A hierarchical collision free path planning method for multi line spatial distributed welding of non standard workpieces

This paper presents a hierarchical path planning method for automatic generation of collision-free welding paths for non-standard workpieces with complex spatial weld distributions. Weld seam information is interactively extracted from CAD models using OpenCASCADE. Path nodes are classified into primary nodes (weld endpoints) and auxiliary nodes (safety points), defining four distinct path types. A two-stage obstacle avoidance strategy is then adopted: local attitude adjustment for short approach/retreat paths, and a global replanning framework built upon vanilla ABIT* with a novel distance-dependent three-stage adaptive optimization objective for long transitional paths. The three-stage objective partitions the path based on distances to the start and goal states, with differentiated cost functions for directional guidance, obstacle avoidance, and goal convergence. Experimental results on typical box-type workpieces demonstrate that the proposed method reduces average path length by 20% and increases minimum clearance by 8% compared to the baseline, while effectively eliminating excessively long paths, and retry operations raise the practical success rate from 52 to 90.7%. This work provides a systematic offline programming solution for welding robots, significantly reducing manual programming effort compared to traditional teach-in methods, while eliminating collisions in physical trials.