空空导弹大攻角俯仰自动驾驶仪设计

研究导弹自动驾驶仪优化控制问题,针对空空导弹在大攻角飞行过程中,系统的空气动力学特性存在强非线性耦合和参数不确定性,引起系统稳定性差.为了提高系统性能,在导弹俯仰运动的非线性数学模型的基础上,以导弹攻角为被控信号,舵偏角指令为输入信号,提出采用反馈线性化方法对导弹模型进行线性化,然后运用变结构控制理论进行控制器设计.控制器结构简单,易于实现,能够抑制被控对象中存在的不确定性.并通过数学仿真与全状态反馈控制方法设计的控制器进行了比较.结果表明采用反馈线性化和滑模变结构方法设计的控制系统对气动参数摄动和外部扰动具有较强的鲁棒性.     

参数自整定PID控制器设计与仿真

对于工业控制领域中的系统普遍存在非线性、时变的特点,采用传统PID作为控制器很难获得满意的控制效果,而神经网络具有任意非线性逼近能力,可以通过对系统性能的学习来实现具有最佳组合的PID控制。设计了基于BP网络整定PID参数的控制器,该控制算法只需粗略给出PID参数便可以根据系统性能自动寻优调整。利用MATLAB软件得到的仿真结果表明,该控制策略可以达到满意的控制效果,且具有很强的鲁棒性和自适应能力。     

非线性系统的PID控制器的研究与设计

研究工业过程控制,非线性系统难以建立其精确的数学模型,常规PID算法难以实现其控制.对此,将神经网络算法和PID算法结合起来,为提高性能和响应速度,设计了针对非线性系统的自适应PID控制器,PID控制器采用单神经元来实现自适应调整.分别采用了三种学习算法来实现单神经元PID控制器参数的调整,即基于二次型性能指标的学习算法、基于BP神经网络辨识的学习算法和基于RBF神经网络辨识的学习算法.三种算法的仿真结果表明,都实现了PID控制器的自适应调整的目的,实现对非线性系统的有效控制,证明三种方案的可行性.     

神经网络直接逆控制在无人机飞控系统中的应用研究

针对无人机发生故障时系统的非线性耦合特性,提出了一种基于神经网络直接逆控制的飞行控制方法,用于在飞机发生故障时进行控制律重构以恢复对飞机的控制;根据无人机发生故障时非线性运动的特点,确定适当的神经网络结构建立无人机非线性系统的逆系统,并与被控对象串连可以对非线性耦合系统进行线性化解耦,然后引入PID反馈控制进一步提高神经网络逆控制系统的性能;仿真分析表明该方法在无人机发生故障采用传统PID控制失效时,在误差允许范围内可以用来对无人机进行控制。     

BTT导弹滚转通道模型参考变结构自动驾驶仪设计

BTT导弹的气动参数强烈变化特点、大机动需求和控制技术要求导弹滚转通道必须具有快的响应速度和强的抗干扰能力.针对这些特点,引入了模型参考变结构控制(MRVSC)设计导弹滚转通道自动驾驶仪,应用Simulink对PID和MRVSC两种自动驾驶仪进行仿真分析;在飞行高度为200m时,PID和MRVSC自动驾驶仪对理想弹道的跟踪效果几乎相同;在10km高度,PID方法的跟踪效果明显变差,而MRVSC具有同样的跟踪效果;仿真结果表明,MRVSC自动驾驶仪能够保证快的响应速度和抵抗参数大范围变化.     

飞航导弹横测通道协调变结构飞行控制系统设计

某型面对称布局飞航导弹采取BTT控制方式,可以使战术导弹在各方面获得良好的性能.但由于其横侧向通道之间具有强烈的耦合,传统的STT导弹采用的控制系统及其综合方法已经不再适用于BTT导弹,一个具有运动学耦合,惯性耦合,以及控制作用耦合的多自由度的系统综合问题被提出;应用变结构控制理论,结合经典的双回路飞行控制系统方案分别设计了偏航和滚动通道自动驾驶仪;仿真结果表明用该方法设计的飞行控制系统能够有效克服横侧向通道间的耦合以及参数摄动影响.     

基于BP神经网络的贴片机运动精度控制

将BP神经网络PID控制方法应用于贴片机运动精度控制器设计;针对传统PID控制器参数难以整定等问题,提出了BP神经网络和PID控制器相结合的方法,该方法既有常规PID控制器结构简单的特点,又有BP神经网络自适应、自学习以及逼近任意函数的能力;首先根据伺服电动机的工作原理建立了电枢控制伺服电动机模型传递函数,在此基础上建立了贴片机单关节轴位置控制器模型传递函数;其次描述了BP神经网络和PID控制器相结合的控制模型,并对具体的控制算法进行了定义;最后利用MATLAB仿真工具对贴片机单关节位置控制进行了仿真;仿真结果表明,结合BP神经网络的PID控制系统提高了系统的稳定性、快速性和动态性能并获得很好的控制效果。     

铁路防尘自动喷洒系统的模糊自适应PID控制研究

针对大滞后、非线性的自动喷洒试验系统,进行了模糊自适应整定参数的PID控制策略研究.对运煤车防尘自动喷洒系统进行了分析;设计了模糊自适应PID控制器;在MATLAB语言环境下编写仿真控制程序.仿真运行结果表明控制方案的有效性和正确性.     

主动磁悬浮轴承的神经网络自适应稳定性控制

针对主动磁悬浮轴承本质非线性和开环不稳定的系统特征,设计了一种BP神经网络自适应PID控制器。该控制器采用改进的BP神经网络PID控制算法,通过BP神经网络的自学习和权值调整寻找最优的PID参数,克服了常规PID控制参数整定困难的缺陷,实现了系统的自适应控制。通过MATLAB/Simulink环境和S-Function模块建立了主动磁悬浮轴承控制系统模型,并进行了系统仿真实验,结果表明,BP神经网络自适应PID控制系统响应速度更快,具有更好的动态性能和稳态性能。     

船舶襟翼舵神经网络控制伺服系统

为了解决船舶襟翼舵在复杂的、非线性、不确定的海域环境中的高精度位置控制问题,将神经网络应用在伺服系统中充当控制器与辨识器,通过设计的神经网络PID控制器,使船舶位置伺服控制系统具有高稳定性,及鲁棒性好的特点,且具有要求的动态和静态性能。针对无刷直流力矩电机做了神经网络PID控制系统仿真,并与PID控制做了比较。仿真结果表明了神经网络PID(NN-PID)优越的动态和静态性能。     

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.