Tool coordinate system calibration method and system based on spherical probe radius compensation

By obtaining the radius of the ball-head probe and the normal vector of the contact plane, and using geometric or iterative compensation strategies, combined with singular value decomposition to fit the plane normal vector, the systematic error introduced by the ball-head radius is solved, achieving high-precision and robust tool coordinate system calibration, which is suitable for industrial and surgical robots.

CN122425703APending Publication Date: 2026-07-21TIANJIN UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
TIANJIN UNIV
Filing Date
2026-05-27
Publication Date
2026-07-21

AI Technical Summary

Technical Problem

In existing technologies, the ball head calibration system is neglected during ball head calibration. As a result, the systematic error introduced by the ball head radius during ball head probe calibration leads to TCP position and attitude deviations, which cannot meet the requirements of precision assembly and sub-millimeter accuracy.

Method used

By obtaining the radius of the ball probe and the normal vector of the contact plane, a geometric or iterative compensation strategy is adopted, and the plane normal vector is fitted by the singular value decomposition method. The coordinates of the ball center are constructed and the position and orientation of the tool coordinate system are solved to form a complete transformation matrix, integrating robust algorithms and verification mechanisms.

Benefits of technology

It effectively eliminates systematic errors introduced by the ball head radius, improves calibration accuracy to the sub-millimeter level, enhances robustness and process integrity, reduces costs, and is suitable for calibration of industrial and surgical robots.

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Abstract

The application belongs to the technical field of robot calibration, and discloses a tool coordinate system calibration method and system based on ball head probe radius compensation, which aims at the problem that the TCP position calibration has systematic errors due to neglecting the ball head radius when using the ball head probe for calibration. The calibration method and system comprises the following steps: fitting the contact plane normal vector and performing ball head radius compensation through multi-point contact; constructing an over-determined equation set by using the compensated ball center point coordinates to solve the tool coordinate system origin position; and fitting the displacement vector by controlling the ball head probe to move along the base coordinate system axis to calibrate the tool coordinate system posture. Through the geometric, iterative, compensation strategy and robust algorithm, the application can effectively eliminate the systematic errors introduced by the radius, significantly improve the calibration accuracy and repeatability, and the method does not need expensive special equipment and is suitable for high-precision calibration scenes of industrial robots, surgical robots and other ball head probes.
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