D-Optimal Simultaneous Multistep Excitations for Aircraft Parameter Estimation

In this study, a numerical procedure for designing an aircraft system-identification maneuver with simultaneous flight-control deflections is described. The elevator, aileron, and rudder multistep excitations that maximize the D-optimality criterion were found by a genetic algorithm. Like for any dynamic system, this input-design process would require determining optimal time-dependent functions resulting in infinite-dimensional optimization. To limit the search-space dimensions, the switching points of the inputs were selected on the basis of the discrete wavelet transform. In the investigation, the design was compared with the maneuvers that used harmonically related multisines and typical multistep inputs (3-2-1-1 on elevator, 1-2-1 on aileron, rudder doublet) for simultaneous flight-control deflections. The case of typical excitations applied one at a time was examined as well. Through simulations, it was found that the maneuvers with simultaneous flight-control deflections that were based on the D-optimality criterion or harmonically related multisine signals are better in terms of accuracy, aircraft response, and resulting G force than the designs based on the typical excitations.