Closed loop control of melt pool width in robotized laser powder-directed energy deposition process

Robotized laser powder-directed energy deposition is a non-linear process, and the dynamic response of the system varies layer by layer. An adaptable PI controller with layer-dependent control gains was developed to ensure a constant melt pool width through the entire build. The laser power was selected as the control output variable, and the melt pool width was chosen as the control input variable. The performance of the controller was evaluated through deposition of thin wall samples. The results showed that the controller, by adjusting the laser power in real time, could successfully maintain the melt pool width and produce a more uniform and finer microstructure as compared to the sample with a constant laser power.