Control-oriented MIMO modeling of laser-aided powder deposition processes

This paper proposes a control-oriented multiple input multiple output (MIMO) model for a class of laser aided powder deposition (LAPD) processes. First, the various components of a multi-physics model of LAPD processes are briefly reviewed including the laser-powder interaction, heat transfer with phase change, fluid flow and surface deformation. The difficulty of capturing these nonlinear, coupled, spatio-temporal multi-physical interactions via lumped parameter modeling is highlighted. Then, a new MIMO model is derived in Hammerstein form by concatenating a linearized dynamics with coupled nonlinear relationships derived from mass and heat balance considerations. This MIMO model captures the coupled dynamics with laser power and scanning speed as inputs and deposited layer height and melting pool temperature as outputs. To identify the unknown model parameters, a constrained optimization problem is solved using the detailed multi-physics models. The MIMO model is in a form suitable for multivariable control designs for LAPD processes.