基于Windows CE的嵌入式手持GPS导航仪

为提高定位精度和系统响应速度，采用嵌入式操作系统Windows CE．net和嵌入式微处理器ARM9，开发了手持式GPS导航定位仪。系统主要包括两部分：一是在S3C2410开发板中实现了GIS功能，二是实现了GIS与GPS的集成，实现了地图数据库查询、定位导航、路径寻优、无线通信、电子地图更新等功能。应用EVC＋＋4．0和MapXMobile开发了嵌入式GPS移动导航系统软件，采用多线程技术，在后台异步运行地图数据库查询等程序。经过测试，基于WindowsCE的嵌入式手持导航仪能准确地获取GPS数据，匹配后电子地图能准确显示位置并指示方向；定位误差和响应时间均能满足设计要求；系统能自动给出最优路径；系统的软硬件集成度较高，稳定性好。     

Generalized unscented Kalman filtering based radial basis function neural network for the prediction of ground radioactivity time series with missing data

On the assumption that random interruptions in the observation process are modeled by a sequence of independent Bernoulli random variables, we firstly generalize two kinds of nonlinear filtering methods with random interruption failures in the observation based on the extended Kalman filtering (EKF) and the unscented Kalman filtering (UKF), which were shortened as GEKF and GUKF in this paper, respectively. Then the nonlinear filtering model is established by using the radial basis function neural network (RBFNN) prototypes and the network weights as state equation and the output of RBFNN to present the observation equation. Finally, we take the filtering problem under missing observed data as a special case of nonlinear filtering with random intermittent failures by setting each missing data to be zero without needing to pre-estimate the missing data, and use the GEKF-based RBFNN and the GUKF-based RBFNN to predict the ground radioactivity time series with missing data. Experimental results demonstrate that the prediction results of GUKF-based RBFNN accord well with the real ground radioactivity time series while the prediction results of GEKF-based RBFNN are divergent.     

基于反馈精确线性化的混沌系统同步控制方法

应用精确线性化方法，通过严格的状态变换和反馈方法，将非线性混沌系统线性化. 考虑到系统的部分状态变量无法测量，设计了混沌系统的状态观测器，求解出了状态观测器的反馈控制律. 将这种控制方法应用于Lorenz混沌系统的同步控制，仿真结果表明，系统三个状态变量的同步误差均能在很短的时间内收敛到零.因此，该同步控制方法在保证闭环系统稳定的前提下，具有较好的同步控制快速性和较高的控制精度. 关键词： 反馈线性化 混沌同步 状态观测器     

基于Stiefel流形的粒子滤波器研究

为了解决粒子滤波的粒子退化和粒子多样性丧失问题,提出了一种基于Stiefel流形的粒子滤波算法.该算法将系统模型置于Stiefel流形上,用朗之万分布描述过程转移概率分布,用矩阵正态分布表示似然函数分布,在流形分布上进行粒子采样.在计算加权粒子的均值时,将流形嵌入到欧氏空间中,先计算欧氏空间中的粒子均值,再将计算结果投影到嵌套流形上,这就排除了噪声统计特性对粒子权重方差的影响,得到了一种受系统状态模型限制较少的重要性概率密度函数通用选择方案.仿真时选取单变量非静态增长模型,仿真结果验证了该算法的实时性、鲁棒性,滤波精度和滤波效率均比无味粒子滤波算法更好.