机器人视觉定位中的路口场景识别方法研究

针对室外巡逻机器人的视觉定位问题,提出了一种基于尺度不变特性变换(scale invariant feature transform,SIFT)和颜色特征的路口场景识别方法.该方法首先提取路口场景图像的SIFT和颜色特征,并计算其在HSI颜色空间中的颜色直方图;然后采用K-D树和Bhattacharyya距离进行特征匹配;最终用决策公式对路口场景进行识别.为了提高SIFT算法进行场景匹配时的速度,还对场景地图库采用基于阈值分割的聚类方法进行了预处理.实验结果表明,该方法对环境光照变化、动态干扰和自身旋转有较强的鲁棒性,并能很好地识别出路1:3,以实现定位.     

基于OpenCV的遥操作工程机器人双目视觉定位技术

针对当前遥操作工程机器人双目视觉定位技术匹配精准度低,导致定位误差过大的问题,提出种基于OpenCV改进的遥操作工程机器人双目视觉定位技术。在分析HSV色彩空间后,建立适合工程机器人的颜色特征识别空间体系,通过分析图像特征及运动坐标确定圆形光点,利用提供的靶点目标,创建模板后通过双目视觉获取具有靶点特征的其他图像,将图像代入OpenCV技术函数库中。在OpenCV技术函数库中通过光流法对图像进行函数匹配,应用将目标的背景模型与图像的处理方式分割开来,提取背景与干扰因素的全部信息,利用二值化阈值处理运动目标的形态,实现无干扰图像显示,确保定位结果的准确性。实验结果表明,基于OpenCV的遥操作工程机器人双目视觉定位技术能够有效提高匹配精度,降低定位误差,具有一定的实际应用价值。     

一种改进SOM的双目视觉特征点快速匹配方法

针对未知非结构化室内环境中双目视觉机器人路标特征匹配的问题进行了研究,提出了基于改进自组织映射网络(Self-Organizing Map,SOM)的双目视觉特征点快速匹配方法。对双目视觉获取的环境图像提取SIFT特征向量作为改进SOM的输入,利用获胜者计算技术完成对输入SIFT特征点的快速匹配,SOM竞争学习过程中用街区距离与棋盘距离的线性组合作为相似性度量函数。实验结果表明,所提方法在路标特征匹配的时间和效果上优于传统SIFT和SURF特征匹配的方法,且能满足实时性要求。     

煤矿救援机器人环境目标图像识别

针对标准尺度不变特征变换(SIFT)算法存在搜索视觉图像中关键点出现计算冗余和目标识别实时性差的问题,提出了一种改进的SIFT算法,并将其应用到煤矿救援机器人的环境信息感知和目标识别匹配中。该方法以马氏距离代替标准SIFT算法中的欧氏距离,简化了特征点提取,避免了特征点的误匹配。现场试验结果表明,改进后的SIFT算法提高了煤矿救援机器人对煤矿井下环境目标识别的实时性和目标匹配的准确性,为煤矿救援自主移动机器人实现避障、行走做好了视觉前提。     

视觉同步定位与地图重建—–基于先验信息的SIFT 匹配算法

鉴于尺度不变特征转换（SIFT）匹配算法存在计算效率不高且容易出现误匹配的问题,针对视觉同步定位与地图重建,提出了一种基于先验信息的SIFT匹配算法．该算法首先根据机器人和特征点的相对距离变化来预测尺度空间的变化;然后根据机器人和特征点的当前状态来预测特征点的图像位置;最后在预测的图像位置进行SIFT匹配．实验结果表明...     

一种机器人导航中自然路标的匹配与跟踪方法

提出了一种基于SIFT和KLT算法的自然路标匹配与跟踪方法。该方法利用SIFT算子提取图像中自然路标的特征点集作为模板,然后将机器人采集图像中的SIFT特征点集与模板特征点集进行匹配,获取二者之间仿射关系,并解算自然路标在视野中的位置,为机器人自定位提供参考信息。机器人在运行过程中,将KLT算法与SIFT算法相结合对成功匹配的自然路标进行跟踪,较好地解决了SIFT算法效率低下的问题。实验结果表明该方法对自然路标具有较好的匹配和跟踪效果。     

Kinect相机的机器人视觉里程计

Kinect相机不仅能够获取彩色图像,还可以得到相应的深度信息.本文探讨了一种通过Kinect相机来实现里程计的方法,该方法由Kinect相机获取周围环境的连续帧信息,提取并匹配连续帧间的SIFT特征点,获取图像帧的描述子,通过特征点的位置变化计算机器人的位姿、里程编码等,从而实现视觉里程计的功能.     

机器人的混合特征视觉环境感知方法

提出一种基于颜色直方图和SIFT混合特征的机器人视觉环境感知方法。该方法将颜色直方图的"色"与SIFT算法的"形"有机结合,有效提高了感知精度和实时性。对图像进行平均亮度调整并对颜色直方图特征加入主颜色直方图,使之对环境光照和动态变化具有更好的鲁棒性;通过控制特征点数和加入局部颜色统计信息方式改进SIFT算法,提高了特征生成速度和匹配准确度。利用分级匹配方法加速了特征检索过程,并采用本文提出的基于数据知识的推理方法进一步提高了感知精度。仿真与实验结果表明,随着数据库规模扩大,本文方法在感知精度和实时性上的性能优势越发明显。     

对扭转鲁棒的SIFT图像匹配在商标识别中的应用

为识别任意角度扭转的货品商标图像,提出了对扭转鲁棒的SIFT图像局部匹配算法。通过模拟商标图像的垂直和水平多角度扭转,对数据库中所有商标图像提取多组SIFT特征。提取查询图像的SIFT特征,并与库中特征进行匹配从而识别商标。提出了一种仅采样少量角度来近似模拟任意角度图像扭转的方法。实验结果表明,该方法在1000幅商品图像集上正确匹配率高于传统的SIFT算法,可从各种角度的图像中有效地检测到商标图像。     

融合颜色词袋特征的视觉词汇树图像检索

针对由图像灰度空间产生的传统词袋模型SIFT特征无法体现图像的颜色信息的问题,提出了一种融合颜色特征的视觉词汇树来对图像进行描述。提取SIFT特征并建立词汇树,获取图像的SIFT表示向量。利用K-means方法对图像库中的所有图像的HSV值进行聚类,获得基于HSV空间的颜色词袋表示向量,避免了传统颜色直方图方法所带来的量化误差。将SIFT特征与颜色词袋特征进行融合,完成了图像的全局特征和局部特征的融合。然后,计算融合特征的相似度,将相似度从高到低排序,完成图像检索。为了验证本方法的有效性,选择Corel图像库对算法性能进行实验分析,从主观评价和客观评价标准分别进行评价,并与传统方法进行了对比。结果表明,特征融合的检索性能与单一特征方法相比有较大提高。特征融合方法的平均检索查准率和查全率-查准率等评价指标,对比传统方法均有不同程度提高。     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).