Development of multi-axis gantry type welding robot system using a PC-based controller

In order to implement factory automation in the ship building industry, the authors have developed a multi-axis gantry type welding robot system for automated fabrication of sub-assemblies of ship building and steel bridge lines. This automatic welding system consists of a 4-axis gantry-type robot with two welding robots over-hanged from it. A gantry robot is controlled by PC based controller (called PC-RC; PC-based robot controller) and two welding robots are controlled by their controllers (called RCs; robot controllers), respectively. Following the movements of the gantry robot to the designated point of work-piece to be welded, the two welding robots perform welding on the both sides of workpiece simultaneously. Synchronizing signals between PC-RC and RCs for moving are performed by digital in-out signals. The job programs for both gantry and the robots are generated by OLP (offline programming) system. Also the PC-RC receives the job programs of gantry and the welding robots from OLP systems via LAN (local area network). The PC-RC also sends job programs of the welding robots to the RCs via serial communication lines. The resultant system was field-tested at the test shop and its performance was proved to be successful.