Towards Feedforward Robot Control: Nonlinear Feedforward Control of Open-Loop Delta 3D Printer using Filtered B-Splines.
Software Compensation of Undesirable Racking Motion of H-frame 3D Printers using Filtered B-Splines
The H-frame (also known as H-Bot) architecture is a simple and elegant two-axis parallel positioning system used to construct the XY stage of 3D printers. It holds potential for high speed and high dynamic performance due to the use of frame-mounted motors that reduce the moving mass of the printer However, the H-frame’s dynamic accuracy is limited during high-acceleration and high-speed motion due to racking – i.e., parasitic torsional motions of the printer’s gantry due to a force couple.
In this work, I introduce a feedforward software compensation algorithm, based on the filtered B-splines (FBS) method, that rectifies errors due to racking. Experiments on an H-frame 3D printer demonstrate a 43% improvement in the shape accuracy of a printed part using the proposed algorithm compared to the standard FBS approach without racking compensation. The proposed racking compensation algorithm can be used in-conjunction with mechanical solutions, or as a stand-alone solution, to improve the performance of H-frame architectures.