A predictive control algorithm for layer-to-layer ink-jet 3D printing

Ink-jet 3D printing is an additive manufacturing process where-in parts are built by jetting material from nozzles layer by layer, with curing between successive layers of deposition. Typically, this additive process is operated in an open-loop manner, i.e., the number of layers and droplet patterns for each layer are determined in advance and are not modified based on measurements of current height profile during the printing process. As a result, the uncertainties in droplet sizes, heights and locations during printing can result in undesired part geometry, such as edge shrinking, unreliable dimensions and uneven surfaces. Naturally, incorporating feedback measurements into the control algorithm will improve performance if suitable models and cost functions are constructed. In this paper, we first propose a control-oriented layer to layer height evolution model for two-material Ink-jet 3D printing. Based on this model, a predictive control algorithm that uses measurements of the current height profile to generate control inputs for successive layers is designed. The effectiveness of the proposed algorithm is demonstrated by simulation studies.