Performance of Recent Large-angle Extensions to Classical Simulator Washout Algorithms

Abstract

Washout algorithms are typically used in flight simulator motion control software to give the pilots flying the simulator the impression that they are experiencing an unlimited range of motion when the Gough-Stewart hexapod providing the motion cues has a comparably very small motion envelope. Since hexapods have generally been adopted by the motion simulator industry and the washout algorithms developed in the 1970s have performed extremely well at giving pilots a very high fidelity training experience despite the very small angular workspace of the motion platforms, research in the area generally came to a halt in the 1980s. We have succeeded in development of the Atlas motion platform which possesses an unbounded orientation workspace that is singularity free, hence we have the need to revisit washout algorithm development to take advantage of the unlimited orientation workspace. In this paper, after a brief review of existing approaches, we outline the development of our unlimited angular washout. Several benchmark cases are presented for two aircraft having very different flight characteristics: a Cessna 172 and a Columbia 400. Additionally, a quantitative comparison of small, large, and unlimited angular washout algorithm performance is reported.