基于Kullback-Leibler距离的闭环系统传感器微小故障诊断

在闭环控制系统中,当故障幅值较小时,由故障带来的影响会被控制量所掩盖.因此,闭环系统中的微小故障诊断实现更为复杂.本文针对闭环系统中的传感器故障,提出了基于Kullback-Leibler(KL)距离的微小故障在线检测与估计方法.本文首先介绍了KL距离的定义及其在多变量故障检测中的应用,然后提出了结合KL距离与快速移动窗口主成分分析(MWPCA)的在线微小故障检测与估计模型.在高斯分布的假设下,利用系统输入输出残差构造MWPCA的数据矩阵,然后通过在线更新数据矩阵主成分的均值与方差实现KL距离的在线更新,最终实现闭环系统中传感器的在线故障检测与估计.仿真实验表明,该方法能有效实现具有低故障—噪声比(FNR)特性的微小故障诊断.     

核双样检验的连杆摆动光流轨迹混叠去除及补偿

在连杆摆动视觉测量中，针对高速曝光产生的背景噪点对前景光流轨迹混叠及阻断导致配准误差，本文提出了一种新的视频滤波与补偿算法。该算法以背景噪声与前景摆杆光流轨迹不同的运动统计特性作为先验模型，通过核双样假设检验检测光流轨迹速度突变，剪除背景噪点轨迹片段实现去噪。为实现轨迹补偿，首先引入机械连杆铰接点为参照物的相对光流采集方式，将各帧摆杆铰接点配准翘曲至第1帧铰接点位置，将连杆摆动轨迹从复合高阶摆线中分离形成低阶理想圆弧。其次采用Pratt拟合翘曲后的摆杆轨迹的圆心与半径，将轨迹聚类为不同半径的弧状轨迹群。最后，将弧状轨迹群的x-y坐标ν-SVR回归作为几何约束，结合x-t动力学回归半监督学习出完整长度的轨迹。在刮刷总成摆角及共轭凸轮的针床推程位移比较的测量实验表明，该算法比传统VBM3D,MeshFlow等算法准确度可提高3.26%,运算复杂度降低2阶，在机械旋转运动视觉故障诊断及机械仪表数字化采集等方面具有广阔应用前景。     

Link budget calculation in optical LEO satellite downlinks with on/off-keying and large signal divergence: A simplified methodology

Direct-to-Earth transmissions with optical on/off-keying are becoming the method of choice to realize telemetry downlinks from low Earth orbit satellites at highest data-rates. Here, we review the calculation procedure for a practical assessment of the mean link budget in this space-ground data communication technology. We present a comprehensive survey of the dynamic orbital and beam-pointing effects as well as the impacts from atmospheric attenuation on the link performance. The paper provides an exhaustive review of the formulas commonly used and propounds a recipe to reliably estimate the received power on ground. An overview of typical data transmitter terminals, transmission channel parameters, and the according optical ground stations is provided. Comparison with measured received powers over transmitter elevation angle and the respective design estimates serves for verification.