A Safety-Space-Based Approach to Inspection Path Planning for the Sheet Metal Assemblies

Abstract

The inspection path planning of sheet metal assemblies plays an important role in the measurement efficiency of large free-form surfaces. In the path generation of a 5-axis coordinate measurement machine (CMM), large calculation of collision detection and obstacle avoidance are needed in the traditional computer-aided inspection planning methods. Owing to structure complexity of large free-form surfaces, the planning procedures for collision detection and automatic collision-free trajectory generation is time-consuming and low-efficiency. To address this problem, a safety-space-based modeling approach is proposed to generate a feasible collision-free path for a large number of key measurement points. At first, based on the decomposition of the dynamic motion trajectory of the probe and discretizing of the inspected object, a continuous envelope space, i.e., safety space is constructed for candidate path generation of the probe. In the proposed planning strategy, the work of collision detection and avoidance are eliminated. Then, a heuristic optimization algorithm is used to generate the feasible trajectory in the constructed safety space for all the measurement points. At last, an inspection path planning case of a car door assembly was used to illustrate the procedure of the proposed method.