复杂低空物流无人机路径规划

针对复杂低空物流无人机路径规划问题，考虑空域环境、运输任务等内外限制，以飞行时间、能耗及危险度最小为目标函数，建立多限制条件物流无人机路径规划模型，设计启发算法以快速解算路径。采用栅格法对规划环境表征，引入物流无人机性能约束确保路径可飞。针对A*算法存在的问题及物流无人机航空运输特色，引入栅格危险度因子、货物质量惩罚系数，增加飞行时间、能耗等代价以提升避障能力、降低成本。为匹配所提启发算法解算效率与精度，采用动态加权法对函数赋权。为筛除冗余路径点及保证平稳飞行，采用双向交叉判断法等对原路径优化平滑。为验证所提路径规划模型及启发算法的有效性，对比4种算法规划结果，分析栅格粒度大小与代价权重值对结果的影响。在既定的运输环境及物流无人机性能约束下，研究结果表明:所提算法与A*算法相比，保证了物流无人机飞行安全、能耗少，将飞行时间由406 s降至386 s，降低了5%；飞行路径点数为129个、栅格危险度因子为11.69，降低了姿态改变次数，保证了运输安全；当栅格粒度大小为5 m，代价权重值为0.4、0.1、0.5时，采用所提算法规划的路径最佳。 

Path planning for logistics UAV in complex low-altitude airspace

To solve the problem of path planning for logistics UAV in the complex low-altitude airspace, internal and external restrictions such as airspace environment and transportation tasks were considered. Taking minimize flight time, energy consumption and path risk as the objective function, the multi-restricted transportation path planning model of logistics UAV was established. To plan the path quickly, an improved heuristic algorithm was designed. The grid method was used to model the environment. The performance constraints of UAV were introduced to ensure that UAV can follow the path. To solve the existing problems of the original algorithm and indicate the characteristics of logistics UAV air transportation, the concepts of grid risk and cargo weight penalty coefficient were introduced, and flight time and energy consumption were calculated to improve the obstacle avoidance ability and reduce the cost. The dynamic weighting method was used to assign the weight of the function to match the efficiency and accuracy of the algorithm. In order to delete redundant path points and ensure smooth flight, bidirectional cross judgment method was used to optimize and smooth the original path. In order to verify the effectiveness of the model and the algorithm, the results of four algorithms were compared. Meanwhile, the influence of grid length and cost weight on planning results was analyzed. With the constraints of the assumed environment and UAV performance, the study results indicate that, compared with the original algorithm, the proposed algorithm ensures the flight safety of logistics UAV with less energy consumption, and reduces the flight time from 406 s to 386 s, which is reduced by 5%. The number of flight path points is 129 and the grid risk is 11.69, which reduces the number of attitude changes and ensures the safety of transportation. When the grid length is 5 m and the cost weight is 0.4, 0.1 and 0.5, the path planned by the proposed algorithm is optimal.