Research on discretization algorithm of free-form surface for robotic polishing

Abstract

Traditional surface processing measures for free-form surface parts are unable to distinguish the curvature of the surface to be machined, nor can they identify the concave and convex characteristics of different areas of the surface, as well as the time-varying characteristics of the contact between the tool and the surface of the part, making it impossible to tailor the processing parameters to the different mathematical characteristics of each area of the part surface. The result is that different areas of the same surface cannot be machined uniformly. In order to solve the above problems, this study proposes a discrete partition algorithm for free-form surface parts from the perspective of free-form surface parts simplification. The algorithm takes the spatial coordinates of each triangular patch after meshing the 3D model of the free-form surface part as input parameters. The partition of the free-form surface part is realized by the criterion for determining the spatial position of triangular patches, the method for detecting overlapping edges of triangular facets based on the principle of co-linear determination and the strategy for determining the difference of normal vectors between triangular patches. The 3D solid model after the corresponding surface partition is further obtained by reverse modeling. In addition, in order to effectively improve the machining efficiency of the free-form surface parts after partition, this study proposes an optimal machining path planning algorithm based on the principle of genetic algorithm. This algorithm ensures that the processing equipment can finish each sub-surface and plan the polishing path based on the results of surface partition, and then achieving the complete polishing process of the surface in the shortest time. Finally, the simulation software was used to simulate and analyze the surface polishing quality before and after the partition processing, which proved that the proposed surface partition algorithm can effectively improve the machining accuracy of free-form parts.