微机电系统姿态估计系统算法与仿真

结合陀螺仪、加速度计误差模型,实现了以微机电系统(MEMS)陀螺仪与MEMS加速度计为基础的姿态估计硬件仿真系统,可用于模拟任意噪声强度和安装偏差下三轴捷联惯导系统(INS),即按照给定运动曲线仿真输出陀螺仪与加速度计数据,为设计姿态估计算法提供仿真验证平台.同时,以姿态四元数为状态变量,载体俯仰角与横滚角为观测值设计了基于扩展卡尔曼滤波器(EKF)的姿态估计算法,俯仰角估计误差小于0.04°,横滚角估计误差小于0.05.,偏航角漂移速度0.01(°)/s.     

基于修正的卡尔曼滤波的姿态估计算法研究

研究惯导系统的稳定性问题,其中微惯性测量单元(MIMU)可以为捷联惯导系统提供实时的姿态和航向信息。研究姿态估计提高导航精度,由于陀螺漂移引起姿态误差,单独使用MIMU使姿态精度差。为了克服陀螺误差随时间积累不断增大,无法长时间提供稳定的姿态的缺点,提出采用磁强计修正的卡尔曼滤波四元数姿态估计算法。算法以姿态四元数为状态向量,通过四元数更新方程建立离散滤波状态方程,将加速度计和磁强计输出的六维数据转化为四元数的量测值建立量测方程,有效减少了计算量,补偿陀螺的漂移误差带来的影响。仿真结果表明改进算法提高了捷联惯导系统的精度和稳定性。     

姿态航向测量与误差补偿方法研究

设计了一种基于MEMS陀螺仪、加速度计、磁传感器的小型姿态航向参考系统;以四元数和角速率偏差为状态矢量,磁场强度和加速度计信息为量测矢量,构建基于Kalman的四元数姿态航向解算方法;通过调整测量噪声方差矩阵,解决动态过程中由于运动加速度造成的姿态角误差;采用陀螺仪误差建模和磁航向罗差补偿技术,进一步提高了系统测量精度。根据飞行数据分析,姿态航向参考系统具有较高测量精度和较好的稳定性、动态性,姿态角均方根误差小于1.5°,航向角均方根误差小于3°。     

一种自适应滤波方法在捷联惯导系统大失准角初始对准中的应用

为了对静基座大失准角捷联惯导系统(SINS)进行初始对准,建立了在静基座下基于四元数的SINS非线性误差模型。该误差模型无需对姿态误差角进行小角度假设。为了在观测噪声方差未知的情况下估计SINS失准角,提出一种在线估计观测噪声方差矩阵的自适应扩展卡尔曼滤波方法。仿真结果表明,该自适应滤波方法能在观测噪声方差未知的情况下有效地对静基座大失准角SINS进行初始对准。     

捷联惯导大方位失准角快速初始对准

捷联惯导方位角快速性能优化问题,传统大方位失准角初始对准方位角收敛速度较慢,直接影响惯导系统的性能。为此提出一种无重置联邦滤波器的以速度误差和比力输出作为观测量的快速初始对准新算法。给出了捷联惯导系统非线性误差模型,并分析了两种观测量,建立了速度观测子滤波器和比力观测子滤波器,同时采用了相应的状态方程和观测方程。用三种方法进行了大方位失准角初始对准的数字仿真。仿真结果对比表明,新方法不仅使方位失准角收敛速度快,而且在加速度计噪声增大10倍的情况下,仍然具有极高的对准精度。     

大方位失准角传递对准非线性模型研究

针对惯导系统大方位失准角传递对准的非线性误差方程不准确问题,同时考虑杆臂效应和挠曲变形两种主要误差因素来建立挠曲变形和杆臂效应加速度一体化误差模型,从而完善惯导系统大方位失准角传递对准非线性模型.针对非线性滤波的稳定性和快速性问题,采用比例修正无味卡尔曼(UKF)滤波模型估计姿态失准角,并采用速度匹配算法对模型的正确性和滤波的有效性进行仿真验证.结果表明,该模型在大方位失准角传递对准时可以满足对准精度和时间的要求.     

基于H∞的低精度捷联惯导系统初始对准方法

由于低精度捷联惯导系统的陀螺精度较低,初始对准时方位失准角的估计精度往往不高;另外,进行初始对准的常用方法是采用Kalman滤波技术,但在实际应用时,其鲁棒性不高,因此迫切需要一种能够改善低精度捷联惯导系统方位失准角的估计精度且兼具鲁棒性的初始对准方法。提出了一种将H∞滤波用于引入磁航向的低精度捷联惯导系统的初始对准方法,能够解决上述问题。建立了一种引入磁航向的捷联惯导系统初始对准的误差模型,通过可观测性和可控性分析,得出可观可控系统,利用H∞滤波方法对其进行了仿真分析,仿真结果表明,能够改善低精度捷联惯导系统方位失准角的估计精度,并能有效抑制有色噪声及建模误差的影响,将其应用于低精度捷联惯导系统的初始对准是切实可行的。     

小型无人直升机嵌入式导航系统算法与飞行试验

基于微陀螺、加速度计、磁强计以及GPS模块构建了姿态航向位置参考系统(Attitude heading position ref-erence system,AHPRS).首先,通过等效旋转矢量法由陀螺解算出估计姿态角;其次通过GPS、加速计的测量值,结合磁强计估计补偿姿态角,推导基于误差四元数的滤波方程,滤波器的周期...     

大摇摆情形的自对准方法

在风等干扰的影响下,载体易产生较大幅度的摇晃,造成捷联惯导系统初始姿态存在较大失准角,而由于缺少基准信息,并且包含失准角信息的导航误差不能直接量测,进而影响自对准精度.由于载体仅发生摇晃,并没有相对移动,从而存在零速的摇晃中心,若视载体为刚体,则载体各点的姿态是相同的.由于摇晃中心处的自对准是较为成熟的静基座对准问题,从而只需获得摇晃中心处的姿态误差即可.为了获得摇晃中心的位置,我们利用杆臂效应原理,通过将水平失准角扩展为待估参数,减小了模型误差,提高了摇晃中心位置的估计精度.对于摇晃基座存在大失准角问题,利用估计状态闭环补偿系统模型,逐步减小模型误差,获得较好的对准精度.最后通过仿真例子进行了验证.     

多传感器融合在地下管道测量中的应用研究

地下管道现有测量技术普遍存在环境干扰影响严重、测量精度低等缺陷,无法实现复杂地下管网的精确定位,导致地下管道管理混乱无序、施工事故频发。针对埋地管道空间位置测量问题,提出一种采用三轴陀螺仪、加速度计和磁力计等多传感器融合的姿态解算方法。利用加速度计和磁力计分量对陀螺仪误差进行修正,构造姿态矩阵,获取修正后的航向角、俯仰角和翻滚角,并对测量装置行程信息进行空间坐标计算,得到地下管道空间位置矢量信息,采用非开挖技术,实现地下管道的精确管理。该方法能满足测量精度的要求,实现对地下管道的准确定位,且能构造出地下管道的走向和三维空间位置形状。试验证明,基于多传感器融合的地下管道空间位置测量系统能够有效降低传感器漂移误差,测量得到的地下管道空间位置矢量信息具有较高的精确性,在地下管道非开挖工程领域具有一定的实用性。     

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.