Robot Angle Detector Eccentricity Correction Under Backlash
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Solution Overview
Problem
Existing methods struggle to accurately correct eccentricity errors in angle detectors of robots due to factors like backlash and elastic deformation, making it difficult to isolate and correct eccentricity errors in the output shaft angle detector.
Innovation Solution
The method involves detecting output shaft angles at multiple positions where the effect of the arm's weight is suppressed, determining the eccentricity error as the difference between the arm angle value and the output shaft angle, and using an error curve to express the relationship between the arm angle value and the eccentricity error, allowing for accurate extraction and correction of the eccentricity error during robot operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction is attempted based on input shaft and output shaft angles at periodic angles, then tip position accuracy is improved, but accurate extraction of eccentricity error is difficult due to interference from backlash and elastic deformation
Solution Approach 1:
The patent applies local quality by focusing measurement and correction on specific local positions where the arm's elastic deformation is minimized - such as vertical positions, horizontal positions, or positions where the arm is supported. By concentrating correction efforts at these specific locations rather than attempting uniform correction across all positions, the system can accurately isolate and measure eccentricity error without interference from elastic deformation.
Data Source
AI summary
In an eccentricity error correction method for an angle detector, an output shaft angle is determined in at least three measurement positions. A difference between an arm angle value at each measurement position and the output shaft angle detected at each measurement position is determined as an eccentricity error. An error curve indicates a relationship between the arm angle value and the eccentricity error, and is determined as a function of the arm angle value by approximating the eccentricity error at each measurement position with a sine wave of which a single cycle is a single rotation of the arm. A correction formula that associates the output shaft angle and the arm angle value is determined using the error curve. A correction value corresponds to the detected output shaft angle, and is determined based on the correction formula and correcting the eccentricity error when the arm is rotated.