RSSI与惯性导航融合的高精度室内定位算法

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"基于RSSI和惯性导航的融合室内定位算法" 本文主要探讨了一种针对高精度室内定位需求的融合定位算法,该算法结合了接收信号强度识别(RSSI)和惯性导航技术的优点,旨在解决单一技术在室内定位中的局限性。作者包括朱亚萍、夏玮玮、章跃跃、燕锋、左旭舟和沈连丰,分别来自东南大学移动通信国家重点实验室和电子科技大学信息与软件工程学院。 室内定位在许多应用领域,如智能建筑、物联网和紧急救援中具有重要价值。传统的GPS等全球导航卫星系统在室内环境下往往无法提供可靠的服务,因此需要寻找替代方案。RSSI是一种常用的无线传感器网络(WSN)室内定位技术,它基于接收到的信号强度来推断设备的位置。然而,RSSI容易受到环境因素如多径效应、障碍物遮挡的影响,导致定位精度下降。 为了解决这个问题,本文提出了一个融合定位算法,首先利用ZigBee节点的RSSI值,通过位置指纹识别法(Fingerprinting)来定位网络中的未知节点。这种方法建立了一个RSSI与位置之间的映射关系,但可能会因为环境变化而出现定位误差。 为了弥补RSSI定位的不足,算法引入了惯性测量单元(IMU)的数据。IMU能够连续提供加速度和角速度信息,用于估计物体的运动状态。然而,单独使用惯性导航会随着时间积累误差,即漂移问题。因此,将IMU数据与RSSI定位结果融合,可以修正定位偏差并减少漂移。 关键在于采用卡尔曼滤波器(Kalman Filter)对融合定位过程进行优化。卡尔曼滤波是一种有效的估计理论,它能根据状态方程描述的动态变化规律,结合预测和更新步骤,不断校正定位结果。在这种情况下,状态方程用于描述待定位节点的位置坐标随时间的变化,IMU提供动态信息,RSSI提供静态参考。 通过仿真对比,该融合定位算法显示出了显著的优势。它既可以减轻RSSI定位对环境干扰的敏感性,又能够缓解惯性导航的累积误差问题,从而显著提高室内定位的精度。文章的关键词包括高精度室内定位、RSSI、惯性导航和融合定位算法。 这项研究为室内定位提供了一种新的解决方案,它将无线传感网络和惯性导航技术有效结合,利用先进的滤波算法实现高精度的室内定位,对于提升物联网设备的定位性能有着重要的理论和实际意义。
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室内定位算法,有助于研究者认清研究方向,给定位算法一个准确的描述,是很好的参考教材。the possibility for the user to be notified by visible and Waveformof Distance audible warnings using buzzer and led ar to Very close to al 1903 Tme「 samples Fig 4 Distance measurement using the RSSi signal The system is used to determine the distance between Fig. 2. Tag4M Data Acquisition System tags and 2, 3, 4 or more APs. The tag scans after the aps ⅣV. EXPERIMENTS and sends the rssi values for each ap to the ap which is associated The system presented above can be used for objects or In order to read the corresponding rSsi values of all people localization in an indoor enviro found access points, a""operation is implemented at Let's suppose a building where several objects are Tag4M level. The time to scan is smaller than few distributed all over milliseconds, because the tag doesnt associate with the all For a better understanding of the system, it is showed an APs. These values are sent to a pC where the localization experiment where the objects are placed only at one floor. algorithm is implemented in LabVIFW20 10 (see Fig. 5) Each of these objects has attached a tag. The devices are Table I presents a scan operation result. In this case used to determine the location of the objects in the four APs(which are placed in the floor building)named building and the distance between tags and APs. To Hawk, Helicopter, Tag4M and WitagServer are detected measure the distance, the RSSI is processed. This method The corresponding rSSi values(in dBm) measured by the is not very accurate and is strong depended to the Tag4M are reported for every AP environment, but is very easy to implement with the TABLE 1. A SEQUENCE OF RESULTS FOR THE SCANOPERATION The Fig 3 presents the experiment environment for one EXFCUTED ON THE TAG4M DEVICE oor where the colored circles represents the APs and the rectangles represents the objects intended to be located This floor is divided in six rooms separated by walls RSSI Scan results: 4 Time Ssid Ch ad-Iloc Sec wps mac Address erp WMM SSI Supported Rates(Mbits, Mandatory) Crypto Suites CW Max/min AP SCAN. llawk. -57 dBm AP SCAN, Helicopter, -50 dBm, AP SCAN, Tag4M.-68 dBm AP SCAN. WitagServer. -45 dBm The Rssi values are converted to distance values using formula(1) The value of the received signal strength is a function of the transmitted power and the distance between the Fig 3. The Experiment Environment sender and the receiver. The received signal strength will decrease when the distance increases as the following First step in finding the location is distance equation shows [23] measurement using the RSSI signal. The experiment for computing the distance is presented in Fig. 4. The RSSI(IOn- logo+A)(1) experimental precisions of measurements are less than 5 meters Where: lal propagation constant al d propagation exponent. d represents the distance from sender, A represents the received signal strength at a distance of one meter worn even by people. The system runs on batterie w sSID having a characteristic life time of a couple of years and 回H offers a platform for sensor measurements. Thus, the system can use any existent infrastructure, with significant decrease of implementation costs REFERENCES [1] H. Liu, H. Darabi, P. Banerjee and J. Liu, ""Survey of wireless Distance 2 Tn] aRch Indoor Positioning Techniques and SystemS", IEEE TRANSACTIONS ON SYSTEMS. MAN. AND CYBERNETICS-PART C: APPLICATIONS AND REVIEWS VOL 37, NO 6, NOVEMBER 2007, pp. 1067-10801 Distance 3[] [2 Want, A. Hopper, V. FalcaO, J. 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CC2431 Location Engine, Application Note power and Wi-Fi transmission capabilities that are An042,fromhttp://focus.tii.co.ip/ip/lit/an/swra095/swra095.pdf embedded in a very small package, why they are suitable 320