一种面向临近空间高超声速再入滑翔目标跟踪算法

针对临近空间高超声速再入滑翔目标的跟踪问题,提出了一种基于回顾成本输入估计的无偏转换量测卡尔曼滤波(Retrospective cost input estimation-unbiased converted measurements Kalman filter, RCIE-UCMKF)。首先,根据再入滑翔目标的飞行特性,将加速度看成是未知的确定输入构建运动学跟踪模型;然后,对目标的非线性量测信息进行无偏转换,并将得到的噪声协方差矩阵进行解耦,降低算法的复杂度;最后,利用回顾成本的输入估计对未知加速度进行重构,采用递推最小二乘法更新输入估计器的参数矩阵,同时将估计的加速度引入到卡尔曼滤波框架下,实现对高超声速再入滑翔目标状态的准确估计。仿真结果表明了该算法的有效性和可行性。     

基于角度分集的机载超宽带MIMO天线设计

为了提高机载通信设备信道容量和进一步减小天线安装空间,提出一种采用角度分集技术的超宽带（UWB）多输入多输出（MIMO）天线。该天线将Vivaldi天线和超宽带槽天线进行了集成设计,无需采用解耦结构便可获得较高的端口隔离度,大大提高了数据传输率。通过在Vivaldi天线辐射臂上开一对方形缝隙和在介质板背面增加长方形辐射贴片,可以有效减小天线的尺寸,设计的UWB-MIMO天线尺寸为36 mm×36 mm×0.8 mm。给出了天线的设计流程,加工了天线实物,并对其进行了测量。仿真和实测结果表明MIMO天线具有超宽的阻抗带宽,可以覆盖整个3.1~10.6 GHz超宽带频段。Vivaldi天线阻抗带宽为2.8~15.9 GHz,UWB槽天线阻抗带宽为1.8~12.7 GHz,天线端口隔离度均在-10 dB以下。测量了天线的辐射性能和增益特性,实测结果与仿真结果吻合较好,证明了该天线的有效性。该天线可以应用于超宽带无线通信系统和机载阵列天线系统中。     

带有引诱角色的有限时间协同制导方法

为实现高价值飞行器的有效突防,采用突防飞行器携带一枚防御器的协同突防方案,在突防器作为引诱角色的情况下,基于有限时间控制理论提出了一种带有拦截角约束的协同制导方法。基于飞行器相对运动学方程和一阶动力学特性,建立了带有拦截角约束的协同反拦截模型;用度量矩阵刻画系统有限时间输入输出动态品质,基于微分线性矩阵不等式给出了有限时间状态反馈控制器设计方法。数学仿真表明,该方法能够确保防御器在有限时间内以预置的拦截角有效拦截对方拦截器;在突防器进行引诱配合的情况下,协同突防方案能够大幅节省防御器需用加速度,验证了协同制导方法的有效性;同时,所提制导方法在不同拦截角度和初始发射条件下都能达到较好的控制效果,表现出较强的鲁棒性。     

Robust H∞ controller design for attitude stabilization of flexible spacecraft with input constraints

This paper addresses the attitude stabilization and vibration suppression problem for flexible spacecraft subject to model parameter uncertainty, controller perturbations, external disturbances and input constraints. The attitude model of flexible spacecraft is described and converted into a state space form in terms of passive and active vibration suppression schemes. A novel state feedback controller is proposed based on the exactly available expectation of a new variable, which is introduced to model a randomly occurring controller gain perturbation. Based on Lyapunov stability theory, sufficient conditions for the existence of the nonfragile H_∞ controller considering input constraints are given based on linear matrix inequalities (LMIs) in terms of additive perturbation and multiplicative perturbation. Then, the developed controller subject to required constraints can be obtained, where the nonfragile property is fully considered to improve the tolerance to uncertainties in the controller. Numerical simulations are performed to demonstrate the effectiveness and superiority of the proposed control strategy in attitude stabilization and vibration suppression, where it should be noted that the passive vibration suppression scheme is superior for high natural frequencies while the active vibration suppression scheme is superior for low natural frequencies. Moreover, the low natural frequencies have more influence on the performance of attitude stabilization and vibration suppression.     

Adaptive fuzzy neural network control for a space manipulator in the presence of output constraints and input nonlinearities

Space manipulator is considered as one of the most promising technologies for future space activities owing to its important role in various on-orbit serving missions. In this paper, a novel adaptive fuzzy neural network (FNN) control scheme is proposed for the trajectory tracking control of an attitude-controlled free-flying space manipulator in the presence of output constraints and input nonlinearities. The parametric uncertainties and external disturbances are also taken into the consideration. First, a model-based controller is designed by using the barrier Lyapunov function (BLF) to prevent the position tracking errors from violating the predefined output constraints. Then, an adaptive FNN controller is designed by using two FNNs to compensate for the lumped uncertainties and input nonlinearities, respectively. Rigorous theoretical analysis for the semiglobal uniform ultimate boundedness of the whole closed-loop system is provided. The proposed adaptive FNN controller can guarantee the position and velocity tracking errors converge to the small neighborhoods about zero, while ensuring the position tracking errors within the output constraints even in the presence of input nonlinearities. To the best of the authors’ knowledge, there are relatively few existing controllers can achieve such excellent control performance in the same conditions. Numerical simulations illustrate the effectiveness and superiority of the proposed control scheme.     

无速度测量下的航天器安全接近位姿一体化控制

针对考虑位姿耦合的非合作航天器交会对接场景,在没有速度测量情况下为了同时解决安全约束、模型不确定性、执行器故障和输入饱和问题,提出一种基于容积卡尔曼滤波算法(CKF)的自主安全接近方法。首先基于容积卡尔曼滤波器和扩张状态观测器(ESO)分别估计目标航天器的位姿信息和相对速度信息;然后通过将一种新颖的安全包络与人工势函数(APF)结合设计自适应滑模控制器,并设计非奇异辅助系统对执行器故障和输入饱和带来的影响进行集中处理。提出的控制策略在不违反安全约束情况下,能在固定时间内实现位置接近和姿态同步。通过李雅普诺夫方法可以保证闭环系统固定时间稳定。仿真结果表明,所提控制方法具有较高的精度和良好干扰抑制能力。     

直流电源输出阻抗测量技术

直流电源输出阻抗是新的特性参数,一些电源产品开始把它列入技术指标手册中。本文分析了电源阻抗的定义,总结了电源阻抗的特点,综述了当前电源阻抗测量技术的现状,提出了基于数字电桥的一种测量方法,提出了直流电源阻抗测量中的技术难点和尚待解决的技术问题。     

减压器启动冲击解决方案

为消除运载火箭上面级高压贮气增压系统启动过程中对减压器的冲击,提出在减压器前增设限流阀的简易方案。基于减压器启动冲击形成机理,给出了限流阀的设计和结构。结果表明：增加限流阀后,减压器入口压力建立时间推迟,出口压力降低,启动冲击被有效抑制,且稳态工作时限流阀的前后压力基本相同,减压器正常工作不受影响。     

利用OH夜气辉反演原子氧数密度时输入参数的不确定度对反演结果的影响

借助OH夜气辉辐射的光化学模式,由OH夜气辉辐射反演中间层-低热层区域的原子氧数密度时,输入参数的不确定性将导致反演得到的原子氧数密度具有不确定性.以在sudden death猝灭模式下通过OH(8-3)振动带体辐射率反演原子氧数密度为例,分别研究了大气参数和OH气辉辐射率的不确定度引起的反演不确定度、化学反应速率常数的不确定度引起的反演不确定度,以及所有输入参数的不确定度共同引起的反演不确定度,找出其不确定度对反演结果影响最大的参数.结果表明,三种反演不确定度均随着高度的升高而增大,温度和体辐射率的不确定度对第一种反演不确定度的贡献最大,反应速率常数b(8)和A(8-3)、的不确定度对第二种反演不确定度的贡献最大.     

船载遥测接收信道门限特性的研究

对船载遥测接收信道一项最重要的传输特性———门限特性进行理论分析,并指出门限特性对执行测控任务和设备性能检测的特殊意义。首先阐述门限效应产生的本质即增加传输带宽是在恶化输入信噪比的前提下提高输出信噪比,输入信噪比的域值即为门限。结合各种不同的船载遥测信道门限输入信噪比,提出统一的、具有普遍意义的标定方法:即调制度定标和载波信噪比的标定。根据信道本底噪声的不同,又分为射频有线和无线两种测试方式,给出了详细的测试过程和步骤。最后还分析双模环电路由于实现了载波的动态跟踪而能显著降低门限效应。