开关磁阻电机高性能间接瞬时转矩控制

针对开关磁阻电机(switched reluctance motor, SRM)在运行过程中存在明显转矩脉动的问题,提出一种基于自适应PI算法的高性能间接瞬时转矩控制方法。通过PI型迭代学习控制算法实现相转矩指令到相电流指令的精确映射,PI型迭代学习控制算法的学习能力可消除传统线性转矩逆模型的求解误差。利用开关磁阻电机中增量电感的特点设计了自适应PI电流环,可自动调整电流控制器的增益,消除电感在不同位置对电流环跟踪控制的影响,进而可有效抑制开关磁阻电机的转矩脉动。对三相12/8极开关磁阻电机调速系统进行了仿真分析,仿真结果验证了所提高性能间接瞬时转矩控制策略的有效性。     

基于脉冲注入的无位置传感器SRM转矩优化研究

位置传感器的引入,使得开关磁阻电机(SRM)结构复杂,可靠性降低,研究了非导通相注入脉冲的转子位置估计方法,该方法不受电机控制方式,以及绕组电流超越饱和阈值的影响.针对响应脉冲电流产生的扰动转矩,设计了基于脉冲注入法的开关磁阻电机转矩优化系统.通过转速环将转矩差转换为给定转矩,建立合理的转矩分配机制,得到给定相转矩,并将直接瞬时转矩控制(DITC)与电流闭环控制相结合使转矩准确吻合给定相转矩,从而实现电机的循环控制,有效减小了脉冲电流产生干扰转矩对转矩波动的影响.建模仿真验证了方法的可行性:对基于脉冲注入的无位置传感器开关磁阻电机的转矩脉动具有良好的抑制效果.     

磁悬浮开关磁阻电机的自适应终端滑模控制

为解决磁悬浮开关磁阻电机受到外部环境未知干扰、内部参数摄动等不确定因素带来的影响,提出一种基于自适应终端滑模控制器的直接瞬时转矩及直接悬浮力控制策略.首先,对电机的数学模型进行分析并建立状态方程,采用直接瞬时转矩控制与直接悬浮力控制方法,以减小系统脉动;其次,设计非奇异终端滑模面,避免常规终端滑模控制中的奇异问题,并引入自适应律,结合终端滑模控制器以抑制不确定因素的干扰,保证系统的快速收敛、强鲁棒性;最后,与传统滑模控制器方法进行对比,验证该方法的有效性.仿真结果表明,所提出方法能迅速精准跟踪控制系统的转速及位移,有效提升状态收敛速度,抗扰能力强,具有良好的动态性能.     

细分驱动技术在开关磁阻电机控制系统中的应用

转矩脉动以及低频噪声是开关磁阻电机的主要缺点之一，本文在借鉴步进电机细步驱动思想的基础上，通过细分绕组换相时到电流使通电绕组在空间合成多个转矩矢量，控制电流大小维持转矩幅值基本恒定．从而减小转矩脉动。本文论述的控制策略在实验过程中得到认证，在减小转矩脉动和噪声方面有显著的成效。     

16/12极开关磁阻电机调速系统设计

影响开关磁阻电机推广的主要因素之一就是其转矩脉动较大.为了降低转矩脉动,在传统四相8/6极开关磁阻电机基础上,提出了四相16/12极开关磁阻电机的新型结构.电机控制单元采用处理速度较强的STM32F051C作为该型电机的控制芯片,并通过直接转矩控制算法对电机转矩进行控制.通过在测功机上的空载和加载试验,得出电机在不同工作状态下的绕组电流波形,经测试分析,该系统调速性能良好.     

无轴承同步磁阻电机逆系统的解耦控制

为了有效解决无轴承同步磁阻电机这一非线性、强耦合的多输入多输出系统的动态解耦问题,提出了基于α阶逆系统理论的无轴承同步磁阻电机解耦控制策略.本文在阐述了无轴承同步磁阻电机径向悬浮力产生机理的基础上,推导出其数学模型,采用α阶逆系统方法将原系统解耦并线性化为一个一阶线性积分子系统和两个二阶线性积分子系统,并应用线性系统理论设计了闭环控制器.最后采用MATLAB软件环境构建了仿真系统,针对系统的阶跃响应、转子起浮、解耦性能等进行了仿真和分析.仿真试验表明这种解耦控制策略能够实现无轴承同步磁阻电机电磁转矩与径向悬浮力之间的动态解耦.并且系统具有良好的动、静态性能.     

无轴承同步磁阻电机逆系统解耦控制仿真研究

研究无轴承同步磁阻电机稳定性控制问题,由于无轴承同步磁阻电机是一个强耦合的非线性系统,为实现负载条件下的稳定悬浮运行,需解除电机转矩和径向悬浮力等多变量之间的耦合关系。针对前馈补偿解耦的缺陷,给出了无轴承同步磁阻电机包含转矩控制和悬浮力控制的统一数学模型,证明电机逆系统存在,设计了一种通过非线性状态反馈的逆系统解耦控制方案,将复杂的无轴承同步磁阻电机系统解耦成两个转子径向位置二阶积分子系统和一个转速一阶积分子系统,并用PI和PID调节器分别对转子位置与转速进行综合设计。运用MATLAB软件对电机控制系统进行仿真。仿真结果证明,解耦控制方案的有效性,为电机系统优化设计提供了保证。     

一种减少SRM转矩脉动的控制策略研究

开关磁阻电机(SRM)由于其简单的结构和优异的性能,应用范围很广泛,但其本身结构导致了转矩脉动的产生,为了解决这个问题,文章研究了一种控制策略—直接转矩控制,以减少开关磁阻电机的转矩脉动。文章详细阐述了直接转矩控制的基本原理和实现方法,并对基于这种控制策略的开关磁阻电机的控制进行了Matlab仿真。仿真结果表明直接转矩控制能够有效地减少开关磁阻电机的转矩脉动,且控制方法简单,系统具有良好的动静态性能。     

永磁型无轴承电机解耦控制策略研究

根据无轴承电机转子悬浮力产生机理,针对一类表面贴装式永磁型无轴承电机提出了基于转矩绕组气隙磁场定向的解耦控制算法,根据转子磁场定向坐标系统中电机数学模型推导出气隙磁场定向坐标系统中电机电磁转矩、气隙磁链以及可控悬浮力数学模型,在此基础上构建了永磁型无轴承电机转矩绕组气隙磁场定向解耦控制系统,有效解决了转子磁场定向控制存在的缺陷.仿真结果证明了提出的控制算法的正确性与可行性.     

基于速度信息观测的无轴承永磁同步电机悬浮解耦控制

无轴承永磁同步电机以转子位置信息为媒介实现解耦控制,整个算法复杂且依赖速度传感器.本文研究电机无传感器运行及解耦算法简化的方法.首先将传统扩张状态观测算法简化为线性形式.然后将二、三阶线性扩张状态观测器分别加入转矩和悬浮系统电流环和位移环,并定义电角速度与转矩d-q轴电流乘积以及转矩系统q轴磁链与悬浮d-q轴电流乘积为扰动项,利用观测器辨识转速信息及悬浮扰动力.接着对转速信息进行处理、对悬浮扰动力进行补偿从而实现无速度传感器运行并简化悬浮解耦算法.最后通过仿真验证所提控制策略能够实现电机无速度传感器运行,保证额定转速下稳定悬浮.     

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.