Welding handicraft is one of the most primordial and traditional technics, mainly by manpower and human experiences. Weld quality and ef?ciency are, therefore, straitly limited by the welder's skill. In the modern manufacturing, automatic and robotic welding is becoming an inevitable trend. However, it is dif?cult for au- matic and robotic welding to reach high quality due to the complexity, uncertainty and disturbance during welding process, especially...