Machine element or mechanism – Control lever and linkage systems – Multiple controlling elements for single controlled element
Patent
1995-03-08
1996-11-05
Herrmann, Allan D.
Machine element or mechanism
Control lever and linkage systems
Multiple controlling elements for single controlled element
901 28, 901 50, B25J 1700
Patent
active
055706096
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an improvement to an industrial robot and, more particularly, to a multi-articulated industrial robot having a plurality of joint axes on which joint drive sources, which include drive motors and reduction gears, are mounted for driving the movable elements of the robot, the robot being further provided with a geometrical reference position setting means capable of simply restoring the original reference positions of respective drive sources about respective joint axes after a drive motor or motors and/or a reduction gears or gear have been replaced.
BACKGROUND ART
Generally, each joint of a multi-articulated industrial robot is conventionally provided with joint drive sources which include drive motors and reduction gears. The operation of the joint drive sources is controlled by a robot controller according to programs, stored in the robot controller, to cause relative displacements between movable elements about corresponding joint axes so that the accumulated relative displacement causes an end effector mounted on the wrist of the robot, i.e., the endmost movable element, to implement a desired operation.
In the described industrial robot, it often occurs at the job site that a drive motor or an associated reduction gear in a joint drive source malfunctions and must be replaced with a new motor or reduction gear.
In such a case, the defective operating element of the malfunctioning joint drive source, i.e., the drive motor or the reduction gear, is removed from the robot unit, and then a new drive motor or reduction gear is mounted on the robot unit to restore the joint drive source to its normal function.
In order to enable the industrial robot to perform any desired robot motion correctly, according to the program in the controller, after the defective drive motor or the defective reduction gear has been replaced with a new one, the geometrical positions of any two movable elements of the robot cooperatively joined together, for motions relative to each other, by the joint in which the drive motor or the reduction gear has been replaced with a new one must be unchanged from those before the replacement of the drive motor or the reduction gear, and the geometrical positions of the movable elements must be correctly taught to the entire system of the robot after completion of the replacement. The two movable elements of the robot are the robot body and the robot upper arm, the robot upper arm and the robot forearm, the robot forearm and the robot wrist, or the different parts of the robot wrist.
That is, the position before replacement, (original position) must be correctly restored and must be correctly taught to the robot.
Accordingly, original position adjustment, namely single-axis mastering, has conventionally been carried out.
The conventional single-axis mastering procedure applied to a multi-articulated industrial robot provided with a robot base 1, a robot body 2 capable of revolving about a joint axis (J1) relative to the robot base 1, a robot upper arm 3 capable of turning about a joint axis (J2) relative to the robot body, a robot forearm capable of turning about a joint axis (J3), supported on the extremity of the robot upper arm 3 relative to the robot upper arm 3, and a robot wrist 5 having three joint axes (J4 through J6) and three degrees of freedom of motion as shown in FIG. 2 will be described by way of example.
When a drive motor Mu of a drive source for driving the robot forearm 4 for rotating about the joint axis J3 malfunctions and it must be replaced with a normal one, the robot forearm 4 is rotated about the joint axis J3 relative to the robot upper arm 3 to bring a reference position P on the robot forearm 4, for original position setting, into contact with the tip of the arm of a dial indicator 9 fixedly held by a magnetic stand or the like on a measuring table 8.
In this state, the measurement indicated by the indicator hand of the dial indicator 9 is recorded, the geometrical position data U corresponding to the position
REFERENCES:
patent: 4372721 (1983-02-01), Harjar et al.
patent: 4702665 (1987-10-01), Nakashima et al.
patent: 4813844 (1989-03-01), Torii et al.
patent: 4892457 (1990-01-01), Bartlett et al.
patent: 5060533 (1991-10-01), Torii et al.
Iwasaki Kyozi
Nihei Ryo
Terada Akihiro
Yamashiro Hikaru
Fanuc Ltd.
Herrmann Allan D.
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