Tool Path Optimization for 7-DOF Robot Machining Based on Sampling Motion Planning Algorithm

Milling or grinding complex curved parts with multi-DOF (degree of freedom) robots has the flexibility advantage of flexible obstacle avoidance and consistent attitude machining. However, in surface machining, only a few degrees of freedom are usually required, such as 3-DOF in ball end milling, and 4-DOF are usually required in side milling. There are redundant degrees of freedom in machining with multi-degrees of freedom robots, and redundant degrees of freedom also provide optimization space for machining process trajectory planning. A 7-DOF robot machining system is composed of a rotating worktable and a 6-DOF robot. This paper proposes an optimization method for complex surface machining joint trajectories using 7-DOF robots, based on a sampling motion planning algorithm. According to machining process requirements, the tool point was constrained to the established machining trajectory, the tool axis vector is limited to a specific area. Finally, using the sampled motion planning method in the Open Motion Planning Library (OMPL) to derive and generate a trajectory that meets the task requirements, the total joint rotation is reduced by 12.4% compared to traditional trajectory planning methods.