Compensation Algorithm and Experimental Study of Error Calibration of Robotic Arm Based on Grating Ruler Measurement

This study addresses the challenge of achieving precise endpoint positioning for robotic arms in high-precision grinding, often compromised by processing and installation errors, as well as non-geometric parameters. Focusing on a five-degree-of-freedom grinding robot, we present an error calibration and compensation method utilizing grating ruler measurement for the robotic arm. Firstly, an improved D-H parameter method establishes the forward kinematic model, coupled with a mathematical model for compensating error parameters in combination with the robotic arm’s geometric configuration. Then, based on the measurement data of the grating ruler, the fusion algorithm is used to solve the error parameter values of the lengths and angles of each joint and compensate them into the kinematic model. Finally, the error calibration results are compared with those of the laser tracker to verify the positioning accuracy of the end of the robotic arm after the grating ruler calibration. The experimental results show that the fluctuation range of the repeat positioning accuracy of the grating ruler calibration and the laser tracker calibration is basically the same, and the stability is good. Compared with the uncalibrated robotic arm, the absolute positioning accuracy has increased by 69.95%, and the difference from the calibration of the laser tracker is 0.069 mm. Its positioning accuracy basically meets the requirements of high-precision grinding. Meanwhile, the cost of the grating ruler equipment is much lower than that of the laser tracker, and it can replace the laser tracker to calibrate the error of the mechanical arm.