【作者】 李骏；

【导师】 周一宇；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2009， 博士

【摘要】 空间目标监视是获取空间态势信息的主要手段之一,空间监视能力是未来空间优势的基础,是实现控制空间的重要基础能力。天基光学监视由于其所具有的能耗低、精度高以及易于小型化实现等方面的优势而更具有发展潜力。本论文在对天基光学监视特点进行分析的基础上,研究如何利用天基光学观测获取的角度测量信息实现对空间目标的被动监视跟踪,重点对其中的天基光学初轨确定、空间目标天基光学跟踪方法以及摄动条件下的空间目标跟踪方法和双行根数拟合方法等理论问题和关键技术进行了深入分析和研究。论文主要工作如下:首先对天基光学监视工作机理、系统特点、观测条件等进行分析,在系统参数和对目标的观测覆盖特点等方面与地基光学监视系统进行对比,明确了天基光学监视信息处理流程,并对相关技术进行归纳分析。最后给出空间目标天基光学监视跟踪相关模型,包括常用坐标系定义与转换、空间目标运动描述以及天基光学测量模型。针对未编目目标的初轨确定问题,在对经典Laplace初轨确定方法进行研究的基础上,通过对短弧测量相关性及测量法方程系数矩阵特性的分析,进一步揭示了短弧测量尤其是天基光学观测条件下的初轨计算病态性和误差特性。考虑天基光学测量数据特点,引入短弧测量属性和约束域概念,充分利用短弧测量信息将目标运动状态有效约束至测量斜距和斜距变化率二维平面内。以弧段测量预测残差为目标函数优选剖分节点作为初始条件,提出两种基于约束域Delaunay三角剖分的约束域分析方法,分别采用约束微分修正和三角网细分搜索策略,利用两个短弧段测量实现对新发现目标的初轨确定,并就其在约束域平面内的误差和收敛特性进行探讨。针对不同层次的监视跟踪需求,以误差传播理论为基础,采用协方差分析描述函数对空间目标的误差传播进行仿真分析。然后根据天基光学监视数据特点对经典EKF跟踪滤波算法进行研究,推导空间目标运动方程与状态转移函数。针对EKF一阶线性化截断误差影响,在状态预测过程中引入UT变换以达到对非线性系统状态的二阶近似,并采用混合状态空间,分别在直角坐标和修正球坐标空间实现状态预测和滤波更新,以提高跟踪滤波稳定性,提出天基光学混合状态SPKF跟踪方法。并进一步根据天基光学测量特点,提出基于样点状态转换的MSC-SPKF方法,提高跟踪收敛性能,并对上述方法的跟踪精度和收敛性能进行了仿真分析。给出跟踪滤波误差下限和系统可观测度定义,并提出瞬时可观测度概念,结合仿真结果对影响系统可观测度的因素进行分析,并对天地基观测系统可观测度进行了对比。在二体问题下的跟踪定轨方法的基础上考虑J 2摄动影响,推导空间目标受摄运动方程与状态转移函数,提出考虑J 2摄动的EKF和相应的SPKF被动跟踪方法。在对空间目标TLE格式和相应SGP4预测模型理论进行理解分析的基础上,对TLE的单点拟合和采样拟合两种方法进行研究和改进;针对空间目标监视应用中运动状态未知的非合作目标,根据两种拟合方法特点,提出面向天基光学监视应用的空间目标TLE拟合方法,利用仅测角数据实现对空间目标尤其是非合作目标TLE的拟合估计。更多还原

【Abstract】 Space surveillance is one of the main means to acquire the situation information in the space. The capability of the space surveillance is the foundation of the dominance in space and is essential for controlling the space in the future. Space-based optical surveillance has great development potential for its advantages in lower power consuming, higher precision, and easier realizing. Based on the analysis on the characteristics of the space-based optical surveillance, the dissertation focus on how to utilize the solid angles measurements obtained by space-based optical sensor to realizing the passive surveillance and tracking of the space objects. The theories and key technologies are discussed and researched particularly, including the initial orbit determination with space-based optical short arcs, space objects passive tracking methods in space-based optical surveillance, tracking and two-line elements (TLE) fitting methods considering the perturbations. The main contributions of this dissertation are demonstrated as follows:Firstly, the working principle, system characteristics and the observation conditions of the space-based optical surveillance system are analyzed. And then compared with the ground-based optical system on the system parameters and targets coverage. The characteristics of the information processing flow and the corresponding information processing technologies are extracted and analyzed. The mathematical models of the space-based optical surveillance are extracted, including the definition and transformation of the coordinates, the kinetic model of the space object, the observation geometry and the solid angles measurements.To solve the problem of the initial orbit determination (IOD) of the un-cataloged target (UCT), the classical Laplace method is studied firstly, and the ill-condition of the IOD with short arc is analyzed. By analyzing the relativity of the short arc measurements and the characteristic of the coefficient matrix, the dissertation ulteriorly demonstrates that the ill-condition and the error characteristic of the IOD of the short arc measurements especially under the situation of the space-based optical surveillance. The concepts of the attributes and the admissible region are introduced, and then the kinetic states of the space object could be effectively constrained within 2-dimension plane of the slant-range and its ratio, using the measurement information extracted from the short arc. Two kinds of the IOD methods, constrained differential correction method and the triangulation iterative subdivision searching method, are put forward based on the triangulation in the admissible region, which take the selected optimal nodes by the cost function as the best initial conditions. Then the initial orbit of the new space object could be determined using two short arcs. The characteristics of the error and the convergency in Admissible Region are discussed according to the analysis on the simulation results.According to the different requirements for surveillance and tracking missions, the Covariance Analysis Describing Function Technique (CADET) is adopted to analyze the error propagating characteristics of the space object. The classical extended Kalman filter (EKF) is studied, the kinetic equation and the state transformation function are deduced especially for the space-based optical tracking. Aiming at the influence of the truncation error in the first order linearization in EKF, unscented transformation (UT) is introduced in the state prediction in order to get the second order approximation to the nonlinear system. Simultaneously the mixed state space is adopted to enhance the stability of the tracking filter, which performs the state prediction in Cartesian coordinates and filter updating in modified sphere coordinates (MSC) respectively. This method is called mixed state sigma points Kalman filter (SPKF) for space-based optical surveillance. Further more, considering the characteristics of the space-based optical measurements and improvement on filtering convergence, the MSC-SPKF method is put forward which is based on state transformation of the sigma points. The performance on tracking precision and convergency of the methods mentioned above are analyzed with simulation results. The definition of the Cramer-Rao low bound (CRLB) and the system observability degree are introduced, and the instantaneous observability degree is brought forward. The factor which may affect the system observability degree are analyzed with the simulation results, and compared with the ground-based system.Considering the influence of the J2 perturbation based on the two-body tracking filter, the kinetic model and state transformation function are deduced. The new EKF and SPKF tracking filters considering J2 perturbation are put forward,. After analyzing on the two-line elements (TLE) and SGP4 orbit prediction model, the single point fitting and sampling fitting method are studied and modified. For the space objects whose kinetic state is unknown, the new TLE fitting methods are put forward for space-based optical surveillance, which can utilize the bearing-only (BO) measurements to realize the estimation and fitting of the TLE, especially for non-cooperative space objects.更多还原