A robotic milling machining accuracy compensation method

An increasing number of industrial robots are being applied in continuous contact machining scenarios, which imposes higher requirements on the machining trajectory accuracy of robots. However, due to inherent defects of serial industrial robots - such as low rigidity, joint backlash, and kinematic model errors - achieving high trajectory accuracy requires specialized methods. This paper conducts an in-depth analysis of the factors influencing the trajectory accuracy of industrial robots, and compensates for trajectory accuracy from three aspects: kinematic parameter calibration, backlash identification and feedforward compensation, and online closed-loop control. Furthermore, it proposes an online feedforward-closed-loop compensation control framework based on a laser tracker. Through workpiece milling experiments, the average trajectory errors of the original trajectory, offline compensation method, and online compensation method are compared. The framework proposed in this paper achieves average errors of 0.112 mm and 0.163 mm in planar milling and curved surface milling scenarios, respectively, with accuracy improvements of 89.3% and 82.2%.