Multivariable closed-loop control for layer geometry in Wire Arc Additive Manufacturing

Abstract

This paper focuses on modelling and control of mass and heat transfer process for Wire Arc Additive Manufacturing (WAAM). It considers a nonlinear model for the deposited layer geometry of thin walls bases on process variables (wire feed speed, arc current, travel speed and contact tip to workpiece distance) and physical variables (arc power, inter-pass temperature) as inputs. The model is based on the Rosenthal solution for the temperature distribution due to a moving heat source in combination with a layer geometry parameterization, which is incorporated in a dynamic model of the GMAW process for control design. A closed-loop control is proposed to guarantee a more accurate deposition geometry considering the linearized model about a given operating point. Numerical simulation results illustrate the efficacy of the proposed control for the regulation and tracking of both layer height and wall width and a experimental setup for validating the control strategy is also proposed.