Modeling and Control of a Novel Over-actuated Tri-rotor UAV*

This paper presents a novel tilting tri-rotor unmanned aerial vehicle (UAV) based on the conventional tri-rotor configuration, with each rotor having two tilting degrees of freedom, which is an over-actuated system. Herein, the dynamic model of this novel UAV is developed, which has nine controllable variables. Owing to the nonlinear and coupled nature of the system, many conventional nonlinear control allocation algorithms are too computationally complex to be calculated online. Therefore, a new control allocation method is proposed by using a reversible mapping to transform the nonlinear control allocation problem to the corresponding linear control allocation problem. The feedback linearization method is used to implement the entire control architecture using the new control allocation algorithm. Furthermore, a nonlinear disturbance observer (NDOB) is used to combat the low robustness of the feedback linearization controller. Finally, several simulation experiments are conducted to validate the proposed method. The simulations reveal that the fuselage can successfully track different spatial trajectories with different attitudes, which corroborates the high maneuverability of the fuselage over the conventional quadrotor.