Augmenting flight simulator motion response to turbulence

Abstract

When flight simulator motion systems are tuned for acceptable response to pilot control inputs, it is found that their response to turbulence may be unduly attenuated. The motion augmentation technique described in this paper allows the designer to increase the simulator's motion response to turbulence without otherwise altering its flight characteristics. The method employs a second set of flight equations excited only by the turbulence signals. The output from these equations is added to that from the primary simulation flight equations before being fed to the motion system. A sample case is developed showing its successful application to the heave channel of the University of Toronto Institute for Aerospace Studies Flight Research Simulator.cKO a 2 *(*) Nomenclature : heave (or z-axis) acceleration of the aircraft cockpit expressed as an F B component = simulator-fixed body axis frame = specific force at aircraft cockpit expressed in F B components = longitudinal turbulence correlation = specific force at simulator cockpit expressed in F s components = acceleration due to gravity expressed in Fj components = lateral turbulence correlation = A: + k + k • • wavenumber expressed in cycles per meter: [Ari k 2 k,] T • -the Fourier transform of n(x) • three independent Gaussian white noise sources:[n\ n 2 n 3 ] T • • the autocorrelation function for x(t) at time delay r • • V/f + rl + r\ • spatial separation between two points in F/: = spatial coordinates in F/ = vertical displacement of simulator in Fj = Kronecker delta = modulating variable = turbulence intensity = turbulence spectrum function [3x3 matrix with elements $//(£)] xx(^) = power spectral density of x(t) $ xy (o)) = cross-power spectral density between x(t) and y(t) co = frequency (rad/s)