The development of welding robots suitable for specially unstructured working enviroments has been become an important development
direction of industrial robot application because large-scale welding structures have been used more and more widely in modern industry. In this paper,an intelligent mobile robot for welding of ship deck with the function of
auto-searching weld line was presented. A wheeled motion mechanism and a cross adjustment slider are used for the welding robot body. A sensing system based on laser-PSD(position sensitive detector) displacement sensor was developed to obtain two dimensional deviation signals during
seam tracking. A full-digital control system based on DSP and CPLD has also been realized to implement complex and high-performance control algorithms. Furthermore,the system has still the function of auto-searching weld line according to the characteristics information of weld groove and adjusting posture itself to the desired status preparing for welding. The experiment of auto-searching welding line shows that the robot has high tracing accuracy,and can satisfy the requirement of practical welding project.