自适应模糊滑模软切换的PMSM无速度传感器鲁棒无源控制

针对永磁同步电机(PMSM)转速调节和估计问题,提出一种无速度传感器的PMSM调速系统.利用双曲正切函数代替符号函数,设计了自适应模糊滑模软切换控制器,实现了软切换连续控制,削弱了抖动现象.通过设计鲁棒无源控制器,得到了旋转坐标系下的u_d和u_q.建立了自适应滑模观测器,并给出了速度辨识律,观测器的增益通过求解线性矩阵不等式得到.仿真结果表明了该控制策略与观测器配合的有效性,且控制系统具有良好的动、稳态性能.     

感应电机无速度传感器直接转矩控制系统

为了实现对感应电动机的高性能控制,针对传统的速度辨识器存在的不足,提出了一种无速度传感器直接转矩控制系统.在该系统中,根据感应电机的数学模型,经过一定的变换,利用电动机易于检测到的定子电压和电流,以及基于BP算法的神经网络设计了一种速度辨识器,从而实现了无速度传感器的闭环控制.对所设计系统进行了仿真,结果表明该调速系统具有良好的稳态性能和动态性能,该设计是合理、有效的.     

基于无速度传感器的改进型矢量控制系统

针对无速度传感器控制系统在精确估算转子速度方面存在的问题,将转速作为未知变量,设计了一个能够同时估算转速和磁链的自适应观测器,同时对传统的PI控制器不能对不同情况下的增益进行及时调整,造成转矩、磁链和电流脉动问题,引入了模糊控制下的SVM矢量控制策略,通过仿真及实验结果表明,系统在稳态下能够获得良好的动态性能。     

采用干扰差分补偿的无切换吸引离散时间控制方法

提出一种基于无切换吸引律的离散控制器设计方法,将干扰差分补偿措施嵌入吸引律中构建理想误差动态,依据理想误差动态推导离散时间控制器.所提控制方案既回避了抖振,也能够有效抑制干扰.给出稳态误差带、绝对吸引层、单调减区间和跟踪误差首次进入稳态误差带的最多步数的具体表达式,用以刻画系统跟踪误差瞬态、稳态性能,并指导控制器参数整定.数值仿真与实验结果验证了所提出方法的有效性.     

无刷直流电动机积分反演模糊滑模控制

针对普通的无刷直流电动机控制策略受电动机本身因素影响,难以达到理想效果的问题,介绍了一种积分反演自适应滑模变结构控制和模糊控制相结合的控制器。该控制器在滑模面中加入积分项,实现了对速度信号的无静差跟踪,提高了系统的稳态精度;用模糊控制器来解决切换控制增益设定只能靠经验的问题;采用模糊控制算法对不确定性进行估计,有效地减小了滑模控制方法带来的抖振;为了进一步提高控制性能,重新设计了趋近律。仿真结果表明,该控制器能够大幅提升无刷直流电动机控制系统的性能。     

无刷直流电动机积分反演模糊滑模控制

针对普通的无刷直流电动机控制策略受电动机本身因素影响,难以达到理想效果的问题,介绍了一种积分反演自适应滑模变结构控制和模糊控制相结合的控制器。该控制器在滑模面中加入积分项,实现了对速度信号的无静差跟踪,提高了系统的稳态精度;用模糊控制器来解决切换控制增益设定只能靠经验的问题;采用模糊控制算法对不确定性进行估计,有效地减小了滑模控制方法带来的抖振;为了进一步提高控制性能,重新设计了趋近律。仿真结果表明,该控制器能够大幅提升无刷直流电动机控制系统的性能。     

基于MRAS无速度传感器的DTC系统Simulink仿真研究

异步电机的精确控制和速度辨识是交流传动系统中重要问题;文中在Simulink软件环境中构建了基于MRAS无速度传感器的异步电机DTC系统;该系统中采用DTC对异步电机进行控制,定子磁链采用在全速范围内有效的u-n模型观测器来估计,电机转速采用MRAS辨识算法来估算;由于速度辨识算法中电压模型的纯积分环节会引起的误差积累和漂移问题,采用改进积分型转子磁链估算模型来解决;仿真结果表明了文中转速辨识方法能准确推算出电机转速,所设计的控制系统动态响应快、稳态静差小、抗负载扰动能力强,具有良好的静、动态控制性能.     

关于滞后不确定系统的变结构控制与仿真

研究变结构优化控制,对于含有状态滞后和输入滞后的不确定离散时间系统,采用传统的变结构控制器设计方法,很难解决控制输入滞后对系统性能造成的影响,并使系统抖振和控制输入切换幅度过大的问题,控制效果不理想.为解决上述问题,对状态滞后和输入滞后相同的一类不确定离散时间,进行变结构控制器的设计.根据系统滑模面可达条件,用系统模型不确定项进行等效替换处理,提出改进的变结构趋近律.利用趋近律设计的控制器克服了系统抖振和控制输入切换幅度过大的问题.仿真结果表明,控制器不仅能够保证系统具有良好的稳态和动态性能,同时动态过程中控制量的切换幅度也可以控制在要求范围内.     

三相电压调整模块无源控制的研究

针对多相交错并联型电压调整模块(VRM)稳态时各相电流纹波大、动态响应难以满足最新VRM标准要求的问题,以三相Buck型VRM为例,从切换线性系统理论角度建立其系统模型,推导出其无源控制策略,既保证了系统的大范围稳定,又提高了系统的动态品质。仿真结果表明,应用无源控制方法的三相VRM闭环系统在稳态工作点上三相电流能保持良好的均流效果,有效地减小了各相的电流纹波,并且能明显改善负载变化时的动态品质。     

双边磁通切换直线电机无速度传感器控制

为了实现良好的双边磁通切换永磁直线电机(DLFSPM)的速度辨识,提出了一种带锁相环的滑模观测器进行控制。首先,基于DLFSPM电机特性,建立其数学模型,并设计该电机的传统滑模观测器的控制策略;然后针对传统滑模观测器存在抖动和角度偏差的问题,引入锁相环算法,并使用新切换函数代替符号函数,从而消弱抖振和较小角度偏差;最后对该系统在速度突变、负载突变工况下的动态性能进行仿真研究。仿真结果表明,优化后的滑模观测器控制策略能有效减小系统抖振,速度识别精准,波动小,电机工作平稳,鲁棒性好,动态响应快,证明了所提控制策略的可行性和有效性。     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。