-receiving surface of the photodetector is either a double concentric circle with photodetectors 12 arranged discretely on the inner and outer peripheries as shown in Figure 4 H)K, or a double concentric circle with photodetectors 12 arranged discretely on the inner and outer peripheries, as shown in Figure 4 (B). circumference.

The size of the zero concentric circle, which is a continuous double concentric circle with a ring-shaped photodetector 13 arranged on the outer periphery, and the size of the light receiving surface are such that the light beam 9 will not be distorted and the effective light will not be blocked. I can add more. The double concentric structure of the photodetectors 12 and 13 is intended to shorten the measurement time by detecting not only the deviation from the rotation center 2' of the light beam 90 but also the direction of deviation. In addition, simultaneous differential detection eliminates in-phase noise, so position resolution can be improved.Next, when specifically setting the joint origin of the robot, first the While moving the light source 4 of the support column 7, the locus of the light beam 9 on the detector surface due to the rotation of the joint 2 is measured by the corner cube 5 for the laser length measuring device, and the trajectory of the light beam 9 on the detector surface is measured from the eccentricity using the corner cube 5 for the laser length measuring device. In order to align the light beam 9 with the center of rotation 2', horizontal movement is also necessary, but this is not shown, but it moves the support 7. is sequentially applied to joints 01 to θ, and each joint θl to θ
Joints θ1~ so that the heights from the base 6 of 1 to
The origin is determined by controlling the rotation angle of the motor θ. As can be inferred from the above, this method does not require an absolute amount of height, but is a relative measurement that requires no variation in the height direction of the rotation center of each of the four interstices. Therefore, strict initial setting of the measurement system is not necessary, and highly accurate origin calibration is possible.

Furthermore, if it is extended to measure the horizontal length in parallel to the measurement of the height of the center of rotation of each joint θ, ~θ, (
For example, it is possible to measure the height and horizontal directions simultaneously using a laser length measuring device.) It is also possible to measure the true arm length.

Effects of the Invention As explained in detail above, the method for calibrating the origin of a robot according to the present invention involves irradiating each joint to be calibrated with a mirror that is received at a constant angle of inclination to the axis of rotation, and irradiating the mirror with a parallel beam. The external dimensions of conventional robots are measured by detecting the reflected light with photodetectors arranged in a ring, and determining the center of rotation of the joint based on the deviation of the reflected light from a perfect circle as the joint rotates. This eliminates instability in precision such as determining the height of the arm from the base, making it possible to calibrate the origin with high precision.

[Brief explanation of the drawing]

Fig. 1 is a diagram for fully explaining the setting of the joint origin of a conventional robot, Fig. 2 is a perspective view of an example of an articulated robot according to the present invention, and Fig. 3 is a diagram for explaining the origin calibration method of a robot according to the present invention. Figure 4 is a diagram for explaining an example of the rotating stone side system used.
b) (o) is a diagram showing the structure of a photodetector used in the measurement system of FIG. 3. In the figure, 2 is the joint 0ri, 2' is the rotation center, 3 is the mirror, 4 is the light, 5 is the corner cube, 6 is the base surface, 7 is the support, 8 is the half sea, 9 (is the light beam, 10 is the true Circle, 11 is a biased circle, 12.13 is a photodetector〇

Claims (1)

[Claims] When calibrating the origin of a robot, a light source includes a mirror attached at a constant angle to a rotation axis for rotating each joint to be calibrated, a light source that irradiates the mirror with a parallel beam, and a height measuring means from a surface plate. and a Yuko detector arranged in a ring shape for detecting the reflected light from the mirror of the light source,
The height of the light source is measured by the height measuring means when the reflected light from the mirror due to the rotation of the joint is detected as a perfect circle on the photodetector based on the deviation from the upper and lower sides of the light source section. A method for calibrating the origin of a robot, characterized in that the rotation angle of each joint is set as the origin of each joint when the value is set as the true center of rotation of the joint, and the height of the center of rotation of each joint is made equal to the height. .