UHF-RFID环境下的移动机器人定位方法

研究UHF-RFID环境中移动机器人的定位问题,提出一种基于自适应UKF滤波器组的移动机器人定位方法,融合UHF-RFID和机器人内部传感器信息,以实现初始位姿未知的移动机器人定位.首先,利用UHF-RFID系统对移动机器人进行初始定位,并根据其初始位置信息随机生成移动机器人的初始状态估计集;然后,考虑UHF-RFID系统定位的量化误差,应用自适应UKF方法对机器人的状态估计集进行预测和更新,并对状态估计集进行有效地裁剪、筛选以及更新,以提高滤波器的估计精度和稳定性.仿真结果表明,相比于标准UKF滤波方法,自适应UKF滤波器组方法具有更高的定位精度和更快的收敛速度.     

基于改进UKF算法的移动机器人定位方法研究

针对移动机器人在多传感器融合定位过程中因噪声统计特性未知或不准确引起的定位精度不高的问题,提出了一种基于Sage-Husa滤波改进的无损卡尔曼滤波(UKF)移动机器人定位算法。首先建立了移动机器人定位相关模型;然后根据噪声统计特性时变特点利用Sage-Husa中的噪声估计器,对状态噪声和量测噪声进行自适应地估计,减小扰动噪声给定位解算带来的误差;接着在状态更新时引入收敛因子,加快算法收敛速度;最后将UKF算法和改进的UKF算法应用到实验室移动机器人中进行仿真实验。实验结果表明,所提出的算法对状态扰动具有较强的抵制能力,对机器人定位的准确性与稳定性的提升具有显著效果。     

一种融合稀疏几何特征与深度流的深度视觉SLAM算法

为了克服移动机器人在视觉退化场景下的位姿估计问题,通过将稠密的深度流与稀疏几何特征相结合,提出了一种实时、鲁棒和低漂移的深度视觉SLAM(同时定位与地图构建)算法.该算法主要由3个优化层组成,基于深度流的视觉里程计层、基于ICP(迭代最近点)的位姿优化层和基于位姿图的优化层.基于深度流的视觉里程计层通过建立深度变化约束方程实现相机帧间快速的6自由度位姿估计;基于ICP的位姿优化层通过构建局部地图来消除局部漂移;基于位姿图的优化层从深度信息中提取、匹配稀疏几何特征,从而建立闭环约束并通过位姿图来实现全局位姿优化.对本文所提出的算法分别在TUM数据集和实际场景中进行了性能测试.实验结果表明本文的前端算法的性能优于当前深度视觉主流算法,后端算法可以较为鲁棒地建立闭环约束并消除前端位姿估计所产生的全局漂移.     

一种用于移动机器人状态和参数估计的自适应UKF算法

为了提高 UKF 的估计精度和收敛性, 提出了一种新的自适应滤波方法. 新息方差阵的测量值和其相应的估计/预测值的差被用于构造指标函数. MIT 规则被用于构造自适应机制以指标函数最小来在线更新过程不确定性的方差值. 更新后的方差反馈给常规 UKF. 这种自适应机制主要用于补偿过程噪声分布的先验信息不足以及提高 UKF 状态和参数的主动估计性能. 讨论了自适应 UKF 的渐进稳定性. 在全方位移动机器人上进行了仿真, 结果表明与常规的 UKF 相比自适应 UKF 更有效更精确.     

面向室内动态环境的半直接法RGB-D SLAM算法

为了解决室内动态环境下移动机器人的准确定位问题,提出了一种融合运动检测算法的半直接法RGB-D视觉SLAM(同时定位与地图创建)算法,它由运动检测、相机位姿估计、基于TSDF (truncated signed distance function)模型的稠密地图构建3个步骤组成.首先,通过最小化图像光度误差,利用稀疏图像对齐算法实现对相机位姿的初步估计.然后,使用视觉里程计的位姿估计对图像进行运动补偿,建立基于图像块实时更新的高斯模型,依据方差变化分割出图像中的运动物体,进而剔除投影在图像运动区域的局部地图点,通过最小化重投影误差对相机位姿进行进一步优化,提升相机位姿估计精度.最后,使用相机位姿和RGB-D相机图像信息构建TSDF稠密地图,利用图像运动检测结果和地图体素块的颜色变化,完成地图在动态环境下的实时更新.实验结果表明,在室内动态环境下,本文算法能够有效提高相机位姿估计精度,实现稠密地图的实时更新,在提升系统鲁棒性的同时也提升了环境重构的准确性.     

室内环境下基于平面与线段特征的RGB-D视觉里程计

针对室内环境的结构特点,提出一种使用平面与线段特征的RGB-D视觉里程计算法．首先根据RGB-D扫描点的法向量对3D点云进行聚类,并使用随机抽样一致（RANSAC）算法对每簇3D点集进行平面拟合,抽取出环境中的平面特征;随后利用边缘点检测算法分割出环境中的边缘点集,并提取出环境中的线段特征;然后提出一种基于平面与线段几何约束的特征匹配算法,完成特征之间的匹配．在平面与线段特征匹配结果能提供充足的位姿约束的条件下,利用特征之间的匹配关系直接求解RGB-D相机的位姿;若不能,则利用匹配线段的端点以及线段点集来实现RGB-D相机位姿的估计．在TUM公开数据集中的实验证明了选择平面与线段作为环境特征可以提升视觉里程计估计和环境建图的精度．特别是在fr3/cabinet数据集中,本文算法的旋转、平移的均方根误差分别为2.046°/s、0.034m/s,要显著优于其他经典的视觉里程计算法．最终将本文系统应用到实际的移动机器人室内建图中,系统可以建立准确的环境地图,且系统运行速度可以达到3帧/s,满足实时处理的要求．     

动态环境下结合实例分割与聚类的鲁棒RGB-D SLAM系统

视觉同步定位与建图（VSLAM）技术常常用于室内机器人的导航与感知,然而VSLAM的位姿估算方法是针对静态环境的,当场景中存在运动对象时,可能会导致定位和建图失败。针对此问题,提出了一个结合实例分割与聚类的VSLAM系统。所提系统使用实例分割网络生成场景中动态对象的概率掩膜,同时利用多视图几何的方法检测场景中的动态点,并将检测到的动态点与获得的概率掩膜匹配之后确定动态物体的精确动态掩膜;利用动态掩膜删除动态物体的特征点,然后利用剩余的静态特征点准确估计摄像机的位置。为了解决实例分割网络欠分割的问题,采用深度填充算法和聚类算法保证动态特征点完全删除。最后,重建图片被动态物体遮挡的背景,在正确的相机位姿下建立静态稠密点云地图。在公开的TUM(Technical University of Munich)数据集上的实验结果表明,在动态环境中,所提系统在保证实时性的同时能实现鲁棒的定位与建图。     

改进ORB特征的机器人RGB-D SLAM算法

基于特征的视觉同时定位与地图构建（Simultaneous Localization and Mapping，SLAM）存在实时性和鲁棒性差等问题，提出一种改进的基于四叉树的ORB特征提取方法，设计包含前后端及地图构建的机器人RGB-D SLAM算法。在前端使用四叉树方法完成ORB特征的均匀提取，计算描述子间汉明距离实现特征匹配。根据随机采样一致性算法思想，结合EPNP（Efficient Perspective-N-Point）和迭代最近点法求解位姿，获取多次迭代后的准确位姿。采用关键帧进行回环检测，并且基于光速法平差优化位姿图，从而构建全局一致的3D地图，达到减少累积误差的目的。通过TUM数据集和多履带式全向移动机器人进行对比验证，实验结果满足实时性和稳定性要求，证明了算法的可行性和有效性。     

用于移动机器人自定位的视觉路标设计

为了实现室内移动机器人的自定位,提出了一种简易美观的新型视觉人工路标以及基于对数极坐标系投影直方图的路标识别方法,并用基于共面四点的位姿估计算法计算机器人位姿.实验结果说明,路标检测具有很高的鲁棒性;路标识别方法抗噪声和形变的能力强;位姿精度足够满足室内移动机器人自定位的需要.     

基于改进闭环检测算法的视觉同时定位与地图构建

针对视觉同时定位与地图构建（SLAM）中容易由误差累积导致构建地图不一致的问题,提出了一种基于改进闭环检测算法的视觉SLAM（V-SLAM）系统。为了减小移动机器人长时间运行带来的累计误差,引入一种改进的闭环检测算法,改进相似性得分函数,减小感知歧义,提高闭环的识别率;同时为了减小计算量,通过Kinect直接获取环境图像以及深度信息,并采用计算量小、鲁棒性好的ORB特征进行特征提取和匹配;采用随机抽样一致性（RANSAC）算法进行误匹配删除,从而获得更准确的匹配点对,然后用PnP计算出相机位姿;更稳定、准确的初始估计位姿对后端处理至关重要,利用g2o对位姿进行无结构的迭代优化;最后在后端采用以集束调整（BA）为核心的图优化方法对位姿和路标进行优化。最终实验结果表明该系统能够满足实时性要求,并可以获得更加准确的位姿估计。     

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.