Research On Trajectory Planning Algorithm Of Plant Protection UAV In Hilly And Mountainous Environmen

With the continuous improvement of the mechanization level of agriculture in our country.Using UAVs for plant protection operations in hilly and mountainous areas is an effective means to improve operational efficiency,but there are problems such as remote control delay and line-of-sight error,which lead to deviated flight paths and missed spraying and re-spraying,affecting the efficiency effect of plant protection operations.Therefore,it is necessary to carry out the research of plant protection UAV trajectory planning algorithm in hilly and mountainous environment.This paper combines the actual operational needs of plant protection UAVs in hilly and mountainous environments,and proposes a method to divide the entire trajectory into full-coverage trajectory and non-operational trajectory and optimize the trajectory separately for problems such as small plots of land and long distances between the operational area and the starting point.Firstly,the flight principle and basic composition of plant protection UAVs are analyzed to get the constraints of plant protection UAVs themselves in the trajectory planning.The existing spatial model is studied,and the3 D reconstruction method is combined with the 3D reconstruction method to derive a 3D reconstruction method that can be used in hilly and mountainous areas,and it is converted into a planning spatial model available to the algorithm.Then,the effect evaluation indexes of full-coverage operation planning are analyzed,and it is clear that the trajectory length,coverage rate and repetition rate are important inspection indexes in full-coverage operation.The basic parameters in UAV trajectory planning are determined by analyzing the self constraints,operational constraints and environmental constraints of the plant protection UAV according to the plant protection UAV operation requirements.The differences between reciprocating and internal spiral were analyzed and compared.Using the planned trajectory coordinates of the UAV in a two-dimensional environment,the final trajectory length and power consumption of the UAV in three-dimensional terrain were calculated,and it was found through comparative experiments that the UAV could reduce the total trajectory length and energy consumption when trajectory planning was carried out in a three-dimensional environment along the contour.Secondly,the advantages and disadvantages of A~* and ant colony algorithms are analyzed and compared,and the ant colony algorithm is improved by dynamically adjusting the search range,improving the heuristic function,performing uneven pheromone allocation,and introducing elite ant colony update strategy in combination with the constraints of plant protection UAVs in non-operational environments.For the obstacles encountered during the flight,an expanded column is used instead to derive the minimum obstacle bypassing trajectory and bypassing direction.Using two elevation maps,comparison experiments are conducted.In the first map,the improved algorithm in this paper reduces the path length by 13.46 % and 18.34 % compared with the A~* algorithm and the ant colony algorithm,and reduces the energy consumption by 12.18 % and 28.80 %.In the second map,the improved algorithm in this paper reduces 4.88 % and 7.79 % in path length and 12.79 % and 18.86 %in energy consumption compared with the A~* and ACO algorithms.In the map with obstacles,the improved A~* algorithm plans the trajectory to bypass the cylindrical obstacles,which verifies the reliability of the obstacle bypassing algorithm.Finally,field aerial photography is conducted to reconstruct the hilly mountainous terrain to simulate and verify the full-coverage planning algorithm and the non-operational trajectory planning algorithm,and the actual performance of the algorithm is verified by building an unmanned aircraft platform and importing the algorithm-generated trajectory points into the unmanned aircraft.The results show that the algorithms in this paper can meet the requirements of plant protection UAV trajectory planning in hilly and mountainous environment.