超寬頻測距及定位系統之設計

Abstract

本論文藉由超寬頻(Ultra-WideBand ; UWB)訊號時間精準度特性，分別提出了不需要部署基站的即時測距系統和四基站多目標定位系統，即時測距系統使用優化的雙向測距法(Two-way Ranging)，修正訊息衝突所造成的測距錯誤，可以同時偵測20個裝置的距離，並且保持超過90%的準確率；多目標定位系統基於一對多雙邊測距法達到基站間無線同步的效果，讓待定位目標接收時間差(Time Difference of Arrival； TDOA)資訊，系統會根據待定位目標數量動態調整定位週期，讓每個定位目標有效率地錯開回傳時間，再經由梯度下降法(Gradient Descent)計算出座標位置，經過模擬與比較驗證梯度下降法確實優於其他常見定位方法，在直視(Line of Sight；LOS)的環境下本系統精準度可達10公分，在干擾嚴重的環境中為了減少非直視造成的測距誤差，則使用基因演算法(Genetic Algorithm；GA)找到能讓定位誤差最低的基站擺放方式，並實際驗證定位誤差與任意擺放相比下降了20公分。最後提出適合應用本論文系統之應用場景，利用本系統即時及高精準的特性，達到安全及智慧化的效果。

This thesis, based on the high time accuracy of the ultra-wideband (UWB) signal, proposes a real-time ranging system that does not require the deployment of base stations and a multi-target positioning system requiring four base stations. The real-time ranging system uses the optimized two-way ranging (TWR) to modify the ranging error due to signal conflict, and can detect the distance of 20 devices at the same time, and maintains the accuracy more than 90%. The multi-target positioning system achieves wireless synchronization among base stations based on one-to-many two-way range, and the targets receive time difference of arrival. The system would adjust the cycle dynamically to make targets return messages efficiently, and calculate the coordinate positions by gradient descent which is better than other positioning algorithm. The root-mean-square error is less than 10 cm in the line of sight (LOS) environment, and the genetic algorithm is applied in the environment with severe interference to find the base station placement method that can minimize the positioning error. The positioning error is reduced by 20 cm compared with other placements. The suitable scenarios are proposed at the end of this thesis, and our system could make the users safer and more intelligent.