Boots – shoes – and leggings
Patent
1992-01-24
1994-07-12
Harvey, Jack B.
Boots, shoes, and leggings
36457104, 395 89, 395 94, 901 47, 348 95, G01C 300
Patent
active
053294696
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a visual sensor calibration method of calibrating a visual sensor in a robot system, and more particularly, to a visual sensor calibration method of calibrating a plurality of cameras or the like.
2. Description of the Related Art
In current practice a robot system is provided with a visual function to enable it to pick up an image of a workpiece by using a camera or the like to determine the position of the workpiece, and thus carry out an operation such as assembling or palletizing or the like. Further, a plurality of cameras are used to accurately determine the position of a workpiece, or to correspond to a plurality of robots.
It is necessary to calibrate the relationship between a a robot coordinate system and a camera coordinate system, to accurately determine the position of a workpiece, and when a plurality of cameras are used, an exclusively designed jig is prepared and used.
Such a calibration jig is large, however, and the jig must be moved by jogging or a similar operation, to thereby pick up images thereof by a camera, resulting in a poor operability.
Further, because most calibration jigs are large, they incur high manufacturing costs and the like, and require a special installation space.
Furthermore, when a plurality of cameras are used, it is difficult to calibrate each camera.
SUMMARY OF THE INVENTION
The present invention is intended to solve the above-mentioned problem, and an object of the present invention is to provide a calibration method for a visual sensor which eliminates the need for moving a jig when implementing a calibration.
Another object of the present invention is to provide a calibration method for a visual sensor by which a visual sensor can be calibrated with a simple calibration jig.
Still another object of the present invention is to provide a calibration method for a visual sensor which permits an easy calibration of each camera.
To fulfill the aforementioned objects, the present invention provides a visual sensor calibration method of calibrating a visual sensor in a robot system, wherein an arm of a robot is provided with a pattern plate for a calibration, the first calibration pattern data of the pattern plate on base coordinates of the robot is sent from a robot controller to a visual sensor controller, the visual sensor controller obtains the second calibration pattern data from the pattern plate, and then acquires calibration data from the first calibration pattern data and the second calibration pattern data, to thereby calibrate a visual sensor.
A robot controller itself holds accurate position data of the pattern plate on the robot coordinate system. More specifically, the robot controller holds the first calibration pattern data of the pattern plate based on a coordinate position of the end of the robot arm and an installation dimension of the pattern plate.
The visual sensor controller reads the first calibration pattern data from the robot controller via a communication line, and further, the visual sensor controller receives an input of an image of the pattern plate from the visual sensor and detects each dot of the pattern to thereby obtain the second calibration pattern data.
The calibration data can be acquired by comparing the first calibration pattern data with the second calibration pattern data.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a configuration block diagram of a whole robot system for implementing the visual sensor calibration method according to the present invention;
FIG. 2 is a detailed view of dot patterns on the pattern plate;
FIG. 3 shows an example of two cameras used to pick up an image of one pattern plate; and
FIG. 4 shows an example whereby, in a robot system comprising four robots and four cameras, all four cameras are calibrated against a robot coordinate system common to all robots.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention is described with reference to the drawings.
FIG. 1 is a
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"Communication Manufacturing Technology," 22nd Annual Meeting & Technical Conference Proceedings of the Association for Integrated Manufacturing Technology, May 14-17, 1985, pp. 256-270.
"Vision Systems for Robot Control," A. Rourke et al., Manufacturing Technology International, No. 1, 1987, London, pp. 185-188.
Fanuc Ltd.
Harvey Jack B.
Wachsman Hal D.
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