Aircraft Loss-Of-Control Recovery Using Optimal High Order Sliding Mode Control with Discontinuous High Order Observers

Abstract

The complexity of modern commercial, military aircraft and space vehicle requires an advanced level of automation that would prevent ight vehicles from losing controllability due to failure, or maneuverability near critical points, and also assist pilots during the recovering process following Loss Of Control (LOC). LOC has been among the most predominant causes of aircraft accidents over the past decade. Few research reports directly address the connection of LOC with in ight bifurcation phenomenon. In this paper we are concerned mainly with bifurcation points of the equilibrium equations, ordinarily associated with stall, spin, falling leaf and others aircraft upset scenarios. Such bifurcation points are not usually associated to a particular failure of components but once the vehicle manoeuvre near those irregular points, it loses its ability to regulate in ight keys outputs due to the occurrence of structurally unstable zero or sliding dynamics. Throughout this analysis, an investigation of the bifurcation point is carried out and a recovery strategy is designed using Dynamic Extension and High Order Sliding Mode Control techniques. In the design process, emphasis is on the design of discontinuous high order sliding mode observers because they play a viable role in an environment where switching is important. The Generic Transport Model (GTM) model is used for illustration of the recovery process.