簡易檢索 / 詳目顯示

研究生: 蔡錦郎
Chin-Lang Tsai
論文名稱: 移動載波相位定位與方向判定及其應用
Motion-based Differential Carrier Phase Positioning, Heading Determination and its Applications
指導教授: 高維文
Wei-Wen Kao
口試委員: 黃安橋
none
陳亮光
none
張帆人
none
林君明
none
學位類別: 博士
Doctor
系所名稱: 工程學院 - 機械工程系
Department of Mechanical Engineering
論文出版年: 2006
畢業學年度: 94
語文別: 英文
論文頁數: 109
中文關鍵詞: 載波相位定位方向判定磁性羅盤校準
外文關鍵詞: carrier phase, positioning, heading determination, magnetic compass calibration
相關次數: 點閱:164下載:12
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報
  • 今天,車輛導航系統已經成為一個很受歡迎的產品了,在這些系統裡面,全球定位系統(GPS)和方位推估法(Dead Reckoning; DR)的技術被廣泛地用來提供車輛即時定位和方向判定。本篇論文研究的架構為將一個由兩個GPS天線所組成的GPS指北針和DR感測器整合在一台車子上以便全時都能提供車子的即時位置和方向等資訊供導航系統使用。雖然以GPS為基礎的多天線三維姿態判定系統(three-dimensional attitude determination system)已經被廣泛地研究,特別是在飛機的應用上,不過,對於商用的車輛,基於安裝空間或是建置成本的考量,通常只在車子上安裝兩個GPS天線形成一個單基線向量判定系統(single baseline vector determination system),這様的系統又被稱為GPS指北針,當這樣的一輛車子在平坦的地面上行駛時,該基線向量(baseline vector)將對應到一個”趨近平面”(quasi-planar)的運動,也就是該基線向量的運動近乎於平面運動但又不完全是平面運動。先前也有一些學者的研究集中在單基線向量判定系統,但是他們的研究結果都有一些限制,那就是該基線向量相對於任意兩個垂直軸必須都有大角度的旋轉或者是該基線向量的運動必須被完全限制在一個平面上。這些研究結果都不太適合於一般陸用車輛的應用。另外,因為GPS衛星所發送的訊號傳送到地球時已經太微弱了,以致於無法通過建築物而被遮蔽,因此,GPS衛星訊號在建築物內是收不到的,在這樣的情況下,GPS虛擬衛星(GPS pseudolite)可以被用來取代GPS衛星的配置並廣播定位訊號供室內車輛的定位和方向判定來使用。相對於GPS衛星而言,虛擬衛星與接收機的距離很近,因此當接收機移動時將產生不同於GPS衛星的幾何運動關係。因此,那些應用在GPS載波相位訊號的車輛定位和方向判定的演算法必須適當的修改以適合建築物內車輛定位和方向判定之應用。
    本篇論文的研究集中在移動載波相位定位與GPS指北針之方向判定及其在陸用車輛、室內和磁性羅盤校準的應用。首先,本篇論文將GPS指北針方向判定的問題重新公式化為限制總最小二乘方(Constrained Total Least Square; CTLS)的非線性最佳化問題,並發展一個以牛頓法(Newton’s method)為基礎的數值演算法來疊代計算這個問題的最佳解。電腦數值模擬的結果顯示採用CTLS方法所得到的解其精確度比傳統的最小平方法(Least Square; LS)所得到的解更好。接下來,本篇論文提出一個正規化的限制總最小二乘方法(Regularized Constrained Total Least Square; RCTLS)來處理當GPS指北針被安裝在陸用車輛時其基線向量對應到”趨近平面”運動所產生的惡劣情況(ill-conditioned)現象,這個方法釋放了先前學者對於單基線向量判定系統的研究所做的限制,電腦數值模擬的結果顯示採用RCTLS方法所得到的解其精確度比CTLS和LS所得到的解更好,而且相較之下,RCTLS方法更強韌且收斂速度比CTLS和LS更快。
    接下來,本篇論文利用一個室內的GPS虛擬衛星定位系統(GPS pseudolite positioning system)來取代GPS衛星的配置並廣播定位訊號供室內車輛定位與方向判定來使用,並且提出一個室內移動載波相位定位演算法以達成室內精準定位與方向判定,另外也提出一個完整性檢核法則來檢驗估測的載波相位整數周波未定值是否已收斂到真值。
    最後,本篇論文提出兩種不同的線上磁性羅盤量測誤差校準方法,一個叫做參數適應演算法(Parameter Adaptive Algorithm; PAA),另一個叫做函數學習演算法(Functional Learning Algorithm; FLA),兩種方法均利用GPS指北針所量測到的方向作為校準訊號。PAA透過使用GPS指北針所量測到的方向來估測磁性羅盤量測值的旋轉橢圓模型的參數,當磁偏角很小且磁性羅盤量測誤差可以完全被這些參數描述的時候,PAA校準的方法極其有效,而當磁偏角很大或者當磁性羅盤量測誤差無法透過只調整旋轉橢圓模型的參數來校準的時候,可以改用FLA的方法來校準,FLA校準學習的函數必須具有週期性的特性,而磁性羅盤量測誤差剛好是週期性函數。透過電腦數值模擬和實際實驗的結果顯示兩種演算法均可有效校準磁性羅盤量測誤差且適合被用在商業用途的導航設備並實現即時誤差校準性能。


    Today, land-vehicle navigation systems have already become a popular subject. In these systems, GPS and Dead Reckoning (DR) technologies are widely used to determine the vehicle positions and headings for navigation. In this dissertation, integration of a GPS Compass and DR sensors on a vehicle to determine the vehicle positions and headings seamlessly for navigation is considered. Although, three-dimensional GPS-based attitude determination system with multiple GPS antennas onboard has been extensively studied, especially in aircraft applications, however, due to the cost consideration or spaces available on commercial land-vehicles, it is beneficial to use only two antennas mounted on a vehicle forming a single baseline vector (heading) determination system, which is known as GPS Compass. When such a vehicle traveling on flat terrains, the baseline corresponds to a “quasi-planar” motion situation where the baseline motions nearly, but not exactly, confine to a horizontal plane. Some of the prior researches focused on single baseline vector determination system but have the limitations that the baseline must have large-angle rotations about any two arbitrary but perpendicular axes or that the baseline motions need to be exactly confined to a plane. These results are not easily applicable to land-vehicle applications. Furthermore, GPS satellite signals are unavailable indoors since they are too weak to be blockaded by obstacle. In that situation, GPS pseudolites can be used to replace GPS satellite constellation and broadcast ranging signal for indoor positioning and heading determination. Hence, the algorithms for outdoor carrier phase positioning and heading determination should be adequately modified and developed for indoor applications.
    The study of this dissertation focuses on the motion-based differential carrier phase positioning, GPS Compass heading determination and its applications to land-vehicles, indoors and magnetic compass calibration. First, the GPS Compass heading determination problem is properly reformulated as Constrained Total Least Square (CTLS) nonlinear optimization problem and a numerical solution algorithm based on Newton’s method is developed to compute the solution iteratively. The accuracy of the CTLS solution is shown to be better than that of the conventional Least Square (LS) solution. Next, a modified CTLS approach based on Tikhonov’s regularization, which is called Regularized CTLS (RCTLS) approach, is proposed to address the ill-conditioned problem occurred in land-vehicle applications. This approach releases the limitations of the prior researches on single baseline vector determination. The results show that the accuracy of RCTLS solution is better than that of CTLS and LS solution. Moreover, the approach is more robust and converges at a faster rate than CTLS and LS approach.
    Following, an indoor pseudolite positioning system is introduced to replace GPS constellation in a space where GPS satellite signals are unavailable and broadcast ranging signals. A motion-based indoor carrier phase positioning algorithm is proposed to achieve accurate positioning and heading determination indoors. Also, a suitable integrity check criterion is proposed to determine when the estimated ambiguity values have converged to the true values.
    Finally, two different online magnetic compass calibration methods, one based on the Parameter Adaptation Algorithm (PAA) and the other based on the Functional Learning Algorithm (FLA), are developed to achieve online self-calibration function for a flux-gate compass using GPS heading as reference signals. PAA estimates parameters of the compass magnetic ellipse by using GPS headings as references, and it is extremely effective when compass errors can be modeled by these parameters and the magnetic declination is small. In the case when the magnetic declination is large or when the compass are subjected to non-parameterized errors and cannot be calibrated by adjusting the parameters of the rotated ellipse model only, FLA can be used instead due to it only requires the compass bias function to be periodical. Both algorithms are shown to be suitable in commercial navigation devices and can be implemented in real time.

    中文摘要 i Abstract iii Acknowledgements v List of Tables viii List of Figures ix Chapter 1 Introduction 1 1.1 Background 1 1.2 Carrier Phase Measurements and its Applications 3 1.3 Prior Research 5 1.4 Scope of the Dissertation 8 1.5 Contributions of the Dissertation 10 1.6 Outline of the Dissertation 11 Chapter 2 GPS Compass Heading Determination Using Constrained Total Least Square Technique 14 2.1 Introduction 14 2.2 Constrained Total Least Square Technique 15 2.3 Problem Formulation of Motioned-based GPS Heading Determination 20 2.3.1 Double difference carrier phase measurement equation 20 2.3.2 Heading determination using baseline rotation 23 2.3.3 Baseline displacement vector measurement 24 2.4 CTLS GPS Compass Heading Determination Problem 25 2.5 Numerical Solution of the CTLS Problem 27 2.6 Error Analysis of the CTLS Solution 29 2.7 Ambiguity Solution and Solution Procedure 30 2.8 Simulations 31 2.9 Discussion 36 Chapter 3 Land-Vehicle Application: Ill-condition Problem and Regularization Approach 37 3.1 Introduction 37 3.2 Ill-Condition Problem in Land-Vehicle Application 39 3.3 Regularization Approach 41 3.4 Numerical Solution of the RCTLS 42 3.5 Error Analysis of the RCTLS Solution 43 3.6 Choosing the RCTLS Regularization Parameter 47 3.7 Simulations 48 3.8 Discussion 55 Chapter 4 Carrier Phase Indoor Positioning Application 56 4.1 Introduction 56 4.2 GPS Pseudolite 58 4.3 Problem Formulation of the Indoor Positioning Using Pseudolites 60 4.4 Indoor Positioning Using Relative Movement 64 4.5 Condition for Ambiguity Resolution 65 4.6 Simulations 66 4.7 Discussion 69 Chapter 5 Adaptive and Learning Calibration of Magnetic Compass 70 5.1 Introduction 70 5.2 Principle of Magnetic Compass 71 5.2.1 Local Vehicle Magnetic Field Effect 73 5.2.2 Sensor Sensitivity Effect 74 5.2.3 Magnetic Declination Effect 74 5.2.4 Conventional Compass Calibration 75 5.3 Online Compass Calibrations 76 5.3.1 GPS Heading Sensor 76 5.3.2 Parameter Adaptive Algorithm (PAA) 77 5.3.3 Functional Learning Algorithm (FLA) 81 5.4 Simulations and Experiments 84 5.4.1 Simulations 84 5.4.2 Experiments 86 5.5 Discussion 92 Chapter 6 Conclusion 93 Reference 97 Appendix A Derivation of the Newton’s Formula for CTLS Solution 102 Appendix B Derivation of the Newton’s Formula for RCTLS Solution 106

    [1] A. E. E. Rogers, C. A. Knight, H. F. Hinteregger, A. R. Whitney, C. C. Counselman, I. I. Shapiro and S. A. Gourevitch, “Geodesy by Radio Interferometry: Determination of a 1.24-km Baseline Vector with ~5mm Repeatability,” Journal of Geophysical Research, Vol. 83, No. B1, pp. 325-334, Jan. 1978.
    [2] C. C. Counselman and S. A. Gourevitch, “Miniature Interferometer Terminals for Earth Surveying: Ambiguity and Multipath with Global Positioning System,” IEEE Transactions on Geoscience and Remote Sensing, Vol. GE-19, No. 4, pp. 244-252, Oct. 1981.
    [3] B. W. Remondi, “Performing Centimeter-Level Surveys in Seconds with GPS Carrier Phase: Initial Results,” Navigation: Journal of The Institute of Navigation, Vol. 32, No. 4, 1985-1986.
    [4] P. Y. C. Hwang, “Kinematic GPS for Differential Positioning: Resolving Integer Ambiguities on the Fly,” Navigation: Journal of The Institute of Navigation, Vol. 38, No. 1, pp.1-15, 1991.
    [5] B. W. Remondi, “Pseudo-kinematic GPS Results Using the Ambiguity Function Method,” NAVIGATION: Journal of The Institute of Navigation, Vol. 38, No. 1, pp.17-35, 1991.
    [6] C. E. Cohen, B. S. Pervan, D. G. Lawrence, H. S. Cobb, J. D. Powell, and B. W. Parkinson, “Real-Time Flight Testing Using Integrity Beacons for GPS Category III Precision Landing,” Journal of The Institute of Navigation, Vol. 41 No. 2, 1994.
    [7] T. M. Nguyen, J. W. Sinko, and R. C. Galijan. “Using Differential Carrier Phase GPS to Control Automated Vehicles,” IEEE Proceedings of the 40th Midwest Symposium on Circuits and Systems, Vol. 1, 3-6 Aug, 1997, pp. 493-496.
    [8] F. V. Graas and M. Braasch, “GPS Interferometric Attitude and Heading Determination: Initial Flight Test Results,” Navigation: Journal of The Institute of Navigation, Vol. 38, No. 4, pp.359-378, 1991-1992.
    [9] P. G. Quinn, “Instantaneous GPS Attitude Determination,” Proceedings of the ION GPS 1993, Salt Lake City, pp. 603-615, Sept. 1993.
    [10] R. A. Brown, “Instantaneous GPS Attitude Determination,” IEEE AES Magzine, June 1992, pp. 3-8.
    [11] R. Brown and P. Ward ”A GPS receiver with built-in precision pointing capability,” Proceedings of IEEE Position Location and Navigation Symposium, Las Vegas, NV, pp. 83-93, Mar. 1990.
    [12] C. E. Cohen, “Attitude Determination,” in Global Positioning System: Theory and Applications, Vo. 2, B.W. Parkinson and J.J. Spilker, Ed., Washington DC: AIAA, 1996.
    [13] H. M. Peng, F. R. Chang, and L. S. Wang, “Rotation Method for Direction Finding via GPS Carrier Phases,” IEEE Transactions on Aerospace and Electronic Systems, Vol. 36, No. 1, pp. 72-84, 2000.
    [14] A. Conway, P. Montgomery, S. Rock, R. Cannon, and B. Parkinson, “A New Motion-Based Algorithm for GPS Attitude Integer Resolution,” Navigation: Journal of The Institute of Navigation, Vol. 43, No. 2, pp. 179-190, 1996.
    [15] J. L. Crassidis, F. L.Markley, and E. G. Lightsey, “Global Positioning System Integer Ambiguity Resolution without Attitude Knowledge,” AIAA Journal of Guidance, Control, and Dynamics, Vol. 22, No. 2, pp. 212-218, 1999.
    [16] C.-H. Tu, K.-Y. Tu, F.-R. Chang, and L.-S. Wang, “GPS Compass: A novel navigation equipment, ”IEEE Transactions on Aerospace and Electronic Systems, Vol. 33, No. 3, pp. 1063–1068, 1997.
    [17] C. Park, I. Kim, G.-I. Jee, and J. G. Lee, “An error analysis of GPS Compass,” Proceedings of the 36th SICE Annual Conference, pp. 1037–1042, July 1997.
    [18] Y. Koura, H. Suzuki, K. Ogawa, Y. Kamei, and M. Nakamura, “GPS Compass: A Low Cost GPS Direction Sensor of Two Antenna Type,” Proceedings of the ION GPS 2001, Salt Lake City, pp. 2700-2707, Sep. 2001.
    [19] J. M. Mendel, Lessons in Digital Estimation Theory, Prentice-Hall, Englewood Cliffs, NJ, 1987.
    [20] T. J. Abatzoglou and J. M. Mendel, “The Constrained Total Least Squares Technique and its Applications to Harmonic Superresolution,” IEEE Transactions on Signal Processing, Vol. 39, No. 5, pp. 1070-1087, May 1991.
    [21] C. E. Davila, “An Efficient Recursive Total Least Squares Algorithm for FIR Adaptive Filtering,” IEEE Transactions on Signal Processing, Vol. 42, No. 2, pp. 268-280, 1994.
    [22] S. Van Huffel and J. Vandewalle, The Total Least Squares Problem: Computational Aspects and Analysis, SIAM, Philadelphia, 1991.
    [23] T. J. Abatzoglou and J. M. Mendel, “Constrained Total Least Squares,” Proceedings of the 1987 IEEE ICASSP, Dallas, Tx, pp. 1485-1488, Apr. 1987.
    [24] S. D. Hodges and P. G. Moore, “Data Uncertainties and Least Squares regression,” Applied Statistics, Vol. 21, pp. 185-195, 1972.
    [25] J. E. Freund and R. E. Walpole, Mathematical Statistics, 4th edition, Englewood Cliffs, NJ: Prentice-Hall, 1987.
    [26] R. Daily and D. M. Bevly, “The Use of GPS for Vehicle Stability Control Systems, IEEE Transactions on Industrial Electronics, Vol. 51, No. 2, pp. 270-277, 2004.
    [27] J.-O. Hahn, R. Rajamani, S.-H. You, and K. I. Lee, “Real-time Identification of Road-bank Angle Using Differential GPS,” IEEE Transactions on Control Systems Technology, Vol. 12, No. 4, pp. 589-599, 2004.
    [28] J. Ryu and J. C. Gerdes, “Integration Inertial Sensors with Global Positioning System (GPS) for Vehicle Dynamics Control,” Journal of Dynamic Systems, Measurement, and Control, Vol. 126, pp. 243-254, 2004.
    [29] A. N. Tikhonov, and V. Y. Arsenin, Solutions of Ill-Posed Problems, Wiley, New York, 1977.
    [30] D. W. Marquardt, “Generalized Inverses, Ridge Regression, Biased Linear Estimation, and Nonlinear Estimation,” Technometrics, Vol. 12, pp. 591-612, 1970.
    [31] N. P. Galatsanos and A. K. Katsaggelos, “Methods for Choosing the Regularization Parameter and Estimating the Noise Variance in Image Restoration and Their Relation,” IEEE Transactions on Image Processing, Vol. 1, No. 3, pp. 322-336, 1992.
    [32] G. H. Golub, M. T. Heath, and G. Wahba, “Generalized Cross-Validation As a Method for Choosing a Good Ridge Parameter,” Technometrics, Vol. 21, No. 2, pp. 215-223, 1979.
    [33] P. C. Hansen, “Analysis of Discrete Ill-Posed Problems by Means of the L-Curve,” SIAM Review, Vol. 34, No. 4, pp. 561-580, 1992.
    [34] V. A. Morozov, Methods for Solving Incorrectly Posed Problems, Springer-Verlag, New York, 1984.
    [35] P. C. Hansen, Rank-Deficient and Discrete Ill-Posed Problem: Numerical Aspects of Linear Inversion, SIAM, Philadelphia, 1997.
    [36] M. Bertero, T. A. Poggio, and V. Torre, “Ill-Posed Problems in Early Vision,” Proceedings of the IEEE, Vol. 76, No. 8, p.p. 869-889, August 1988.
    [37] G. H. Golub and C. F. Van Loan, Matrix Computation, 2nd Ed., The Johns Hopkins University Press, Baltimore, Maryland, 1984
    [38] V. Z. Mesarovic, and N. P. Galatsanos, and A. K. Katsaggelos, “Regularized Constrained Total Least Squares Image Restoration,” IEEE Transactions on Image Processing, Vol. 4, No. 8, p.p. 1096-1108, August 1995.
    [39] X. Fan, N. H. Younan, and C. D. Taylor, “A Perturbation Analysis of the Regularized Constrained Total Least Squares,” IEEE Transactions on Circuits and Systems-II: Analog and Digital Signal Processing,” Vol. 43, No. 2, pp. 140-142, February 1996.
    [40] K. Pahlavan and X. Li, “Indoor Geolocation Science and Technology,” IEEE Communications Magazine, pp. 112-118, February 2002.
    [41] D. Klein and B. W. Parkinson, “The Use of Pseudo-Satellites for Improving GPS Performance,” Global Positioning System (Red Book), Vol. III, Institute of Navigation, pp. 135-146, 1984.
    [42] T. A. Atansell, “RTCM SC-104 Recommended Pseudolite Signal Specification,” Global Positioning System (Red Book), Vol. III, Institute of Navigation, pp. 1117-134, 1986.
    [43] H. S. Cobb, GPS Pseudolites: Theory, Design, and Applications, Ph.D. Dissertation, Stanford University, Stanford, CA, USA, 1997.
    [44] S. Cobb and M. O’Connor, “Pseudolites: Enhancing GPS with Ground-based Transmitters,” GPS World Magazine, pp. 55-60, March 1998.
    [45] C. Kee, H. Jun, D. Yun, B. Kim, Y. Kim, B. W. Parkinson, T. Langestein, S. Pullen, and J. Lee, ”Development of Indoor Navigation System Using Asynchronous Pseudolites,” Proceedings of the ION GPS 2000, Salt Lake City, Utah, pp. 1038-1045, 2000.
    [46] C. Kee, D. Yun, H. Jun, B. Parkinson, S. Pullen, and T. Langenstein, “Centimeter-Accuracy Indoor Navigation Using GPS-Like Pseudolites,” GPS World Magazine, pp. 14-22, November 2001.
    [47] D. Yun and C. Kee, “Centimeter Accuracy Stand-Alone Indoor Navigation System by Synchronized Pseudolite Constellation”, Proceedings of the ION GPS 2002, Portland, Oregon, USA, 2002.
    [48] H. Isshiki, et al, “Theory of Indoor GPS by Using Reradiated GPS Signal,” Proceedings of the ION NTM 2002.
    [49] Y. Zhao, Vehicle Location and Navigation Systems, Artech House, 1997.
    [50] J. E. Lenz, “A Review of Magnetic Sensors,” Proceedings of the IEEE, Vol. 78, No. 6, pp. 973-989, 1990
    [51] B. Hofman-Wellenhof, H. Lichtenegger, and J. Collins, Global Positioning System Theory and Practice, Wien:Springer-Verlag, 1992
    [52] E. Abbott and D. Powell, “Land-Vehicle Navigation Using GPS,” Proceedings of the IEEE, Vol. 87, No. 1, pp. 145-162, 1999
    [53] D. M. Bevly, “Global Positioning System (GPS): A Low-Cost Velocity Sensor for Correcting Inertial Sensor Errors on Ground Vehicles,” Journal of Dynamic Systems, Measurement, and Control, Vol. 126, pp. 255-264, 2004.
    [54] D. M. Bevly, et al, “The Use of GPS-based Velocity Measurements for Improved Vehicle State Estimation,” Proceedings of the American Control Conference, Chicago, IL, pp. 2538-2542, 2000.
    [55] W. Messner, R. Horowitz, W. W. Kao, and M. Boals, “A New Adaptive Learning Rule,” IEEE Transaction of Automatic Control, Vol. 36, No.2, 1991
    [56] W. Messner and R. Horowitz, “Identification of a Nonlinear Function in a Dynamical System,” Journal of Dynamic Systems, Measurement and Controls, Vol. 115, No.4, 1993.
    [57] P. D. Wasserman, Neural Computing: Theory and Practice, Van Nostrand Reinhold, New York, 1989
    [58] J.-H. Wang and Y. Gao, “A New Magnetic Compass Calibration Algorithm Using Neural Networks,” Measurement Science and Technology, Vol. 17, pp. 153-160, 2006.
    [59] C. E. Cohen, Attitude Determination Using GPS, Ph.D. Thesis, Department of Aeronautics and Astronautics, Stanford University, 1992.
    [60] C. Beatty, “Land Vehicle Navigation-From Concept to Production,” Proceedings of the 1st International Symposium on Land Vehicle Navigation, pp. 9.1-9.17, 1984.
    [61] J. Last and C. Scholefield, “The Combined Use of Low Frequency Radio and Dead Reckoning for Automatic Vehicle Location,” Proceedings of the 1st International Symposium on Land Vehicle Navigation, pp. 14.1-14.19, 1984.
    [62] J. Muraszko, “Pathfinder-An Automatic Vehicle Location and Status Monitoring System,” Proceedings of the 2nd International Symposium on Land Vehicle Navigation, pp. 8.1-8.12, 1989.
    [63] S. Alban, Design and Performance of a Robust GPS/INS Attitude System for Automobile Applications, Ph.D. Thesis, Department of Aeronautics and Astronautics, Stanford University, 2004.
    [64] E. Prigge and J. How, “An Indoor Absolute Positioning System with No Line of Sight Restrictions and Building-Wide Coverage,” Proceedings of the 2000 IEEE International Conference on Robotics and Automation, San Francisco, CA, pp. 1015-1022, April 2000.
    [65] K. Kaemarungsi, “Distribution of WLAN Received Signal Strength Indication for Indoor Location Determination,” Proceedings of the 1st International Symposium on Wireless Pervasive Computing, pp. 1-6, Jan. 2006.
    [66] A. Kotanen, M. Hannikainen, H. Leppakoski, and T. D. Hamalainen, “Positioning with IEEE 802.11b Wireless LAN,” Proceedings of the 14th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, Vol. 3, pp. 2218-2222, Sept. 2003.
    [67] H. Tuan, W. Yao, and Y. Song, “Location Sensing in Enhanced IEEE802.11e WLANs,” Proceedings of the 20th IEEE International Conference on Advanced Information Networking and Applications, Vol. 2, pp. 423-428, April 2006.

    QR CODE