基于Leader-Follower编队的无人机协同跟踪地面目标制导律设计

对地面目标的自动跟踪是无人机在任务应用阶段需要解决的重要问题之一,多无人机协同跟踪能够提高对目标运动状态的估计精度并降低目标丢失的概率,因而具有重要研究意义。本文提出了一种基于Leader-Follower编队的无人机协同跟踪制导方法,解决了传统Standoff跟踪模式对地面目标的速度范围限制问题。首先,通过控制无人机的航向不断趋近于地面目标牵连跟踪圆切线方向的方法设计了Leader无人机自动跟踪地面目标的制导律并完成了稳定性证明;其次,通过控制Follower无人机的速度和航向角逐渐趋近于Leader无人机速度和航向的协同跟踪策略,分别设计了Follower无人机自动跟踪Leader无人机的制导律和编队相位协同制导律并完成了稳定性证明;最后,分别针对静止目标、匀速直线运动目标和变速运动目标的跟踪问题进行了仿真验证,结果表明所提出的制导方法能够实现对不同运动状态地面目标的自动协同跟踪,并且跟踪性能优于基于李雅普诺夫向量法的制导方法。     

航空机电作动器神经网络快速终端滑模控制

目前机电作动器由于具有干净、维护方便等优点,越来越受到航空业的青睐。航空机电作动器的特点是控制精度、稳定性和响应速度要求高,针对以上特点,提出了一种基于多层神经网络的快速终端滑模控制策略。为了提高航空作动器响应速度和跟踪精度,设计了快速终端滑模控制策略,不仅可以加快系统响应而且可以在无扰动情况下实现系统的有限时间稳定。针对系统参数不确定性和外部扰动,设计多层神经网络进行估计并通过前馈方法加以补偿。针对神经网络的重构误差,设计了非线性鲁棒项加以克服。利用李亚普洛夫稳定性定理证明了控制系统在有扰动情况下可以实现有界稳定。实验结果表明：所设计的控制器具有良好的参数自适应和抗干扰能力,同时具有更高的跟踪精度和更快的响应速度。     

Target-Handling Capacity of a Phased-Array Tracking Radar

The factors which affect the target-handling capacity of an agile-beamelectronically scanned multitarget-tracking radar are reviewed and analyze.Consideration is given to the choice of strategy for dwell allocation amongtargets, the choice of trajectory extrapolation algorithms for target tracking, and the determination of saturation target acquisition rates. Emphasisis placed upon radar systems with control computers having limited speed and memory, and recommendations are made for allocation strategy and targetytracking algorithms, based on uniform sampling, to be used in maximizing thetarget-handling capacity in this situation.     

Use of map information for tracking targets on airport surface

A generic and novel approach for integrating airport map information with sensor measurements in the track estimation process is proposed and evaluated. The surface restrictions imposed by the network of roads, taxiways, and runways, represented by a simplified geometric model, are included in both the target observation and the dynamic models, to derive the target state estimates. The performance of the methods proposed is illustrated in representative airport surface scenarios, taking as a reference for comparison other tracking alternatives such as VS-IMM (variable structure interacting multiple model estimator) ground target tracking, or standard ones that do not make use of ground information.     

Prescribed fast tracking control for flexible air-breathing hypersonic vehicles: An event-triggered case

In this paper, a prescribed fast tracking control scheme is proposed for Flexible Air-breathing Hypersonic Vehicles (FAHV) subject to lumped disturbances and limited resources. To maintain tracking errors of velocity and altitude converge to a predefined region with a prescribed time and release the transient intense fluctuations encountered in classical Prescribed Performance Control (PPC) using a fast decaying rate, a tracking differentiator-based PPC is presented, where the reaching time and the maximum time differentiation of preselected envelopes can be regulated as a prior via fixing an acceleration factor, so that a guaranteed fast convergence speed can be realized with reduced oscillations. Besides, to avoid the excessive occupation of limited resources (energy and communication) and guarantee a remarkable tracking accuracy, switching event-triggered mechanisms are constructed for FAHV control realization, which provide a promising way to pursue a desired level of tracking performance with a low energy consumption. Subsequently, Uncertainty and Disturbance Estimators (UDE) and Sigmoid function-based Tracking Differentiators (STD) are employed to provide disturbance estimation and reference derivation with a low computational complexity. Finally, robust control laws are designed to compensate for the sampling error induced by event-triggered conditions, meanwhile Zeno phenomena can be effectively eliminated. The simulation results and comparisons validate the effectiveness of the proposed scheme.     

单天基平台测向的空间非合作目标跟踪

针对仅含角度测量信息的单个天基平台可观测性较弱的问题,提出了一种含脉冲机动检测的空间非合作目标跟踪算法,并设计了非合作目标实时跟踪数据处理流程.该算法利用抗差估计技术和UKF（Unscented Kalman Filter,无迹卡尔曼滤波）算法构造目标跟踪滤波器,并综合残差多项式拟合和新息分布特征等方法实现目标机动检测,在天基平台观测信息类型有限和观测几何较差的情况下,可以同时排除孤立野值和成片测量野值的影响,实现非合作机动目标的连续稳定跟踪.数值实验验证了算法的可行性和有效性,也表明了跟踪精度和可靠性与测量精度密切相关.     

基于超短基线声传感器阵的高速目标轨迹估计

针对低空高速飞行目标跟踪问题,首先研究了某典型目标噪声信号的时频特性,发现其信号呈现宽带低频特征,难以从频域对目标轨迹进行估计。在此基础上,从各路接收信号的到达时延量入手,考虑到声基阵只能布设于有限空间内的制约,提出了一种基于超短基线阵时延估计的目标跟踪方法。该方法利用各个超短基线阵接收声强极值点分别估计目标运动轨迹垂线方向,计算多个垂线的叉乘向量实现对目标运动方向的估计,再利用多面交汇的方式获估计得到目标运动轨迹。分别对目标俯仰角、方位角及运动轨迹估计的理论误差进行了推导,根据理论估计误差,为能够实现对目标运动轨迹的估计,各个超短基线阵应尽量保证与目标运动轨迹不在同一平面上。根据仿真结果,在采用4个传感器基阵时,角度估计平均误差在4°以内,位置估计相对误差在5%左右。仿真结果验证了该方法的有效性。     

Delay Depending Decentralized Adaptive Attitude Synchronization Tracking Control of Spacecraft Formation

This paper deals with the problem of cooperative attitude tracking with time-varying communication delays as well as the delays between inter-synchronization control parts and self-tracking control parts in the spacecraft formation flying. First, we present the attitude synchronization tracking control algorithms and analyze the sufficient delay-dependent stability condition with the choice of a Lyapunov function when the angular velocity can be measured. More specifically, a class of linear filters is developed to derive an output feedback control law without having direct information of the angular velocity, which is significant for practical applications with low-cost configurations of spacecraft. Using a well-chosen Lyapunov-Krasovskii function, it is proven that the presented control law can make the spacecraft formation attitude tracking system synchronous and achieve exponential stability, in the face of model uncertainties, as well as non-uniform time-varying delays in communication links and different control parts. Finally, simulation results are presented to demonstrate the effectiveness of the proposed control schemes.     

Adaptive on-line flux estimation in field-oriented control of an IM

An adaptive technique for the online estimation of the rotor field vector to use as a feedback for the field-oriented control of an induction machine (IM) is described. This method makes use of the stator voltage and rotor speed measurements. It uses the least square estimation technique for identifying the machine parameters to be used in the estimation of the field vector. The position and magnitude of the flux vector are identified during the normal operation of the machine by applying some special constraints to the forcing function. This constraint is applied only for a short duration to make some measurements, and the machine performance is not affected. Extensive simulation of the system has been carried out, and the results are presented     

空间谱估计经典算法性能比较

空间谱估计是阵列信号处理的一个重要研究方向。空间谱估计理论与技术已日趋成熟,近几十年的经典谱估计技术包括：常规波束形成（CBF）、Capon谱估计、多重信号分类（MUSIC）、旋转不变子空间算法（ESPRIT）、最大似然（ML）、子空间拟合（SF）,及这些算法的扩展和变形。上述算法在各个分散的文章中均有具体深入的理论分析和研究,亦有类似的2种或3种算法的性能比较,但是针对这些所有算法的性能比较,就笔者所知尚无公开报道,而使工程实现时对算法的选择没有依据。本文对这些经典算法做了简介,列出各个算法的优缺点,并对性能进行仿真比较,能直观地得到各个算法的性能对比,给工程实现算法选择提供理论依据。     

被动式寻的导弹的运动跟踪变结构制导

应用运动跟踪变结构控制理论设计被动式寻的导弹的制导律。这种运动跟踪变结构制导律（ＭＴＶＳＧ）可以令导弹－目标相对视线角速度按照给定的运动规律变化,从而增强被动跟踪问题（等价于一个非线性系统）的可观性,同时保证导弹有很高的命中精度。仿真研究表明,在ＭＴＶＳＧ下,系统的可观性明显增强,因此系统状态的估计精度较高。进一步的研究表明,ＭＴＶＳＧ对系统状态估计误差有很强的鲁棒性。ＭＴＶＳＧ的上述各种优点使得导弹有很高的命中精度。     

Streamlining measurement iteration for EKF target tracking

The estimation problem is defined, and a review of how the linear estimation approach of Kalman filtering is extrapolated to form an extended Kalman filter (EKF), applicable for state estimation in nonlinear systems is presented. A mechanization of an EKF variation known as an iterated EKF, offering improved tracking performance, is treated. A streamlined version of an iterated EKF that has a lesser computational burden (fewer operations per cycle or time step) than prior formulations is offered. A nonlinear filtering application example, to be used as a testbed for this new approach, is described, and the detailed modeling considerations as needed for exoatmospheric random-variable radar target tracking are discussed. The performance of the streamlined mechanization is illustrated in this radar target tracking example, and comparisons are made with the performance of an EKF without measurement iteration     

Heading and Speed Errors for x, y Tracking Filters

Heading and speed errors are analytically determined for noneumavering targets at the output of an x, y tracking filter which processes range and bearing measurements from a radar sensor in a track-while-scan (TWS) operation. These errors are shown to depend upon target range and speed, the angle between the radius and velocity vectors, sensor accuracies, and tracking filter parameters. eters. Depending upon the tracking filter implementation, these errors may also be a function of target bearing.     

基于健康蜕化的航空发动机传感器故障诊断(英文)

改进在线故障诊断算法使其能适应发动机健康蜕化是目前故障诊断所面临的困难,如果诊断算法没有自适应能力,在发动机健康蜕化后将失去其诊断功能。为了解决此问题,提出在线故障诊断算法,采用跟踪滤波器估计发动机的健康状况,机载模型根据跟踪滤波器的估计结果进行更新。更新后的机载模型能够与真实的发动机相匹配。这使得当发动机健康蜕化后在线故障诊断仍能保持其有效性。最后采用一组卡尔曼滤波器来对航空发动机传感器故障进行诊断与隔离。通过设计好的一组卡尔曼滤波器,能够诊断并隔离出故障。本文使用非线性发动机模型来验证此方法,仿真结果表明本文提出的在线诊断方法在发动机健康蜕化后仍能保持其有效性。     

飞行模拟转台高精度数字重复控制器的设计

从工程的角度讨论了离散重复控制系统的设计,所提出的重复控制方法可保证速度跟踪误差快速收敛为零。在重复控制器中采用了高阶低通滤波器和动态补偿器,改善了跟踪精度,保证了系统的稳定性,减少了周期性扰动误差。将所提出的方法应用于飞行模拟转台伺服系统的速度控制中,仿真结果表明,针对周期指令信号和周期干扰信号可保证较高的跟踪精度和较强的稳定性和鲁棒性。     

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。     

Modified input estimation technique using pseudoresiduals

An adaptive tracking filter for maneuvering targets is proposed using modified input estimation technique. Pseudoresiduals are defined using measurements and the velocity estimate at the hypothesized maneuver onset time. With the pseudoresiduals and a new target model representing transitions of nominal accelerations, a new input estimation method for tracking a maneuvering target is derived. Since the proposed detection technique is more sensitive to maneuvers than previous work, the shorter window length can be employed to detect and compensate target maneuvers. Also shown is that the tracking performance of the proposed filter is similar to that of interacting multiple model method (IMM) with 3 models, while computational loads of our method are drastically reduced     

基于极限学习机的修正当前统计模型跟踪算法

针对当前统计(Current Statistical,CS)模型由于先验知识的缺乏和其结构特点导致的跟踪精度降低的问题,通过使用极限学习机(Extreme Learning Machine,ELM)并根据目标历史状态信息,实时估计并修正CS模型的加速度估计值,提出了基于ELM的修正CS模型跟踪算法.ELM的训练结果表明...     

Three-dimensional target motion analysis using angle and frequency measurements

It is well known that passive target tracking by a single observer, commonly referred to as target motion analysis (TMA), can be done using angle and/or frequency measurements. Depending on the measurement set, different passive tracking procedures result: angle-only tracking (AOT), frequency-only tracking (FOT), and angle/frequency tracking (AFT). Whereas the two-dimensional passive tracking problem has been solved for a multitude of scenarios, thus giving a good insight into the parametric dependences, the three-dimensional problem has been discussed only in a few specific cases. To get a deeper insight into the parametric dependences of three-dimensional TMA, this work analyzes AOT and AFT in typical three-dimensional Airborne Warning and Control System (AWACS) scenarios. A Cramer Rao (CR) analysis of the problem reveals the parametric dependences of both methods and gives a clear idea of the increase in estimation accuracy by using AFT instead of AOT. The results obtained in this way are well confirmed by Monte Carlo simulations taking maximum likelihood (ML) as estimation procedure.     

敏捷卫星的联合执行机构控制策略

 针对对地观测敏捷卫星大角度快速机动、高控制精度的任务需求,提出了联合推力器与飞轮作为执行机构的控制策略。该控制策略综合利用2种执行机构的优点:推力器以前馈的形式提供机动过程中所需的主要力矩以实现航天器大角度的快速机动,而飞轮以反馈的形式提供精准的控制力矩以提高机动过程中的姿态控制精度。为补偿由于初始状态偏差和推力器输出力矩不准确所带来的控制误差,采用变结构控制设计了2种姿态跟踪控制器,使航天器能够渐进地跟踪上参考轨迹。并对姿态机动控制过程中,飞轮力矩及转速可能出现的饱和问题作了相应的修正。仿真结果表明了所提控制策略及所设计控制算法的可行性和有效性。