基于LQR的无人直升机姿态控制器设计

无人直升机控制系统是一个易受环境干扰的、各通道相互耦合的非线性系统.为了实现无人直升机能在不同环境下自主飞行,需要设计抗干扰能力强的控制器;采用系统辨识的方法得到直升机横向通道和纵向通道姿态环路的线性系统模型;根据线性最优二次型理论,对直升机横向通道和纵向通道的姿态环路设计了LQR最优控制器,使用MATIAB仿真选取最优控制器参数后,在ALIGN 700N直升机上进行了实际飞行试验,仿真和飞行试验表明,采用LQR控制技术设计的无人直升机姿态控制器具有较强的鲁棒性和实用性.     

基于双目视觉的小型无人直升机位姿检测

无人直升机的位置与姿态检测是直升机自主飞行控制的基础。基于双目视觉原理,对直升机标志点进行检测并跟踪,利用基于顺序一致性的极线约束匹配方法,对检测到的多个标志点进行立体匹配,计算标志点三维坐标从而得到无人直升机的位置与姿态信息。设计一个基于双目视觉的小型无人直升机空间位姿测量托架,用于飞行控制模型及飞行控制算法的研究及验证。     

具有输入输出约束的无人直升机预设性能安全跟踪控制

针对无人直升机姿态与高度系统存在未知外部干扰、输入饱和、姿态与高度约束等问题, 本文提出一种具 有输入输出约束的预设性能安全跟踪控制方法. 首先, 针对无人直升机的姿态与高度约束, 通过设计一类边界保护 算法, 构建了新的安全期望跟踪信号. 为了保证系统对于安全期望跟踪信号的跟踪性能, 将预设性能函数与边界保 护算法进行结合, 并对跟踪误差进行转换. 针对系统的输入饱和现象, 使用Sigmoid函数进行逼近; 同时, 针对饱和函 数的逼近误差与未知外部干扰构成的复合干扰, 采用参数自适应方法对其上界进行逼近. 然后, 结合反步控制方法 设计了安全跟踪控制器, 并通过Lyapunov稳定性理论证明了闭环系统所有信号的收敛性, 保证了无人直升机的安全 跟踪性能. 最终, 通过数值仿真验证了所提控制方法的有效性.     

小型无人直升机模型辨识数据处理方法研究

针对小型无人直升机模型频域辨识过程中的姿态角速率测量误差,提出了一种飞行数据处理方法。该方法采用飞行试验扫频测试技术,确保激励信号能够满足不同频段下模型辨识对飞行数据的需求;设计基于有色噪声的卡尔曼滤波器以降低紊流风场对飞行测量数据的影响,同时,对飞行测量数据使用数据预处理的方法以剔除测量噪声、野值、直流成分和低频分量。在小型无人直升机系统各通道中进行验证,验证结果表明,所提出的飞行数据处理方法能够满足小型无人直升机模型辨识对姿态角速率数据精度的要求,为精确建模提供了较高质量的飞行数据。     

一种线性自抗扰控制器的无人直升机姿态控制方法研究

针对无人直升机模型复杂,控制器难于设计,易受外界干扰等问题,本文在建立亚拓系列直升机动力学模型基础上,提出了一种改进的二阶线性自抗扰控制器。首先,将线性扩张状态观测器用于估计影响输出结果的扰动,并加入跟踪微分器。然后,改进了控制器结构与反馈补偿系数,使直升机姿态角能够更快地响应所输入的指令,并能够按设定的角度飞行,以完成要求的任务;最后,通过引入白噪声干扰模块,来验证本文控制器的抗干扰能力。对比仿真结果表明,本文所提出的控制器对于无人直升机的姿态角有较好的控制效果,优于其他两种控制器。特别是在噪声干扰的条件下,也有较好的动态性能和鲁棒性。     

适应扰动的无人直升机姿态跟踪控制

无人直升机在实际飞行过程中,会受到阵风等外界因素的干扰,并且模型不确定性也会对控制效果带来不利影响.为应对这些挑战,本文设计了一种基于扩张状态观测器的自抗扰反步控制器.首先,建立了无人直升机姿态动力学模型.随后,引入扩张状态观测器,用以实时观测由外界扰动和模型不确定性组成的总和扰动.观测得到的总和扰动估计值与基于Lyapunov函数的反步法控制器控制算法相结合,用以消除总和扰动的影响,使得无人直升机在各种飞行条件下均能对运动指令进行快速和准确的跟踪.最后,仿真研究和飞行实验验证了该控制律的有效性.与同等条件下的PID控制器相比,该控制律表现出更优的飞行性能.     

基于径向基函数神经网络与扩张状态观测器的无人直升机控制

针对具有系统不确定和外部干扰的无人直升机飞行控制问题,提出了一种基于神经网络和扩张状态观测器的控制方法.利用神经网络逼近系统的不确定性,引入扩张状态观测器对神经网络的逼近误差和系统外部干扰进行估计.基于神经网络和扩张状态观测器的输出,对无人直升机的主旋翼挥舞角、姿态角速率、姿态角、速度与位置系统分别进行了控制器设计,以增强系统鲁棒性和抗干扰能力.同时,引入动态面控制方法以避免对虚拟信号进行直接求导,并通过李雅普诺夫方法分析了闭环控制系统的稳定性.最后使用无人直升机数据进行仿真验证,结果表明设计的控制律能使无人直升机有效跟踪控制指令,具有良好的稳定性与鲁棒性.     

改进非线性干扰观测器的机械臂自适应反演滑模控制

针对传统滑模和传统干扰观测器在机械臂关节位置跟踪中存在的控制输入抖振、需要测量加速度项、应用模型受限等问题,提出一种改进非线性干扰观测器的机械臂自适应反演滑模控制算法。首先,设计改进的非线性干扰观测器进行在线测试,在滑模控制律中加入干扰估计值对可观测的干扰进行补偿;然后选择合适的设计参数,使观测误差指数型收敛;其次,引入反演自适应控制律,对不可观测的干扰进行估计,进一步改善控制系统的跟踪性能;最后,利用李雅普诺夫函数验证了闭环系统的渐近稳定性,并将其应用于机械臂关节位置跟踪。实验结果表明,与传统滑模算法比较,所提控制算法不但加快了系统的响应速度,而且能有效地削弱系统抖振、避免测量加速度项并扩大应用模型使用范围。     

小型无人直升机的姿态与高度自适应反步控制

针对小型无人直升机的姿态与高度控制问题, 本文提出了一种基于反步法的自适应控制策略. 具体而言, 首先对小型无人直升机的运动学模型进行了等效变换, 使系统中未知参数满足线性参数化条件, 然后应用反步法设计了包含主旋翼挥舞模型的姿态与高度自适应控制器, 并借助Lyapunov方法和芭芭拉定理对闭环系统的稳定性进行了严格的数学分析. 最后, 对该控制器的性能进行了仿真验证, 结果表明在直升机质量和惯性矩阵存在不确定性(未知)的情况下, 该控制算法依然能够取得良好的控制效果.     

基于MEMS器件的姿态航向参考系统设计及应用

在小型无人直升机的控制中,需要有高精度的运动测量信息作为导航状态输入,通常这些小型直升机因需要在特定的情况下工作而往往体积较小,因而也对导航设备提出了高精度、低功耗、微型化、低成本等多方面的苛刻要求.介绍一种基于MEMS器件的小型姿态航向参考系统的设计及实现,该系统已应用于小型无人直升机的导航控制中.     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。