一种多层次数据融合的SLAM定位算法

针对2D激光SLAM(同步定位和地图构建)机器人导航中激光点云匹配计算量大、轨迹闭合效果差、位姿累积误差大、以及各环节传感器观测数据利用不充分等问题,提出一种基于多层次传感器数据融合的实时定位与建图方法——Multilevel-SLAM.首先,在数据预处理方面,利用IMU(惯性测量单元)数据预积分结果为激光点云配准提供坐标转换依据.对激光点云进行特征采样,降低点云匹配计算量.其次,通过无迹卡尔曼滤波算法融合IMU、LiDAR(激光雷达)观测量得到机器人位姿,来提高闭环检测效果.最后,将激光点云配准约束、闭环约束、IMU预积分约束加入到SLAM算法的后端优化中,对全局地图位姿节点估计提供约束配准,实现多层次的数据融合.在实验中利用LiDAR-IMU公开数据集对Karto-SLAM、Cartographer和Multilevel-SLAM算法进行性能测试对比.Multilevel-SLAM算法的定位精度始终保持在5 cm以内,而对比方法则存在不同程度的定位偏移.实验结果表明,在没有显著增加计算量的前提下,Multilevel-SLAM算法有效提高了闭环处的轨迹闭合效果,具有更低的定位误差.     

基于多传感器融合的双轮差速机器人定位研究

针对单一传感器有一定的误差与使用场景限制的问题,往往需要通过融合滤波技术对多传感器的测量信息进行优势互补。为改善由惯性姿态测量单元(Inertial measurement unit, IMU)与轮式里程计（Wheel Odometry）组成的航迹推算（Dead Reckoning, DR）长期使用时产生不可忽略的积分误差,以及全球定位系统（Global Positioning System, GPS）在遇到信号被遮挡或者干扰的情况下将无法正常工作等情况所引起的问题,本研究结合GPS、IMU、轮式里程计三种传感器对双轮差速机器人进行定位,以起到互补的作用,使其能够适应更加多样化的环境;同时,我们定时使用GPS模块对DR推算位置信息进行修正,并比较IMU互补滤波解算法与DMP解算法,选取效果更好的方案获取机器人欧拉角,最后使用扩展卡尔曼滤波(Extended Kalman Filtering, EKF)算法对传感器数据进行融合处理,得到机器人的最优定位。结果表明,在采用了多传感器融合的方案之后,机器人的定位精确度较之只有单一传感器的方案有了显著的提升。     

基于多传感器融合的移动机器人定位算法研究

针对移动机器人在室外环境下全局位姿定位精度低、定位耗时长的问题,提出一种基于多传感器融合的机器人定位算法。首先构建移动机器人的运动模型,并选用里程计、惯性测量单元IMU和激光雷达作为移动机器人的基础传感器;然后采用自适应蒙特卡罗定位算法对传感器融合位姿进行位姿误差计算,获取移动机器人初始位姿;最后进行激光点云匹配,获取全局地图,并利用基于全局正态分布地图的NDT算法进行初始位姿修正,最终实现全局位姿校正和高精度定位。结果表明,基于多传感器融合的移动机器人定位误差控制在0.04 m范围内,定位时长均值为0.045 s,定位误差较小,定位损耗时间较少。由此说明,本定位算法可提升移动机器人的定位精度和定位效率,可实现移动机器人全局位姿快速、精确定位,提出的定位算法具备一定的有效性。     

多传感器信息融合在移动机器人定位中的应用

机器人自定位是实现自主导航的关键问题之一。为了满足机器人在导航时精确定位的要求,提出一种基于多传感器信息融合的自定位算法。根据对机器人运动机构的分析和运动机构间的刚体约束,建立起机器人的运动学模型;由传感器的工作原理建立里程计和超声波传感器的观测模型;利用扩展卡尔曼滤波(EKF)算法将里程计和超声波传感器采集的数据进行融合;最后,由匹配的环境特征对机器人的位置进行修正,得到精确的位置估计。实验结果表明:该算法明显地消除了里程计的累计误差,有效地提高了定位精度。     

传感器数据融合与单一传感器在同步定位与构图中的对比研究

针对室内环境下单一传感器数据在同步定位与构图中的局限性问题,提出了一种使用模糊贴近度和自适应加权相结合的传感器数据融合方法。首先建立了观测模型,并使用模糊贴近度的方法将Kinect深度摄像头获取的数据和激光雷达数据进行首次融合;然后使用自适应加权的方法对权值系数进行二次加权修正;最后将使用该方法构建的地图与单一传感器构建的地图进行了对比分析。通过实验证明,使用该方法获得的数据更加可靠,获取的地图精确度更高、环境特征表现更加平滑,验证了所提算法的有效性。     

一种自适应残差补偿算法在移动机器人姿态估计中的应用研究

针对两轮移动机器人MEMS IMU姿态估计的数据融合问题,提出一种以卡尔曼滤波为基础的自适应残差补偿算法。该算法结合惯性传感器误差模型与移动机器人姿态模型构建卡尔曼滤波器,利用卡尔曼滤波量测更新的加速度残差自适应补偿非重力载体位移加速度对姿态估计的影响。实验结果表明,该算法有效的融合了MEMS IMU姿态测量数据,抑制了传感器随机漂移误差,同时自适应补偿了非重力载体位移加速度。     

基于改进MSCKF算法的室内机器人定位方法

针对传统多状态约束卡尔曼滤波算法(MSCKF)在实现机器人室内定位时,速度和位置状态方程需要对IMU中加速度计的测量数据进行积分,存在漂移和累计误差,且加速度计受重力干扰问题,本文提出改进MSCKF算法.改进MSCKF算法避免使用加速度计传感器,利用轮式里程计传感器对平移测量较为精确的优点,将IMU中陀螺仪和轮式里程计的数据进行融合,改进MSCKF算法的扩展卡尔曼(EKF)状态方程.首先利用陀螺仪传感器的角速度数据得到改进EKF姿态方程,然后利用轮式里程计传感器的平移数据,结合姿态方程中的旋转信息得到改进EKF速度和位置方程.最后在机器人操作系统(ROS)上实现MSCKF及其改进算法,并结合Turtlebot2机器人在室内进行实验验证.实验结果表明,改进MSCKF算法的运动轨迹更接近于真实轨迹,定位精度较改进前所有提高,改进前平均闭环误差是0.429 m,改进后平均闭环误差是0.348 m.     

基于多传感信息融合的儿童教育机器人研究

针对当前儿童教育机器人地图构建、定位和路径规划效果不佳的问题,提出基于运动模型和观测模型融合的儿童教育机器人。通过改进RBPF-SLAM定位算法,实现地图构建和准确定位,利用混合路径规划算法实现全局寻优。实验结果表明,改进的RBPF-SLAM定位算法计算结果更接近于真实状态值,比改进前的算法更精确,算法性能更佳。且提出的混合路径规划算法可在复杂环境下找出最佳路径,由此可知,巡检机器人可实现地图构建和路径规划。     

基于集员滤波的双Kinect人体关节点数据融合

以Kinect为代表的深度图像传感器在肢体康复系统中得到广泛应用.单一深度图像传感器采集人体关节点数据时由于肢体遮挡、传感器数据错误和丢失等原因降低系统可靠性.本文研究了利用两台Kinect深度图像传感器进行数据融合从而达到消除遮挡、数据错误和丢失的目的,提高康复系统中数据的稳定性和可靠性.首先,利用两台Kinect采集患者健康侧手臂运动数据;其次,对两组数据做时间对准、Bursa线性模型下的坐标变换和基于集员滤波的数据融合;再次,将融合后的健康侧手臂运动数据经过“镜像运动”作为患侧手臂运动指令;最后,将患侧运动指令下发给可穿戴式镜像康复外骨骼带动患者患侧手臂完成三维动画提示的康复动作,达到患者主动可控康复的目的.本文通过Kinect与VICON系统联合实验以及7自由度机械臂控制实验验证了数据融合方法的有效性,以及两台Kinect可有效解决上述问题.     

基于Kinect的仿人机器人控制系统

为实现对具有16个自由度仿人机器人的姿态控制,采用Kinect传感器对人体姿态的坐标数据进行采集,根据坐标信息利用Processing软件开发基于SimpleOpenNI库的上位机软件,建立人体关节模型,并利用空间向量法对仿人机器人的步态规划以及重心控制算法分析,解析各关节的转动角度,经由无线WiFi模块向仿人机器人发送指令以控制舵机的运动,最终实现对机器人的控制,搭建了基于Kinect传感器的测试平台.测试结果表明:仿人机器人上肢在运动范围内无死角,通过对重心的控制,下肢可实现简单的步行,符合预期效果.     

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.