Optimal melt pool width control for metal 3d printing with directed energy deposition

Laser-based directed energy deposition (DED) is an additive manufacturing technique used for 3d printing of metals. In processes of this type, the laser power is often kept constant or controlled with very simple controllers. An appropriate feedforward laser power signal has the potential to increase the geometric quality of the printed product. We derive a computationally efficient reduced order model (ROM) from a finite-element (FE) model and simulation that describes the temperature field induced by the moving laser heat source. We show the ROM can be used to find an optimal laser power signal by solving an optimal control problem that would be cumbersome with the FE model. The optimal control solution achieves reference tracking for the melt pool width and outperforms a PI width controller even if this PI controller is tuned systematically.