Abstract: In light of the difficulty in accurate right-angle weld tracking, an approach of combining rotating arc sensor and path planning is put forward. Differential motion of left and right wheels of the robot or stretch of horizontal sliders are controlled by filtering the welding current captured by the rotating arc sensor and adopting least squares offset identification and fuzzy control algorithm. Weld tracking at quarter turns is based on path planning and horizontal sliders stretch, and is based on differential motion of left and right wheels before quarter turns. Experimental results show that the algorithm can track right-angle weld accurately.