Non-minimum phase output reference trajectory tracking for a PVTOL aircraft

An approximate solution to the general reference trajectory tracking problem, specified in terms of a desired behavior for the non-minimum phase aircraft center of mass position coordinates, is proposed by indirectly defining a suitable trajectory tracking task for the (minimum phase) flat outputs of the system represented by the equivalent to the Huygen's center of oscillation of the aircraft. The approach uses an approximating sequence which appears to be related to an infinite order differential flatness of the system with respect to the non-minimum phase output variables.