Research On Fault-tolerant Strategy Of Quadrotor Unmanned Aerial Vehicle Based On Trajectory Planning

People are paying more attention to the autonomy and intelligence of unmanned aerial vehicle(UAV)in the context of an increasingly complicated flight environment and task.Trajectory planning technology is critical for ensuring the safe flight of quadrotor UAV and is also an important component of autonomous flight.Simultaneously,when the quadrotor UAV’s actuator fails,it is also crucial to formulate effective strategies to help the UAV continue to complete the flight.Based on the existing research results,this paper studies the trajectory planning method and fault-tolerant strategy based on trajectory planning in quadrotor UAV.Firstly,the trajectory planning framework of the quadrotor UAV was developed,which was carried out in two stages from path planning to trajectory planning.Establish mathematical models of task space and obstacles.Analyze the constraint conditions that the path planning needs to satisfy,and the cost evaluation function is determined.Using particle swarm optimization algorithm(PSO)as path planning algorithm,introduces the common improvement methods of PSO.And modify the path to further shorten the flight distance.The curve fitting method is used to smooth the path as the basis for subsequent research.Secondly,the trajectory planning method of quadrotor UAV is studied.Establish a complete dynamic model of quadrotor UAV.Combined with differential flatness theory,polynomial parameterized differential flatness output is used to express the trajectory of quadrotor UAV.Analyze UAV’s own state constraints,task constraints and obstacle constraints,give trajectory evaluation function,and transform trajectory planning into nonlinear programming(NLP)for solving.Nonlinear programming is used to calculate the trajectory polynomial parameters of the UAV.This trajectory does not specify auxiliary waypoints that must be passed.To improve the solving efficiency of nonlinear programming,two solving strategies and an initial calculation method are proposed.The simulation results show the effectiveness of the proposed method.Finally,the fault-tolerant strategy based on trajectory planning is designed for the quadrotor UAV’s actuator fault.Analyze the fault model and the influence on the quadrotor UAV.Different from the method of fault-tolerance through control,replanning the reference trajectory is used as a processing method.The fault-tolerance strategy is proposed to deal with the fault before and during flight respectively.The feasible trajectory method is designed,and the new trajectory conforming to the current motor speed is quickly calculated on the basis of the original trajectory.Simulation experiments are designed to prove the effectiveness of the designed strategy.