A technology framework for robotic profiling of blade edges based on model reconstruction and trajectory replanning

Abstract

Precision belt grinding of complex blades with an industrial robot is a great challenge owing to the micro-features of blade edges as well as the flexible contact state, thereby resulting in the uncertain machining allowance characterized by over- and under-cutting. In order to guarantee the desired blade profile accuracy, it is necessary to further implement the profiling operation on the blade edges after the global grinding. In this paper, a technology framework for robotic profiling of blade edges is proposed in accordance with the measurement-machining integrated manufacturing strategy. This framework consists of two parts: (1) model reconstruction, which aims to obtain the blade edge allowance data when the blade surface is globally ground. Both the robot relocalization based hand-eye calibration and the dynamic threshold constrained ICP algorithm for point cloud registration are presented; and (2) trajectory replanning, which adaptively plans the path and grinding points at the blade edges to be machined. Thus the iso-scallop height algorithm with material removal profile (MRP) model and the optimized constant chord-height error algorithm are then put forward. Based on these two parts, a closed-loop control software integrating visual inspection and trajectory planning functions is developed to execute the robotic profiling operation on the blade edges. The experimental results prove the effectiveness of the proposed technology framework in model reconstruction and machining accuracy, and particularly provide a valuable reference for the subsequent work towards robotic precision grinding of complex components.