微小型无人直升机建模与航迹跟踪控制

无人直升机航迹跟踪控制系统对控制器性能要求较高,而现阶段很多控制器对复杂航迹跟踪效果一般,误差较大,很难为真实无人直升机航迹飞行提供理论依据.针对上述问题,首先,对无人直升机外部进行PID控制器设计,并针对PID控制器提出一种改进粒子群算法对控制器进行参数整定.然后,采用改进人工势场法的航迹与无人直升机模型相结合的方式...     

小型无人直升机发动机转速控制系统设计

良好的活塞式汽油发动机控制系统是小型无人直升机稳定飞行和保持恒定转速的前提条件.本文针对某型无人直升机发动机控制系统中采用的GV-1进行控制器参数的辨识,最后基于自抗扰控制技术设计出简单、可靠和成本低廉的转速控制器,实验结果表明,该控制器可以到达稳定飞行的需要.验证了所设计的控制器的有效性,可进一步简化小型无人机的转速...     

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.     

相位差结合小波包的无人直升机故障诊断

针对低成本的微小型无人直升机（MUH）传感器性能不稳定,容易出现故障的缺陷,提出了一种基于相位差和小波包分析相结合的故障诊断方法。根据MUH传感器输出信号的特点,建立了基于相位差的故障诊断模型,利用相关分析法估计相位差进行故障检测,采用小波阈值法对采样信号进行预处理,以提高相位差的估计精度,运用小波包分析进行故障分离。结合实验数据进行仿真,结果表明该方法是一种行之有效的MUH传感器故障诊断方法,已成功应用在某微小型无人直升机的飞行实验中。     

基于人工蜂群算法的无人直升机LQG/LTR控制律优化设计

针对无人直升机线性二次型高斯/回路传输恢复(LQG/LTR)飞行控制律设计中加权矩阵的选定问题, 提出一种基于人工蜂群算法优化控制器加权矩阵的方法. 采用LQG/LTR控制方法设计无人直升机的内外环自主飞行控制系统; 利用蜂群算法的全局寻优能力, 通过最小化性能指标对状态反馈控制器进行优化; 在系统噪声和阵风的干扰下, 对该无人直升机飞行控制系统进行轨迹跟踪仿真. 研究结果表明, 该优化设计方法提高了控制器的设计效率, 优化后的控制器的跟踪性能和鲁棒性有了明显提高.     

基于神经网络的小型无人直升机非线性鲁棒控制设计

针对小型无人直升机的姿态控制问题,为补偿系统参数不确定性和外界扰动的影响,设计一种连续的非线性鲁棒控制器.首先,利用神经网络在线估计系统不确定性,采用基于误差符号函数积分的鲁棒控制算法抑制外界扰动,同时补偿神经网络估计误差; 然后,利用基于Lyapunov函数的分析方法,证明所设计控制器的闭环稳定性,确保无人直升机姿态误差的半全局渐近收敛;最后,在无人直升机飞行实验平台上,进行无人机抗风扰控制实验.实验结果表明,所提出的控制方法具有良好的控制效果,对系统不确定性和外界扰动具有良好的鲁棒性.     

微小型无人直升机建模与姿态控制

建立了微小型无人直升机数学模型,并采用误差预报法进行参数辨识,获得了较高精度的数学模型。应用H_∞回路成形鲁棒控制方法设计了微小型无人直升机姿态控制器,并进行了频域分析,开环控制系统的成型效果良好。在模型浮动20%条件下进行仿真,结果表明控制系统具有较强的鲁棒性。飞行试验获得了良好的控制效果,验证了建模与控制器设计方法的可行性和有效性。     

基于Dubins曲线的无人直升机轨迹规划

为提高无人直升机的控制性能,提出了一种基于Dubins曲线的轨迹规划算法,并对其各个部分的实现进行了研究和设计。该算法利用Dubins曲线原理对定点飞行任务的两点或者多点目标进行分析计算,寻找出一条最短的飞行路径,从而提高了飞行效率。根据无人直升机系统多变量、非线性和强耦合的特点,采用串级PID方法设计了飞行控制器,该控制器能够修正无人直升机的姿态和位置,从而提高了轨迹规划的稳定性和准确性。最后,以某小型无人直升机为实验平台表明了该轨迹规划算法和控制器的可行性。     

小型无人直升机浸入–不变集自适应控制

本文基于浸入–不变集理论,针对小型无人直升机存在的参数不确定性问题,设计一种新型的自适应控制器.利用基于Lyapunov的分析方法和La Salle不变性原理,进行闭环系统的稳定性分析,确保无人直升机姿态角的跟踪误差全局渐进收敛,以及闭环系统的稳定性.在无人直升机姿态飞行控制实验平台上,进行了无人机姿态跟踪控制实验.实验结果表明,本文所提出的控制方法具有良好的跟踪控制效果.     

直升机强跟踪自适应变稳控制器设计

变稳控制是直升机飞行模拟的关键技术之一,气动参数的不确定性是其设计的困难所在.对此,提出了利用双目标直升机模型构造原型直升机的强跟踪自适应变稳控制器,它将强跟踪的反馈补偿机构和自适应控制参数设计相分离,简化了控制设计,同时实现了提高自适应参数修正过程的系统稳定裕度和显著降低跟踪误差的目的.仿真实验结果验证了所提出方法的有效性和可行性.     

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。     

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。