Simple and High-Precision Hand-Eye Calibration for 3D Robot Measurement Systems

Three dimensional (3D) robot measurement systems, with binocular planar structured light cameras (3D cameras) installed at the terminal flange of robots, are widely used to measure complete workpieces by stitching point clouds obtained from various sampled poses. To ensure accurate stitching, hand-eye calibration is necessary. However, 3D cameras often demonstrate low precision in measuring jumping edges and vertices, resulting in challenges when selecting appropriate calibrators and calibration methods for hand-eye calibration. We propose a simple and high-precision hand-eye calibration method for 3D robot measurement systems. Initially, a single sphere is utilized as the calibrator, and its poses are observed using specific robotic motions. Subsequently, the hand-eye calibration problem is formulated as a well-known equation, AX=XB$A X = X B$, relying solely on the high-precision relative pose of the robot. Finally, a novel simultaneous solution for AX=XB$A X = X B$ and the corresponding closed-form initial solution are introduced. Simulations and experiments confirm that the proposed method exhibits high noise resistance and achieves high-precision calibration, even with a limited calibration data quantity. Compared with traditional methods, the fitting error of the proposed method can be reduced from over 0.9 mm to less than 0.6 mm. To tackle the hand-eye calibration challenge in 3D robot measurement systems, this study proposes a straightforward calibration method that employs a single sphere. This method demonstrates high calibration accuracy, minimal data quantity requirements, and remarkable noise tolerance compared to traditional methods.image & COPY; 2023 WILEY-VCH GmbH