Flight control design for a nonlinear non-minimum phase VTOL aircraft via two-step linearization

• Published in: Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228) Vol. 1; pp. 217 - 222 vol.1
• Main Authors: Saeki, M., Sakaue, Y.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2001
• Subjects: Acceleration; Aerospace control; Aircraft; Backstepping; Computer simulation; Design methodology; Gain; Helicopters; Linear approximation; Robust control
• ISBN: 9780780370616; 0780370619
• DOI: 10.1109/CDC.2001.980101

In this paper, we offer a new design method for the flight control of a nonlinear nonminimum phase VTOL aircraft. The nonminimum 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; we call this method a 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 using a twin rotor helicopter model also show equally good performance.