制导弹药方案弹道跟踪与控制

研究飞行制导优化问题,针对一种旋转制导炮弹,为了保证弹道跟踪的精确性.提出设计输出指令为加速度值的高性能非线性制导律,并采用过载控制方案设计了制导控制系统.选择弹道上的参考点,利用GPS得到的制导弹药飞行位置及速度信息,得出一种非线性过载制导信号控制飞行器跟踪曲线弹道.采用非线性过载制导指令作为制导外环,加速度自动驾驶仪作为控制内环,根据变结构控制理论设计了自动驾驶仪.对设计的制导控制系统进行了数字仿真.仿真结果表明,非线性制导律及加速度自动驾驶仪能够保证制导弹药准确地跟踪设计轨迹,使跟踪误差处于合理范围内.     

新型制导炸弹半实物仿真系统研究

针对新型制导炸弹滑翔增程和运动目标捕获问题,设计了新型制导炸弹半实物仿真系统。分析了系统的软硬件设计、功能流程、提出了几项关键技术,并给出了解决方案。该系统的实现能够为导引头的自动目标识别跟踪算法提供测试平台,并能作为新型制导炸弹滑翔增程技术和制导方式的验证平台。     

飞行器转向时的航迹起始算法

在飞行器转向优化控制的研究中,传统的逻辑法在飞行器高速机动转向时因外推点与真实量测点距离偏大且跟踪波门偏小而丢失航迹真实量测点,从而导致雷达对观测目标航迹起始的失败.为了解决传统航迹起始算法所存在的问题,提出了采用修正外推点的方位角和放大的跟踪波门的改进的航迹起始算法.与传统算法相比,改进算法能够使目标的真实量测点更准确地落在雷达跟踪波门内.仿真比较和性能分析表明,上述算法对于提高飞行器等高速目标转向时航迹起始的正确率是有效和可行的.     

远程分布式图像制导仿真实验系统

针对开展图像制导技术研究在科研与教学方面的需要,考虑自动导引技术的特点,设计并开发完成了远程分布式图像制导仿真实验系统。实验系统利用无线网络技术,对于分布式客户端与服务器端共同完成对运动目标的图像采集、预处理、图像分割、目标识别、目标锁定与跟踪等数字处理过程,实时生成导引算法,控制转台驱动实验装置实现对目标的动态跟踪。目前设计的仿真实验系统能用于实现分布式图像制导仿真、多种图像制导算法的验证与实验,并已经用于科研与实验教学,取得了较好的结果。     

载人登月飞行器高速返回再入制导技术研究

返回再入段是载人登月任务完成后,保证宇航员安全返回地球的关键阶段,其跳跃式再入制导方法的研究是我国载人登月任务需要突破的一项重要关键技术.由于探月返回飞行器速度极高,其弹道特性与神舟飞船一类的近地轨道返回的飞行器有较大差别,也给制导导航与控制(简称GNC,以下同)系统设计带来较大挑战.与无人再入飞行器相比,载人飞行器需要具备防过载超限能力、大范围再入航程适应能力、高精度落点控制能力.为了满足上述要求,本文提出了一套基于全系数自适应校正的预测制导方案.在再入前,通过对基本倾侧角进行校正,提高了规划弹道对再入初始条件散布的适应性;再入后利用外环的预测与全系数自适应校正实现对规划弹道的持续修正,保证规划弹道与飞行器状态的匹配性,内环则采用短周期的弹道跟踪制导;对于横向制导,本文给出和比较了采用实时漏斗制导律、独立预测–校正制导律方案以及横航向独立自校正和耦合自校正方案.     

仿猎鹰扑翼飞行器自主飞行控制系统设计

仿生扑翼飞行器作为一种新型的飞行器,具有噪声小、隐蔽性好、机动性强、能量利用效率高等优势,在民用和军用领域具有广阔的应用前景.仿生扑翼飞行器的自主飞行能力是高效执行飞行任务的关键.目前,国内外飞行器的自主飞行研究已经取得了一些成果,然而鲜有以仿生扑翼飞行器为载体的研究.仿生扑翼飞行器特有的驱动结构给自主飞行控制研究带来了较大的挑战.本文以仿猎鹰扑翼飞行器作为研究平台设计了自主飞行控制系统.由于仿猎鹰扑翼飞行器的负载较小,本文采用了重量较轻的STM32微型计算平台作为主控芯片设计了硬件系统.由于微型计算平台的算力有限,本文综合考虑制导精度和运算速度,提出了一种线性/非线性切换制导算法,并通过仿真实验与线性制导、非线性制导算法进行了对比,证明了其更加适合于仿猎鹰扑翼飞行器.考虑到仿猎鹰扑翼飞行器的机构滞后问题,对其滚转角和高度设计了一个串级PID控制器.结合面向仿猎鹰扑翼飞行器的地面站软件,最终实现了基于仿猎鹰扑翼飞行器的自主定高圆弧轨迹跟踪任务.     

基于双目视觉的无人飞行器目标跟踪与定位

针对小型无人飞行器跟踪目标的问题,提出了一种基于双目视觉和Camshift算法的无人飞行器目标跟踪以及定位算法。双目相机得到的左右图像通过Camshift算法处理可得到目标中心特征点,对目标中心特征点进行三维重建,得到机体坐标系下无人飞行器与目标间的相对位置和偏航角,应用卡尔曼滤波算法对测量值进行了优化,将所得估计值作为飞行控制系统的反馈输入值,实现了无人飞行器自主跟踪飞行。结果表明所提算法误差较小,具有较高的稳定性与精确性。     

带落角约束的高超声速飞行器一体化制导控制

本文针对高超声速飞行器高速俯冲过程中的质心运动与绕质心运动之间存在强耦合的特点,提出了一种基于全量耦合模型的满足落角约束的一体化制导控制方法.首先建立基于视线角的飞行器与目标的相对运动方程和绕质心运动方程,通过微分同胚处理得到一体化制导控制模型.接着采用自适应块动态面反演方法提出了一体化制导控制方法.该方法充分考虑了飞行器质心运动与绕质心运动之间的耦合作用,显著提高高超声速飞行器高速俯冲过程中的整体控制性能.本文提出的一体化制导控制方法能使得飞行器闭环系统的状态一致最终有界,且视线角速率的界可以达到任意小.最后,通过仿真结果验证了全量耦合一体化制导控制方法的有效性.     

闭环制导实时仿真系统设计

研究飞行器制导系统实时性优化问题,由于飞行器闭环制导对于系统的实时性和制导快速性有着较高的要求,因此缺乏应用于工程实践的模型.为了能够在实验室环境下,实现飞行器闭环制导的实时仿真,提出设计闭环制导实时仿真系统.利用嵌入式系统,采用间接法求解最优制导问题.最后对系统进行了实时性测试,并对特定的吸气式高超声速飞行器模型进行轨迹仿真,结果表明,设计的系统完全能够满足飞行器闭环制导对实时性和快速性的要求.     

四旋翼航迹跟踪控制与仿真

四旋翼是一种运用广泛的飞行器,轨迹跟踪控制是四旋翼的研究热点。为了实现四旋翼对轨迹的精确跟踪,基于非线性制导算法进行轨迹跟踪控制。建立了四旋翼运动学模型,并介绍了基于非线性制导算法的轨迹跟踪控制。建立了非线性制导算法的带宽与速度和导引长度的关系,通过计算四旋翼姿态控制器带宽与期望航迹带宽,并根据香农采样定律求解出了非线性制导算法导引长度的取值限制范围。仿真结果表明,采用在取值限制范围内的导引长度,能够稳定快速地收敛到期望航迹,拐弯处航迹误差小于1.5 m,此时,四旋翼有最优的航迹跟踪效果。     

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.