GB2547200A

GB2547200A - Tool center point setting method for articulated robot

Info

Publication number: GB2547200A
Application number: GB1602301.2A
Authority: GB
Inventors: Challinor Steven; Bailey Gavin; Iwasaki Masahiro
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2016-02-09
Filing date: 2016-02-09
Publication date: 2017-08-16
Anticipated expiration: 2036-02-09
Also published as: GB2547200B; GB201602301D0

Abstract

In an articulated robot 10, a first axis of rotation 22 is disposed on a first arm member 16, the first arm member 16 and a second arm member 18 being connected through a second axis of rotation 24, a coordinate detecting jig 34 is rotatable about the first axis of rotation 22, an image capturing unit 36a, 36b is rotatable about the second axis of rotation 24. In setting a tool centre point the coordinate detecting jig 34 is moved to a focal point P of the image capturing unit 36a, 36b by rotating the first arm member 16, and the coordinates of a tool center point are determined by setting the angle of rotation of the first axis of rotation 22 at this time to 0°. The coordinate detecting jig 34 may be a linear body which can be fabricated simply, occupies a small volume and can be attached easily to the first arm member 16.

Description

TOOL CENTER POINT SETTING METHOD FOR ARTICULATED ROBOT BACKGROUND OF THE INVENTION Field of the Invention:

The present invention relates to a tool center point setting methoa for an articulated robot in which arm members that make up an arm of the robot are connected tcaether through respective axes of rotation.

Description of the Related Art:

With an articulated robot, arm members that make up an arm. or the robot are connected to each other through respective axes of rotation. Ordinarily, an operating tool for performing a predetermined operation such as application of a coating or the like to a workpiece is disposed on a distal end arm member, which is positioned on a distal end of the arra. In addition, by turning (or rotating) the arm members centrally about the axes of rotation, the operating tool is made to face toward a workpiece, for example, to carry out a coating operation or the like to apply a coating material.

In order for the articulated robot, to perform operations with respect to regular points on the workpiece, it is necessary for a point of action of an operating point, i-e., the coordinate system of a tool center point, of an operating tool of the articulated robot to be set. As one such coordinate system setting method, for example, in Japanese Laid-Open Patent Publication No. 2013-082032, a tool coordinate system, origin point setting .method is disclosed, in which a tool center point setting jig is mounted on a suction pad tool., and the tool coordinate system origin point is set by moving a distal end of the tool setting jig to reference points on a reference jig at four or more postures of the articulated robot.

Alternatively, an origin point setting method is known conventionally, in which instead of using the tool setting jig of the aforementioned patent publication, the origin point is set by first setting a virtual tool center point at the focal point of a camera, and then moving the virtual tool center point to reference points of a reference jig.

In such a method, as shown in FIG. 2, a stereo camera 2 is attached to a distal end arm 1 of the articulated. robot, and tne rocal point of the stereo camera 2 is made to coincide w i th t h e virtual t ο ο1 cen te r point.

SUMMARY OF THE INVENTION

However, for example, if the operating tool is a coating nozzle, and a configuration is provided in which a rotating mechanism is used to rotate only a comparatively small part such as the coating nozzle by an axis of rotation (oriented along the same axis of the direction of extension of the arm) of a distal end arm member, which is a final axis of the articulated robot, even if a camera is installed on the coating nozzle, a problem occurs in that a sufficient space for enabling installation cannot be provided,

Therefore, the tool center point coordinate system cannot be set by the camera. A main ooject of the present; invention is to provide a tool center point setting method for an articulated robot, which enables a tool center point thereof to be easily set.

According to the present embodiment, a tool center point setting method for an articulated robot is provided for setting a tool center point of the articulated robot that includes a plurality of axes of rotation, comprising the steps of: providing a coordinate detecting jig that is rotated by a first axis of rotation from a side of a distal end arm member that makes up part, of the articulated robot; and arranging an image capturing unit configured to perform coordinate detection and which is rotated by a second axis of rotation from a side of the distal end arm member, wherein by rotating the distal end arm member about the first axis of rotation, the coordinate detecting jig is moved to a focal point of the image capturing unit, and the coordinates of the tool center point are determined by setting the angle of rotation of the first axis of rotation at this time to 0°.

In the foregoing manner, the tool center point can easily be set by a simple operation in which the coordinate detecting jig is moved together with rotation of the first axis of rotation, and then is moved to the focal point of the image capturing unit. In addition, the operating tool on the distal end of the robot can easily be exchanged with the coordinate detecting jig. Ultimately, according to the present invention, the setting operation of the tool center point can easily be performed.

The coordinate detecting jig preferably is a linear body. In this case, fabrication of the coordinate detecting jig is simple. Further, since the coordinate detecting jig can be of a small size and occupy a small volume, even in at narrow space, attachment of the coordinate detecting jig is easy to perform. Furthermore, interference of the coordinate detecting jig with a second arm member or the like can be avoided. For the above reasons, the operation for setting the tool center point proceeds smoothly.

The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an outline overall perspective view of an articulated robot in which a tool center point setting method according to an embodiment of the present invention is carried out; and FIG. 2 is a perspective view of essential components in an articulated robot, showing a state in which a tool center point setting method according to a conventional technique is carried out. DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a center point setting method for an articulated robot according to the present invention will be described in detail below with reference to the accompanying drawings. As is well known, an. N-axis articulated (multi-joint) robot includes N respective axes of rotation. Counting from the side of a distal end arm member, which corresponds to a wrist, a 1st positioned axis of rotation is referred to as a first aixis of rotation, a 2nd positioned axis of rotation is referred to as a second axis of rotation, etc., and counting from the distal end arm member, an Nth positioned (final) axis of rotation is referred to as an Nth axis of rotation. In a similar manner, the distal end arm member is referred to as a first arm member, the next arm member (subsequent to) of the G.isr.a.J. end arm member: is referred to as a second arm member, and tne next arm member subsequent thereto is referred to as a third arm member. FIG. 1 is an outline overall perspective view of an articulated robot 10 in which a tool center point is set.

The articulated robot 10 includes a base 12 and an arm 14. Concerning the arm 14, a first arm member 16 {distal end arm member), a second arm member 18, and a third arm member 20 are provided, wherein among the arm members, the third arm member 20 is supported on the base 12. A first axis of rotation 22 is disposed on the first arm member 16, Therefore, the first arm member 16 can be torsional!y rotated (twisted) by 360° or greater by the first axis of rotation 22.

Further, the first arm member 16 and the second arm member 18 are connected through a second axis of rotation 24. Accordingly, the first arm member 16 can be rotated about the center of rotation of the second axis of rotation

9 A d *

The second arm member 18 can be torsionally rotated by 360° or greater by a third axis of rotation 26. Further, the second arm member 18 is connected with respect to the third arm member 20 through a fourth axis of rotation 28. Accordingly, the second arm member 18 can be rotated about the center of rotation of the fourth axis of rotation. 28.

Further, the third arm member 20 can be rotated by a fifth axis of rotation 30 and a sixth axis of rotation 32, which are capable of being rotated horizontally and vertically with respect to the base 12, Ultimately, the articulated robot 10 is a six-axis type of articulated robot having six respective axes of rotation, A ηαη-illustrated control circuit controls the amounts of rotation and timings at which the first axis of rotation 22 through the sixth axis of rotation 32 are rotated. Stated otherwise, the arm 1« of the articulated robot 10 carries out a predetermined operatron under the control of the control circuit, and as a result, is placed in a predetermined working posture.

As shown in FIG. 1, the articulated robot 10 is further equipped with a coordinate detecting jig 34, which is disposed on the first arm member 16, and a first camera 36a and a second camera 36b serving as an image capturing means, which is disposed on the second axis of rotation 24.

Among such members, the coordinate detecting jig 34 is constituted by bending a metallic thin rod-shaped body {linear body). One end thereof is attached to the distalmost end of the first arm member 16, Thus, the coordinate detectincj jig 34 is capable of being rotated about the center of rotation of the first axis of rotation 22. The other end of the coordinate detecting jig 34 is a so-called free end, which in accordance with the angle of rotation of the first axis of rotation 22, for example, can be placed in facing relation to the side of the second arm member 18,

On the other hand, a camera body 38 is supported on the second axis of rotation 24, As shown in FIG. 1, the first camera 36a is disposed on a lower end side of the camera body 38, whereas the second camera 36b is disposed on am upper end side of the camera body 38. The camera body 38 rotates in following relation to the axial rotation of the second axis of rotation 24, accompanied by the first camera 36a and the second camera 36b being rotated in unison about the center of rotation of the second axis of rotation 24.

In FIG, 1, the other end of the coordinate detecting-jig 34 is shown in a state of being arranged at the focal point P of the first camera 36a and the second camera 36b.

As will be discussed later, the control circuit recognizes that the angle of rotation of the first axis of rotation 22 at this time is 0°, and determines the coordinate origin point,

The articulated robot 10 which is constructed in the foregoing manner is used as a coating robot for applying a predetermined coating agent with respect to a workpiece. In this case, when coating is carried out, a coating nozzle is attached to the distalmost end of the first arm member 16 in place of the coordinate detecting jig 34.

The tool center point setting method according to the present embodiment is carried out in the following manner, in an articulated robot 10 which is configured basically as described above.

At first, the coating nozzle on the distalmost end of the first arm member 16 is replaced by the coordinate detecting jig 31. Thereafter, in a state in which axial rotation of the second axis of rotation 24 is stopped, only the first axis of rotation 22 is rotated. In following relation thereto, the coordinate detecting jig 34 is rotated as shown by the arrows about the center of rotation ot the first axis of rotatiοn 22.

As described above, the other end of the coordinate detecting jig 34 is a free end, "which accompanying rotation thereof, approaches toward or separates away from the second arm member 18, On the other hand, the first camera 36a and the second camera 36b face toward the side of the third arm member 20, and therefore, by the angle of rotation of the first axis of rotation 22, the other end of the coordinate detecting jig 34 enters into the image capturing field of view of the first camera 36a and the second camera 36b.

The first camera 36a and the second camera 36b are commonly focused on the apex position of an isosceles triangle {for example, an. equilateral triangle) the base of which is defined by the distance between the first camera 36a and the second camera 36b, More specifically, when the other end of the coordinate detecting jig 34 reaches the apex position, the other end is placed in a state of being arranged at the focal point P of the first camera 36a. and the second camera 36b, The control circuit recognises that the angle of rotation of the first axis of rotation 22 at this time is 0°.

Thereafter, in the same manner as in the conventional tool center point setting method, the articulated robot. 10 is placed in. different postures without changing the position of the distal end part of the first arm member 16.

In addition, when placed in such postures, in the same manner as described above, the other end. of the coordinate detecting jig 31 is placed in a. state of being arranged at the focal point P of the first camera 36a and the second camera 36b, whereupon it is recognized by the control crrcu.it that the angle of rotation of the first ax.is of rotation 22 is 0°.

By repeating tnese operations a plurality of times, the tool center point is set. Accordingly, by decoupling the coordinate oetecting jig 34, and furthermore, replacing it with the coating nozzle, it is possible to pexrform a coating operation using as a reference the coordinate origin point based on the tool center point.

In this manner, in the present embodiment, by exchanging or replacing a predetermined operating tool with the coordinate detecting jig 34, the tool center point can be set. Hence, the tool center point can be set with a simple operation,

In addition, a bent thin rod-shaped body is used as the coordinate detecting jig 34, Fabrication of such a coordinate detecting jig 34 is simple. Furthermore, since the coordinate detecting jig 34 can be of a small size and occupy a small volume, even if there is only a narrow space around the articulated robot 10, attachment of the coordinate detecting jig 34 to the distaimost end of the first arm member 16 is easy to perform.. In addition, interference of the coordinate detecting jig 34 with the second arm member 18 can be avoided. In other words, the operation for setting the tool center point proceeds smoothly.

Claims

CLAIMS 'i. A tool center point setting method for an articulated robot for setting a tool center point of the articuiatea robot that includes a plurality of axes of rotatiοn, eomprising the steps of: providing a coordinate detecting jig that is rotated by a first axis of rotation from a side of a distal end arm member mat makes up part of the articuiated robot; and arranging an image capturing unit configured to perform coordinate detection and which is rotated, by a second axis or rotation from a side of the distal end arm member, wherein by rotating the distal end arm member about the first axis or rotation, the coordinate detecting jig is moved to a focal point of the image capturing unit, and coordinates of the tool, center point are determined by setting an angle of rotation of the first axis of rotation at this time to 0°.
2. The tool center point setting method for an articulated robot according to claim 1, wherein a linear .oody is used as the coordinate detecting jig. J. A tool center point setting method for an articulated robot, substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.