【作者】 范利涛；

【导师】 汤国建；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2009， 博士

【摘要】 论文以自动转移飞行器(ATV)为背景,深入研究了不同飞行任务下的自主导航方法。研究了ATV在中低轨飞行时的自主导航方法。建立了ATV的飞行运动状态方程、误差状态方程及观测方程。为提高导航精度,将ATV上的惯性测量装置误差方程中的惯导工具误差系数增广为状态变量,同时考虑了杆臂效应的影响,将观测量与惯性测量装置的误差系数联系在一起。提出了采用单接收机天线定姿方案对ATV进行姿态校正,该方案无需增加额外的硬件,简单可靠。分析了紧组合和松组合两种方式对导航精度的影响,结果表明紧组合的导航精度优于松组合。为了降低状态方程的维数,减轻导航计算机的负担,提出采用惯性测量装置的一阶惯性模型替代误差系数模型,仿真分析了两者的等价性,并证明了一阶惯性模型可以节省大量的计算时间。研究了ATV在中高轨飞行时的自主导航方法。通过计算卫星信号在空间链路中衰减因子,分析了ATV在中高轨飞行时GNSS卫星的可用性。在ATV进行轨道机动时,采用连续两个时刻历元的星敏感器测量信息对其姿态进行校正,该方案仅需一个星敏感器,节省了导航设备成本。中高轨ATV飞行高度跨度很大,为避免在此过程中引力偏差统计特性不准确造成滤波发散,本文采取两个措施,一是将引力偏差作为一阶马尔科夫过程来考虑,二是引入了强跟踪滤波器进行信息融合,并分析了不同强跟踪滤波器对导航精度的影响,结果表明强跟踪无迹卡尔曼滤波(STUKF)的精度优于强跟踪扩展卡尔曼滤波(STEKF)的精度,且STUKF比STEKF具有更快的收敛速度。针对不同滤波过程的特点,利用不同参数来表征ATV的姿态运动,在STEKF中,采用四元数表征ATV姿态运动;在STUKF中,则引入了Rodrigues参数避免在运算过程中四元数无法满足归一化条件的问题。仿真表明,采用这样的方案,在GNSS卫星可用性很差的情况下,ATV最终位置导航精度(1σ)优于100m,速度导航精度(1σ)优于0.1m/s。研究了ATV与合作目标交会时的自主导航方法。提出了利用GNSS差分对ATV和合作目标进行相对导航的方案,该方案摆脱了对地面站的依赖,不需要在多套导航设备中进行切换。首先对ATV和合作目标上两接收机测得的数据进行时间同步,进行周跳处理,然后,在远距离导引段末端采用位置差分的方法获得ATV与合作目标的相对位置和速度;近距离导引段,采用双差载波相位平滑伪距差分技术,提高相对导航精度;在逼近阶段,使用滤波器估计整周模糊度的浮点值,利用估出的值解算ATV与合作目标的相对位置和速度;在靠拢对接段,提出了一种适用于单频接收机的整周模糊度快速求解算法,利用解得的整周模糊度整数解提高导航精度。仿真表明,此方案简单方便,易于工程实现,且完全能满足ATV与合作目标交会时的精度需求。研究了ATV与非合作目标飞行器交会时的自主导航方法。以时间载波相位差分信息为观测量,利用EKF进行信息融合以提高ATV的导航精度。在J2000坐标系下建立了非合作目标的绝对运动方程,在轨道坐标系下建立了ATV与非合作目标的相对运动方程,利用两种不同运动方程解算非合作目标间导航信息,比较了两种不同模型的导航精度。仿真表明,采用时间载波相位差分信息,ATV的位置导航精度可达厘米量级,速度导航精度可达毫米/秒的量级;采用绝对运动方程的非合作目标间最终导航精度稍优于采用C-W相对运动方程的导航精度。上述研究成果可为我国新一代空间运输系统的自主导航方案提供重要的技术支持。更多还原

【Abstract】 The purpose of this research is to investigate proper navigation methods for different missions of Automated Transfer Vehicle(ATV).Autonomous navigation method is presented to meet the navigation precision of low earth orbit ATV. Coupled GNSS/SINS navigation systems are hired to compensate the lack of one single system. In a tightly coupled system, GNSS pseudorange and deltarange measurements are processed by the data fusion algorithm to calibrate the IMU, which allows for a limited aiming of the SINS in situations with less than four satellites in view, where the GNSS receiver cannot provide postion and velocity information anymore in a loosely coupled system. The system dynamic model and GNSS mesasurement models are discussed which are the key to the development of GNSS/SINS data fusion algorithms. To improve the navigation precision, the guidance instrumentation error coefficients are modeled as augmented states and the leverarm effect is also considered. SINS errors are modeled as Markov processes to reduce the order of the system. Simulation results indicate that two different coupled systems have similar results in accuracy and the Markov process model can spend less time to accomplish the filter and achieve the similar navigation precision.For high orbit ATV, the usable conditions of GNSS are analyzed by estimating the carrier to noise spectral density which includes the received power plus constant assumptions regarding the noise figure of the receiver and antennas, the system noise tempreture, and the implementation losses in the receiver. A star sensor is utilized to correct the ATV attitude when a ATV moving occurs. Strong tracking EKF and UKF are derived to avoid the steady bias in identifying the parameter bias fault of nonlinear system and restrain the influence of modeling errors. Quaternion and Rodrigues parameters are expressed to describe ATV attitudes. Simulation results show that even GNSS satellite visibility is not good, it is feasible to use GNSS for ATV navigaton.Differential GNSS methods are developed when ATV approaches a cooperative target. Raw GNSS data are first processed through time synchronizing and cycle detection. Coordinate diffential navigation is used during the far-distance rendezvous mission planning. In the course of automatic homing, the method of double-differential carrier phase smoothing is applied. When the two spacecrafts are close, the float solustion is very efficient. A method is presented to resolve the integer ambiguity when using single frequency receiver. Firstly, the differential technique for carrier phase smoothing pseudorange is used in relative positioning to estimate the floate numbers of integer ambiguities. Secondly, the LAMBDA searching method is utilized to achieve the solution of integer ambiguity. After the integer ambiguity acquision, the integer solution can have a very high precision.Time differenced carrier phase(TDCP) measurements without the need of ambiguity resolution techniques are developed to acquire high precision of ATV. Absolute dynamic functions and relative dynamic functions are built to compare the navigation results using two different navigation algorithms. Simulation results indicate that TDCP method can obtain centimeter precision and absolute navigation algorithm is better than C-W algorithm.更多还原