Material or article handling – Vertically swinging load support – Grab
Patent
1985-03-11
1987-10-27
Valenza, Joseph E.
Material or article handling
Vertically swinging load support
Grab
901 3, 901 50, B25J 900
Patent
active
047026650
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method and a device for determining the reference positions of an industrial robot, more specifically to a method and a device capable of simply and highly precisely determining the reference positions of an industrial robot having a fixed base and a wrist front section of a plurality of degrees of freedom of motion relative to the fixed base.
2. Background Art
Industrial robots equipped with a wrist unit attached to the extremity of the robot arm, i.e., one of the motion systems, and having a plurality of degrees of freedom of motion relative to a fixed base have come into use. Industrial robots, in general, are numerically controlled according to a program, in which the wrist unit holding a robot work tool or a robot hand is controlled relative to the fixed base for predetermined working motions according to the program through the motion systems such as a swivel body, robot arms, and a wrist. Accordingly, it is necessary to determine the reference positions of the motion systems with respect to all the directions of motion corresponding to the degrees of freedom of motion of the industrial robot to make a program for numerically controlling the industrial robot. In the case of a six-axis articulated industrial robot, reference positions of the arms and other motion systems for motion about six axes must be determined.
According to a conventional method, the original position of the arm is a horizontal position determined by a level. This method, however, has the disadvantage that the unchanging determination of the original position of each arm with respect to the fixed base of the robot is difficult, when the floor surface on which the robot is installed is not horizontal.
According to another conventional method, marks or indices for indicating the reference positions or locating pins are provided on the corresponding ends of arms at the joint. This method, however, has the disadvantage that a large cumulative error in the position of the wrist unit results from the accumulation of errors in the alignment between the marks or locating pins.
The above-mentioned determination of reference positions of an industrial robot is necessary when the industrial robot is to be controlled by the use of the same program as has been used, after changing the industrial robot, after changing the part or parts of the motion system of the industrial robot or after dislocating the previous reference positions of the industrial robot by accidentally knocking the extremity of the robot arm against an obstacle. However, the above-mentioned conventional methods are unable to determine the reference positions simply and highly precisely.
DISCLOSURE OF THE INVENTION
Accordingly, in view of the disadvantages of the prior art, it is an object of the present invention to provide a method and a device capable of simply and highly precisely determining the reference positions of an industrial robot.
The object of the present invention is achieved by a method for determining the reference positions of an industrial robot having a fixed base and a wrist unit interlocked with the fixed base through motion systems and having a plurality of degrees of freedom of motion relative to the fixed base, comprising the steps of previously forming datum surfaces in the fixed base, attaching a reference position determining device having setting means for setting reference positions of the wrist unit for motions in a plurality of directions to the fixed base on the datum surfaces, providing the wrist unit with a gradual motion toward a position where the wrist unit front section is in contact with the setting means for setting reference positions and in alignment with respective reference positions, and giving information to the industrial robot to teach the reference positions with respect to the directions of motion corresponding to the degrees of freedom of motion of the industrial robot. This method is carried out by a device for determining the reference positions of an i
REFERENCES:
patent: 3336676 (1967-08-01), Aldeborgh
patent: 3496758 (1970-02-01), Sunnen
patent: 4372721 (1983-02-01), Harjar et al.
patent: 4406069 (1983-09-01), Clement
patent: 4481592 (1984-11-01), Jacobs et al.
Article by Koliskor et al., entitled "Methods for Checking the Operating Accuracy of Industrial Robots", published by Machines & Tooling, vol. 49, No. 8, 1978, pp. 7-10.
Inagaki Shigemi
Ito Susumu
Nakashima Seiichiro
Toyoda Kenichi
Alexander Jay I.
Fanuc Ltd.
Valenza Joseph E.
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