Machine-assisted travel speed control in manual welding torch operation

Welding is a skill-demanding, labor-intensive operation which should be automated whenever possible. Unfortunately, manual welding will still be irreplaceable in applications where the needed versatility and accessibility cannot be achieved by robots. On the other hand, the skills needed for manual welding typically require a long time to develop. In particular, maintaining the torch to travel in desired speed is a challenge. This paper thus proposes to use a feedback control system to assist the welder in regulating his/her arm movement in real time to achieve the desired torch travel speed. To this end, the travel speed (system output) is tracked by a motion sensor. The welder is instructed by a visual command to adjust the travel speed as system input. An auto-regressive moving average model has been used to correlate the system output to the system input as the human welder response model. To determine how the input needs to be adjusted to assisting the human welder to achieve the desired speed, a feedback control algorithm has been developed. Experiments verified that the proposed feedback control system is capable of assisting the human welder to track the desired travel speed.