Research On Autonomous Flight Control System Of Multi-Rotor UAV Based On Backstepping

Since micro multi-rotor UAV possesses many advantages, such as simple mechanical structure, high maneuverability, capability of vertical take-off and landing (VTOL), and effective protection against personal casualty, it has wide applications in meteorological reconnaissance, aerial photography, disaster rescue, intelligent transportation, precision farming and so on. In this paper, we studied the whole scheme design of UAV and its dynamic model, and the design of autonomous flight control system, in order to design a micro multi-rotor UAV for meteorological reconnaissance.Firstly, according to the specific design requirements of a micro multi-rotor UAV for meteorological reconnaissance, the whole design schemes of its airframe, embedded system and flight control system are determined. Here, the airframe design is analyzed from the points of airframe size, load capacity, cruising capacity and maintainability. And the embedded system design is mainly focused on hardware selection and workflow design of software system. As for the flight control system, the implement schemes of many flight modes and the control loop division of autonomous flight control system are realized.Then, the mathematical model for micro quad-rotor UAV is established, and its control system is designed. The nonlinear dynamic model of quad-rotor UAV is built based on flight theory and spatial rigid motion equation, combined with specific object of UAV. And the design of autonomous flight control system is divided into four control loops, to control position along X-direction, position along Y-direction, altitude and yaw angle respectively. Besides, according to the nonlinear property of system and the control requirement of system robustness, controllers based on Backstepping and Mode Reference Sliding Mode Control (MRSMC) are designed.Finally, to testify the properties of control system, outdoor flight experiments are performed on the controller we designed. The experimental results demonstrate that, the designed controller has good control performance and is capable to accomplish outdoor autonomous flight. This fulfills the basic demand of UAV for meteorological reconnaissance, and also proves the validity of our designs for both airframe and control system.