The working principle of the rotating arc sensor used in seam tracking is introduced.For the demanding of the cabined

angle changing largely seam tracking situation

a more compact and stable new rotating arc sensor is developed.The rotary detecting circuit is designed and using single chip processor to be core controller for rotary close loop speed control.The experiments show that these circuits have good characteristics of anti-interference

the position detection is reliable

the rotation velocity is stable and accurate.The developed arc sensing system has been applied successfully in the wheeled welding mobile robot for seam tracking.