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基于扩维QLEKF的脉冲星/星间定向组合导航

熊凯,魏春岭,李连升,周鹏   

  1. 北京控制工程研究所
  • 收稿日期:2021-08-16 修回日期:2021-10-09 出版日期:2021-10-12 发布日期:2021-10-12
  • 通讯作者: 熊凯
  • 基金资助:
    民用航天技术预先研究项目

Pulsar/inter-satellite LOS integrated navigation based on augmented QLEKF

  • Received:2021-08-16 Revised:2021-10-09 Online:2021-10-12 Published:2021-10-12
  • Contact: Kai XIONG

摘要: 面向星座卫星高精度自主导航技术需求,设计了一种融合X射线脉冲星和星间定向观测信息的组合导航方法。通过X射线探测器获得脉冲到达时间观测量,通过照相观测星相机和星间链路设备获得星间相对位置矢量观测量,设计导航滤波器对观测量进行处理,估计参与导航的星座卫星的运动状态。针对地球星历误差影响组合导航性能的问题,将地球相对于太阳系质心的位置扩充为状态向量,设计了扩维扩展卡尔曼滤波器,利用敏感器观测量对导航所需的地球位置矢量进行实时估计,从而削弱地球星历误差的影响。进而,针对滤波器参数选取影响状态估计精度的问题,设计了一种Q学习扩展卡尔曼滤波器(QLEKF),主要思路是利用Q学习方法的决策能力,自适应地选择适当的滤波器参数以改善估计性能。数学仿真结果表明,所提方法能够有效减小地球星历误差对星座自主导航的影响,取得优于传统滤波算法的定位精度。

关键词: X射线脉冲星导航, 星历误差, 扩展卡尔曼滤波器, Q学习, 卫星星座

Abstract: An integrated navigation method based on X-ray pulsars and inter-satellite LOS (line-of-sight) measurements is de-signed for constellation satellite autonomous navigation with high-accuracy requirement. The X-ray detector is used to achieve the pulse arrival time. The relative position vector measurement between the satellites is obtained from star cameras and inter-satellite links. The kinematic states of the satellites that participate in the navigation can be esti-mated with a properly designed navigation filter for data processing. To cope with the problem that the ephemeris error of Earth affects the integrated navigation performance, the position vector of Earth relative to the solar system bary-center is augmented as state, and an augmented extended Kalman filter is designed. The position vector of Earth for navigation is estimated in time, such that the effect of the ephemeris error of Earth is suppressed. In addition, to cope with the problem that state estimation accuracy is affected by the choice of the filtering parameters, a Q-learning ex-tended Kalman filter (QLEKF) is designed. The key idea is to select the appropriate filtering parameters adaptively with the Q-learning method, which has the decision-making ability. It is illustrated via the numerical simulations that effect of the ephemeris error of Earth to the autonomous navigation performance for constellation is decreased effi-ciently using the presented algorithm. The QLEKF is superior to the traditional filtering algorithms in positioning accu-racy.

Key words: X-ray pulsar navigation, Ephemeris error, Extended Kalman filter, Q-learning, Satellite constellation

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