A Hybrid Distorted Coordinate System and Bilayer TSP Optimization for Toolpath Planning in Wire-Arc Additive Manufacturing

This article addresses key limitations in conventional toolpath planning for wire arc additive manufacturing (WAAM), including excessive nonproductive travel, frequent sharp turns, and inefficient coverage in multiply-connected regions. To resolve these issues, we introduce a novel approach that integrates a hybrid deformable coordinate system with a bilayer traveling salesman problem (TSP) optimization framework. The method adaptively combines Cartesian and polar coordinates using anisotropic deformation factors to align deposition paths with local geometric features, while a penalty-based distance matrix minimizes nonproductive travel across hollowed areas. Comprehensive experiments on representative benchmark models, such as a circular coin with a square hole and a star-rectangle composite structure, demonstrate that the proposed approach reduces nonproductive travel to 217.1 mm and 165.6 mm, respectively. This represents a reduction of up to 82.9% compared to conventional zigzag, Hilbert curve, contour-offset, and spiral strategies, while maintaining favorable coverage and turn count. The results validate the framework's effectiveness in balancing global motion efficiency with local deposition quality, offering a robust automated solution for path planning in WAAM applications with complex internal geometries.