基于双闭环结构的时栅转台自动标定系统设计

时栅转台精度的标定是时栅产业化过程中非常重要的一道工序,是时栅转台精度和可靠性体现。针对传统的标定系统采用激光干涉仪、光电自准直仪和金属多面体,人工操作效率低,可靠性差,提出用自制的数控控制箱结合嵌入式技术,开发了一种时栅转台自动标定系统。该系统以高精度的海德汉圆光栅RCN8510作为基准量仪,双微控制器与上位机为基础,形成双闭环控制结构,实现了实时在线误差修正与补偿。实验结果表明：采用双闭环控制系统时栅转台标定系统具有较高的稳定性,提高了时栅转台标定效率,时栅转台的精度达到2.4″。     

高精密多极磁感应角位移传感器校正方法的技术研究

高精密多极磁感应角位移传感器精度通常为±(3～5)″,很难达到±1.5″以内，这限制了其应用在一些高精尖的精密测试及制造领域，为实现更高精度则需对系统进行软件校正，目前常用的软件校正方法有查表法、神经网络法、小波分析法等，但这些校正方法需要采集大量连续的误差标定数据，而满足此精度等级、能实现连续化误差标定的测角装置极难获取，而23面(或24面)棱体与光电自准直仪组成的测角标定装置虽可满足精度要求，但它只能实现360°内离散化误差标定，基于多面棱体与光电自准直仪有限离散的误差标定数据，在此基础上提出一种二次精度校正技术以实现对角位移测量系统的软件修正，实验证明，应用此方法后，角位移测量系统精度由±3.1″提升到了±1.35″,从而验证了所提出的误差校正技术。     

基于参数辨识的时栅转台在线自动标定系统

提出一种在线自动检测时栅转台误差、辨识误差模型系数和误差补偿的方法。该系统由高精度的基准量仪圆光栅、微控制器与上位机组成。在对极点8个待定参数和对极内20个待定参数分别进行傅立叶变换的参数辨识,得到辨识误差模型的系数,实现了实时在线误差补偿。为了检验在线自动标定效果,利用光电自准直仪与基于参数辨识的在线自动标定系统进行对比实验。实验结果表明,采用傅立叶变换的参数辨识,提高了时栅转台标定精度与标定效率,时栅转台的精度达到2.8″。     

基于STM32的时栅转台高精度自动标定系统设计

针对目前时栅转台采用手动方式进行标定,工作效率低、精度难以保证的现状,设计了一种能够进行数据采集、处理和误差补偿的时栅转台自动标定系统。该系统以激光干涉仪作为测量基准,采用了闭环控制技术,进行测量误差补偿。实验结果表明:该系统标定精度高,经过该系统标定后的时栅转台精度达到±2″,且标定速度是手动方式的2倍以上,显著提高了时栅转台标定效率。     

多面棱体工作面偏差补偿的符号问题

讨论了利用多面棱体和自准直仪进行精密角度检定时多面棱体工作面偏差的补偿问题,给出了工作面偏差补偿符号的判定方法。     

一种光电编码器精度自动检测系统

随着光电编码器的广泛应用,市场对其需求也逐渐增大。利用自准直仪－金属多面棱体对光电编码器精度检测的传 统手动检测方法具有检测效率低的缺点,严重制约了光电编码器生产效率的提高。针对上述问题,设计了一种光电编码器精度自动检测系统,MATLAB程序控制电机带动待测光电编码器同步旋转,通过对比待测光电编码器及电机运动角度的数据计算待测光电编码器的精度,实现光电编码器精度自动检测。系统采用沿面检测算法减小测量结果的分辨率误差,采用傅里叶谐波分析方法对电机转角误差进行修正,进而提高了检测精度,使用该系统对某型号的 16位光电编码器进行检测.实验结果显示该系统检测精度不大于±２″,该系统具有结构简单,检测精度高的优点,可提高光电编码器的生产和检测效率。     

三轴伺服转台三轴不正交度对台面测角精度的影响

1.概述三轴伺服转台一般需要安装导航仪器,三轴的位置精度应反映台面框架的姿态精度。高精度的三轴伺服转台要求三轴角位置精度达10~(-3)度或更高。实际台面框架能否达到此项精度指标,除了框架轴和框架的扭曲变形以及包括框架在内的轴系的弯曲变形以外,三轴不正交度(即三轴不垂直度)的存在使轴角精度不能完全反映台面姿态。现在国内外验收转台所用的方法是将标准的多面棱体及激光角度测试仪装在轴上,与轴上测角系统进行比对,这实际只标定了三个独立轴的角位置精度,它不能完全反映台面框架的真正姿态。为了真正反映台面框架的精度,多面棱体等标准角度基准仪器应放在安装台面上进行标定。由于高精度三轴转台对三轴不正交度要求很高,     

时栅角位移传感器误差分离与建模方法研究

为实现时栅角位移传感器的误差分离,进而对其误差进行修正,提高时栅角位移传感器的测量精度,采用多路信号叠加原理,针对时栅角位移传感器的定子和转子在加工过程中存在的误差进行分离,消除了大部分的长周期误差,并对分离出来的误差成分进行谐波分析,建立误差修正模型,利用该模型对时栅角位移传感器的定子和转子的线槽分度误差进行修正,修正后的场式时栅角位移传感器的测量精度显著提高,精度优于±2"。实验证明,这种误差分离的方法对消除圆周分度误差十分有效,所建立的误差修正模型对传感器误差修正效果明显。     

基于Qsys的时栅信号处理系统设计与实现

为提高时栅传感器位移测量精度和测量分辨力,研究采用FPGA嵌入式锁相环倍频产生4路同频且相位差为45°的高频时钟脉冲作为测量基准,利用多路并行双边沿计数方法对时栅参考信号和时栅感应信号进行相位测量,通过相位差转换得到具有高分辨力的时栅位移信号, 采用Qsys开发平台设计Nios－II软核进行数据处理,利用傅立叶级数谐波修正技术对测量结果进行误差修正,提高时栅传感器的测量精度,在72对极磁场式时栅角位移传感器上进行精度测试,实验结果表明:经过误差修正后,该系统测量的整周误差从－57.2″~ 92.5″下降到－2.0″~2.5″,作为角位移传感器满足高端装备高精度定位需求,具有重要的工程应用价值。     

一种适用于单轴MEMS倾角仪的快速标定方法及实现

针对单轴倾角仪核心元件MEMS加速度计零点电压和标度因数在反复上电后会发生改变,且在外场环境下,不能通过转台对其进行修正的问题,本文根据MEMS加速度计的安装误差、输出模型推导了单轴倾角仪的标定模型,提出了一种适用于单轴倾角仪的快速标定方法,并利用实验室研制的MEMS单轴倾角仪及LABVIEW软件编写的上位机对该方法进行了试验验证.实验表明,该快速标定方法可快速、准确地修正MEMS加速度计零点和标度因数的漂移,从而保证倾角仪的测量精度,具有良好的工程实践意义.     

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.