Optimal control applied to aircraft longitudinal axis for energy trajectory recovery.

The main study illustrated in this paper deals with the computation of commands which allow an aircraft to recover a nominal energy trajectory from a low/high energy state during the approach phase. Two study cases are taken into account in this paper. The first study case deals with the optimization of the slat/flap commands allowing to recover a nominal energy state during approach starting from a moderate low/high energy state. In this study case, it is supposed that the aircraft maintains a known vertical trajectory, simplified by a constant ground slope, while no engines and airbrakes are used. Two methods are tested : a) Hermite-Simpson, trapezoidal collocation methods, b) Sequential numerical integration method. The second study case deals with the augmentation of the optimization parameter vector by adding the vertical path in addition to the slat/flap commands. In this study case, the engines and airbrakes are supposed to be not used. These different methods are tested and simulation results are given for comparison, with different initial velocities permitting to change the initial energy state. Simulation results also show the benefit that brings a vertical trajectory modification to add or remove additional energy