The Real-Time Local Surface Model Construction Method of Unknown-Model Workpieces for Robotic Polishing

Polishing is a critical surface processing technology that has a significant impact on the surface quality and service life of workpieces. Although robots are capable of performing automated operations in structured scenarios, robotic polishing systems for workpieces without a surface model still heavily depend on manual operation due to the inability to plan the polishing pose on the workpiece surface, resulting in high cost, low efficiency, and uncontrollable quality. This article presents a hybrid contact/noncontact measurement method for obtaining a local surface model consisting of three parts: first, a method is proposed for modeling a local workpiece surface based on a binary quadratic equation; then, the design and calibration of a hybrid measurement device is proposed for simultaneously obtaining four discrete points on the surface used to construct its model; and finally, a method is proposed for verifying the accuracy of the constructed local surface model by obtaining and tracking the normal direction of the surface. The proposed method is validated through simulation analysis and actual evaluation in various types of experimental scenarios. The results demonstrate that the proposed method can effectively obtain the unknown model workpiece surface model and realize the requirement of a robotic polishing process along the normal direction of surface.