Tracking Control for a Non-Minimum Phase Autonomous Helicopter

This paper develops a general control algorithm for precision output tracking of nonlin-ear non-minimum phase dynamics of an autonomous three degree-of-freedom unmanned helicopter. Previous approaches in flight control literature have shown approximate track-ing by neglecting the coupling between the forces and moments generated by the control effectors. However, it is shown that this coupling is significant in the model under study and cannot be neglected. In this paper the coupling is retained and natural time-scale de-composition of the vehicle model is employed for accomplishing asymptotic tracking. The design procedure determines the desired internal state trajectory and the control scheme to stabilize the helicopter in hover. Stability is analyzed using Lyapunov methods and results show that the approach is able to accomplish perfect tracking while stabilizing the closed-loop system and keeping all closed-loop signals bounded. Nomenclature f,g,h sufficiently smooth vector fields s intermediate variables of the system u control input vector of the syste