A generalized method for C3 continuous toolpath planning and its application in robot machining

Abstract

High-order parametric continuity in toolpath generation and smooth passage through singular regions are paramount in five-axis machining. This paper introduces a generalized method for toolpath planning of a 5-DOF machining robot, which encompasses a two-pronged strategy: a toolpath smoothing technique and a singularity avoidance strategy. Initially, the control points of smoothing B-splines are analytically derived using curvature derivative continuity criteria for both linear and arc path segments. On this basis, an effective corner smoothing method, which is capable of addressing the line-line, line-arc, and arc-arc pairs, is developed for the tool position path, and a specialized approach similar to spatial arc-arc pair smoothing is employed for the tool orientation path. Subsequently, an analytical parameter synchronization technique is applied to generate a C³ continuous toolpath. A real-time singularity avoidance strategy is then proposed to improve the toolpath continuity near the singular configuration of the machining equipment. The effectiveness of the proposed method is verified through simulations and experiments on a robot machining platform, with the integration of a jerk-continuous feedrate profile. The findings indicate that the equipment can operate effectively throughout its entire workspace thanks to the proposed toolpath planning method.