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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/35737

Title: 基於無跡粒子濾波器之GPS追蹤迴路設計
GPS Tracking Loop Designs Using the Unscented Particle Filter
Authors: Chia-Sheng Hsu
許家盛
Contributors: NTOU:Department of Communications Navigation and Control Engineering
國立臺灣海洋大學:通訊與導航工程學系
Keywords: 無跡粒子濾波器;追蹤迴路;多路徑效應;向量追蹤迴路;非高斯
Unscented Particle Filter;Tracking loop;Multipath;Vector Tracking Loop;Non-Gaussian
Date: 2013
Issue Date: 2013-10-07T02:58:25Z
Abstract: 本論文探討使用無跡粒子濾波器於GPS追蹤迴路設計,主要分為兩大主題,主題一為無跡粒子濾波器於GPS追蹤迴路之多路徑參數估計。主題二為基於無跡粒子濾波器於向量追蹤迴路設計。 多路徑效應為影響GPS定位性能的眾多干擾源之一,尤其容易發生在具有反射物體的地方,如都市中的高樓大廈,橋梁等等的建築物就是反射物體的一種。通常接收機在反射物體旁時,容易會有反射訊號干擾,進而影響後續的定位解算。 粒子濾波器(Particle Filter, PF)是一種基於貝氏估測的濾波方法,相較於擴展型卡爾曼濾波器(Extended Kalman Filter, EKF)、無跡卡爾曼濾波器(Unscented Kalman Filter , UKF),它具有處理高度非線性及非高斯的優點,然而粒子的退化和估測誤差的累積是很難以克服的,而增加粒子數,雖可以改善誤差,但卻增加硬體運算的負擔,為了解決上述的問題,本論文採用UKF來當作PF之提議分佈,稱為無跡粒子濾波器(Unscented Particle Filter, UPF)。 本論文第一個主題提出無跡粒子濾波器於GPS追蹤迴路之多路徑參數估計。將包含多路徑影響的觀測訊號,以積分相關器之同相I(in-phase)與正交Q (quadrature)訊號輸出至UPF估測直接訊號及多路徑訊號之參數,如振幅、碼延遲、相位及頻率。我們與UPF相比較的非線性濾波有EKF、UKF。 本論文第二個主題提出基於無跡粒子濾波器於向量追蹤迴路設計。向量追蹤迴路較傳統純量追蹤迴路具有較多優勢。傳統純量追蹤迴路每個通道為獨立的運作方式,而向量追蹤迴路使用每一個衛星訊號和使用者動態之間的關聯性,具有同時追蹤GPS訊號並估測使用者導航狀態。在第二個主題中,我們使用基於預濾波器之向量追蹤迴路的設計,而導航濾波器使用UPF與 UKF,在非高斯的環境下進行比較。 模擬結果顯示,在第一個主題,使用UPF之GPS追蹤迴路在估測直接訊號及多路徑訊號之參數優於EKF、UKF。在第二個主題,在非高斯的環境下,使用UPF向量追蹤迴路的性能優於使用UKF向量追蹤迴路。
This thesis investigates the GPS tracking loop designs using the unscented particle filter (UPF). The research work covers two parts: (1) the UPF-based tracking loop design with multipath parameter estimation; and (2) the vector tracking loop design based on the UPF. Multipath error is the code tracking loop error caused by the direct signals of satellite and the reflected signals in the vicinity of the receiver. In the first part, the UPF-based GPS tracking loop with multipath parameter estimation and mitigation capability is proposed, in which the multipath interference is one of the dominant sources of errors. The I (in-phase) and Q (quadrature) accumulator outputs from the GPS correlators are used as the observational measurements of nonlinear filters to estimate the multipath parameters such as amplitude, code delay, phase, and carrier Doppler. Since the measurement of (I and Q) for the filter and the system states are highly nonlinearly related, the nonlinear filters are potentially useful. For certain problems, a Gaussian assumption cannot be applied with confidence. One of the adequate methods is to use the Bayesian filter/particle filter (PF) to improve the estimation. The PF possesses superior performance as compared to extended Kalman filter (EKF) and unscented Kalman filter (UKF) as an alternative estimator for dealing with the nonlinear, non-Gaussian system. The degeneracy of particles and accumulation of estimation errors in the PF are difficult to overcome. To handle the problem of heavy-tailed probability distribution, one of the strategies is to incorporate the UKF into the PF as the proposal distribution, leading to the UPF. Performance evaluation for the UPF as compared to the conventional approaches is presented. The second part of the thesis deals with the vector tracking loop design based on the UPF .The vector tracking loop better than the scalar tracking loop .The scalar tracking loop uses the independent parallel tracking loop approach, and the vector based tracking loop technique uses the correlation of each satellite signal and user dynamics. In second part, the vector tracking loop design based on pre-filter is selected, and the navigation filter used includes the UPF and the UKF. The results show that the tracking loop based on the UPF can effectively estimate multipath parameters. Furthermore, the vector tracking loop design based on the UPF demonstrates better performance than the UKF-based vector tracking loop design, especially for the non-Gaussian noise.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0010067033
http://ntour.ntou.edu.tw/handle/987654321/35737
Appears in Collections:[通訊與導航工程學系] 博碩士論文

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