Iterative Learning Control for Laser Scanning based Micro 3D Printing

This paper proposes an iterative learning control (ILC) for a micro stereo lithography (MSL) setup to enhance both the speed and the quality of 3D printing. The MSL setup is built based on a commercial confocal microscope while the scanners of both x and y axes are replaced with fast galvanometer scanners considering requirements of random trajectories in 3D printing application. With the stabilized galvanometer scanners, a frequency domain ILC is applied for a precise operation of desired 2D scanning trajectories. For fast scan trajectories up to 400 features per second of a 0.6 x 0.6 mm square, the RMS beam tracking error of the ILCs is reduced by a factor of 25.9 compared with a conventional feedback controllers, also significantly reducing the velocity variation. The printing results with the MSL setup also demonstrate that ILC can improve uniformity of line thickness as well as accuracy of the trajectory. (C) 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.