Transition controllability research on tri-tilt rotor unmanned aerial vehicle in wind tunnel free flight tests

A small-scaled tri-tilt rotor unmanned aerial vehicle (TTR UAV) is tested to simulate transition process with 3-degree-of-freedom in wind tunnel. The moment acting on vehicle is an uncertain function of current tilting angle, rotor speeds and incoming flow velocity, which is trimmed and controlled by combination of aero surfaces, differential tilting angles and differential rotor speeds. In wind tunnel experiment, tilting angles are instructed by a ramp signal in transition process. The closed-loop controlled dynamic characteristics are studied, and the validity of control allocation and feedback control laws are verified. Furthermore, the controllability in case of failure by locking on control mean of three is also studied.