LFT Generation by Flatness Approach, for Mu-Analysis of HIRMplus Fighter Aircraft
Résumé
an LFT model representing the longitudinal dynamic of the gap between the open loop nominal HIRM+ model and the perturbed model on a trajectory is given. Five of the most relevant uncertainties on the pitch axis are considered. This model describes the gap along a trajectory passing through flight condition FC1, with an angle of attack equal to 6°. The proposed approach is based on a simplified longitudinal model used to determine a nominal trajectory and corresponding input. The specific outputs are angle of attack and pitch angle. These outputs allow a parametrisation of state-space trajectory. First the LFT generation by flatness approach is described. Then an LFT model of the open loop HIRM+ model for the above flight condition is given. Thereafter an LFT model of the closed loop HIRM+RIDE is proposed to allow the identification of worst case stability margin.