捷联导引头隔离度分析与寄生回路滤波器设计

分析了捷联导引头惯性视线角速度提取的间接解耦方法与直接解耦方法的制导回路特点以及两种方法的等效关系,推导了描述捷联导引头隔离度的表达式并讨论了隔离度对制导回路的影响。通过设计寄生回路滤波器使导引头测量信息传递通道与姿态测量信息传递通道的时频特性一致,抑制信号测量与传递过程中的噪声干扰。最后通过仿真算例验证了滤波器的有效性。     

Digital accumulators in phase and frequency tracking loops

Results on the effects of digital accumulators in phase and frequency tracking loops are presented. Digital accumulators or summers are used extensively in digital signal processing to perform averaging or to reduce processing rates to acceptable levels. For tracking the Doppler of high-dynamic targets at low carrier-to-noise ratios, it is shown through simulation and experiment that digital accumulators can contribute an additional loss in operating threshold. This loss was not considered in any previous study and needs to be accounted for in performance prediction analysis. Simulation and measurement results are used to characterize the loss due to the digital summers for three different tracking loops: a digital phase-locked loop, a cross-product automatic frequency tracking loop, and an extended Kalman filter. The tracking algorithms are compared with respect to their frequency error performance and their ability to maintain lock during severe maneuvers at various carrier-to-noise ratios. It is shown that failure to account for the effect of accumulators can result in an inaccurate performance prediction, the extent of which depends highly on the algorithm used     

新生目标强度未知的双门限粒子PHD滤波器

传统粒子概率假设密度(PHD)滤波器假定新生目标强度已知,当新生目标在整个观测区域随机出现时不再适用。为解决新生目标强度未知时的多目标跟踪问题,提出了一种基于量测信息的双门限粒子PHD(PHD-DT)滤波器。首先基于似然函数设定门限对存活目标量测进行粗提取,利用上一时刻的目标估计值构建圆形波门进行精细提取,并对门限设定方法进行分析,然后根据提取结果对目标PHD进行分解,得到存活目标和新生目标的PHD预测及更新表达式,最后给出了滤波器的实现方法并同基于量测驱动的PHD(PHD-M)滤波器和Logic+联合概率数据互联(JPDA)方法进行了仿真对比。仿真结果表明,在新生目标强度未知时,PHD-DT可有效避免Logic+JPDA在杂波背景下因航迹起始错误带来的估计误差,并较好地解决了PHD-M的目标数目过估问题,多目标估计性能更优,且杂波越强性能优势越明显。     

基于UKF自主定姿方法研究

轻小型飞行器在飞行中卫星导航失效时,余度控制回路要求导航系统具有自主确定姿态的能力.提出了基于IMU的输出确定水平姿态的方法,并采用UKF实现飞行中的实时滤波估计.对某无人机实际飞行的MEMS型IMU数据进行了仿真,结果表明该方法给出的姿态角信息满足控制精度需求.将UKF与EKF滤波估计结果进行比较,UKF更具有优越性.     

A mean level adaptive detector using nonconcurrent data

Convergence results for a mean level adaptive detector (MLAD) are presented. The MLAD consists of an adaptive matched filter (for spatially correlated inputs) followed by a mean level detector (MLD). The optimal weights of the adaptive matched filter are estimated from one batch of data and applied to a statistically independent batch of nonconcurrent data. The threshold of the MLD is determined from the resultant data. Thereafter a candidate cell is compared against this threshold. Probabilities of false alarm and detection are derived as a function of the threshold factor, the order of the matched filter, the number of independent samples per channel used to calculate the adaptive matched filter weights, the number of samples used to set the MLD threshold, and the output signal-to-noise power ratio of the optimal matched filter. A number of performance curves are shown and discussed     

对飞机的跟踪方法

 本文叙述对作机动飞行（加速、转弯等）的飞机进行实时跟踪的方法,该方法采用自适应（一阶）多项式滤波,其中用X²分布法探测飞机机动,分别用方差匹配法及两种算法估计由机动产生的模型噪声方差Qk。模拟计算表明,两者对飞机机动的跟踪都是成功的,而后者对工程应用更方便一些。     

FM Threshold Performance of the Frequency Demodulator with Feedback

The FM threshold performance of the frequency demodulator with feedback (FMFB) is experimentally optimized. Rules of thumb for the practical design of the FMFB with limiter in the loop are proposed. Such design rules provide for optimum FMFB threshold performance given specifications of the received signal. Equivalences among the FMFB, phase-locked loop, and limiter- discriminator offer some additional physical insight into the threshold-extending mechanism of the FMFB not presented by previous investigators.     

Real-Time Motion Desmearing of Airborne Imagery

This paper considers the real-time ?desmearing? of motion- ?smeared? imagery telemetered from an airborne platform. The specific configuration considered is the direct raster scan readout of a satellite-mounted vidicon. Three types of smearing are considered: 1) linear uniform smearing, 2) linear nonuniform smearing, and 3) nonlinear smearing. The simplest type of smearing, linear uniform, has as its desmearing or inverse filter a circulating delay line (CDL) cascaded with a differentiator. An error analysis of this filter is presented along with an experimental simulation. Linear, non-uniform smearing characterized by the operator begin{equation*}int^{t}_{t-delta(t)}I(tau){ }{dtau}end{equation*} is considered next. Two possible realizations for the inverse filter are discussed as to accuracy and practicality. Finally, an error analysis is performed for the nonlinear smearing that results from a skewing of the raster scan.     

Flexible loop filter design for spacecraft phase-locked receivers

A flexible loop filter design for spacecraft phase-locked receivers is proposed. The loop filter is implemented as digital hardware with coefficients that are set by registers. Either a perfect or an imperfect integrating loop filter can be effected. This flexibility is important since not one type of loop filter is preferred for all circumstances. An imperfect integrator is preferred when, as is often the case for spacecraft receivers, it is important to minimize the best-lock frequency drift of an idling loop. A perfect integrator is preferred when the tracking performance of the loop is the most important consideration     

Nonlinear modeling of integrally actuated beams

A set of nonlinear, intrinsic equations describing the dynamics of beam structures undergoing large deformations is presented. The intrinsic kinematical equations are derived for the general case of a moving beam. Active force/strain terms are added to the equations to take into account active components. The equations are then discretized into finite elements, transformed into state-space form and finally decomposed into modes. Actuation and sensor models are established before implementing a simulation model in Matlab/SIMULINK. The model is validated by comparison with exact, analytical results and then used to analyze the dynamic behavior of an active helicopter blade in vacuum. Beside the analysis of the inherent dynamics of this system in terms of eigenvalues and vectors, the influence of centrifugal stiffening on the modal controllability of the blade is discussed. Finally, the design of a MIMO controller based on full-state optimal control (LQR approach) and optimal state estimation (Kalman filter) is presented with the aim to add vibrational damping to the weakly damped system. The closed loop properties are validated by both analytical methods and simulation runs.     

Noise Dynamics of the Phase-Locked Loop with Signal Clipping

Employing techniques similar to the averaging methods of Krylov and Bogoliubov, an approximate noise analysis of the phase-locked loop with signal clipping is presented. The validity of the method is demonstrated by comparing the stationary probability density function for the phase error, generated by a system simulation, with the derived theoretical results. The latter portion of the paper discusses the relation of the phase-locked loop to Kalman-Bucy filter theory and presents a demodulator design that illustrates the self-adaptive properties attainable in phase-locked loops with signal clipping.     

北斗/惯性深耦合接收机速度误差特性研究

北斗/惯性深耦合接收机利用了惯性辅助和微惯性器件误差实时补偿技术,具有更好的高动态适应性与抗干扰能力。深耦合接收机中,惯性测量模块与接收机模块的信息相互利用,形成了2个闭合的误差传递通道:位置通道和速度通道。针对速度通道分析了误差传递特性。首先,考虑了三阶锁相环所实现的载波跟踪环路,在对组合滤波器进行简化的基础上,建立了速度通道的传递函数模型;然后,推导了惯性辅助误差到接收机速度误差的传递关系,分析了其误差特性;进一步将惯性辅助误差分为由惯性器件误差和由辅助信息更新率低引起的误差,分别分析了它们对接收机速度误差的贡献。分析结果表明:1)惯性辅助误差到接收机速度误差的传递模型表现为高通特性;2)由惯性器件误差所引起的速度误差,因受载波跟踪环路滤波器的作用而大大减小;3)比较而言,由辅助信息更新率低所引起的速度误差更为显著。     

检测滤波器在FADEC系统传感器FDI中的应用研究

研究将检测滤波器应用于全权限航空发动机控制系统(FADEC)的传感器故障检测和隔离(FDI).完整设计了针对于某型FADEC系统传感器的检测滤波器系统, 然后利用非线性发动机模型进行了仿真。数字仿真结果表明, 检测滤波器是十分有效的。      

用卡尔曼滤波器估计目标机动加速度

为了使基于线性二次型高斯理论的LQG最优制导规律得到工程应用，设计了一种寻的回路中的卡尔曼滤波器，利用仿真技术，用这种滤波器对目标机动加速度进行了估计，仿真结果表明，这种滤波器可以准确估计目标机动加速度。     

基于I、Q信号的北斗接收机跟踪环路设计

传统的北斗接收机一般采用标量跟踪环,每个通道的卫星相互独立,在此 基础上,又发展起来了基于矢量跟踪的接收机,使每个通道的卫星跟踪不再相互独立。 提出的基于I、Q 信号观测的接收机跟踪环路,保留矢量跟踪的特点,并且采用EKF 作 为跟踪环路预处理滤波器,代替传统跟踪环路的鉴别器,可以在高动态的环境下对卫星 信号进行跟踪,提高环路的稳定性,从而可以有效地提高BDS/INS 深组合导航滤波器观 测量的估计精度。主要对高动态信号跟踪进行仿真,并与传统的标量跟踪方法和矢量跟 踪方法的跟踪能力进行比较。实验表明, 改进的矢量跟踪环能够在高动态的环境下运 行,比起传统环路有更小的跟踪误差。     

Third-Order Loop Filter Design for Acceleration-Rate Tracking

A perfect third-order loop filter design that can be implemented as a digital filter is obtained which minimizes the noiseless steady-state acceleration rate (jerk) error for a fixed loop noise bandwidth. Simulations were performed to obtain transient responses of the third-order loop plus a sample fourth-order loop under a jerk input. The results enable one to obtain a loop design that minimizes the loop noise bandwidth required for a given steady-state jerk error and thus obtain better noise jitter performance.     

GPS/SINS超紧组合导航的性能分析

GPS接收机在高动态环境下很容易失锁,特别是载体的高动态造成的应力对接收机载波跟踪环影响很大。为了解决高动态环境下的组合导航,分析了GPS接收机载波跟踪环的测量误差和跟踪门限,采用惯导速度辅助GPS接收机跟踪环路的超紧组合结构。超紧组合需要涉及到GPS接收机跟踪环内部编排及高动态环境下的实验数据,难度较大。针对超紧组合仿真专门开发了GPS实时软件接收机、高动态GPS中频信号仿真器和惯导模拟器并构建了一个完整的GPS/SINS超紧组合仿真系统。仿真结果表明,该超紧组合导航系统可以跟踪50g的加速度和10倍音速。     

Multiple target tracking using products of position measurements

The continued development of the symmetric measurement equation (SME) filter for track maintenance in multiple target tracking (MTT) is considered, focusing on the case in which the SMEs are generated by forming sums of products of the original position measurements. The SME filter is developed for the case of N targets whose motions consist of random perturbations about constant-velocity trajectories. It is assumed that measurements of x-coordinate positions are available, and that the number of measurements is equal to the number of targets. Various analytical properties of the SME filter are studied. It is shown that under a very weak condition, the estimation error equation is locally exponentially stable. The performance of the SME filter is investigated by comparing it with an optimal (minimum-variance) estimator and by generating a computer simulation in the six-target case     

模糊线性/非线性自抗扰切换控制及其应用

针对干扰弹在作战过程中所遇到的强非线性的干扰、模型不确定性的影响等特性,提出了一种模糊线性/非线性自抗扰切换控制器。首先,以干扰弹滚转运动模拟装置为研究对象,分别建立了以飞轮角速度为被控量、滚转角为被控量的数学模型;提出了用模糊规则改进线性/非线性自抗扰切换控制条件,进而实现更为平稳的模糊软切换;然后选择采用飞轮角速度线性自抗扰控制内环和滚转角模糊线性/非线性自抗扰切换控制外环的双闭环控制策略;最后,搭建了系统的仿真模型与实验平台。仿真与实验结果都表明该控制器兼具了线性自抗扰与非线性自抗扰的优势,具有较高的实际应用价值。     

飞行器伺服回路的变结构设计

 根据变结构系统（VSS）理论对某飞行器伺服回路进行了变结构设计,给出了控制器设计的详尽步骤,设计方法几何意义直观,在IBM4341机上通过了数字仿真,给出了仿真框图;与原伺服回路的控制性能进行了比较。仿真表明,VSS比传统普通控制系统具有以下几个突出的优点:（1）快速、无超调、无稳态误差;（2）对系统参数交化具有鲁棒性;（3）对外界干扰具有鲁棒性。