Abstract
In this paper, we offer a new design method for the flight control of a nonlinear non-minimum phase VTOL aircraft. The non-minimum phase property is caused by the small coupling between rolling moments and lateral acceleration, and a few researchers have derived control laws by neglecting the coupling. We show that the true model can be transformed equivalently into a model with zero coupling by changing the plant output from the center of mass to the Huygens center of oscillation. Then, we design a controller by applying a linear high gain approximation of backstepping to the model where we call this method briefly as two-step linearization. Computer simulation shows that the control law robustly stabilizes the true model with good tracking for both small and large couplings. Experiments for a twin rotor helicopter model also show such a good performance.
