Calibration and accuracy analysis of robotic belt grinding system using the ruby probe and criteria sphere

Calibration in the robotic belt grinding of complex blades is considered as one of the key bottlenecks of measurement accuracy. To enhance the accuracy of robotic calibration system, an improved method is proposed in this paper to calibrate the tool (grinding machine) frame and workpiece (aero-engine blade) frame by holding the ruby probe as the main calibration tool. Firstly, the sphere-to-sphere method replacing the traditional point-to-point method is put forward to calibrate the flexible and fixed probe frame. Secondly, the calibrated flexible and fixed probe frame is employed to precisely seek the origin point of tool frame and then to calibrate it accurately. Thirdly, both the rough calibration (manual calibration) and fine calibration (auto calibration) are adopted to calibrate the workpiece frame, the resulting translation and rotation errors are controlled at small values to improve the calibration accuracy. Finally, a typical case on robotic belt grinding of aero-engine blade is conducted to validate the calibration results of the robotic belt grinding system (RBGS).