基于UKF的水下航行器IMU故障检测与诊断方法研究

惯性测量单元（IMU）作为水下航行器导航系统关键传感器,其可靠性直接影响航行器的导航性能。为了提高IMU的容错能力,本文提出一种基于无迹卡尔曼滤波（UKF）算法的IMU故障诊断技术。首先根据水下航行器的动力学方程和导航系统特点,建立描述IMU故障与导航状态量关系的解析模型;接着基于UKF非线性滤波的特点,进行导航滤波解算,基于此,提出了解耦矩阵法以实现IMU的故障检测;并且根据无迹卡尔曼滤波器新息正交原理,提出了实时估计IMU故障的方法,从而完成水下航行器IMU故障的在线检测与诊断。最后,通过实际航行数据验证了所提出算法的有效性。     

基于UPF的INS非高斯噪声故障检测

由于实际组合导航系统很可能受到非高斯噪声的影响,而传统的故障检测方法对非高斯噪声情况讨论较少.基于粒子滤波的故障检测技术非常适合处理非线性、非高斯问题,并且有效地克服了传统方法的不足,但是普通的粒子滤波器存在粒子“退化”等问题.为此,本文提出了一种基于UPF滤波器的导航系统故障检测方法,通过在普通粒子滤波中引入UKF产生建议分布及重采样的方法,有效抑制了普通粒子滤波器粒子“退化”的问题.并针对噪声的非高斯特性,将似然检测方法与粒子滤波可以估计似然函数的特点相结合,提出了一种基于UPF的故障检测方法.通过GPS/SINS组合导航系统在噪声服从瑞利分布情况下的故障检测仿真实例,表明此方法适用于在非高斯噪声情况下的导航系统故障检测.     

基于SVR 的惯性/卫星组合导航系统故障诊断方法

在惯性/卫星组合导航系统中, 针对传统X² 检验法检测出故障但无法准确识别故障子系统的不足, 提出一种基于支持向量回归的故障诊断方法. 采用残差X² 检验法实时对组合导航系统进行故障检测, 并构建基于支持向量机的回归预测模型, 实现对惯性导航系统状态的预测; 根据系统模型输出和预测模型输出之差辅助进行惯性导航系统的故障判别, 诊断出系统故障源. 仿真结果表明, 所提出的方法能够快速准确地识别故障子系统, 并进行有效的系统隔离和重构, 从而使组合导航系统的性能得到保障.

     

强跟踪滤波器在卫星紫外导航中的应用研究

对基于紫外敏感器的卫星自主导航方法进行了研究,为了保证卫星紫外导航系统的精度和工作可靠性,要求导航系统具有一定的故障检测和自适应调节能力,并将强跟踪滤波器应用于该导航系统的故障检测中.仿真结果表明:本方案能够获得较高的定轨精度,当系统出现故障时,该方案能够保持对缓变状态和突变状态的强跟踪能力,提高了紫外导航系统的导航精度和工作可靠性.     

组合导航系统故障检测方法的比较研究

对组合导航系统故障检测方法进行了对比研究。除介绍了X^2检验法、数据变化率检验法,还提出了一种基于模糊综合评价的故障检测方法．它以模糊综合评价算法为基础,对组合导航系统中的每个子系统的测量值进行综合判断,以确定该子系统的工作状态。最后,利用GPS／INS组合导航系统对上述三种故障检测方法进行了对比研究。实验结果表明,X^2检验法对于软故障不敏感,数据变化率检验法对连续长时间出现的故障无法判断．而基于模糊综合评价的故障检测方法针对具体的组合导航系统,通过适当调整参数,对所有类型的故障都能很好地检测。     

基于近距无线电导航的容错组合导航系统

针对组合导航子系统的特性,提出了一种基于近距无线电导航的容错组合导航系统方案.给出了完整的无线电导航系统的误差模型.针对残差X2检验和状态X2检验的特点,提出了一种结合状态递推的残差检验法,该方法对软故障的检测能力较强,并采用分量检测法提高故障检测灵敏度,将该算法嵌入到基于局部反馈校正的无重置联邦滤波器中提高导航系统的容错能力.仿真结果表明,融合输出结果不受故障影响且精度高于任一子滤波器导航精度,验证了算法的正确性.     

无人机飞控/导航系统便携式测试仪设计

针对当前某型无人机飞控/导航系统现场联调发生故障时无法快速定位故障点而造成调试周期过长的问题,根据有固定航姿参数输入的飞控/导航系统会产生固定输出的原理,提出并实现了一种基于现场测试仪的快速诊断方法;基于DSP和CPLD的便携式飞控/导航系统测试仪通过实验电缆把测试仪与被测设备相连,可以方便、直观、快捷、可靠地确定出被测设备是否存在故障。     

嵌入式设备故障检测和诊断系统设计

本文分析嵌入式设备的特点,并在此基础上提出充分利用嵌入式设备提供的接口资源,实现故障检测和诊断的方法,将设备故障定位到电路板级,为板级电路的故障检测和诊断奠定基础。此种方法在复杂工程环境下,无需拆卸嵌入式设备即可判断整机性能,达到故障检测和诊断的基本要求。在这一方法基础上,本文以某车载GPS导航系统为被测对象,详细介绍了故障检测和诊断系统设计。     

基于主成分分析和奇偶向量的动态检测方法

导航系统中冗余IMU传统故障检测方法由于数学模型过于复杂,计算量大,存在较大延时,难以实现实时故障检测,而主成分分析法仅仅应用于静态情况下的故障检测与隔离,针对主成分分析法无法在动态情况下对冗余IMU进行故障检测的缺点,提出了一种基于奇偶空间法改进主成分分析的故障检测算法,该方法利用奇偶向量隔离车辆的动态变量,以消除动态变量对故障检测的影响,再用PCA方法检测数据以实现对车辆传感器信息的实时检测,通过将原始数据集转置到特征平面来形成图案,实现了IMU传感器正常与故障模式的准确分离,提高了冗余IMU故障检测的结果精确性和可靠性。实验结果表明,该方法能够较好检测动态状态下冗余IMU的故障,提高了主成分分析的故障检测性能,可有效消除导航系统运动的负面影响。     

基于多假设解分离算法的BDS/SINS紧组合完好性监视

完好性是民航基于性能的导航（PBN）运行的关键性能要求,是导航安全性的重要支撑。北斗导航系统（BDS）/惯性导航系统（SINS）紧组合导航系统将SINS信息加入到完好性监视中,增加了冗余信息,通过多假设解分离算法进行故障卫星的检测与隔离,满足民航特定飞行阶段高完好性要求。论文利用BDS接收机接收到的BDS卫星数据,通过设置飞行轨迹,模拟卫星故障,对BDS/SINS组合导航系统的完好性算法进行测试验证。实验结果表明,基于多假设解分离方法的BDS/SINS紧组合导航系统可以较好地实现故障卫星的检测与隔离,保护限计算符合预期。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.