Research On Mission Flight Path Planning And Optimization Method For Fixed-wing UAV

Flight path planning plays a very important role in the mission flight of unmanned aerial vehicle(UAV), which affects if the flight mission of UAV can be successfully completed or not. The present method being adopted, which is designed by manual, has the disadvantages of time-consuming, no reusability and low accuracy. With the increase of the complexity of the flight mission, it can not meet the needs of the mission planning. Aiming at overcoming the shortcomings of the current path planning method in the project, the paper designs the automatic path planning methods under different mission scenarios. On the basis of the generated initial flight path, the optimization method of the local flight trajectory of the climbing process is studied.For the above purposes, the main research work and contributions of this paper are summarized as follows:Firstly, according to the correlative characteristic parameters of UAV and analysis of the measured datum, atmospheric model, aerodynamic model, engine thrust and fuel consumption models and UAV flight envelope are analyzed and modeled. Then, according to the force conditions and six-degree-of-freedom dynamic model, the kinematics characteristics of the UAV are analyzed in detail.Next, the corresponding path planning method is proposed for the two kinds of task scenarios. According to the mission requirements and motion performance of UAV, the flight maneuver library is established. Then in view of the UAV's obstacles constraints and waypoints constraints under low altitude flight condition, the paper designs the shortest path generation method based on genetic algorithm and Dubins curve. And the tangent method is used for obstacle avoidance. In view of the airspace boundary constraints and the flight mission constraints under high altitude flight condition, the rules for the call of flight maneuver library based on transition point are designed. Then the method of track tree dynamic search is used to find the global optimization of the tracks. The simulation results show that the planned paths can greatly improve the efficiency of the path planning and reduce the cost of flight path.Finally, in order to improve the maneuvering performance and the ability to complete tasks of the UAV, the local optimization of the climbing trajectory is further carried out. Based on the analysis of the characteristics of the UAV and the climbing process, the optimization model of the UAV's climbing trajectory is established. And by comparing the results of several commonly used trajectory optimization algorithms, this paper shows the advantages of the Gauss pseudospectral method. In the next, the cascade optimization method combined with genetic algorithm and sequence quadratic programming method is used to solve the discrete NLP problem. Finally, the fuel consumption and time optimization results of the climbing trajectory are simulated and verified. The results show that the optimized trajectory can effectively reduce the fuel consumption or time of the climb process, which is of great significance to improve the task performance of the UAV.