A novel filling strategy for robotic multi-layer and multi-pass welding based on point clouds for saddle-shaped weld seams

Research question

How can a saddle-shaped header-to-tube groove with varying cross-sections be filled in multiple passes without teaching every point?

Method

Three-dimensional scans, Tr-ICP registration and RANSAC pipe-axis fitting establish the workpiece geometry. Segmented groove features support a filling strategy that combines abdomen pre-filling with circumferential passes and compensates assembly deviations.

Main findings

For a specimen with a 140.7 mm branch diameter, 25 pass trajectories were generated in 54.465 s and tested through multi-pass welding. Point-cloud registration distances were within 0.2 mm, supporting automated planning for complex intersecting joints.