Research On Path Planning Technology Of Plant Protection UAV In Hilly Area Under Wind Environment

Because the farmland in mountainous and hilly areas fluctuates greatly,it was not suitable for large-scale ground spraying equipment for plant protection.Because of the advantages of high efficiency,no seedling pressing and convenient operation,plant protection UAV operations in hilly areas had been widely used.However,there were some problems in plant protection UAV,such as insufficient load capacity and short endurance.Therefore,it was necessary to carry out the study of energy-saving path planning.In order to improve safety and reduce energy consumption,an optimization method of path planning for plant protection UAV was proposed in this study.The main contents of this study were as follows.(1)Firstly,this study introduced the composition and basic flight principles of plant protection UAV.Then,the rigid control model of the electric six-rotor plant protection UAV was established,and the motion equation of the UAV in the ground coordinate system was solved.At last,the attitude control and position control methods of the plant protection unmanned aerial vehicle were studied.(2)By introducing the constraints of terrain,wind field and UAV maneuverability,the mathematical model of path planning in mountainous and hilly areas was established.The planning space was described by free space and barrier space.The wind field disturbance model could be divided into average wind,wind shear,turbulence and gust,etc.In this study,the airspeed vector was obtained according to the velocity vector triangle.Parameters such as maximum range,the maximum flight time,the minimum turning radius,the maximum climbing angle,the minimum step length and UAV fuselage size were used to constrain the fuselage.According to the mathematical model of path planning,the trajectory cost function was established,and the planned path was evaluated through evaluation index.(3)This study compared modeling methods such as geometric map,topological map,grid map and octree map,and selected the grid method to establish a three-dimensional spatial model of mountain areas.The basic principles and processes of ant colony algorithm and A*algorithm were studied.A*algorithm was optimized in the search direction and constraint,and the search efficiency after optimization is improved by 34.6%.Compare the two curves of Bezier and B-spline,select B-spline curve for path smoothing.(4)MATLAB software was used to design simulation experiment,and different path planning algorithms were compared.Compared with the ant colony algorithm,the planning time of the proposed algorithm was shortened by 6.4 times,and the number of planning path was reduced by 24.2%.Simulation experiments were carried out in fixed and variable wind fields respectively,comparing the classic A*algorithm and researching and proposing the optimized algorithm for track length,flight time and flight energy consumption.The test results showed that the highest saving rates of the optimization algorithm were 27.6%,26.2%and 33.1%,respectively.Finally,B spline curve smoothing algorithm was used to plan the path.The test results showed that the algorithm could effectively plan a safe and reliable three-dimensional trajectory in shorter distance and time.It provided an effective path planning method for plant protection UAV in mountainous and hilly areas.