Robust Autoland Design by Multi-Model ℋ∞ Synthesis with a Focus on the Flare Phase

Abstract

Recent advances in the resolution of multi-model and multi-objective control problems via non-smooth optimization are exploited to provide a novel methodology in the challenging context of autoland design. Based on the structured H ∞ control framework, this paper focuses on the demanding flare phase under strong wind conditions and parametric uncertainties. More precisely, the objective is to control the vertical speed of the aircraft before touchdown while minimizing the impact of windshear, ground effects, and airspeed variations. The latter is indeed no longer controlled accurately during flare and strongly affected by wind. In addition, parametric uncertainties are to be considered when designing the control laws. To this purpose, extending previous results published by the authors in a conference paper, a specific multi-model strategy taking into account variations of mass and center-of-gravity location is considered. The methodology is illustrated on a realistic aircraft benchmark proposed by the authors, which is fully described in this paper and freely available from the SMAC (Systems Modeling Analysis & Control) toolbox website (http://w3.onera.fr/smac).