具有输入饱和的电液伺服位置系统自适应动态面控制

针对具有非线性、参数不确定性及输入饱和问题的电液伺服位置系统,提出了一种自适应动态面控制器的设计方法.该方法充分考虑饱和特性,利用双曲正切函数和辅助控制信号对系统非线性模型进行等价变换,进而采用动态面方法设计抗饱和控制器.设计过程中引入Nussbaum函数,以补偿输入饱和引起的非线性项.通过构造合适的Lyapunov函数,证明闭环系统的所有信号一致最终有界.仿真结果表明,所设计的控制器具有良好的跟踪效果,并有效地削弱了输入饱和对系统造成的不良影响.     

电压型Buck电路控制器的复频域设计及仿真研究

通过分析电压型Buck电路控制器,在复频域下用模拟和数字两种方法对Buck变换器的补偿网络进行了设计.应用PSpice软件建立了系统的模拟电路模型,对系统的频率特性进行了仿真,并用Mathcad仿真软件对复频域下系统连续模型的频率特性进行了验证.然后运用根轨迹理论讨论了一种基于根轨迹和零极点配置的数字控制器设计方法,根据系统性能指标设计了补偿网络,并用Matlab仿真软件对控制系统离散数学模型进行了特性仿真.仿真结果表明用该方法所设计的控制器性能与模拟电路建立的控制器性能完全相同.经过离散化的控制器数学模型可以方便地在DSP等数字信号处理器上实现,为开关变换器的数字化控制提供了简便的实现方法.     

具有区域极点配置的飞控系统混合H2/H∞控制

研究飞控系统特性,针对某型飞机纵向运动的参数摄动不确定性,为了提高控制系统的稳定性和优化系统的性能,采用基于线性矩阵不等式(LMI)的混合H2/H∞控制方法设计控制器,减小不确定性对系统的影响,以实现对系统鲁棒性能的要求,并将被控系统的闭环极点配置在预期的区域内,进一步保证系统具有良好的动态特性.通过实例仿真验证分析,系统不但满足了动态性能指标,且当系统参数不确定性在一定范围内时,控制器对系统仍能进行有效的控制,表明了控制器对一定范围内的参数不确定性具有较好的抑制作用,验证了设计方法的实用性与有效性.     

一种连续控制器离散化方法

本文根据控制器近似化原理,以连续系统的闭环稳定性为标准,应用采样控制系统的H∞设计方法给出了一种新的连续控制器离散化方法。该方法的突出特点是考虑到了系统中连续信号的全部信息,降低了离散化误差对系统性能的影响,仿真表明方法有交,且在采样周期较大时有优势。     

输入具有齿隙非线性特性的周期系统的自适应控制

针对一类输入含齿隙非线性动态特性的周期时变系统, 在周期不确定性可时变参数化的条件下设计自适应控制器. 对周期时变参数进行傅里叶级数展开, 并采用微分自适应律估计未知傅里叶系数和齿隙动态特性参数, 通过鲁棒方法消除截断误差和齿隙模型的有界误差项对系统性能的影响. 采用双曲函数替代符号函数确保控制器可微, 同时能有效抑制颤振. 引入Δ函数, 避免参数估计发散, 并保证系统输出渐近跟踪理想轨迹. 理论分析与仿真结果表明, 闭环系统所有信号有界.     

带钢跑偏电液伺服控制系统的PID控制器设计

为了对带钢卷取机的跑偏进行控制,建立带钢卷取机电液伺服跑偏控制系统的数学模型,并用MATLAB软件对此系统的时域性能指标进行分析。对系统采用常规PID控制器和模糊自适应PID控制器设计,使系统性能达到设计要求。对两种方法进行仿真,表明模糊自适应PID比常规PID控制系统有更好的动态性能和稳态特性。     

反馈控制系统的控制器设计与仿真研究

讨论了单位反馈控制系统在满足稳态特性条件下的控制器设计问题。通过具体例子给出了参考输入和干扰信号为阶跃函数、正弦函数、方波函数等典型信号时系统满足稳态误差要求的控制器的设计方法 ,并给出计算机仿真结果。同时对满足灵敏度最小的控制器设计也作了讨论。     

光伏三相并网系统的自抗扰控制

光伏三相并网发电系统是一个典型非线性系统,受电网和外部环境的影响,系统存在许多不确定性干扰.本文以三相光伏并网发电系统为对象,利用自抗扰控制器的扩张状态观测器,对系统模型中的不确定因素和外部干扰进行动态观测,设计一自抗扰控制器,使系统具有较好的适应能力,并对系统进行了仿真研究.结果表明所设计的控制器具有良好鲁棒性和较好的动、静态特性.     

基于扰动补偿的无微分模型参考自适应控制系统设计

针对一类含有参数不确定性和未知非线性扰动的系统,本文提出一种基于扰动补偿的无微分模型参考自适应控制方法,实现系统输出对参考模型输出信号的高精度跟踪.首先,利用被控对象模型信息设计扰动估计器,对系统非线性扰动进行在线估计;其次,基于非线性扰动估计值设计参考模型和无微分参数更新律,构建无微分模型参考自适应控制器,建立基于扰动补偿和状态反馈的自适应控制律,以消除参数不确定性和非线性扰动对系统输出的影响,保证系统输出对参考模型输出的准确跟踪;然后,给出闭环系统误差信号收敛条件和控制器参数整定方法;最后,通过数值仿真验证所提方法的有效性和优越性.     

反馈控制系统的控制器设计与仿真研究

讨论了单位反馈控制系统在满足稳态特性条件下的控制器设计问题。通过具体例子给出了参考输入和干扰信号为阶跃函数、正弦函数、方波函数等典型信号时系统满足稳态误差要求的控制器的设计方法,并给出计算机仿真结果,同时对满足灵敏度最小的控制器设计也作了讨论。     

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。