Robust control for nonlinear PVTOL aircraft with uncertain non-minimum phase dynamics

A robust control approach for a planar vertical/short takeoff and landing aircraft via linear matrix inequality method is presented. The aircraft is considered in the mode of hovering operation for motion in the vertical-lateral plane and presented by a six-order nonlinear dynamics which possesses uncertain non-minimum phase arisen from parasitic coupling effect between aircraft's lateral force and rolling moment. The aircraft dynamics is decomposed into a nominal linear parameter varying (LPV) system and a linear system with norm bounded uncertainty matrix multiplied by an uncertain parameter, which is the parasitic non-minimum phase coupling. The vertices of the nominal LPV system and the magnitude of the uncertain matrix are addressed by the approach of robust quadratic stabilization with an invariant ellipsoid interpretation for control magnitude constraint. The magnitude of control efforts, the maximum relative stability and the sustainable coupling uncertainty are the design parameters for this robust parameter varying takeoff and landing (PVTOL) aircraft control.