| Summary: | 碩士 === 國立臺灣海洋大學 === 電機工程學系 === 97 === The thesis is aimed to design and implement an ultrasonic-based indoor positioning system(IPS). In current literature, two types of ultrasonic-based IPS are included ; one type is to use extra RF device for synchronization and the other type is RF-free. Their positioning errors are almost within 5cm in X-axis and Y-axis. Positioning parameters commonly used are time of flight (TOF) and time difference of arrival (TDOA). In the thesis, a prototype of IPS is implemented using RF-free scheme and TDOA as positioning parameter.
In the system deployment, four ultrasonic receivers are placed at four corners on a plane with the length of 3m, the width of 1.8m and the height of 1m. When ultrasonic wave of 40kHz is transmitted with a period of 0.2sec, its time of arrival (TOA) is detected and measured using a data acquisition card connected to the receivers, and coordinates of the transmitter are estimated based on a specific positioning algorithm coded in MATLAB. The salient features of the system include : 1. No synchronization between transmitter and receivers is required ; 2. Timing sequence of the transmitter is simple, thus requiring no SoC(System-on-a-Chip) ; 3. The Maximum positioning errors are 2.31cm, 2.24cm, 9.47cm in X-axis, Y-axis and Z-axis respectively.
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