单星只测角对低轨卫星的EKF跟踪分析

利用扩展卡尔曼（EKF）滤波原理研究基于天基光学平台对低轨卫星的跟踪问题，根据单星只测角观测值建立了相应的状态模型和观测模型，并进行低轨卫星的跟踪仿真，结果表明：该方法可以获得较高的跟踪精度，这使得基于单星只测角星上滤波跟踪成为可能。     

机动辐射源单站无源定位可观测性分析

针对采用非线性较强的脉冲到达时间差、观测角等参数的固定单站无源定位跟踪系统，对辐射源作机动运动的可观测性进行分析，得到了与辐射源作匀速运动相同的可观测条件。通过计算机仿真验证了结论的正确性。     

低轨卫星对高轨卫星仅测角初轨计算方法

针对我国地面测站对高轨卫星监视能力缺乏的问题,提出一种低轨卫星对高轨卫星仅测角初轨计算方法。该算法引入天基跟踪坐标系,消除测距信息影响,建立仅测角观测方程;引入法向运动,增加摄动因素影响,建立扩展拉普拉斯动力学模型;推导分析观测模型和动力学模型的关系方程,将初轨计算问题转换为非线性方程求解问题,利用高斯全主元消去法完成方程求解。通过实战和仿真测角数据对方法进行检验,结果表明,该方法能利用仅测角数据对非合作目标进行初轨确定,精度在公里量级,可为我国地基监视系统提供补充参考。     

双星编队对空间非合作目标的仅测角跟踪方法

针对单星仅测角对目标跟踪误差较大和不良测量条件下跟踪精度下降的问题,提出利用编队卫星对非合作目标进行联合跟踪的方法。采用考虑地球非球形J2引力摄动的轨道动力学模型,建立多视线测量模型,融合编队卫星对目标的观测数据。然后,基于新息设计增益调节矩阵提高滤波器在测量故障条件下的鲁棒性。最后,建立仿真模型进行验证。仿真结果表明,相比单星跟踪,该方法的位置误差和速度误差分别减少了27.06%和26.96%。在系统存在异常量测时,相比常规滤波,该方法也具有更高的精确性和更好的鲁棒性。     

基于连续同伦算法的天基仅测角初定轨方法

要进一步提高天基短弧初定轨的精度,在观测资料精度较高的情况下,仅考虑二体问题是不够的,还应考虑轨道摄动的影响。因此,基于无摄初轨的单位矢量法原理和矢量斜分解方法,给出了考虑摄动的天基仅测角初定轨单位矢量法。针对天基仅测角观测条件方程组求解过程中易出现迭代不收敛或收敛到平凡解的问题,引入连续同伦算法求解观测条件方程组,提出了单星观测方式下的空间目标天基仅测角初定轨方法,并通过数值仿真算例验证了该算法在较大范围的收敛性和数值稳定性。     

感应电机全阶状态观测器及其无源性转速控制

为了实现感应电机的高动态调速性能,针对电机的非线性本质,提出了一种基于全阶状态观测器及其转速自适应估算的感应电机无源性转速控制方案。在基于感应电机无源性与稳定性分析的基础上,设计了渐近稳定转矩跟踪无源性控制器。针对无源控制律所需转子电流难以观测的问题,提出了一种旋转坐标系下以转子电流和转子磁链为状态变量的全阶状态观测器,并应用该观测器对转速进行估算,实现了感应电机无速度传感器的无源性转速控制。仿真结果表明该控制方法易于实现,采用全阶观测器观测转子电流值和估算转速值更为准确,显著提高了感应电机的动静态性能。     

s7123a观测实验测角归算结果讨论

讨论了2007年1月23日我国VLBI网4天线对某卫星跟踪观测实验（s7123a）的测角归算结果。分析指出，相比于仅仅解算卫星横向位置参数，解算三维位置改正的方式在原理上更为可取。通过s7123a跟踪数据不同组合情况下测角计算结果的比对和原理性分析，指出四站跟踪测角计算时，只有当距离约束与时延观测误差相当时才会对解有显著影响，而对于三站跟踪，虽然解的形式误差可能会很小，但解会受到卫星径向距离误差和时延系统误差的影响，不属于无偏估计。本文对于探月工程中的卫星VLBI测轨有参考意义。     

基于卫星信息的惯导系统可观测性分析

可观测性分析是组合导航系统进行滤波器设计的重要内容,直接影响状态估计时的收敛速度和收敛精度,因而需要对状态变量的可观测程度进行定量分析。文章针对基于卫星的惯导系统在机动方式时的可观测性分析进行研究,改进了组合导航系统的可观测度,省略了外观测量的求取,有效减少了计算量,简化了分析步骤。仿真结果证明了该方法的有效性。     

三星时差无源跟踪算法研究

基于卫星平台的无源定位系统可以通过卫星的绕地运动和轨道覆盖,实现对全球地面辐射源的被动侦察,具有侦察隐蔽性强、侦测范嗣广和不受地理位置限制的优点。把一种新的修正协方差扩展卡尔曼滤波（MVEKF）方法引入三星对运动目标的时差无源定位跟踪中,克服了EKF受初始状态和测量误差影响大的缺点,也不用像MGEKF一样需要观测方程的修正函数,仿真表明该滤波方法相对来说收敛速度更快,跟踪性能更好。     

空间多机器人协同的多视线仅测角相对导航

研究了空间多机器人对非合作目标的多视线协同仅测角相对导航问题。为利用多视线信息融合提升仅测角相对导航性能,给出了一种可观测度优化的多视线仅测角相对导航方法。首先基于二阶CW方程构建了中心机器人与目标相对动力学模型和状态方程,并构建了仅包含多伴飞机器人视线角的观测方程,结合扩展卡尔曼滤波算法,形成多视线仅测角相对导航系统;然后分析推导得到可观度最优的视线间夹角条件,提出了兼顾可观测度和长期自然维持的多伴飞机器人观测构型优化方法;最后,数学仿真结果表明,提出的多视线仅测角相对导航系统、可观测度最优的视线夹角条件和观测构型优化方法,可以显著提高距离状态可观测度和估计性能,且具有较好的工程可用性。     

Observability Criteria for Bearings-Only Target Motion Analysis

The observability requirements for bearings-only target motion analysis (TMA) are rigorously established by solving a third-order nonlinear differential equation. Closed form expressions are developed and subsequently used to specify necessary and sufficient conditions on own-ship motion that insure a uniquetracking solution. It is shown that for certain types of maneuvers the estimation process remains unobservable, even when the associated bearing rate is nonzero. Such maneuvers are frequently overlooked in heuristic discussions of TMA observability, which may account for some common misconceptions regarding the characteristics of acceptable own-ship motion.     

基于倾斜角的多目标测向无源定位技术

对多目标测向无源定位问题进行了研究。虽然无源观测站不同,针对同一目标的方位角和俯仰角数据也不同,但它们有共同的倾斜角。基于此,提出了基于倾斜角的多目标测向无源定位算法。该算法分别计算一组与多个目标对应的倾斜角,然后利用倾斜角最接近原则对这2组数据进行关联判断,解决多目标测向数据的关联和定位问题,并通过仿真实验,对算法的有效性和可行性进行了验证。     

Comments on “Discrete-time observability and estimabilityanalysis for bearings-only target motion analysis”

Discusses the extensive mathematical analysis carried out by the authors of the original paper [see ibid., vol. 33, no. 1, p. 178-201, 1997] and submits the following points. The authors used pseudo measurements for recasting the observability problem into a linear framework. They treated the bearings-only passive target tracking system as a deterministic system. It is already established that for deterministic systems, the pseudo measurements are linear functions of the states of the system, though the coefficient matrix is a nonlinear function of the original measurements, By using the pseudo measurements in a linear observer, global stability can be shown. However, if the pseudo measurement observer, for which the analysis is mostly carried out by the authors, is used in a noisy environment as a pseudo measurement filter (PMF), biased estimates are arrived at. Hence, though the approach of authors is quite direct and provides insights about the algebraic structure of the BOT problem, as pseudo measurements are used throughout the analysis is not of much use to the TMA community, as the nonlinear measurement equation along with measurement noise are required to be considered in the BOT problem to obtain unbiased results     

存在观测站位置误差的转发式时差无源定位

无源定位中,由于观测站安放在运动平台等原因造成的观测站位置误差会影响无源定位精度性能。另外到达时间差(简称时差)(TDOA)的转发式测量需要将不同观测站截获到的辐射源信号都转发到同一位置,如主观测站。针对这两个问题,提出了基于约束总体最小二乘(CTLS)的无源定位算法。首先将转发式时差的非线性定位方程转化为不需要中间变量的直接线性方程,再基于CTLS算法依次转化为约束优化问题和无约束优化问题,最后推导给出定位近似闭式解。仿真实验表明在观测站误差较大时,该算法与其他算法相比定位精度性能较好。     

Analysis of dynamics of a passive line-of-sight stabilization system with four-axis gimbal suspension

A mechanical model of the line-of-sight stabilization system for the optical device mounted on a movable carrier vehicle is considered. The nonlinear Lagrange equations of motion for a four-axis gimbal suspension are derived. Requirements on design and parameters for the passive line-of-sight shock absorption system of the optoelectronic payload are worked out.     

飞行器壁板颤振的无限维非线性分析

 一、无限维Hopf分叉定理和中心不变流形定理 由于偏微分方程的矢量场（在任一适当的Banach空间中）常常不是光滑函数,Marsden-McCracken利用（相）流的光滑性提出了流的Hopf分叉定理和中心流形定理。这里的流都是半（相）流,也就是半群。     

Bearings-only and Doppler-bearing tracking using instrumentalvariables

In bearings-only tracking (BOT) or Doppler and bearing tracking (DBT), both common passive sonar problems, the measurement equations are nonlinear. To apply the Kalman filter, it is necessary either to linearize the equations or to embed the nonlinearities into the noise terms. The former sometimes leads to filter divergence, while the latter produces biased estimates. A formulation of BOT and DBT which has a constant state vector and simplifies the tracking problem to one of constant parameter estimation is given. The solution is by the instrumental variable method. The instrumental variables are obtained from predictions based on past measurements and are therefore independent of the present noisy measurements. The result is a recursive unbiased estimator. The theoretical developments are verified by simulation, which also shows that the formulation leads to near optimal estimators whose errors are close to the Cramer-Rao lower bound (CRLB)     

TMA from bearings and multipath time delays

A novel approach for target motion analysis (TMA), which uses conventional passive bearing together with multipath time-delay measurements is examined. This so-called "Multipath TMA" offers two tactical advantages over the classical bearings-only TMA: no requirement for any ownship maneuver, and a good performance in terms of estimation error achieved in a shorter time. Both known and unknown multipath cases are addressed. Finally, Monte-Carlo simulations and at-sea trials demonstrate the practical efficiency of such a multipath TMA.     

Bearings-only target motion analysis with acoustic propagation models of uncertain fidelity

The augmented bearings-only target motion analysis (TMA) problem arises when the bearing measurements of the classical bearings-only TMA problem are augmented with received signal-to-noise ratio (SNR) measurements. A combined acoustic propagation and sensor (CAPS) performance prediction model specifying the conditional density of the SNR measurements is assumed given; however, mismatch may exist between the CAPS model and the real world. We present a novel "missing data" formulation of the augmented bearings-only TMA problem using an empirical maximum a posteriori (EMAP) method for target parameter estimation, and show that it provides a natural and straightforward technique for mitigating CAPS model mismatch. The EMAP approach leads to an iteratively reweighted, linear least-squares algorithm for solving both the augmented bearings-only TMA problem and the classical (nonaugmented) bearings-only TMA problem. Examples are provided.