Large Angle Washout Algorithms for Flight Simulators

Abstract

This thesis presents modifications to classical washout algorithms to allow for large angular motion. This allows flight simulators with large angular motion envelopes to more effectively produce the motion cues for edge-of-envelope aircraft manoeuvres for pilot training. Classical washout is commonly used for flight simulation motion cues, but was originally designed for small simulator angular motion. With the development of the Atlas motion base allowing unbounded rotation about any axis, there is a need for washout algorithms which can exploit this extended angular motion envelope. Classical washout is implemented and the implementation is validated using numeric metrics, normalized Pearson correlation, integral of the error, and maximum error; and plots of the modelled vestibular response for the aircraft simulator pilot compared to previous reported results. This implementation is then used as a performance baseline for two proposed modifications to extend washout to larger angular motion envelopes. Large-angle washout uses quaternions and eliminates the small-angle approximations present in classical washout but continues to use highpass filters to impose restrictions on the simulator's angular motion during sustained angular velocity cues. Unrestricted angular washout removes the high-pass filters and allows for unbounded rotation about all axes. Using the numerical metrics and vestibular responses to assess the performance of the algorithms, for manoeuvres with small angular motion cues, the original classical washout algorithm designed for small angles performs best, and unrestricted angular washout has comparable performance. For manoeuvres with large angular motion cues, unbounded angular velocity washout performs best. Large-angle washout outperforms the small-angle washout for some large angular motion cues, but is outperformed by unrestricted angular washout, and performs badly for manoeuvres with small angular motion.