Thermomechanically Driven Polymer Actuator for High-Precision Optical Alignment

Precise thermomechanical positioning has been demonstrated in an actuator device based on a silicone elastomer with a high thermal expansion coefficient. The actuator performance has been characterized using optical microscopy, and the actuator has been deployed in an optical coupling experiment to demonstrate the precise positioning of a ball lens between two single-mode fibers. Tuning of the coupling efficiency has been achieved in excellent agreement with calculated values and precise positioning (better than 200 nm) over a range of 20 mum has been achieved with low power dissipation and temperature control of plusmn0.2 degC. The actuation is linear with temperature over the entire range of motion. This linearity was achieved while amplifying the thermally induced expansion of the elastomer along the alignment axis by a factor of 2.1 over its nominal isotropic expansion value by physically constraining the material in the device. The device performance gives favorable implications for the use of such actuators in optical packaging applications     

基于音圈电机的精密扫描定位设计

针对目前精确定位技术在精微操作领域的应用,设计了基于音圈电机的精密扫描定位装置,用于实现光谱扫描测量中的成像光斑的定位。根据不同电机驱动的对比,选择直线型音圈电机作为精密定位的驱动装置。结合不同直线型直流电机的分类,详细叙述了音圈电机的工作原理、参数及选择依据。在结构设计中采用了柔性轴承和悬臂,并对柔性悬臂进行受力分析。结合精确定位及音圈电机的工作需求,设计了专门的驱动装置。通过实验对扫描定位装置进行性能验证,结果显示,定位装置的稳定时间小于30 ms,长时间的偏移小于1.5 μm,满足扫描定位的微米量级的设计要求。     

压电陶瓷致动器自适应逆控制方法的研究

压电陶瓷器件在精密定位和微位移控制中得到了广泛的应用，但是它也存在着迟滞，蠕变和位移非线性等不足，该文将自适应逆控制思想应用于对压电陶瓷致动器的控制，通过对其机电变换特性的分析，用自适应法建立压电陶瓷的迟滞蠕变模型和逆模型，并且在此基础上建立实验系统，对压电陶瓷致动器进行自适应逆控制法的研究，实验数据分析结果表明，该控制方法有良好的学习功能，系统的输出线性误差从28．1％减少到1．56％。     

基于测量为目的的故障定位技术

提出了一种基于测量为目的的,通过电力系统在GPS时间基准下通过对各保护继电器的开关动作,调整的先后顺序来进行精确故障定位的技术。这种定位技术用价格低廉的晶体振荡器代替原子钟作为本地钟,通过计算由于晶体振荡器频率漂移和偏差造成的时间误差,在最后的结果中通过数据处理扣除时间误差,进而达到高精度的要求。     

基于牛顿插值的RFID室内定位算法

随着近年无线网络的发展,出现了多种与室内定位相关的技术与应用。文中提出了一种基于牛顿插值的室内定位算法。该算法主要是基于射频识别技术(RFID)并结合Larndmarc系统利用插值求解虚拟的标签,从而对待测标签得到更精确地定位。实验证明,与k邻域算法相比,该算法在定位精度上得到了显著提高。     

Positioning beacon system using digital camera and LEDs

This paper is on a novel use of lighting or signaling devices constructed by light-emitting diodes (LEDs) as a positioning beacon. The idea is that the surface of the LED lighting device is divided into regions and used to show different visual patterns that are not noticeable by the human eye due to the high-frequency switching of the LEDs. A digital camera is used as a receiver to capture a sequence of images of the LED positioning beacon transmitter. Image-processing algorithms are used to decode the location code that is encoded in the visual patterns transmitted by the LED device. This idea can be applied to any LED traffic lights or signaling devices on the road and turn them into parts of a positioning beacon system. Such a system made up of high-brightness visible LEDs can provide the function of open-space wireless broadcasting of the positioning signal. The LED signaling method, transmission protocol, camera frame rate, LED flash rate, together with an implemented system and the experimental results, are presented in this paper.     

Energy adaptive MAC protocol for IEEE 802.15.7 with energy harvesting

The medium access control (MAC) protocol for indoor visible light communication (VLC) with energy harvesting is explored in this paper. The unfairness of throughput exists among devices due to the significant difference of their energy harvesting rates which changes with distance, acceptance angle and the obstruction probability. We propose an energy harvesting model, a new obstruction probability model and an energy adaptive contention algorithm to overcome the unfairness problem. This device can adjust its contention window according to the energy harvesting rate. As a result, the device with lower energy harvesting rate can get shorter contention window to improve its transmission opportunity. Simulation results show that our MAC protocol can achieve a higher degree of fairness.     

基于多元高斯混合模型的离线指纹数据库

针对室内环境下单次采样测量值的波动变化及信号间的相互干扰,该文提出一种基于分区多元高斯混合模型(MVGMM)的室内定位系统。根据信号接入点(AP)铺设位置与空间结构,系统采用一对多支持向量机算法对目标区域做分区操作,以精确信号变化的区域范围。利用狭小分区内信号间的耦合关系,建立基于信号间相互干扰的多元高斯混合模型,以改善信号波动所造成的定位精度下降。当室内环境发生变化时,基于分区多元高斯混合模型的自适应更新算法可对各分区指纹数据的可信度做出判断,并以自适应算法更新信号波动较大分区的模型参数,提高模型与现有环境间的耦合程度。实验结果表明,该文算法可利用相对少量样本数据,构建稳定可维护的室内信号分布模型,相较于其他算法,其定位精度也有一定程度提高。     

多基站无源定位技术在区域定位网络中的应用

多站时差定位是一种较精确的定位方法，它通过处理三个或三个以上测量站采集的信号到达时间来对辐射源定位。文中论述了多站时差无源定位的基本原理，提出了以TDOA多基站小区无源定位系统为基础构建区域定位网络的方案。论述了时差双基无源定位的基本原理，以及小区定位系统的几何布站，地面观测站对空中平台的实时精确定位算法，同步技术，区域组网与越区切换等主要问题的实现方案。     

一种以自主方式提高GPS定位精度的方法

本文介绍了一种提高ＧＰＳ（全球定位系统）定位精度的新方法,该方法基于本文提出的对ＡＲＭＡ模型的修正所得到的在线实时建与预测算法。通过准确地对ＧＰＳ定位数据进行在线实时的建模和预测和在此基础上的自适应滤波;能够提高ＧＰＳ定位精度３至５倍、一数据处理证明了此方法的有效性,方法对于运载体的最估控制特别是军事用户具有一定的实用价值。     

Locata——一种新型的定位星座

本文介绍了由澳大利亚GPS生产商Locata公司研发的Locata全新定位技术,Locata技术在GNSS不可用时提供高精度定位能力。Locata技术包括时间同步伪卫星收发器（LocataLite）,多部LocataLite组成的网络（LocataNet）,发射的信号相当于GPS信号,并采用系统时间同步（TimeLoc）专利技术实现网内LocataLite的自主同步。Locata接收机（移动接收机）通过载波相位测量即可得到单点定位。     

Algorithm for automatic alignment in 2D space by object transformation

Automatic alignment problem was coupled with the numerical coordinates on a machine, a vision system and wafer device. This paper proposes a method for constructing a general model for automatic alignment and formulating equations from three coordinates. The algorithm was derived under the assumption of precise positioning control and vision inspection. The idea for this algorithm originated from rigid body transformation, which is employed to describe the movement of a wafer on a dicing machine. The algorithm was based on simultaneous x, y, θ alignment. The formulated equation is in a simple matrix form, which can be connected to other mathematical equations. This equation could be used to write the current alignment models. The equation also gives a solution for direction changes among the coordinate systems. The algorithm is composed of matrices, and is very simple. An experiment was carried out on the dicing machine, and sufficient alignment performance was achieved.     

Adaptive access points deployment for Indoor bluetooth positioning accuracy enhancement

The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency. In the existing positioning approaches, much consideration is given to the positioning accuracy improvement by using the angle of signal, but the optimization of access points (APs) deployment is ignored. In this circumstance, an adaptive APs deployment approach is proposed. First of all, the criterion of reference points (RPs) effective coverage is proposed, and the number of deployed APs in target environment is obtained by using the region partition algorithm and full coverage algorithm. Secondly, the wireless signal propagation model is established for target environment, and meanwhile based on the initial APs deployment, the simulation fingerprint database is constructed for the sake of establishing the discrimination function with respect to fingerprint database. Thirdly, the greedy algorithm is applied to optimize APs deployment. Finally, the extensive experiments show that the proposed approach is capable of achieving adaptive APs deployment as well as improving positioning accuracy.     

利用现有无线局域网进行室内定位算法研究

目前,多种WiFI室内定位方案被提出,但是往往需要重新部署无线AP,造成成本和复杂度上升。本文充分利用现有无线局域网的拓扑结构进行室内定位研究,提出了一种自适应网络变化的WKNN指纹算法,该算法通过实时监控无线AP的匹配数,自动根据位置适应网络变化,定位精度明显提高。在此基础上,为了减少无线信号不稳定引起的定位误差,提出了一种新的数据修正方法,该方法根据移动平均速度动态预测标准,动态调整a参数将预测坐标与实测坐标加权,从而得到最终定位坐标。最后,算法在实际环境中验证表明,利用现有无线局域网的自适应网络算法和数据修正使定位获得了33.5%的误差改善。      

基于自适应Levy飞行的黄金正弦可见光定位研究

为了提高室内可见光定位的精度，采用了基于Levy飞行变异机制、结合自适应移动因子、改进黄金正弦算法的接收信号强度指示可见光定位方法, 将室内屋顶的发光二极管灯按3×3网格状排布，接收到光强信号通过朗伯模型得到未知节点与参考节点的距离，并采用Levy飞行变异机制提升算法搜索空间的多样性，结合自适应移动因子提高算法收敛速度，使得个体更新受局部极值约束力下降。结果表明, 改进算法平均定位误差为1cm，平均迭代次数40次~80次; 改进黄金正弦算法的定位速度和定位精度均得到提升。该研究对室内大型场所实时、快速精确定位有帮助。     

量子定位系统在沙尘暴背景下的最优纠缠度自适应策略

量子定位系统(quantum positioning system,QPS)具有定位精度高、安全系数高的特点,然而沙尘暴会使得光量子纠缠度产生较大变化,进而影响到量子定位系统的定位误差。为了降低这种误差,本文基于双卫星星地链路切换策略提出了抵抗沙尘暴干扰的最优纠缠度自适应(optimal entanglement degree adaptive,OEDA)策略。建立了沙尘暴各参数、传输距离与纠缠度之间的关系,并且将沙尘暴整体特征对系统的定位误差在自适应调整前后进行对比。仿真结果表明,当沙尘暴整体特征聚合因子为10,传输距离为10 km时,采用OEDA算法后,系统定位误差由0.14 m缩减至0.02 m,因而可知经过OEDA策略后可以提高沙尘暴天气下QPS的精确度。     

Cluster-Based RF Fingerprint Positioning Using LTE and WLAN Signal Strengths

Wireless Local Area Network (WLAN) positioning has become a popular localization system due to its low-cost installation and widespread availability of WLAN access points. Traditional grid-based radio frequency (RF) fingerprinting (GRFF) suffers from two drawbacks. First it requires costly and non-efficient data collection and updating procedure; secondly the method goes through time-consuming data pre-processing before it outputs user position. This paper proposes Cluster-based RF Fingerprinting (CRFF) to overcome these limitations by using modified Minimization of Drive Tests data which can be autonomously collected by cellular operators from their subscribers. The effect of environmental changes and device variation on positioning accuracy has been carried out. Experimental results show that even under these variations CRFF can improve positioning accuracy by 15.46 and 22.30% in 95 percentile of positioning error as compared to that of GRFF and K-nearest neighbour methods respectively.     

基于电源线和位置指纹的室内定位技术

该文提出将室内环境不可或缺的电源线作为天线,通过在电源线上注入宽带高频信号构造室内空间的位置指纹,进而实现室内空间精确定位。首先介绍了电源线上宽带高频信号注入模块的实现技术,以及室内空间位置指纹的构造方法;其次,介绍了基于朴素贝叶斯分类算法的室内定位原理;最后,通过实验分析证明在多训练样本情况下,基于朴素贝叶斯分类算法的定位算法比基于K最邻近点(KNN)分类算法的定位算法有更好的定位准确率和时间迁移适应能力。     

基于电荷驱动的多通道压电变形镜电源设计

压电变形镜具有频率响应高,变形量大,稳定性好等优点,已广泛应用于自适应光学领域,但因在电压驱动方式下压电材料迟滞特性较大,使压电变形镜的精确控制难。为降低压电变形镜的迟滞影响,设计了一种基于电荷驱动的多通道压电变形镜驱动电源,介绍了驱动电源的构成及原理,并搭建了一套基于夏克哈特曼波前传感器的自适应光学测试平台来验证驱动电源的性能。实验结果表明,该驱动电源可有效降低压电变形镜的迟滞效应,整体迟滞约1%,镜面变形的分辨率均方根误差(RMS)值约1.1 nm,能够满足在自适应光学领域对多通道压电变形镜精确控制的要求。     

一种基于LTE-MR劣化场景模式识别的自动优化方法

要进行LTE网络的精细优化必须依赖于对覆盖和干扰的地理分布精确掌握。本文基于MR数据建立精确定位干扰矩阵,形成从覆盖、干扰、用户、空间、时间等多维度定位网络问题的MR分析方法。 基于模式识别理论和MR数据的精确定位分析,智能识别出覆盖和干扰的场景,针对这些问题场景通过迭代算法自动生成相应的优化策略。