The Design Of Indoor Wireless Locating System

With the fast and deeply developing of mobile internet, the service based on location is increasing constantly. The indoor locating technology is rising in recent years. It is expected to have a broad prospect in shopping center, warehouse, mine, hall and so on. The indoor locating technology can provide the service of indoor location, navigation and some other individuation service. Kinds of indoor locating technology have been put forward, such as WLAN locating technology, ultrasonic locating technology, ZigBee locating technology and so on.This system use ultrasonic technology, TOA ranging method to range the distance between nodes. It chose maximum likelihood localization algorithm to calculate the moving node’s coordinates, then display coordinates on the LCD, and save the coordinate in SD card. The thesis discuss the system’s overall architecture, working process, main devices, each module’s design in detail, and finish the ranging and locating experiments.Several frequently-used indoor locating technologies has been introduced, and their basic principles also has been discussed. Then this thesis describes several main indoor localization algorithms, including range-based algorithms and range-free algorithms. Several distance measurement methods which are matched to the range-based algorithms, such as RSSI measurement, TOA measurement, TDOA measurement, have been introduced. And their advantages and disadvantages have been analyzed too. The indoor ultrasonic locating system is divided to two subsystems:the locating subsystem and display subsystem. The locating subsystem consists of moving node, beacon node and gateway node. The node in locating subsystem chose CC2430to be the main control chip. The locating subsystem locates the moving node. The display subsystem displays the moving node’s location and stores the location data to the SD card. It is developed on S3C2410chip which is based on ARM9and VxWorks operating system. Design and implement radio transceiver module, ultrasonic transmitting module, ultrasonic receiving module, LCD display module, SD card access module and so on. Set up and debug the system, and design experiments to test the system. In the test, the system’s ranging accuracy is5cm; the locating accuracy is10cm. Results show that the indoor ultrasonic locating system can be a feasible indoor locating scheme.