Adaptive control of deposited height in GMAW-based layer additive manufacturing

A passive vision sensor system has been developed to monitor the nozzle to the top surface distance (NTSD) in layer additive manufacturing (LAM) using gas metal arc welding (GMAW). The deviations in the NTSD are compensated by the movement of the working flat, and the adjustment of the deposition rate on next deposition layer. After simplification of the controlled process into a linear system, an adaptive control system has been designed to keep the NTSD constant. The effectiveness of the controller is evaluated through deposition of single-bead multi-layer walls, and the experimental results confirm that the process stability can be improved when applying the developed controller. (C) 2013 Elsevier B.V. All rights reserved.