JPS61202203A - Conversion method for coordinate system of robot and work - Google Patents

Abstract

PURPOSE:To shorten the teaching time of a robot by teaching a substitute point on a work without teaching directly a point on an X or Y axis of a work coordinate system. CONSTITUTION:The coordinate systems are converted between a robot 7 and a work 10 by means of a storing device 1 for the work form data defined by the work coordinate system, a device 2 which produces a robot action locus in the work coordinate system from the form of the work 10, a device 3 which calculates the conversion equation (homogeneous conversion matrix) between the robot and work coordinate systems, a conversion device 4 for said conversion equation, a robot controller 6, etc. The signal 11 that described the coordinate value of a substitute point on the work 10 in the work coordinate system is supplied to the device 3 together with the signal 12 which described three point on the work 10. Then the homogeneous conversion signal 13 of the work coordinate system to the robot coordinate system is delivered to perform the conversion between the substitute point coordinate system and the robot coordinate system. Then the conversion is carried out between the robot and work coordinate systems.

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a coordinate system conversion method for converting a teaching point described in a workpiece coordinate system to the aforementioned teaching point in a robot coordinate system. This invention relates to a method for converting coordinate systems between a robot and a workpiece, which is suitable for cases where points cannot be directly taught. [Background of the Invention] Methods for saving the labor of teaching robots can be broadly classified into the following two types. (1) A method of creating new teaching data using data that has been taught once. (2) A method of converting a teaching point described in the workpiece coordinate system using CAD data etc. into a description in the robot coordinate system. Method (1) is effective when the workpieces have the same shape but their positions have changed from before, and a known example is, for example, Japanese Unexamined Patent Publication No. 182205/1983. On the other hand, method (2) is effective when it is easy to describe the robot motion trajectory in the workpiece coordinate system.In order to realize transformation between different coordinate systems, homogeneous transformation is It is also known that it is only necessary to find the position coordinates of a total of four points, the origin of the other coordinate system, the unit vectors of the X-axis, y-axis, and Z-axis, with reference to the coordinate system of
Written by Wakamatsu et al. “Endurance Robot Reader”, Nikkan Kogyo Shimbun, p. 136)
. Therefore, in order to implement method (2), it is sufficient to know the position coordinates of the four points in the workpiece coordinate system based on the robot coordinate system. The method of measuring the above four points of the workpiece coordinate system lOO using the robot with reference to the robot coordinate system was developed in the robot language AL. -1 calculation i method is explained on page 139 of Wakamatsu et al., supra, where the origin of the workpiece coordinate system is 0. One point on the X axis! 20° 1 point on the Y axis 130 total 3
It is only necessary to teach the robot so that the point can be touched with a pointer 140 (position measurement jig) attached to the robot's hand (see Fig. 1).
(See a), 1) A point on the X-axis is determined by the cross product of the unit vector of the X-axis and the unit vector of the Y-axis. The above measurement method will hereinafter be referred to as a three-point measurement method. Note that the measurement axes may be any two axes among the X, Y, and Z axes, but for convenience of explanation, the X and Y axes will be used. A known example using the concept of the three-point measurement method is
9-60507, but I have not found anything that discusses the 31 measurement method taking into consideration the shape of the workpiece6. For example, for the workpiece 200 with a free-form surface shown in FIG. 1(b), the measurement method shown in FIG. Unlike case a), the points on the X and Y axes do not exist on the workpiece, so it is virtually impossible to directly teach those points that exist in space.For this reason, the three-point measurement method It was necessary to improve the method of converting the coordinate system using . [Object of the Invention] The object of the present invention is to form a workpiece with a one-dimensional curved surface.
Directly teach points on the X-axis or Y-axis of the workpiece coordinate system! The purpose of this invention is to provide a method for converting coordinate systems between a robot and a workpiece, which is effective even when the robot and workpiece cannot be used. [Summary of the Invention] In order to achieve the above object, in the present invention, instead of directly teaching points on the X-axis or Y-axis of the workpiece coordinate system, alternative points 210. ．． Take the method of teaching '220 (
(See Figure 1(b)). First, from the coordinate values of the alternative point obtained by teaching, we first calculate the transformation between the robot coordinate system and the temporarily provided alternative point coordinate system. Find the transformation to and from the coordinate system. A feature of the present invention is that the transformation between the robot coordinate system and the workpiece coordinate system is determined from these two transformations.

〔Effect of the invention〕

According to the present invention, the transformation relationship (homogeneous transformation) between the robot coordinate system and the workpiece coordinate system can be calculated even when the point on the axis of the workpiece coordinate system is not on the workpiece, so it can be used for any shape of workpiece. , the robot motion trajectory described in the workpiece coordinate system can be converted to a description in the robot coordinate system. As a result, since teaching can be completed by describing the robot motion locus in the workpiece coordinate system, the teaching time can be reduced to about 1710 seconds compared to teaching using an actual machine. In particular, the effect becomes even greater when the robot motion trajectory is automatically generated in the workpiece coordinate system by combining it with CAD data.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the present invention in detail, Fig. 2 is a configuration diagram of an embodiment, Fig. 3 is a flowchart showing the processing procedure of the present invention, and Fig. 4 is a diagram illustrating the coordinate system conversion method of the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Workpiece shape data storage device, 2... Robot motion trajectory generation device in robot coordinate system, 3... Conversion calculation device between robot coordinate system and workpiece coordinate system, 4...
Description of the robot motion trajectory in the robot axis system This conversion device: 5°°°0 robot joint rotation angle wave packet device,
6...Robot controller, 7...Multi-joint robot, 8...Pointer, 9...Teaching button □x, 10...Workpiece, 1.1...Coordinates of alternative point on workpiece Signal whose value is described in the work coordinate system, 12...
・Signal that describes three points on the workpiece in the robot coordinate system, 1
3... Work bright standard system! HoVJ for pot coordinate system
r Figure ('(L), '(bn.

Claims (1)

[Claims] 1. Storage means for workpiece shape data defined in the workpiece coordinate system, calculation means for determining the robot motion trajectory in the workpiece coordinate system from the workpiece shape data, means for converting between the robot coordinate system and the workpiece coordinate system, and the workpiece coordinate system. means for converting the robot motion trajectory described in the robot coordinate system into a description in the robot coordinate system, a calculation means for calculating each joint angle of the robot in time series from the motion trajectory in the robot coordinate system, a robot controller, and an articulated robot. A robot teaching system comprising: a position measuring jig attached to the tip of the articulated robot; and means for moving the jig to a desired position.
A coordinate system conversion method for a robot and a workpiece, which is characterized by measuring an alternative point on the workpiece instead of measuring a point on the axis of the workpiece coordinate system.