1989 Volume 7 Issue 2 Pages 268-275
The authors proposed an off-line programming system which consisted of four levels of software modules hierarchically; i) task level, ii) tool level, iii) robot level, and iv) machine code level. This paper describes the generation of the trajectory for the weld torch on the work model at the tool level.
The torch angles specified by the system user along each of weld lines is checked automatically by calculating intersections between planes of the work model and the check plane, which is an imaginary plane defined by the weld line and the axis of torch head. If an intersection beyond the weld line is detected, it is recognized that a corner obstacle is there, and the obstacle is avoided by tilting the torch head along the weld line. If the intersection can be avoided by rotating the check plane, it is recognized as a projection obstacle, and the torch angle is modified with the torch head in the rotated plane. If the intersection still exists, it is recognized as a bridge obstacle above the weld line. When the obstacle is near either end of the weld line, the bridge obstacle is avoided by inserting the torch head with tilting. Otherwise the weld line is divided into two segments at the center of the bridge area.
The validity of the algorithm is confirmed using some sample objects with the motion simulation on display monitor.
