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Weighted centroid localization algorithm based on RSSI for wireless sensor networks

Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) 2006年第2期30卷 265-268页

作者： Chen, Weike Li, Wenfeng Shou, Heng Yuan, Bing School of Logistics Eng. WUT Wuhan 430063 China Dept. of Mechanical Eng. Hunan Metallurgical Professional Technology College Zhuzhou 412000 China Hunan Railway Professional Technology College Zhuzhou 412000 China

Localization of nodes is a key technology for application of wireless sensor network. By analyzing the model of radio wave propagation loss, this paper provides a weighted centroid localization algorithm that uses coefficients, which are decided by the influence of beacons to unknown nodes, to prompt localization accuracy. A criterion which is used to select beacon nodes for computing the position of nodes and improving localization accuracy is also suggested. Weighted centroid localization algorithm is simple and no communication is needed while locating. The weighted centroid localization algorithm has higher accuracy than maximum likelihood estimation and can be applied to many applications.

关键词： Beacon node centroid algorithm Localization Maximum likelihood estimate Wireless sensor network

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A new localization algorithm in complex environment for wireless sensor networks

A new localization algorithm in complex environment for wire...

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IEEE International Conference on Automation and Logistics

作者： Xi-mei Liu Zhang chao Hu Jizhen E China Univ Sci & Technol Sch Informat Sci & Engn Shanghai 200240 Peoples R China Qingdao Univ Sci & Technol Qingdao 266042 Peoples R China

ISBN: (纸本)9781424425020

Localization is one of the supporting technologies in wireless sensor networks. Many techniques have been proposed that attempt to localize in a distributed manner. But the border problem (nodes near the edge of the sensor field are poorly positioned) is not solved perfectly. In this paper we propose a novel localization algorithm with the following merits. First, we use classification method to classify the nodes into two categories-border nodes and non-border nodes. Then we localize the border nodes based on mere connectivity information (i.e., hop counts only), and deal with the non-border nodes based on improved weighted centroid algorithm. The simulation results show that the border problem is solved well and the average localization error will be reduced to about a quarter and 10% in the complex environment with fewer anchor nodes compared to the centriod algorithm and diffusion algorithm.

关键词： wireless sensor networks position estimation centroid algorithm RSSI classification

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Real time phase-slopes calculations by correlations using FPGAs

Real time phase-slopes calculations by correlations using FP...

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Conference on Adaptive Optics Systems

作者： Trujillo Sevilla, J. Valido, M. R. Rodriguez Ramos, L. F. Boemo, E. Rosa, F. Rodriguez Ramos, J. M. Univ La Laguna Fac Ciencias Fis San Cristobal la Laguna 38202 Spain Inst Astrofis ES-38200 La Laguna Spain Univ Autonoma Madrid Spain

ISBN: (纸本)9780819472250

ELT laser guide star wavefront sensors are planned to handle an expected amount of data to be overwhelmingly large (1600 x 1600 pixels at 700 fps). According to the calculations involved, the Solutions Must consider to run on specialized hardware as Graphical Processing Units (GPUs) or Field Programmable Gate Arrays (FPGAs), among others. In the case of a Shack-Hartmann wavefront sensor is finally selected, the wavefront slopes can be computed using centroid or correlation algorithms. Most of the developments are designed using centroid algorithms, but precision ought to be taken in account too, and then correlation algorithms are really competitive. This paper presents an FPGA-based wavefront slope implementation, capable of handling the sensor Output stream in a massively parallel approach, using a correlation algorithm previously tested and compared to the centroid algorithm. Time processing results are shown, and they demonstrate the ability of the FPGA integer arithmetic in the resolution of AO problems. The selected architecture is based in today's commercially available FPGAs which have a very limited amount of internal memory. This limits the dimensions used in Our implementation, but this also means that there is a lot of margin to move real-time algorithms from the conventional processors to the future FPGAs, obtaining benefits from its flexibility, speed and intrinsically parallel architecture.

关键词： Adaptive optics. wavefront phase slopes correlation algorithm centroid algorithm Sack-Hartmann sensor FPGA real-time processing

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Precision circular target location in vision coordinate measurement system

Precision circular target location in vision coordinate meas...

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Conference on Advanced Materials and Devices for Sensing and Imaging III

作者： Wang, Liwen Zhang, Lei Yu, Zhijing Chen, Fei Si, Xiayan He, Dongrui Civil Aviat Univ China CAAC Ground Support Equipment Res Base Tianjin 300300 Peoples R China

ISBN: (纸本)9780819470041

The precision circle target sub-pixel centroid location is one of the key factors of large space 3D coordinates measurement. In this paper, the circle retro-reflective targets and optical targets used in large space 3D coordinates measurement are analyzed, and the characteristics and applied fields of target sub-pixel centroid location algorithms such as gray weighted and squared gray weighted centroid location algorithms which combine with bi-linear interpolation or improved cubic convolution interpolation method, are discussed. The influencing factors and improving methods for circle target location are also analyzed. These factors include the resolution of the CCD camera, image grab noise, the size of targets, the choice of exposure time and threshold value, the noncoincidence of centroid and center of the ellipse imaging targets, the distortion influence of deformational targets and so on. Based on these, proper compensating measures are brought out for the problems such as target choice and location, influencing factors and eliminating measures.

关键词： computer vision coordinate measurement target location centroid algorithm influencing factors

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Localization in Wireless Sensor Networks Using a Mobile Anchor Node

Localization in Wireless Sensor Networks Using a Mobile Anch...

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第二届中国传感器网络学术会议暨第一届中韩传感器网络学术研讨会(CWSN2008\CKWSN2008)

作者： HU Zhen LIU Lei LI Hui-juan School of Electronics and Information Engineering Changchun University of Science and TechnologyChangchun 130022China

In wireless sensor networks(WSNs),sensor location plays a critical role in many *** a GPS receiver On every sensor node is *** paper describes MACL,a mobile anchor centroid localization method,which uses a single mobile anchor node to move in the sensing field and broadcast its current position *** proposed method is radio-frequency based,so no extra hardware or data communication is needed between the sensor *** use simulations to investigate the performance of MACL,and find that the localization method is principle simple,less computing and communication overhead,low costly,and flexible accuracy.

关键词： Localization Mobile anchor node centroid algorithm Wireless sensor networks

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Summary of algorithms for white-light scanning interferometry

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Guangxue Jishu/Optical Technique 2006年第1期32卷 115-117+120页

作者： Yang, Tian-Bo Guo, Hong Li, Da-Cheng State Key Laboratory Precision Measurement Technology and Instrument Tsinghua University Beijing 100084 China

White light interference is an extremely powerful method of optical measurements. When the structure of the interferometer, the spectrum width of the light source, and the scanning step is certain, the right algorithm can achieve higher precision. The algorithms such as centroid algorithm, phase shift algorithm, envelope fitting algorithm and spatial frequency domain algorithm were discussed and compared. A complete reference was supplied for choosing of white light interferometry algorithm.

关键词： centroid algorithm Envelope fitting algorithm Phase shift algorithm White-light interferometry

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Bilinear interpolation centroid algorithm using for circular optical target location

Bilinear interpolation centroid algorithm using for circular...

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2nd International Conference on Image and Graphics

作者： Yu, ZJ Chen, G Che, RS Liu, CY Ma, SY Tian, W Harbin Inst Technol Dept Precis Instruments Harbin 150001 Peoples R China

ISBN: (纸本)0819446564

In the close digital photogrammetric three-dimension coordinates measurement, the circular target is often taken as imaging feature and mounted on the measured object or the probe for 3D coordinates detection. The accuracy with which circular targets are located determines the effectiveness of measurement. Subpixel level accuracy is one of the methods that can improve the accuracy of target location. Many methods which based on subpixel edge or centroid detection have been developed and analyzed for target location, but little research focused on circular optical target location. In this research, a new algorithm named bilinear interpolation centroid algorithm was developed for circular optical target subpixel location. In this technique, the accuracy of the squared gray weighted centroid algorithm can be improved by increasing the available pixels which obtained by bilinear interpolation. The intensity profile of the imaging points and the signal-to noise ratio, which affect the subpixel location accuracy, are optimized by automatic exposure control. The experiments have shown that the accuracy of this algorithm is better than the traditional centroid algorithm, and the absolute error of less than 0.01 pixels is obtained on the image of a rigid reference bar.

关键词： computer vision subpixel precision optical target location bilinear interpolation centroid algorithm 3D coordinates measurement

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Exact tests for comparing two paired proportions with incomplete data

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BIOMETRICAL JOURNAL 2004年第1期46卷 72-82页

作者： Tang, ML Tang, NS Harvard Univ Sch Med Channing Lab Dept Med Cambridge MA 02138 USA Yunnan Univ Ctr Appl Stat Kunming 650091 Peoples R China

Various asymptotic test procedures have been developed previously for testing the equality of two binomial proportions with partially incomplete paired data. Test procedures that discard incomplete observations have been shown to be less powerful than those procedures that utilize all available observations. On the other hand, asymptotic test procedures that utilize all available observations may not be reliable in small-sample problems or sparse data structures. In this article, unconditional exact test procedures are proposed for testing the equality of two paired binomial proportions with partially incomplete paired data under a random mechanism. The proposed unconditional exact test methods are illustrated with real data from a neurological study. Empirical studies are conducted to investigate the performance of these and other test procedures with respect to size and power.

关键词： asymptotic test centroid algorithm incomplete data paired binary data unconditional exact test

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Optical probe imaging based stereo cameras 3D coordinate measuring system

Optical probe imaging based stereo cameras 3D coordinate mea...

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Conference on Optical Manufacturing Technologies

作者： Yu, ZJ Chen, G Che, RS Liu, CY Huang, QC Ma, SY Tian, W Harbin Inst Technol Dept Precis Instruments Harbin 150001 Peoples R China

ISBN: (纸本)0819447102

An optical probe imaging based, fully automatic and rather flexible stereo vision system for 3D coordinate on-line measurement is presented and analyzed. In this system, the relative position of the two cameras can easily calibrated by observing an optical reference bar in different locations and orientations throughout the measurement according to epipolar constraint and the certified distance of the features on the reference bar. For measurement, the system takes an optical probe, which has one reference mark and five optical feature points, as imaging target, and makes use of the measurement results of these feature points space coordinates to calculate the measured object point coordinate which contacts with probe tip. To improve the calibration and measurement accuracy, the system takes infrared LED as optical feature point, and optimized signal to noise ratio by automatic LED light intensity, located these feature imaging points by bilinear centroid sub-pixel algorithm. The effectiveness of the proposed system has been test by experiments.

关键词： 3D coordinate measurement stereo vision optical probe epipolar geometry bilinear interpolation centroid algorithm

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Subpixel Target Location Techniques for 3-D Coordinate Measuring System

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Semiconductor Photonics and Technology 2002年第2期8卷 111-115页

作者： YUZhi－jing MASu－ying 等 HarbinInstituteofTechnology Harbin150001CHN HebeiVocation－TechnicalTeachersCollege Changli066600CHN

the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured object and take image of targets to determinethe object coordinate. The subpixel location of target image plays animportant role in high accuracy 3-D coordinate measuring *** this paper, some subpixel location methods are reviewed and somefactors which affect location precision are analyzed.

关键词： Subpixel precision target location centroid algorithm bilinearinterpolation

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