基于神经网络的多机协同编队控制器设计

针对多架无人机协同编队飞行控制问题,设计了一种基于BP神经网络的无人机编队飞行控制器.以两机编队为单元,僚机同时跟踪长机和相邻僚机,根据相对位置和参考坐标系统,采用BP神经网络训练得到最佳的PID控制参数,设计三通道PID控制器并对编队系统进行分布式协同控制,使系统快速跟踪指令并保持编队队形.对四架无人机组成的编队系统进行仿真,系统编队可快速保持期望队形,表明设计的编队控制系统具有良好的稳定性和较强的抗干扰能力.     

多无人机编队递归非奇异终端滑模容错控制

为解决四旋翼无人机编队飞行过程中易受到外部干扰、空气阻力、执行器故障等不确定因素影响的问题,提出了一种基于补偿函数观测器(CFO)的递归非奇异终端滑模控制(RNTSMC)方法来提高四旋翼无人机编队系统性能。首先,引入具有高精度估计的补偿函数观测器,实时估计外部干扰、执行器故障等信息,通过设计递归积分终端滑模面改进非奇异终端滑模面等效控制器对估计信息进行补偿控制,并给定滑模面初始值,保证两滑模面依次连续到达平衡点,确保跟踪误差在有限的时间内快速收敛到0。其次,根据长机-僚机法建立编队模型,基于滑模控制理论,设计编队协同控制器,保证无人机编队完成飞行任务。最后,通过对比仿真结果表明,该方法对四旋翼无人机编队具有良好的容错性能。     

伪卫星协同编队控制与仿真

为保持4颗编队伪卫星的最佳几何布局,设计了一种综合自适应神经网络编队控制器,利用李亚普诺夫稳定性理论证明了“长机-僚机”方式的两机编队系统的稳定性。以两机编队为单元,根据相对位置和参考坐标系统,采用综合自适应神经网络结构对伪卫星系统进行分布式协同编队控制,使系统快速跟踪指令并保持最佳编队队形。对以无人机为平台的4颗伪卫星编队进行仿真,结果表明僚机能够快速跟随长机飞行并保持最佳编队队形,证明该编队控制器具有良好的稳定性和鲁棒性。     

基于多任务的无人机编队控制研究

考虑到多架无人机编队飞行的特点,将松散编队及协同思想应用到紧密编队控制中,提出了一个三架无人机协同作战编队的飞行控制系统设计方法;在编队飞行动力学模型的基础上,设计了基于特征结构配置的无人机横侧向控制律,进行指定航路的飞行控制;然后,设计编队控制器,两架僚机可紧紧跟随长机并保持队形稳定;仿真结果表明,设计的控制器可以控制多架无人机进行紧密编队飞行,具有一定的实用性和推广价值。     

无人机编队飞行神经网络自适应逆控制器设计

针对无人机编队飞行时存在的气动耦合和外部干扰等影响因素,提出基于“长-僚机”模式的神经网络自适应逆控制器设计方法.详细推导了气动耦合影响,建立了完整的编队飞行非线性数学模型,设计了非线性动态逆控制律,提出了改进的 BP 神经网络算法,自适应地逼近和在线补偿动态逆误差,改善了控制效果,并针对队形变换提出了简单有效的设计思想.仿真表明,该控制器能有效实现编队队形的保持或变换,控制系统结构具有良好的扩充性.     

基于非线性动态逆的无人机编队协同控制

针对多无人机在空间机动过程中的编队形成与保持控制问题,提出一种基于非线性动态逆的无人机编队控制方法.将编队控制过程分解为两步:首先给出分布式长机状态估计算法,各编队无人机根据"相邻"无人机状态解算自身的期望运动指令;其次是设计接于非线性动态逆的编队控制器,使各无人机快速跟踪其期望指令并形成和保持稳定队形.仿真实验表明,编队长机进行空间机动过程中,各僚机能够准确估计其状态,快速形成并维持队形稳定.     

基于领航-跟随的有人/无人机编队队形保持控制

针对有人/无人机编队飞行过程中的队形保持问题,采用领航-跟随策略设计一种有人/无人机编队队形保持控制器.首先从编队作战体系和控制原理角度设计有人/无人机编队控制系统结构;然后基于领航有人机与跟随无人机平面位姿的几何关系,建立编队内相对距离-角度运动学模型;最后在考虑僚机控制系统时变扰动的情况下,针对编队运动学模型特点设计动态反馈自适应编队队形保持控制器,并利用李雅普诺夫理论证明编队控制器的稳定性.仿真结果表明,所设计的控制器能够克服僚机控制模型不确定性带来的扰动影响,可以实现编队由初始误差到期望队形的快速调整以及稳定队形的保持.     

无人机编队飞行导航方法及其仿真研究

研究无人机导航优化编队问题,编队各成员的高精度定位是无人机协同编队飞行的关键技术和难点.为了提高编队定位的精度,提出了一种长机组合导航和长/僚机相对测量的编队成员导航定位方法,在编队导航系统模型的基础上,采用卡尔曼滤波原理估计出各成员的惯导误差,经校正后得到精确的导航信息,并进行仿真.仿真结果表明,改进的方法对所设计的长机与僚机的导航定位是完全可行的,编队各成员均获得较高的测地导航精度.     

基于自适应滤波的无人机编队防碰撞系统研究

针对无人机双机近距编队飞行时,易发生碰撞事故的问题,文中提出了有效控制的防碰撞算法,并建立了半物理仿真系统。采用自适应Kalman滤波为防碰撞控制算法,使编队的距离保持在安全范围之内。该算法通过预测僚机的状态,实时控制僚机机动,当编队达到警戒距离时,僚机迅速执行规避动作,双机分离。搭建了模拟编队飞行的半物理仿真平台,用Zigbee实行无线通讯,以超声波实现机间测距。实验结果表明,该系统能防止编队发生碰撞,并且有效抑制滤波发散,具有较好的鲁棒性和实时性。     

基于三维程控的无人机协同编队飞行研究

基于三维程控飞行策略,对多无人机(UAV)协同编队飞行控制进行研究,提出一种多机同方位任务需求的编队控制方法.采用“长机-僚机”编队结构模式控制编队飞行,以编队中的长机航迹坐标为基准坐标系实现了僚机与长机相对位置一致的控制;实现了编队中所有无人机同时到达指定位置并保持速度相对稳定的控制.通过航路规划和编队遥调,实现了人工干预与自动控制结合的编队飞行策略.仿真结果表明,该方法具有较好的可实施性、管理性、应用性和安全性.     

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.