Measuring and testing – Instrument proving or calibrating – Displacement – motion – distance – or position
Reexamination Certificate
2000-02-24
2001-03-20
Raevis, Robert (Department: 2856)
Measuring and testing
Instrument proving or calibrating
Displacement, motion, distance, or position
Reexamination Certificate
active
06202466
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a calibration method using a sensor, and more particularly, to a calibration method for compensating an offset occurring when a driving element such as a motor and a belt in a transmission part attached to a body of the robot or a sensor for sensing the movement of a shaft of an arm in the robot is exchanged with a new one.
2. Prior Art
When a mechanical appliance requiring a precise position control such as an industrial robot undergoes a troubleshooting on a part or entire parts thereof, or it is disassembled and assembled in order to exchange parts therein with new ones, an offset may occur which is a variation of the initial position of a moving part such as an arm in the robot from a preset position thereof. Such an offset results in the reduced accuracy of the position control on the basis of the preset calibration data. Therefore, a new calibration should be necessarily performed so that the preset calibration data are amended, in order to compensating the offset after the parts are exchanged with new ones.
In conventional art, if the offset has to be compensated after the parts in a robot body such as a motor are exchanged, the calibration has been performed by utilizing a jig for exclusive use in calibration, or on the basis of marks signed on the robot body.
The calibration using the calibration jig is performed according to the following steps.
(1) detaching a working tool attached to the robot body.
(2) attaching a calibration tool.
(3) performing calibration using the calibration tool.
(4) amending calibration data or compensating an offset with the performed calibration results.
(5) detaching the calibration tool.
(6) attaching the working tool again.
Such a calibration method using the calibration jig requires a high preciseness of the calibration jig. Further, the working tool and the calibration tool must be exchanged with each other two times, so the calibration process is very troublesome and much time is consumed, which may cause a lowering of productivity.
Meanwhile, the calibration using the marks inscribed on the robot body is performed according to the following steps.
(1) moving every part of the body to the marked positions.
(2) amending the calibration data or compensating the offset using the present position of the robot.
Such a method does not bring about the troublesome job of exchanging the tools as the case of utilizing the calibration jig, however, that method is not preferable since the preciseness of the calibration is low.
SUMMARY OF THE INVENTION
The present invention has been proposed to overcome the above-described problems in the prior art, and accordingly it is the object of the present invention to provide a calibration method of a robot, which can amend the offset simply and precisely without the troublesome job of exchanging the tools in order to use a calibration jig.
To achieve the above object, the present invention provides a calibration method of an industrial robot, comprising the steps of: preparing a signal generation part attached on a moving part of the robot, the signal generation part for providing a signal about a position of the moving part, and a signal detection part for detecting the signal from the signal generation part; moving the moving part; generating calibration data on the basis of the position of the moving part detected by the signal detection part; calculating a difference between the generated calibration data and preset calibration data; and amending the preset calibration data on the basis of the difference so that an offset is compensated.
Here, the step of moving the moving part comprises the steps of, rotating the moving part in one rotational direction, stopping the moving part when a variation of the signal detected by the signal detection part is checked, and rotating the moving part in a reverse rotational direction. Furthermore, in the step of generating the calibration data, the calibration data are generated on the basis of the position of the moving part at a time point that the variation of the signal detected by the signal detection part is checked during the step of rotating the moving part in the reverse rotational direction.
Preferably, the moving part is rotated at a high rotational velocity during a rotation thereof in the one rotational direction, and at a low rotational velocity during a rotation thereof in the reverse rotational direction.
According to the present invention, the calibration can be performed in a short period of time without the inconvenience of exchanging a calibration jig. Furthermore, the preciseness of calibration is high.
REFERENCES:
patent: 4380696 (1983-04-01), Masaki
patent: 4753569 (1988-06-01), Pryor
patent: 4873655 (1989-10-01), Kondraske
patent: 5086641 (1992-02-01), Roselli
patent: 5331232 (1994-07-01), Moy et al.
patent: 5418890 (1995-05-01), Ishihara et al.
Burns Doane Swecker & Mathis L.L.P.
Raevis Robert
Samsung Electronics Co,. Ltd.
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