ISILON-An intelligent system for indoor localization and navigation based on RFID and ultrasonic techniques

Accurate localization and navigation are indispensable for mobile agents to walk in large-scale indoor public space, such as intelligent building and disaster rescue. In this paper, an intelligent localization and navigation system called ISILON is designed and developed. The system consists of a mobile terminal and multiple sensor nodes (also called landmarks) installed in the environment. The mechanism and function of the mobile terminal and the landmarks are same, and they are composed of microprocessor, RFID transceiver, ultrasonic transceiver and related interface circuits. RFID module and ultrasonic module are integrated in each node to provide ID information and range measurement simultaneously. And TDOA (Time Difference of Arrival) between radio frequency and ultrasonic signals is determined to estimate distance between the mobile terminal and the sensor nodes, and trilateration localization technique is applied to achieve accurate position information of the mobile terminal. Moreover, according to the localization result, the mobile terminal can realize path planning, in which an optimal motion path is calculated to guide the terminal to navigate to the given destination. Experiments in a classroom are presented to show the effectiveness of our system.