Controlling torch height and deposition height in robotic wire and arc additive manufacturing on uneven substrate

Wire and arc additive manufacturing (WAAM) shows a great application potential to manufacture large-size metal components rapidly. However, the research on WAAM to build structural parts on uneven substrates in some practical engineering applications is still a challenging issue. Controlling torch height and deposition height is the major barrier that limits the high level of automatic manufacturing of parts directly on uneven substrates. This study proposes a cooperative sensing and control strategy to achieve the process stability and deposition height control in robotic pulsed gas tungsten arc additive manufacturing (P-GTA AM) on an uneven substrate. The feedforward and feedback heights during the deposition process are monitored by a passive vision sensor. A feedforward controller and a feedback controller are designed to adjust the GTA torch height and the wire feed speed in real time, respectively. A thin-wall part was fabricated on a V-type substrate. The results demonstrate that the developed cooperative sensing and control strategy can ensure the process stability and realize the deposition height control in robotic P-GTA AM.