When an industrial robot is operational continuously at a high speed
the heating of the motor and joint friction heat will result in a higher temperature in the manipulator; furthermore
the position of the end flange will drift and significantly influence the robot's repeatability and accuracy. To deal with these problems
in this paper
an in-line thermal compensation method based on binocular stereo vision was presented for an industrial robot working in the manufacturing field. A thermal compensation model was established based on the principles of differential kinematics and vision measurement method. In this method
a standard sphere was installed at the end of the robot arm and a vision sensor was installed around the base of the robot. After working in a regular circulation
the robot carried the standard sphere to the working field of the vision sensor to be measured from different postures. Besides
significant parameters were chosen to compensate for the thermal error from all joint parameters after analyzing their time-varying patterns. With fewer parameters that correspond to the thermo-drifting pattern
the measuring times and time consumption could be effectively reduced. The experimental result demonstrates that the proposed in-line thermal error compensation method can maintain the repeatability of the robot within ±0.1 mm and the compensation time is approximately 10 s
which can noticeably improve the operating precision of the industrial robot at the manufacturing site.
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Keywords
references
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