Design of estimator-based nonlinear dynamic inversion controller and nonlinear regulator for robust trajectory tracking with aerial vehicles

For the purpose of trajectory tracking with aerial vehicles, a hybrid extended Kalman filter and a nonlinear regulator are designed to increase the robustness of the nonlinear dynamic inversion controller against modellisng uncertainties and atmospheric disturbances. The goal of hybrid extended Kalman filter is the online estimation of aerodynamic forces and moments acting on the vehicle using discrete measurements of the noisy sensors. Moreover, hybrid extended Kalman filter considers any uncertainties or un-modeled dynamics as additional external forces and moments. This specification of hybrid extended Kalman filter helps the nonlinear dynamic inversion controller to successfully cancel the nonlinearities between the inputs and outputs in presence of uncertainties. To improve the robustness of the aerial vehicle against atmospheric disturbances, a nonlinear regulator is also designed to regulate the aircraft angular rate perturbations and assist the nonlinear dynamic inversion controller to maintain the desired attitude. The simulation results illustrate the effectiveness of the proposed estimator-based controllers in guiding the NASA HL-20 reentry vehicle to a desired challenging trajectory in the presence of atmospheric disturbances and vehicle parametric uncertainties.