使用可定址發光二極體燈管實現室內定位系統

Abstract

隨著可見光定位的科技過去十年的發展，其逐漸在室內定位領域展露頭角，並佔有一席之地，主因來自燈具密集地佈置在各個建築物和光不受多路徑傳輸影響的種種優點。又因為光的多元特性，許多設計ID的方法被提出並應用於多元場域。本論文中我們提出一種可見光定位系統，利用具有數個可定址LED燈的燈管作為傳輸端，並以手機的前置鏡頭作為接收端。我們提出獨特的ID辨識演算法，使得室內定位可以有效地被執行。系統核心概念在於使各個LED燈帶有不同亮度，來傳遞訊息。在妥善的格式設計下，系統可以非常精準地辨識ID。 接收端的部分，我們將整個系統實作成一個iOS App，因此只需一支手機，不需其他額外硬體即可使用。啟動我們的應用程式後，系統就能夠馬上開始接收照片、辨識ID並達到室內定位。我們的系統可以在只接收到一個燈管的情況下，實現精準定位，因此在佈置上可以非常分散。又由於傳輸端元件都是目前市場上可輕易購買且組裝的，加上已開發完成的手機程式，我們的系統可以在耗費很小的成本下，立即應用在各個場域。我們進行了多項實驗，針對人們多數會拿手機的環境下，進行ID辨識和定位的效能評估，結果顯示超過95%的ID辨識率，以及90個累積百分比的7.5公分之定位精準度。

For over one decade, visible light positioning technology is becoming more popular in indoor positioning field with advantages of dense deployment of light fixtures and multipath-free propagation. Due to diverse features of light, numerous light identification scheme are designed and can be adopted in most scenarios. We propose an indoor positioning system with special light identification scheme that utilizes off-the-shelf addressable LED tube as transmitter, and rolling shutter camera which is equipped on most mobile phones as receiver. The key idea is that the transmitter possesses numerous LEDs and the system uses different brightness set to the LEDs to transmit message. With proper modulation on each LED, the transmitter can send IDs with higher precision. As for the receiver, we implement our system as an iOS application. It only requires a mobile phone without any extra hardware installation. Our system can achieve precise positioning even when merely a part of a single tube is captured by the camera, making sparse deployment feasible. Due to commercial off-the-shelf (COTS) components of transmitters and accomplished application, our system can be implemented right away with only a little cost. We have conducted several experiments to evaluate identification and positioning performance under most scenarios where people using their phones. The results show that our system achieve overall more than 95% identification accuracy and a 90-percentile positioning precision of 7.5 cm.