自主在轨服务航天器空间对接过程建模与仿真

发展在轨服务技术是延长航天器的使用寿命,提升航天器的整体性能的一种有效手段.对采用了一种新型对接机构的两颗自主在轨服务航天器的空间对接过程,进行了运动学和动力学建模,并利用多体动力学仿真软件ADAMS建立控制系统的方法,进行了三组具有不同初始条件及控制作用的对比仿真分析,结果证明对接机构性能良好,在一般初始条件下均可实现可靠对接.另外,还结合仿真结果给出了部分改进设计,为对接机构的进一步完善提供了参考.     

航天器中含间隙机构非线性动力学问题及其研究进展

介绍了航天器中含间隙空间机构动力学的研究进展。论述了间隙非线性研究对新型航天器设计及在轨运行性能分析的重要意义。提出了待解决的若干含间隙空间机构动力学关键问题,其中包括空间机构间隙接触非线性动力学分析设计、在轨运行机构稳定性分析。以及在轨含间隙空间机构动力学性能全局预测模拟的仿真软件研制等．     

一种自移动空间机械臂末端执行器的研制

针对中小型自移动空间机械臂在轨操作和"换位行走"的任务需求,研制了一种小型化、大容差、高刚度可靠连接的末端执行器及其相应的目标适配器.末端执行器采用单一驱动实现捕获、拉紧锁合、解锁和电连接器插拔等多种功能.考虑捕获容差条件及锁合性能要求,对末端执行器的关键机构参数进行设计.通过ADAMS建立虚拟样机,对捕获容差及锁合的功能性能进行验证.最后通过样机实验对末端执行器的功能进行验证,验证了设计的可行性及仿真的准确性.     

空间电磁对接控制问题

航天器空间电磁对接能避免诸如推进剂消耗、羽流污染和对接冲击等现有基于推力器对接所固有的缺陷,应用前景广阔.空间电磁对接控制目前国内外还没有有效研究,论文主要针对此问题开展初步研究工作.论文首先重点分析空间电磁对接特性及其主要控制问题,然后采用反馈线性化方法对地面二维电磁对接控制模型进行线性化处理、以及基于线性化模型应用Kalman滤波方法估计电磁对接运动状态,最后采用二阶稳定性方法设计控制律并进行仿真分析.理论研究和仿真分析表明:航天器空间电磁对接是可行的,电磁对接非线性模型可以采用反馈线性化方法实现精确线性化,基于线性化模型的二阶稳定性方法满足控制律设计要求.     

基于超二次曲线障碍描述的航天器交会对接地面实验研究

航天器交会对接技术是众多空间任务得以开展的关键性技术,在进行空间在轨飞行任务之前,需开展相应的地面实验研究.首先,基于二维交会对接模型,提出了一种基于势函数法的交会对接控制方法.其次,考虑与类矩形障碍物的避撞约束以及与心形目标航天器的安全对接区域约束,并采用超二次曲线去描述该障碍物外形.然后,基于花岗岩气浮平台搭建了二维交会对接地面实验系统,设计了航天器气浮模拟器以及电磁对接机构,并开展了交会对接地面实验研究.实验结果表明了所搭建实验系统的可行性,同时也验证了所提出交会对接控制方法的有效性.     

空间机器人操作任务可视化仿真研究

利用先进的可视化软件仿真空间机器人的复杂任务过程是进行空问机器人研究的重要途径.围绕空间机器人操作任务的可视化仿真,在分析空间机器人任务过程基础上,采用层次建模思想构建空间机器人几何模型.基于几何模型库的树状层次结构,以配置文件和动态链接库相结合的方式实现空间机器人特征功能,并通过动态数据分发管理、区域过滤、多频采样插值等方法实现仿真系统的数据交互与处理.最后利用Orbiter软件的OrbiterAPI进行二次开发,实现了空间机器人任务过程的可视化仿真,真实度高,仿真效果好.研究成果可扩展应用到其它新型航天器系统的可视化仿真.     

空间大型末端执行器抓捕容差优化及其仿真

为了使空间大型末端执行器的抓捕操作性能得到最大程度的发挥,不同于传统的从机构设计角度得到末端执行器固定抓捕容差的方法,本文从优化设计学的角度出发,根据末端执行器的工作过程及其原理,将抓捕容差划分为捕获容差和拖动容差两部分,通过分析影响大型末端执行器抓捕容差的结构因素,分别建立了末端执行器捕获容差和拖动容差的数学优化模型,并基于线性加权法和惩罚函数法获得了抓捕容差最优值(128.58mm,128.58 mm,100 mm,15.12,15.12,16.32)T,同时得到了末端执行器本体相对应的结构参数.最终,采用仿真研究方法进行了抓捕容差优化及抓捕性能实验研究.实验结果验证了理论分析的正确性,证明本文提出的末端执行器数学优化模型合理,优化算法正确.     

双气腔油气式缓冲器充填容差仿真分析

在飞机起落架优化设计的研究中,双气腔油气式缓冲器具有功量吸收能力大,缓冲效率高的特点,但性能易受初始充填情况的影响,如何对双气腔油气式缓冲器进行仿真分析成为研究重点.首先建立起落架的数字模型,通过ADAMS软件中的Aircraft计算分析模块结合特性文件对起落架着陆撞击的动力学特性进行仿真.通过对比正常充填条件下的仿真结果与试验结果,发现误差在4.3％以内,仿真方法有效可信.依据缓冲器高低压气腔不同的充填情况,分别进行仿真,对比不同充填情形下的仿真结果,得出该型起落架缓冲器的充填容差特性.建立了一种研究双气腔油气式缓冲器双腔充填对缓冲性能影响的分析方法.仿真结果有一定的工程应用和参考价值.     

航空电源系统的容差分析及仿真研究

介绍了可靠性设计的基本技术之一的容差分析的意义及整体流程,详细论述了蒙特卡罗分析和最坏情况分析的基本原理,提出了基于软件应用仿真方法进行电路容差分析的方案,结合实际某飞机的辅助电源电路,给出了利用仿真软件研究电路参数偏差的容差分析方法,并证明该方案的可行性.     

面向自主运行的深空探测航天器体系结构设计 及自主任务规划方法

传统的航天器运行管控方式严重依赖地面指控、人力成本耗费大且对任务响应时间长,难以满足深空探测远距离通信时延突出的任务特点,航天器的智能化水平亟待进一步提高.本文通过对航天器自主运行问题进行系统地分析,提出一种基于多智能体的航天器自主运行的体系结构,面向自主系统结构、运行流程等进行了设计.重点针对小行星探测任务,提出了一种包含平台和载荷任务管理的两阶段航天器自主任务规划算法设计方案,能够实现平载一体的航天器自主任务管理,根据高级任务目标输出完整的指令序列.并通过自主任务规划仿真,对相关算法和模型的正确性和可行性进行了可视化验证和分析,为航天器自主运行技术研究提供了一种有益的思路和方法.     

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.