基于线性型霍尔元件的伺服定位控制与仿真

永磁同步电机广泛应用在中小容量,高精度传动领域。由于永磁电机的转子为永久磁铁,为了获得较好的同步运转,需要得到转子位置信号。为了解决永磁同步电机转子的初始定位,在分析永磁同步电机工作原理,推导出永磁同步电机数学模型的基础上,提出了一种新的基于线性型霍尔元件的位置及速度检测技术,并以永磁同步电机为被控对象构成伺服控制回路,进行MATLAB平台仿真实验。仿真实验表明,该方法具有较好的稳定性和精确度。     

永磁同步电机无位置传感器控制研究

位置传感器会增加电机控制系统的成本,降低系统的可靠性和性能,在无法安装位置传感器的电机调速场合或在恶劣环境中难以应用.论文针对永磁同步电机给出一种转子位置实时估计方法,利用反电势得到的位置特征点对转子位置进行估计,实现了无位置传感器永磁同步电机的空间矢量控制.实验结果表明,本文提出的估计算法可以实时估计转子位置和转速,采取该算法对无位置传感器永磁同步电机进行矢量控制,算法易于实现,实时性好,电机控制系统调速范围广、运行稳定.     

永磁同步电机脉振高频电压注入转子位置检测

永磁同步电机的转子位置检测精度直接决定了电机能否平滑起动,为提高转子位置检测精度,提出了基于脉振高频电压注入的表贴式永磁同步电机转子位置检测方法。向永磁同步电机定子绕组中注入脉振高频电压信号,通过电机d、q轴磁路饱和程度的差异,实现永磁同步电机转子初始位置的检测。实验结果表明提出方法的转子位置检测精度高,适用于永磁同步电机的无传感器起动及低转速稳态运行。     

基于EKF的永磁同步电机的无传感器控制研究

基于位置传感器永磁同步电机控制,一方面提高了设计成本,另一方面降低了系统可靠性。对扩展卡尔曼滤波（extended Kalman filter,EKF）原理进行分析研究,将 EKF 优化算法应用到永磁同步电机控制中,对永磁同步电机转子转速、转子位置进行预测估计。最后,基于MATLAB仿真平台,构建扩展卡尔曼滤波( EKF)仿真模型。仿真结果表明,永磁同步电机转子位置、转子转速能够被准确预测估计,表明了基于扩展卡尔曼滤波( EKF)算法仿真模型是有效的,为永磁同步电机控制系统研究提供了坚实理论基础。     

表贴式永磁同步电机无位置传感器控制

位置传感器会增加系统成本和测量噪声,且无法应用在一些恶劣环境.论文在研究表贴式采磁同步电机无位置传感器的控制策略的基础上,提出一种基于反电动势的位置估计方法.利用两相旋转坐标系下电机方程的反电势形式,结合前馈控制,计算出转子位置的偏差角度,再采用锁相环结构对电机的相位和速度进行估计.在电机的低速运行阶段改进锁相环结构,保证速度估计精度,并进一步改善系统动态性能.建立了永磁同步电机的仿真模型,验证了该控制方法的可行性.在STM32F103X(ARM)为主控制器的实验平台上实现了所提出的表贴式永磁同步电机无位置传感器控制方法,实验结果表明该控制方法能够准确估计出电机的转速和转子位置,估计算法简单,系统稳态精度高、响应速度快.     

基于电感变化的永磁同步电机新型启动方法

通过分析内埋式永磁同步电机(IPMsM)磁饱和特性,建立永磁同步电机数学模型.根据在施加不通电压矢量时电流瞬间特行不同,采用无位置传感技术,提出了一种检测永磁同步电机在停止状态时转子位置的方法.在此基础上,通过设定直轴电流值为零、交轴电流为常数,设计了一种控制定子交直轴电流的新型永磁同步电机变频启动方法.最后,在以ST...     

基于EKF永磁同步电机无传感直接转矩控制研究

为了解决传统永磁同步电机直接转矩控制中磁链估算需要知道转子初始位置、纯积分导致的直流偏置以及机械传感器的引入导致系统鲁棒性降低等问题.这里提出了一种基于扩展卡尔曼滤波器的PMSM无传感控制方法.选择易检测的定子电压电流为输入输出变量,以d-q坐标系下定子磁链、转子转速和位置为状态变量,应用EKF(Extended Kalman Filter,EKF)算法来实现状态的准确估算.仿真表明,该方法克服了DTC定子磁链计算过程中的直流偏置和严格初值要求等问题;避免了直接以电机定子磁链为状态变量带来的磁链相位移动的问题和以定子电流为状态变量引起的多解问题;能对状态变量进行准确的估计,提高了PMSM-DTC系统性能,实现了一种高性能PMSM无传感控制.     

基于MPC的无传感器永磁同步电机NFTSMC仿真研究

为了提高注塑机中永磁同步电机控制系统的运行可靠性,优化永磁同步电机的调速系统动态性能,提出了一种基于模型预测电流控制的无速度传感器永磁同步电机非奇异快速终端滑模控制策略.以模型预测电流控制作为电流控制内环,取代传统的PI调节器,能够有效地抑制电流纹波,提高电流的动态跟踪性能.根据非奇异终端滑模的设计原理,构造外环速度控制器,从而生成期望的q轴电流,提高了系统的稳定性.设计无速度传感器对电机运行转速进行在线辨识,实现对转速和转子位置准确地估计.并与传统的PI调节器进行对比,仿真与实验结果表明该控制策略具有较高的可靠性和快速性.     

基于广义超螺旋算法的无速度传感器永磁同步电机有限时间速度控制

针对三相表贴式永磁同步电机,本文首先根据广义超螺旋算法(GSTA),设计出广义超螺旋观测器,能够估计电机的转子位置和转速.然后基于上述设计的广义超螺旋无速度传感器,结合有限时间控制理论,设计出有限时间速度控制器,可以实现基于无速度传感器下的有限时间速度调节.通过仿真和实验验证了上述方法的有效性.     

CORDIC算法在永磁同步电机的位置处理上的应用

在永磁同步电机的变频调速系统中,电机转子位置的检测和处理准确与否直接影响整个控制系统的精度。提出一种基于FPGA的电机转子位置定位和处理方法,通过检测复合式增量编码器的A、B、Z、U、V、W 6路信号,经过四倍频及判向电路、位置检测及变换、CORDIC处理器,可精确得到当前电机转子角度位置的正余弦值。实验证明:位置检测与处理模块可以准确地检测到实时转子的位置,误差只有0.144°;快速准确处理电机转子的角度值;在硬件平台上实现了算法,效率高、效果好、硬件资源消耗少,为矢量控制的坐标变换模块提供精确的输入,提升了整个伺服系统的性能。     

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.