针对无人机在三维复杂场景中实现长距离航迹规划时存在效率不高的问题，本文提出了一种基于局部软约束优化的实时无人机航迹规划方法。该方法可分成以下两个步骤：首先，在theta*算法的基础上加入安全距离约束，同时利用转弯代价改进启发函数来减少无人机转弯所带来的时间消耗，最终生成由少量关键点组成的初始路径；其次，采用局部优化策略对初始路径中存在安全隐患的片段进行软约束优化，并利用贝塞尔曲线的速度特性进行时间分配，确保航迹的连续、平滑和动态可行性以及提升无人机的飞行效率。实验结果表明，本文方法在保证无人机安全的同时具有更短的飞行距离和飞行时间以及更好的规划效率，并且在实际的四旋翼飞行中得到验证。

In order to improve the efficiency of the quadrotor long-distance trajectory planning in 3D complex scene, this paper proposes a real-time quadrotor trajectory planning method based on local soft-constrained optimization. The method can be divided into the following two steps: Firstly, the safety distance constraint is added to theta* algorithm, and the heuristic function is improved by using the turning cost to reduce the time consumption caused by quadrotor turning, and finally the initial path composed of a small number of key points is generated; Secondly, the local optimization strategy is used to optimize the segments with potential safety hazards in the initial path based on soft constraints, and the Hodograph property of Bézier curve are used for time allocation to ensure the continuity, smoothness and dynamic feasibility of the trajectory and improve the flight efficiency of quadrotor. Experimental results show that the proposed method has shorter flight distance and flight time and higher planning efficiency while ensuring the safety of quadrotor. This method can also be successfully applied to the actual quadrotor flight.