Complete Coverage Path Planning For UAVs In Mountainous Areas

With the progress of agricultural modernization in Guizhou,agricultural UAVs are becoming an important tool for the development of modern mountainous characteristic and efficient agriculture in Guizhou.This makes the coverage path planning problem of agricultural UAVs become an inevitable research hotspot.In the process of path planning of agricultural UAVs,the whole operation areas should be covered completely,spray evenly,without overlapping or missing,and the optimal flight path and the shortest flight time should be considered.At present,most of the research on coverage path planning still focuses on obtaining the shortest path at the expense of coverage,and few constraints are considered in combination with reality,and the time complexity of the algorithm is a little high.Therefore,in this paper,different operation areas are studied.According to the different types of areas,different coverage path planning methods are proposed for the operation environments without and with obstacles.At the same time,considering the execution of operations on large farmland,agricultural UAVs has a limited capacity of drugs and batteries loaded at one time,which makes it difficult to complete spraying operations in one flight,and it is necessary to return to the supply point for replenishment.This requires optimizing the flight path of agricultural drone spraying operations to minimize the operation time.This requires the flight path of agricultural UAV spraying operation to be optimized to make the operation in the shortest time.Around these problems,this paper conducts research in the following three aspects.（1）Aiming at operation areas without obstacles,a complete coverage path planning method is proposed.Firstly,by analyzing the number of turns,the length and time of operation path of UAVs along different spraying directions,the coverage mode commonly used in actual farmland is selected,and the coverage mode with the shortest operation path and the least number of turns is selected for operation.Secondly,the problem of redundant mulching is avoided by setting the appropriate spacing.Finally,simulation experiments are conducted for regular and irregular operation areas respectively,and the experiments show that the algorithm can cover different types of operation areas.（2）Aiming at the operation areas with obstacles,a complete coverage path planning method using grid partitions is proposed.Firstly,the clustering technology is used to decompose the work area into regular areas of different sizes according to the map information.Secondly,the regional connectivity graph is established to solve the optimal traversal order of the sub-areas.Thus,the constraint solving problem is transformed into the multi-objective traveling salesman problem.Thirdly,the shortest path between the current sub-areas and the next sub-areas is calculated using the A^*algorithm.Finally it is verified that this algorithm can meet the operational needs of agricultural UAVs through simulation experiments in this paper.（3）Aiming at the constraints of agricultural UAVs on electricity and drug dosage,a complete coverage path planning method is proposed,which are applied for the return of multiple UAVs.The traditional constraints of power and dosing is considered in this paper,the path planning under other constraints is also study,such as the location of the return of the spray operation should be close to the boundary of the supply point as far as possible.According to the above constraints,a nonlinear objective function with the shortest non planting operation time was established,and the constraint problem is transformed into the unconstrained problem using the penalty function in this paper.The SSA algorithm can be optimized each plant protection flight path.Finally the simulation experiments and comparative analysis are conducted in this paper.