基于滑模观测器的SPMSM位置速度估计

针对面装式永磁同步电机(SPMSM)无传感器的控制问题,提出了一种基于改进滑模观测(SMO)和锁相环(PLL)相结合来估计转子位置和速度的新方法。改进滑模观测器采用S型函数对静止坐标系下反电动势(EMF)分量进行估算,提取转子位置和速度信息,有效减小了运用传统滑模观测器估算反电动势所带来的抖振现象,估算的反电动势通过锁相环(PLL)解耦得到准确的转子位置和速度。构建了Lyapunov函数,证明了改进滑模观测器的收敛性,解决了无位置估计算法中鲁棒信差、算法复杂的问题。通过使用ST(意法半导体)的STM32F10X-128K-EVAL电机开发套件和Matlab仿真,对该方法做了详细验证。实验结果表明,该方法能够准确获得电机转速和转子位置的观测值,构成的无传感器矢量控制系统稳态精度和动态性能良好且易于工程实现。     

滑模变控制在CNC精密成型磨削设备上的DSP实现

本文阐述了一种应用在CNC精密成型磨削设备上的新型控制系统,采用基于DSP芯片的永磁同步电机(PMSM)构成其伺服系统.在PMSM矢量控制中,需要利用转子位置信息实现转子磁场高性能的定向控制.本文设计了一个基于滑模观测器的无传感器矢量控制系统,以估算电机转子位置.并介绍了利用DSP实现的软件和硬件设计.仿真结果表明,由该滑模观测器构成的控制系统具有良好的动态性能和稳态品质.     

基于ESO的无速度传感器PMSM系统自适应滑模FCS-MPC

为了提高三相永磁同步电机(PMSM)控制系统的性能,基于反双曲正弦函数的扩张状态观测器(ESO)技术,提出一种新颖的无速度传感器自适应滑模有限控制集模型预测控制(FCS-MPC)策略,采用ESO技术构造PMSM系统转速和反电动势的观测器,实现对电机转速和反电动势快速准确估计.用带有负载ESO的自适应滑模控制作为系统的转速调节器,以提高系统的鲁棒性;利用基于快速矢量选择的FCS-MPC策略,达到减少转矩脉动、降低系统算法计算量的目的.仿真结果表明,基于ESO的无速度传感器自适应滑模FCS-MPC策略能够使PMSM系统可靠稳定运行,达到满意的转矩和转速控制效果.与基于积分型滑模面的自适应滑模FCS-MPC策略相比,所提出的控制策略能使系统具有良好的动态性能和抗负载干扰能力.     

基于滑模观测器的永磁同步电机无位置传感器控制的研究

简要论述滑模观测器的理论基础,根据PMSM的数学模型,建立基于滑模观测器的PMSM无传感器控制的系统模型。根据滑模观测器原理,通过电机的定子电压和相电流估算出电机的转角和转速。利用MATU姬工具建立无位置传感器的永磁同步电动机调速系统的仿真平台,仿真实验检验滑模观测器法的有效性。在采用DSP2812的伺服控制平台上,验证滑模观测器法的正确性和可行性。实验结果表明滑模观测器法具有良好的动静态性能。     

弱滑模观测器在无刷直流电机中的仿真研究

深入讨论了基于幂次趋近率方法的滑模观测器,并对一系列切换函数进行对比研究,总结出弱滑模观测器的规律.通过软硬件方式间接获得可靠的转子位置信号是无位置传感器无刷直流电机矢量控制的基础.在状态观测器设计法中,基于幂次趋近率方法的滑模观测器对电机启动时的反电动势信号具有跟踪速度快、观测精度高等特点,且算法结构简单,便于实现.仿真结果表明该方法在电机启动时反电动势信号微弱的情况下可以准确地估算反电动势信号,快速跟踪实际信号,并证明了该方法的正确性与有效性.     

永磁同步电动机新型滑模观测器无传感器控制

由于传统滑模观测器算法存在固有抖振, 根据永磁同步电动机的数学模型, 设计了一种新的滑动模态观测器转子位置自检测控制算法; 切换函数采用饱和函数代替开关函数; 选择合适的边界层厚度以削弱抖振; 将反电动势估算值反馈到定子电流的观测计算中, 通过选择合适的反馈值来提高低速时转子位置角的估算精度和高速时系统的稳定性. 为了简化驱动系统的硬件结构以提高滤波效果, 设计了一个截止频率可随转子转速变化的低通滤波器对延迟进行补偿. 以1台表面式永磁同步电动机为对象进行实验, 实验结果表明, 这种新型滑模观测器对电机参     

智能观测器在伺服系统控制中的应用

研究优化伺服控制系统策略,永磁同步电动机( PMSM)的伺服系统优化,可改善电动机系统的稳定性和响应特性.通过提高伺服系统定位精度和抗干扰能力,有效保证机器运行效率.针对传统有速度传感器矢量控制增加了系统复杂度和成本的问题,为优化伺服系统控制结构,提出了一种采用神经网络观测器的伺服系统无速度传感器矢量控制策略.系统中不需要安装传感器来检测PMSM转子位置/速度信号,而是利用神经网络观测器从电机反电动势信号中估算转子位置/速度,从而优化了系统整体结构,减小了系统复杂度.通过对PMSM的伺服系统无速度传感器矢量控制系统的建模与仿真测试,结果表明,所设计的神经网络观测器能够准确估算转子位置/速度,控制系统能够精确跟踪给定转速指令,改进了伺服系统优化控制问题,为实际应用提供了参考.     

开关磁阻电机无位置传感器控制系统仿真

该文提出了一种基于滑模变结构观测器的无位置传感器的开关磁阻电机控制仿真模型.滑模变结构观测器主要用于开关磁阻电机的转子位置和转速估计,这种控制模型仅需要测量磁阻电机的端电压和相电流,能在取代传统位置传感器后获得较好的观测效果.该文应用Matlab/Simulink仿真环境建立了开关磁阻电机的非线性模型,设计了控制律,并在三种不同的工作情况下对观测器结构进行了数字仿真.结果表明该方法能够很好地预测电机转子位置,同时在中高速情况下,观测精度可以达到比较满意的效果.     

基于分数阶滑模观测器的永磁同步电机无传感器矢量控制

为解决基于传统滑模观测器的永磁同步电机转速和位置估计精度不高以及抖振过大等问题,设计了一种分数阶滑模观测器。首先根据分数阶理论提出一种分数阶滑模趋近律,并证明其稳定性;然后将永磁同步电机的定子实际电流与估计电流的差值作为滑模面,利用分数阶滑模趋近律设计滑模观测器的控制律,获取反电动势后采用锁相环提取转速和位置;最后建立了永磁同步电机无传感器矢量控制的仿真模型。仿真结果显示新型分数阶滑模观测器不仅静态性能好,而且与基于指数趋近律设计的滑模观测器相比,具有动态跟踪速度快、观测精度高、抖振小等优点。     

基于滑模观测器的永磁同步电机无位置传感器控制

本文提出了一种基于滑模变结构控制原理的无位置传感器控制方法。通过分析永磁同步电机的模型,应用滑模变结构控制原理,提出了一种针对永磁同步电机的无位置传感器控制策略。它利用电机中容易测得的定子电流、直流母线电压,通过滑模变结构控制原理来估算转子位置。利用Matlab／Simulink对系统进行了仿真,仿真结果表明,转子位置估算结果基本与实际位置一致。     

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。     

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.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).