Dynamic Reconfiguration Motion Analysis and Attitude Control of H-shaped Transformable Rotorcraft

Current tandem-type transformable rotorcrafts can realize the motion in a limited space, but some problems still exist in the stable flight control in the high-passability configuration, and also in the smooth control during the transforming process, caused by the time-varying center-of-gravity. To solve these problems, an H-shaped transformable tilt-rotor aircraft is proposed. The aircraft body is a segmented rotational structure, with both sides of arms spinning around the body. In this way, not only the tandem-type high-passability configuration is achieved, but also the adverse situation is avoided that the center-of-gravity locates outside the body. After the analyses on the aircraft flight control methods and the construction of motion models, a dynamic PID (proportional-integral-differential) control method and the corresponding allocation strategy are proposed based on motion characteristic values. The experimental verification is conducted on the motion attitude control response ability in the high-passability configuration, and the control stability during reconfiguration. Results of actual flight experiments show that, with the high-passability configuration, the maximum tracking error of the attitude angle in each axis is less than 4°, the tracking response time is less than 0.15 s, and the maximum passing-through size can be reduced to 44.2% compared to that of the normal flight configuration; in the reconfiguration process, attitude angle errors in each axis can be controlled within ±2.3°. The mentioned flight in high-passability configuration reflects a good motion response characteristics, while the control response is generally smooth in the transition configuration. Overall, the aircraft has a good ability of the continuous traversal flight.