一种三构态变胞并联机构运动学及工作空间分析

常规并联机构运动不够灵活,难以提高机械腿的地面适应能力.本文在可转轴线转动副的基础上,提出一种可用于机械腿的2-PrRS+PR(P)S变胞并联机构.首先分析机构3种构态的自由度特性,然后建立机构的逆运动学模型,给出其约束条件及主要参数的取值范围.再采用蒙特卡洛法得到该机构的工作空间点云图,用自适应网格划分方法计算此空间的体积.与无变胞特性的同参数并联机构进行对比,发现工作空间形状有明显差异,且体积增大了29.36%.最后分析了其主要结构参数对工作空间体积的影响.该工作可为该变胞并联机构的尺度综合提供依据.     

新型6-HTRT并联机器人工作空间和参数研究

本文介绍了新型6-HTRT并联机器人的机构型式和工作原理，给出了考虑到约束条件的 位置逆解算法和存在多组解时的逆解选取准则．利用逆解算法和三维搜索，得到了确定该类 型机器人工作空间的方法和工作空间体积的计算公式．分析了6-HTRT并联机器人工作空间 的形态特点以及机器人结构参数和运动参数对工作空间体积的影响．     

6-DOF并联机器人工作空间边界分析与判定算法

6-DOF并联机器人的工作空间是控制过程研究的主要问题之一,所谓活动空间的边界分析,即指各液压缸活动过程中相互不能发生碰撞,如果碰撞发生,则该点即为边界点.对6-DOF并联机器人的机构和工作原理进行了介绍,给出了对于工作空间边界分析必要的位置算法,根据机构的特点与机器人的运动特性对6-DOF并联机器人的工作空间边界进行了细致的分析并给出了可操作的运动边界判定算法.实现了对液压缸碰撞的判定.     

冗余驱动仿下颌运动机器人工作空间分析及试验验证

根据人类下颌系统冗余驱动的生理特性,即下颌受颞下颌关节约束且受多于本身自由度数目的下颌肌肉驱动的特点,介绍了一种采用点接触高副模拟人体颞下颌关节的6PUS-2HKP(higher kinematic pair)冗余驱动并联机构来完成下颌运动,该机构可应用于牙科义齿性能测试.首先,建立机器人的坐标系,针对机构存在点接触高副的特点,分析和推导了冗余并联机构的独立位置参数和运动学方程.然后,采用下颌运动轨迹描记仪对实验对象下颌切点边缘性运动进行了采集.通过分析各驱动机构及点接触高副的运动范围,采用数值分析的方法获得了机器人的工作空间.最后,采用实验的方法,测量了仿下颌运动机器人做最大运动时下颌切点的运动轨迹.通过对比实验对象切点边缘性运动和工作空间仿真结果可知,该仿下颌运动机器人能够满足人类下颌运动空间要求.     

3-PRC并联机构运动学分析及结构参数优化

根据3-PRC并联机构的结构特点,分析了并联机构的运动学逆解,通过牛顿迭代法得到并联机构的运动学正解。使用SolidWorks、MATLAB和Adams软件对并联机构进行三维建模和运动学仿真,并验证了并联机构运动学正反解的正确性。为了限制整体结构尺寸并获得较大的工作空间,对相关结构参数进行了优化,最终通过三维搜索法得到机构的工作空间。     

五轴并联机床的尺度综合

基于逆向思维提出了一种满足工作空间要求的五轴并联机床的尺度综合方法．首先用极坐标来描述并联机床的姿态空间;然后基于工作空间的要求得到运动平台上铰链点与固定平台上铰链点的距离极值表达式;最后考虑到杆件的力传递性能,得到一组性能较优的参数．该方法对类似的并联机构的尺度综合具有较高的参考价值．     

智能材料DE 驱动的两态串并联机器人系统的运动特性

本文利用电活性绝缘弹胶体DE 的机电驱动特点,结合两态驱动的概念,设计了一种包含3 个两态驱 动器件的并联机构,将其作为串—并联离散驱动机器人系统的基本单元,并据此构建多个单元串联组成的多级离散 驱动系统．文中首先利用智能DE 材料制作满足这一驱动特性的圆柱形两态驱动器件,先测试其直线驱动特性,即 变形值．其次,将该变形值作为并联机构数学模型的驱动值,分析单级及多级并联机构的运动状态、特性及工作空 间的特点．最后,利用数学工具Mathematica 描绘出上述两态驱动并联机构系统所能达到的工作空间分布点云图, 分析了结构参数与驱动量对系统工作空间的范围、精度的影响．     

基于螺旋理论的水下机器人矢量推进球面并联机构的运动学建模

为设计结构简单、具备旋转运动传递和空间姿态调整双重功能的水下机器人推进机构,采用构造过约束并联机构的方法设计了一种3自由度球面并联矢量推进机构.基于螺旋理论构建了机构的拓扑结构模型,分析了机构的运动特性,计算了机构的位姿正、逆解.在闭链约束方程的基础上运用矢量代数法推导出了机构的雅可比矩阵.利用特征结构配置的解耦法建立了机构速度和加速度的解析模型,并进行了相应的数值算例分析,计算了机构的运动学正、逆解,得到了可达工作空间,并用仿真软件Adams验证了数值计算方法的正确性.设计的矢量推进机构具有较大的偏转范围.     

仿生并联眼动机构多目标优化设计

针对低空空域视觉监控系统需同时保证大范围搜索和对目标持续平滑跟踪的要求,依据仿生原理,设计了一种模拟人类眼外肌功能的仿生并联眼动机构构型.为克服当前并联眼动机构多采用单目标优化方法而无法保障动平台倾角及运动精度、机构灵巧度、运动传递性能等运动性能同时取优的问题,在安装空间、驱动件尺寸、铰链偏角等约束条件下,采用改进非支配排序遗传算法(NSGA-Ⅱ)优化机构的结构参数.根据优化得到的结构参数搭建了实验样机.实际测量结果表明,所设计的机构能够在动平台最大倾角、综合运动性能方面取得较为理想的效果,动平台倾角可达55.94?,精度可达0.01?,优于人类视觉系统及相关研究,满足低空空域监控需求.     

耦合型3自由度并联稳定平台机构及其运动特征

基于舰船摇荡运动的耦合特征,采用耦合型3-SRR/SRU 3自由度并联机构作为舰载稳定平台机构,实现了稳定平台三轴驱动、动平台五轴联动补偿的目标．运用螺旋理论分析了机构的自由度和运动特征, 并讨论了输入关节选取的合理性|采用坐标等效运动的方法,建立机构耦合运动约束方程,得到了位置解及工作空间．本文将耦合型3-SRR/SRU 3自由度并联机构用于舰载稳定平台五轴联动补偿,拓展了少自由度并联机构的应用领域．     

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.