Research On The Control Methods Of Dual-tilt-rotor Unmanned Aerial Vehicle

With the development of technology and the reduction of costs,miniaturized unmanned aerial vehicles(UAVs)are gradually serving more and more industries.UAV technology will play a huge role in the process of Industry 4.0,and the increasingly complex working environment and task requirements pose new challenges to the shape,structure,and motion performance of UAV.As a new rotor UAV,the dual-tilt-rotor UAV can control the flight attitude by changing the speed and tilt angle of the two rotors.It not only has the ability of vertical take-off and landing of the rotor UAV,but also has the advantages of small size,flexible steering,and high flight efficiency compared with the multi-rotor UAV.In addition,as a nonlinear and strongly coupled multiple-input and multiple-output system,the dual-tilt-rotor UAV is very sensitive to external disturbances,so it is of great theoretical significance to study its reliable control system.This paper takes the dual-tilt-rotor UAV as the research object,and mainly completes the following tasks:Firstly,the flight motion mechanism is determined by analyzing the structural characteristics of the dualtilt-rotor UAV,and the coordinate transformation relationship is established to describe the position and attitude of the UAV.On this basis,the dynamics expression of the dual-tilt-rotor UAV is established according to the Newton-Euler equations.According to the motion mechanism,the control system structure of the dualtilt-rotor UAV is designed and the PID control method is used to verify the effectiveness of the model and the feasibility of the control system.Then,in order to improve the disturbance rejection performance of the dual-tilt-rotor UAV,a nonsingular fast terminal sliding mode controller with double power reaching law is designed to track the attitude of the UAV.The double power reaching law ensure that the system states can converge to the sliding mode surface quickly in the global scope,while the non-singular fast terminal sliding mode control can make the system states converge to the equilibrium point from the sliding mode surface in finite time.The non-singular fast terminal sliding mode control is compared with the traditional sliding mode control and PID control.The simulation results show that the non-singular fast terminal sliding mode control has good robustness when the model has parameter uncertainties.In addition,the non-singular fast terminal sliding mode control exhibits higher tracking accuracy under the same external disturbance.Finally,the software and hardware systems of the dual-tilt-rotor UAV are built.The hardware part includes the structure design of the UAV,the module selection,and the construction of the test UAV.The software part is implemented based on Free RTOS,including task logic design,control signal reading,sensor data reading and processing,attitude calculation,and control algorithm implementation,etc.The simulation results show that the Mahony algorithm is better than the general complementary filtering algorithm in attitude calculation.Then,the attitude tracking experiment and the flight experiment are carried out on the test UAV,and the effectiveness of the proposed control strategy is verified.