高超声速飞行器基于Back-stepping的离散控制器设计

根据高超声速飞行器纵向模型的特点,提出了基于Back-stepping的离散控制器设计方法.首先通过合理的简化,将飞行器的模型转化为连续非线性系统的严格反馈形式;然后采用欧拉法得到其近似的离散模型,根据近似离散模型并结合Back-stepping和反馈线性化方法,设计了高超声速飞行器的离散控制器.利用高超声速飞行器的纵向模型对算法进行仿真验证,得到了较为满意的控制效果.     

基于INA—QFT的高超声速飞行器鲁棒控制器设计

针对高超声速飞行器数学模型的不确定性,提出基于逆奈氏阵列法设计预补偿器和定量反馈理论设计控制器相结合的方法。该方法首先对相互关联的飞行器三通道进行预补偿,使开环前向通道的逆传递函数矩阵成为对角优势阵。然后根据某型号飞行器俯仰通道多个模型参数变化范围,利用定量反馈理论进行鲁棒控制器设计。线性和非线性仿真结果表明,该方法跟踪效果良好,具有较强的工程应用价值。     

基于sigmoid函数的高超声速飞行器自适应姿态控制

针对高超声速飞行器无动力再入过程中具有强耦合、气动参数摄动及不确定性的非线性姿态模型,提出了飞行器姿态控制的一种非线性设计方法。首先基于时标分离原理分内外环设计非线性动态逆控制器,并利用Sigmoid函数分通道制定控制律。针对单纯使用动态逆控制鲁棒性弱的特点,引入基于扩张状态观测器(Extended State Observer,ESO)的自适应控制器对参数摄动和不确定性进行补偿,在参数拉偏和风干扰条件下仿真结果验证了设计控制器具有较强的鲁棒性。     

高超声速飞行器神经网络动态逆姿态控制器设计

以一类通用高超声速飞行器纵向模型为研究对象,推导了飞行器纵向姿态运动方程。考虑受到飞行器附加攻角扰动以及气动参数不确定性的影响,对运动方程中速率变化快慢不同的攻角和俯仰速率分别引入精确线性化动态逆反馈,并利用神经网络对系统逆反馈误差进行补偿,有效地抑制了模型参数摄动,实现了对攻角指令的精确跟踪。将设计的控制器对高超声速非线性模型进行系统闭环仿真,仿真结果说明所设计的姿态控制器具有抗参数摄动的性能,能够满足高超声速飞行器复杂飞行条件下的姿态控制要求,具有较强的鲁棒性。     

高超声速飞行器基于Back-stepping的离散控制器设计

!根据高超声速飞行器纵向模型的特点,提出了基于Back-stepping的离散控制器设计方法.首先通过合理的简化,将飞行器的模型转化为连续非线性系统的严格反馈形式;然后采用欧拉法得到其近似的离散模型,根据近似离散模型并结合Back-stepping和反馈线性化方法,设计了高超声速飞行器的离散控制器.利用高超声速飞行器的纵向模型对算法进行仿真验证,得到了较为满意的控制效果.

     

高超声速飞行器应用保护映射的大包线控制律

针对高超声速飞行器模型具有高度非线性和易变的动态特性,应用保护映射理论提出了一种高超声速飞行器大包线控制律设计方法.首先,结合间隙度量理论建立高超声速飞行器线性变参数(linear parameter-varying,LPV)模型,然后设计控制器结构并计算初始点的控制器参数,并根据保护映射理论分析初始控制器使闭环系统稳定的参数区间,通过迭代运算自适应地获得满足性能要求的控制器参数集合.仿真结果表明,建立的LPV模型具有良好的精确度;所设计的大包线控制律能够满足高超声速飞行器的性能要求,并且保证系统在飞行域内全局稳定.     

基于Backstepping的高超声速飞行器模糊自适应控制

提出了高超声速飞行器的模糊自适应控制方法.根据飞行器纵向模型的特点,分别设计了基于动态逆的速度控制器和基于Backstepping的高度控制器,模糊自适应系统用来在线辨识飞行器模型由于气动参数的变化而引起的不确定性,采用Lyapunov理论设计的自适应律保证了系统的稳定性与指令跟踪的精确性.仿真使用了高超声速飞行器的纵向模型对算法进行了验证,得到了较满意的控制效果.     

一类高超声速飞行器自适应容错控制器设计

高超声速飞行器控制系统具有非常突出的强耦合、强非线性、时变的力学特性,在其研究与设计过程中,需要处理高速飞行带来的弹性形变、多输入多输出、气动参数不确定以及高温高热等原因导致的各种传感器故障和部分作动器故障等一系列问题,因此该类飞行器控制系统的研究与设计面临着传统飞行器控制系统研究所未有的困难和挑战.针对高超声速飞行器飞行过程中遇到的部分作动器故障问题,本文提出了非线性观测器与控制器一体化设计的高超声速飞行器自适应反演容错控制方法.首先将飞行器作动器故障模型转换为一类状态不能完全测量,且具有未知参数和未知控制增益的SISO输出反馈非线性最小相位系统,然后,基于改进的K-滤波器理论对状态向量进行重构,在系统只有输出可以测量的情况下,设计了一种新型观测器,确定出收敛的状态向量,设计出强自适应能力的控制器,保证了系统所有信号的有界性.在自适应反演设计时,采用动态面设计方法,引入一阶滤波器,得到虚拟控制量的微分,消除传统反演设计中的"项数膨胀"问题,用Lyapunov稳定性定理保证误差一致有界.仿真实验验证了该算法的有效性.最后以高超声速飞行器纵向通道为例,验证了上述理论.     

高超声速飞行器最优PIF-LQR控制器设计

以一类通用高超声速飞行器的非线性纵向模型为研究对象,对其线性化后,应用LQR理论设计了一种多输人多输出的最优控制器.通过引入比例积分滤波器(PIF),有效地抑制模型参数变化所引起的扰动,实现飞行器对速度和高度变化指令精确跟踪.将所设计控制器应用于具有不确定参数的高超声速飞行器扰动模型,通过仿真对控制器的鲁棒性进行评估.仿真结果表明,尽管存在参数不确定性,所设计控制器能够满足高超声速飞行器在复杂飞行条件下的控制要求,具有较强的鲁棒性.     

高超声速飞行器考虑数据丢失的预测控制研究

以高超声速飞行器纵向通道为研究对象,考虑飞行器控制系统中传感器–控制器以及控制器–执行器通道均存在数据丢失的问题,提出一种能有效处理丢包的预测控制方法。首先,对高超声速飞行器纵向通道非线性模型进行局部小扰动线性化,得到平衡点处线性化模型;接着,建立有数据丢失的系统动态模型,使用终端状态约束集和终端代价函数方法设计预测控制器并设计相关补偿策略,以实现高超声速飞行器输入指令的跟踪;最后,基于MATLAB和Truetime平台进行数值仿真。结果表明,所设计的预测控制器能保证系统在出现数据丢失时具有良好的跟踪性能和鲁棒性。     

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。     

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.