基于自适应均方根EKF的惯性辅助航天器仅测角导航方法

Inertial-aided spacecraft angles-only navigation method based on adaptive square-root EKF

针对微小卫星等航天器对空间非合作目标交会操作中的自主相对导航问题,提出了一种基于自适应均方根EKF的惯性辅助航天器仅测角导航方法。首先,推导了一种基于Clohessy-Wiltshire(CW)方程的仅测角导航模型。然后,基于误差状态推导了一种仅测角/惯性组合相对导航模型。接着,基于Cholesky分解得到组合导航系统的状态协方差矩阵,并引入“新息”协方差匹配方法对测量噪声进行在线自适应调整,构建了一种自适应均方根EKF对该组合导航系统状态进行动态滤波估计,并采用Fisher信息矩阵对该组合导航系统的可观性进行评估。最后,在搭建的半物理仿真平台上进行了仿真验证,得出终端时刻采用自适应均方根EKF比EKF的迹向滤波精度平均提高了35%,径向和法向滤波精度平均提高了25%。

Aiming at the problem of autonomous relative navigation of spacecraft such as micro-satellites to rendezvous with non-cooperative targets in space,an inertial-aided spacecraft angles-only navigation method based on adaptive square-root EKF is proposed.Firstly,an angles-only navigation model based on the Clohessy-Wiltshire(CW)equation is derived.Then,an integrated angles-only/inertial relative navigation model is derived based on the error states.Next,the state covariance matrix of the integrated navigation system is obtained based on the Cholesky decomposition,and the"innovation"covariance matching method is introduced to adjust the measurement noise adaptively,and an adaptive square-root EKF is constructed for estimating the relative states of the integrated navigation system,and the Fisher information matrix is used to evaluate the observability of the integrated navigation system.Finally,the simulation verification is carried out on a semi-physical simulation platform,and the results show that the average along-track filtering accuracy of the adaptive square-root EKF is increased by 35%,and the average radial and normal filtering accuracy is increased by 25%compared with that of the EKF at the terminal time.