针对空间非合作目标近程交会自主无源仅测角相对导航系统状态不可观测的问题,提出基于相机偏心安装"杆臂效应"提供状态可观测性的仅测角相对导航算法.首先建立了相机偏置情况下的视线测量模型,然后提出了一种"类线性"变换的方法对系统进行可观测性分析,获得了使状态可观测的相机偏置条件,最后以建立的基于无迹卡尔曼滤波的仅测角相对导航算法和典型的交会轨迹进行理论结果的非线性Monte Carlo打靶数值仿真验证.仿真结果表明了理论分析结果的正确性,采用Clohessy-Wiltshire(CW)方程5 m偏置时,相对距离估计误差约2.5%,10 m偏置时约1.5%,采用Tschauner-Hempel (TH)方程时则分别为1.5%和1.1%.%To solve the non-observable problem of the passive angles-only relative navigation state of space non-cooperative target during close-in proximity phase, an angles-only relative navigation algorithm is proposed by using the camera offset from the chaser center-of-mass to provide the observability. Firstly, the line-of-sight measurement model based on camera offset is established. Then, a novel transformation method based on "analogous linearizing" to the measurement model is proposed to make the observable analysis and obtain the observable conditions of camera offset. Lastly, Monte Carlo simulations are made by using the proposed algorithm based on unscented Kalman filter and several classical proximity trajectories. Simulation results demonstrate the effectiveness of the proposed approach. The distance estimation uncertainties, for 5 m offset and 10 m offset, are about 2.5% and 1.5% respectively for the cases using Clohessy-Wiltshire dynamics, while they are about 1.5% and 1.1% respectively for the cases using Tschauner-Hempel dynamics.
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