Proposed in this thesis is an approach to developing a computer graphics simulation system for robot welding process. The purpose of the simulation model is to help plan robot welding operations. In planning robot welding operations, the system designer has to determine the workplace layout, select positioner configurations, and find welding positions and sequences.
A robot welding station consists of one or more welding robots, a positioner, and the welding structure which is a collection of plates to be welded. Each plate is modelled by using a reference plane concept, and welding lines as tracks. Robots (including welding torch and sliding base) and positioners are represented by homogeneous coordinate frames. Also include in the model are such technical constraints as weaving patterns, weld joint types, and inclination angle allowances. An interactive means is provide to input the welding structure and welding lines through a graphic terminal.
The simulation program is written in FORTRAN on VAX computer with a Tecktronix terminal. The simulation model first calculate the center of the mass of the welding structure. This information is essential in designing a positioner. To determine feasible welding lines (ie, welding lines that can be covered by robots), the simulation model automatically performs inclination angle checking, weaving checking, workspace checking, interference checking, and inverse solution checking, for a given configuration. It will then calculate the percentage of welding operations that can be covered by robots and an estimated cycle time. A case study is compiled for the robot welding of Center Frame.
