Eigenmode Distortion: A New Perspective on Motion Cueing Fidelity in Flight Simulation

Eigenmode distortion is a novel quantitative methodology developed to objectively evaluate motion cueing fidelity in flight simulation. It relies on an explicit coupling of linearized vehicle and Motion Cueing Algorithm dynamics. Modal analysis subsequently performed on this coupled system reveals the degree of distortion imposed by the Motion Cueing Algorithm on to the dynamics of the simulated vehicle. Eigenmode distortion thereby provides unprecedented insight into the combined dynamics of the two systems along modal coordinates. Compared with existing methods for motion cueing fidelity assessment, the eigenmode distortion method enables a systematic analysis of the coupled vehicle and Motion Cueing Algorithm dynamics. This is mainly because it does not consider the Motion Cueing Algorithm in isolation and does not inherently rely on assumptions regarding the excitation of the simulated vehicle dynamics. This paper outlines the theoretical foundation of the eigenmode distortion method and includes a case study on helicopter longitudinal dynamics and a sensitivity analysis to demonstrate its utility. The results presented in this paper shown that the eigenmode distortion method can reveal interactions between the Motion Cueing Algorithm and the vehicle dynamics that are currently not captured by other established methods, such as the Sinacori–Schroeder criteria and the Objective Motion Cueing Test.