Design of a Model-based Controller with Temperature Feedback for Laser Cladding

Laser cladding, also known as direct metal deposition, is an additive manufacturing technique for the production of freeform metallic parts. High quality parts can be created with the use of feedback control systems which stabilize the melt pool during the cladding process. Current laser cladding control systems are based on low order, empirical models of the process, which have low dynamic accuracy and limit the performance that can be achieved. In this paper, a control system based on a physical heat conduction model of the melt pool dynamics is presented. The control structure consists of a static linear state feedback control law designed using pole placement and combined with a PI controller. The controller is able to regulate the melt pool size by modulating the laser power using a number of surface temperature measurements as the feedback signal. Simulation results using a detailed finite element model show that the controller has good tracking behavior and disturbance rejection properties.