Bearing-only target localization is a fundamental problem in optical measurement and finds extensive applications in unmanned aerial vehicle (UAV) technology. Effective trajectory planning establishes favorable observation geometries, thereby enhancing the target localization accuracy of bearing-only UAV systems. This paper proposes an trajectory optimization method for unmanned aerial vehicles (UAVs) in bearing-only target localization scenarios. By leveraging the Fisher Information Matrix (FIM), the proposed approach dynamically integrates the geometric configuration and vehicle maneuverability into the optimization framework. Specifically, we introduce a spectrally-weighted FIM objective function that provides better gradient dynamics near degenerate configurations, enabling the planner to rapidly escape from poor observation conditions. For dual-UAV scenarios, an intersection angle sine term is introduced to optimize triangulation geometry by improving the sight-line intersection angle, thereby preventing trajectory aggregation. Furthermore, we propose an improved Particle Swarm Optimization (PSO) algorithm with motion model constraints and particle normalization to ensure the physical feasibility of the trajectory and enhance the compatibility with the objective functions. Simulation results demonstrate that the proposed method reduces the median localization error by 99.21% compared to conventional FIM-based approaches in single-UAV scenarios, and achieves a 69.70% improvement for dual-UAV configurations, exhibits superior performance in long-duration bearing-only target localization of maneuverability targets at extended ranges.

翻译：纯方位目标定位是光学测量中的基础问题，在无人机技术中具有广泛应用。有效的轨迹规划可建立有利的观测几何构型，从而提升纯方位无人机系统的目标定位精度。本文提出了一种适用于纯方位目标定位场景的无人机轨迹优化方法。通过利用Fisher信息矩阵，所提方法将几何构型与飞行器机动能力动态整合至优化框架中。具体而言，我们引入一种谱加权FIM目标函数，该函数在退化构型附近具有更优的梯度动态特性，使规划器能够迅速摆脱不良观测条件。针对双无人机场景，引入交角正弦项以优化三角测量几何构型，通过改善视线交会角防止轨迹聚合。此外，我们提出一种改进的粒子群优化算法，通过引入运动模型约束与粒子归一化机制，确保轨迹的物理可行性并增强与目标函数的兼容性。仿真结果表明，在单无人机场景中，所提方法相较于传统基于FIM的方法可将中位定位误差降低99.21%；在双无人机构型中可实现69.70%的定位精度提升，在远距离机动目标的长时间纯方位目标定位任务中展现出优越性能。