Control System Design Of Quad Tilt-wing UAV In VTOL Mode

Combining the advantages of rotor wing UAVs and fixed wing UAVs, the Quad Tilt-wing unmanned aerial vehicle (QTW-UAV) could achieve the tasks as vertically taking-off and landing, fixed point hovering and high-speed cruise flight. The flight mode of QTW-UAV can be divided as vertical taking-off and landing mode, transition flight mode and fixed wing flight mode. The emergence of QTW-UAV fills the gaps of flight speed envelope between rotor wing aircraft and fixed wing aircraft. Therefore, it can complete the tasks that can not be solely achieved by rotor wing UAVs or fixed wing UAVs and play an important role in both civilian and military areas. This paper using a QTW-UAV as research object establishes a QTW UAV experimental platform for outdoor flight and also designs its control algorithm when it is in VTOL mode.At first, according to the QTW-UAV’s mechanical, control and flight mission’s requirements, this paper designs a reliable body structure, and selects desired versions of components including micro controllers, actuators and sensors. At the end of this part, the QTW-UAV experimental platform is established.Secondly, based on the analysis of mechanics and dynamics of the designed QTW-UAV, QTW-UAV’s three dynamic equations are established, Based on the linearization of VTOL mode, the controllers have been designed. The designed controllers use different control algorithms including PID algorithm, linear quadratic optimal control algorithm and Sliding mode control algorithm. In order to achieve real-time control, a hierarchical control method is proposed. The three-tier controllers contain attitude controller, velocity controller and position controller. To the control of pitch and roll, a controller using LQ optimal control algorithm is designed. To control the speed in horizontal direction, a controller using sliding-mode algorithm is proposed. This controller has strong robustness and anti-interference to the system’s uncertain factors.Finally, the designed controllers are verified in the simulation environment, and some of them are tested in the QTW-UAV experimental platform. Experimental results show that the established QTW-UAV experimental platform and the designed controllers have good performance.