Modularized Control Architecture of an Embedded Controller for Mobile Welding Robot in the Shipyard

The present study describes the development of controller hardware and control software for a mobile welding robot, which can move in the transverse and longitudinal directions (Moving Tasks), perform the welding tasks of the U-shaped parts and bracket parts in a double hull structure (Welding Tasks), and detect points of the welding path (Sensing Tasks). Controller hardware consists of a main controller and a welding machine controller. The main controller, which is mounted on the mobile welding robot, consists of a CPU board, a motion controller, and an incremental encoder type AC servo motor driver. The welding machine controller, which is mounted on the welding machine located on the outside of the double hull structure, controls the welding machine. Communication between the two controllers is made via the RS485. Control software consists of 4 layers: Task Manager, Task Planner, Actions for Task, and Task Executer. Each Layer consists of modules such as the Action Module, Motion Generator Module, Servo Module, etc. Suitable combinations of modules enable the control software to perform the required tasks. Control software is developed using C programming under QNX Operating System, which is well known to have a reliable hard-realtime performance.