Multivariate Simplex Spline Based Nonlinear Dynamic Inversion Control of High Performance Aircraft

Abstract

High performance flight control systems based on the nonlinear dynamic inversion (NDI) principle require highly accurate models of aircraft aerodynamics. In general, the accuracy of the internal model determines to what degree the system nonlinearities can be cancelled; the more accurate the model, the better the cancellation, and with that, the higher the performance of the controller. In this paper, a multivariate simplex spline based NDI control system is presented which is applied to control a high performance aircraft (F-16) with a large flight envelope. Simplex splines have a much higher approximation power than ordinary polynomial models, and are capable of accurately modelling nonlinear aerodynamics over the entire flight envelope of an aircraft. The new control approach is applied to a high-fidelity F-16 simulation model. The simulation results indicate that the simplex spline based NDI controller can achieve perfect feedback linearization through the entire flight envelope, and as a result provide accurate global tracking performance.