含无序量测的多传感器信息融合算法研究

由于通信时间的延迟性,在多传感器系统中常常会出现无序量测情况.为提高估计的精度,系统须对无序量测进行处理,状态更新法是处理无序量测问题的一种有效方法.对于多传感器信息融合问题,给出了一种处理无序量测的状态估计更新算法.仿真计算表明该算法能有效的提高融合估计的精度.     

基于选择融合的任意步滞后无序量测滤波算法

在目标跟踪系统中,由于传感器具有不同的预处理时间与采样速率,以及信道固有的随机通信延迟,传感器量测数据可能出现无序到达融合中心的现象,即无序量测问题。在系统工作过程中,通常有多个无序量测相继或同时出现。为此,将多无序量测情形进行分类,基于选择融合提出任意步滞后无序量测滤波算法。利用基于对数似然比的假设检验筛选出需要处理的无序量测。在前向预测框架内,根据无序量测最优滤波过程,采用融入等价量测的信息滤波方法对目标状态估计与误差协方差矩阵进行更新。仿真结果验证了算法的精确性与有效性。     

加权融合法处理无序量测问题

针对集中式多传感器目标跟踪系统中存在的无序量测问题,基于协方差加权融合的思想,在融合估计误差协方差矩阵迹最小意义下,建立了基于最优融合的多步延迟无序量测更新算法。该算法先将无序量测配准到最新状态估计的时刻,将其与之进行协方差加权融合。为进行无序量测与各传感器量测噪声相关性的计算,引入了等效量测。通过理论分析和仿真实验说明该算法能有效处理无序量测多延迟问题,其性能接近最优且随延迟步数增加性能下降非常小,而且有与最优的数据缓存法相同的滤波精度,以及较小的额外存储量。     

噪声相关的一步滞后无序量测递推融合算法

因传感器网络特殊的通信方式,以及传感器节点预处理量测的时间也各有不同,常会出现源于同一目标有序的测量数据却经网络传输后无序地到达融合中心的现象,即无序量测问题.加之,现有的相关融合算法大都是在各量测数据间噪声独立情况下建立的.为此,针对一个由多个子系统组成的传感器网络无序量测系统;其中假定每个子系统均是由两个分别与融合中心同步与异步且采样率相同的传感器组成;并在考虑各传感器测量噪声相关条件下,利用顺序加权融合技术,在融合中心建立一个能实现对目标状态实时估计且在线性最小均方误差意义下最优的递推加权融合算法.理论分析与计算机仿真表明,与现有方法相比,新算法在适用范围、实时处理能力、存储量和融合估计精度等方面均有显著的优势.     

粒子滤波的噪声相关下单步延迟无序量测更新算法

在目标跟踪系统中,因通信延迟等原因会出现传感器量测无序地到达融合中心的现象,将这些量测称为无序量测(OOSM).针对过程噪声、量测噪声相关的非线性系统中出现的无序量测问题,在现有算法基础上,提出了一种可处理单步延迟无序量测的新算法.在前向预测滤波框架下,对系统方程去相关化,并利用粒子滤波(PF)进行状态估计.仿真结果验证了算法的有效性.     

基于模糊熵的多传感器加权融合算法

针对目前多传感器数据融合时,各传感器的权值难以确定的问题,结合模糊理论,提出一种基于模糊熵的多传感器加权融合算法.该算法不需要任何的环境先验信息和传感器参数信息,根据各个传感器的当前有效量测数据的模糊程度不同,通过求取实时有效量测集合的模糊熵来确定该传感器在融合时的权值.仿真实验证明:该算法具有很好的环境适应能力,可以在一定程度上提高量测精度.     

量测不确定下多传感器交互式多模型自适应滤波算法

针对量测不确定下多传感器多模型混合系统中量测信息的有效利用和融合问题,给出了一种多传感器交互式多模型自适应滤波算法.采用交互式多模型机制实现目标运动模式的确认;通过计算每个传感器的量测似然度完成对于不含扰动传感器量测数据的选取;利用传感器量测数据间统计距离的构建实现对于量测系统中剩余传感器量测数据是否包含扰动影响的判定,并在此基础上实现传感器量测数据的合理选取和融合.新算法量测不确定下扰动对于滤波精度的不利影响.理论分析和仿真实验验证了算法的有效性.     

无序量测问题研究综述

无序量测（OoSM）是多传感器融合系统亟需解决的不可回避的问题.在总结相关文献基础上,对OoSM进行了分类,从单步延时OoSM滤波、多步延时OoSM滤波、多个OoSM滤波、非线性非高斯条件OoSM粒子滤波算法、杂波/机动目标条件OoSM跟踪算法等方面,按照由简单到复杂的研究路线综述了国外开展的相关研究,并对未来研究方向进行了探讨与展望.     

基于粒子滤波和检测信息的多传感器融合跟踪

从概率角度审视低检测率、低信噪比下的多传感器融合算法.首先建立传感器检测概率模型，然后计算传感器检测响应、量测信息的融合似然度，在贝叶斯框架下建立一种非线性目标基于粒子滤波器的多传感器多源信息融合算法，该算法融合了传感器的量测信息和检测响应，提高了跟踪精度蒙特卡洛仿真结果表明了算法的有效性.     

基于UT变换的单步滞后无序量测算法

针对滞后无序量测((OOSM)的单步滞后滤波问题,在现有算法的基础上,推导非线性单步滞后无序量测更新方程.提出用UT变换来计算其中涉及到的状态向量以及相关量测之间的协方差,从而有效解决了状态转移方程为线性而量测方程为非线性的非线性Gauss系统的单步滞后OOSM问题.然后,针对多传感器单步滞后OOSM情况,给出了基于U...     

Enhanced maximum likelihood grid map with reprocessing incorrect sonar measurements

In this paper, we address the problem of building a grid map as accurately as possible using inexpensive and error-prone sonar sensors. In this research area, incorrect sonar measurements, which fail to detect the nearest obstacle in their beamwidth, generally have been dealt with in the same manner as correct measurements or have been excluded from the mapping. In the former case, the map quality may be severely degraded. In the latter case, the resulting map may have insufficient information after the incorrect measurements are removed because only correct measurements are frequently insufficient to cover the whole environment. We propose an efficient grid-mapping approach that incorporates incorrect measurements in a specialized manner to build a better map; we call this the enhanced maximum likelihood (eML) approach. The eML approach fuses the correct and incorrect measurements into a map based on sub-maps generated from each set of measurements. We also propose the maximal sound pressure (mSP) method to detect incorrect sonar readings using the sound pressure of the waves from sonar sensors. In several indoor experiments, integrating the eML approach with the mSP method achieved the best results in terms of map quality among various mapping approaches. We call this the maximum likelihood based on sub-maps (MLS) approach. The MLS map created using only two sonar sensors exhibited similar accuracy to the reference map, which was an accurate representation of the environment.     

快速路交通事件自动检测系统及算法

交通事件是引发快速路交通延误的主要因素，检测交通事件并采取有效的救援措施是快速路交通管理与控制的重要组成部分；首先对交通事件自动检测系统的组成及运行流程进行了介绍，在此基础上，对交通事件数据采集中使用的检测器进行了比较分析，对各种检测器的使用性能及所能检测的交通参数进行了评述，提出了检测器的选用原则；阐述了事件检测算法的性能评价指标，对比分析了各种自动检测算法，指出了各自的不足之处及适用范围；最后对未来的研究方向进行了展望。     

Detection principles and development of microfluidic sensors in the last decade

Microfluidic sensor converts a physical quantity to useful signal with the help of microfluidic platform. Microfluidic sensors have got a wide attention in the last decade because of the increased demands from the automation and control in microsystems. This review on microfluidic sensors focuses on various types of sensors which have been developed for the microfluidic systems or applications based on the research contributions in the last decade. We start with a detailed comparison on the research developments in the last decade on microfluidic sensors with the help of year and country wise statistical charts on published works in the area. The review continues with the basics of microfluidic sensors and the working principles of microfluidic sensors by classifying various microfluidic sensors based on the parameter to be sensed. This review concludes with the attempt to provide an idea on research gap in the area of microfluidic sensors.     

Driving situation recognition with uncertainty management and rule-based systems

The recognition of a temporal sequence is a complex problem, especially in the framework of driving situations. However, this recognition is essential for the development of driving assistance systems. This paper presents a rule-based system that manages the real-time measurements got from sensors of an experimental vehicle, in order to determine the current possible maneuvers worked out by the driver. The particularity of the proposed system is that it manages the inaccuracy of the data and the uncertainty of the recognition, using fuzzy subsets and beliefs on hypotheses.     

Fiber optic humidity sensors for high-energy physics applications at CERN

This work is devoted to a feasibility analysis for the development of novel fiber optic humidity sensors to be applied in high-energy physics (HEP) applications and in particular in experiments actually running at the European Organization for Nuclear Research (CERN). On this line of argument and due to the wide investigations carried out in the last years aimed to assess the radiation hardness capability of fiber optic technology in high energy physics environments, our multidisciplinary research group has been recently engaged in the development of near-field fiber optic sensors based on particle layers of tin dioxide to perform the monitoring of low values of relative humidity RH even at low temperatures.While this sensor type has been successfully employed for ppm and sub-ppm chemical detection in air and water environments, it is the first reported use for relative humidity measurements.The RH sensing performance of fabricated probes was analyzed during a deep experimental campaign carried out in the laboratories of CERN, in Genève. A very good agreement was observed between humidity measurements provided by the optical fiber sensors and commercial polymer-based hygrometers at 20 °C and 0 °C, with limits of detection for low RH regimes below 0.1%.     

MIS sensors for hydrogen content measurements in 10?4–102 volume percent range

New types of MIS (metal-insulator-semiconductor) sensors enabling direct measurements of hydrogen content in a wider range (up to 10 vol %) are developed. Using these sensors with special sampling techniques allows to measure hydrogen content up to 100 vol %. New class of hydrogen analyzers for various applications in hydrogen power engineering could be designed on the basis of new MIS sensors.     

Effect of micro-electrode geometry on NO2 gas-sensing characteristics of one-dimensional tin dioxide nanostructure microsensors

Electrodes with micro-gaps are fabricated by using dc-sputtering and FIB techniques. SnO₂ nanowires are deposited on the micro-gap (1-30 μm) by suspension dropping method to fabricate a micro-gas sensor. The sensing ability of various SnO₂ micro-gap sensors is measured. A comparison between sensors reveals that the short-gap electrode has numerous advantages in terms of reliability, high sensitivity and detection of low concentrations of NO₂, while the large-gap electrode is relatively sensitive for high concentrations. Conductance measurements are carried out at different surface temperatures and NO₂ concentrations in order to investigate the effects that the gap size has on the overall sensor conductance. The results suggest that the interface between the electrode and sensitive layer has a very important role for the sensing mechanism of tin dioxide gas sensors.     

具有多传感器的CPS系统的攻击检测

信息物理系统（cyber-physical systems，简称CPS）是基于环境感知实现计算、通信与物理元素紧密结合的下一代智能系统，广泛应用于安全攸关的系统和工业控制等领域.信息技术与物理世界的相互作用使得CPS容易受到各种恶意攻击，从而破坏其安全性.主要研究存在瞬态故障的CPS中传感器的攻击检测问题.考虑具有多个传感器测量相同物理变量的系统，其中一些传感器可能受到恶意攻击并提供错误的测量.此外，使用抽象传感器模型，每个传感器为控制器提供一个真实值的可能间隔.已有的用于检测传感器被恶意攻击的方法是保守的.当专业攻击者在一段时间内轻微地或不频繁地操纵传感器的输出时，现有方法很难捕获到攻击，如隐身攻击.为了解决这个问题，设计了一种基于融合间隔和历史测量的传感器攻击检测方法.该方法首先为不同的传感器构建不同的故障模型，使用系统动力学方程把历史测量融入到攻击检测方法中，从不同的方面分析传感器的测量.另外，利用历史测量和融合间隔解决了两个传感器的测量相交时是否存在故障的问题.该方法的核心思想是利用传感器之间的成对不一致关系检测和识别攻击.从EV3地面车辆上获得真实的测量数据来验证算法的性能.实验结果表明，所提出的方法优于现有方法，对各种攻击类型都有较好的检测和识别性能，特别是对于隐身攻击，检测率和识别率大约提高了90%以上.     

Manufacture of robust surface plasmon resonance fiber optic based dip-probes

Surface plasmon resonance (SPR) spectroscopy has been conducted on both prism and fiber optic (FO) based sensors for several years. This technique measures the refractive index (RI) of a solution or layer adsorbed to a thin (50 nm) Au layer on the sensor substrate. To date a succinct set of protocols have not been published regarding the optimization of fiber-based SPR dip-probe sensors. Such sensors would allow application of SPR to a wider variety of applications. This paper focuses on consideration of the choice of fiber, isolation of the mirror from the sensing area, and orientation of the probes in the metal layer sputter deposition chamber in the manufacture of SPR dip-probes for reproducibility and robustness. Optimization of the process yields sensors with a batch to batch reproducibility as low as 0.5 nm in the location of the SPR spectral minima. Further study of RI measurements by the same probe over 2 months show these SPR dip-probes have a long shelf-life. A selection of probes was exposed to various solutions to monitor their drift. The data shows the probes’ response indicated a lowering of the RI measured over a period of 3 or 7 days depending on the probe type. Evidence of surface porosity and damage upon exposure to hydrothermal water seems to indicate these sensors are prone to chemical attack. Further research is needed to characterize this attack and allow creation of more robust sensors.     

Pedestrian Detection via Periodic Motion Analysis

We describe algorithms for detecting pedestrians in videos acquired by infrared (and color) sensors. Two approaches are proposed based on gait. The first employs computationally efficient periodicity measurements. Unlike other methods, it estimates a periodic motion frequency using two cascading hypothesis testing steps to filter out non-cyclic pixels so that it works well for both radial and lateral walking directions. The extraction of the period is efficient and robust with respect to sensor noise and cluttered background. In order to integrate shape and motion, we convert the cyclic pattern into a binary sequence by Maximal Principal Gait Angle (MPGA) fitting in the second method. It does not require alignment and continuously estimates the period using a Phase-locked Loop. Both methods are evaluated by experimental results that measure performance as a function of size, movement direction, frame rate and sequence length.