Indoor Location Technology

Abstract

People rely on GPS to reach destinations, but once the destination is reached, there is no system for navigation to a desired location inside a building. With an indoor positioning system (IPS), users could view their location in a building and determine indoor routes. Additionally, the FCC has set an objective to implement IPS to improve E911 accuracy. Currently, there are over 200 start-ups and large firms in competition to develop IPS, with most utilizing signals such as Bluetooth Low Energy (BLE) or WiFi. A better IPS product can be developed using magnetic positioning to generate a magnetic field using an extremely low frequency (ELF) signal. ELF consumes little energy and can travel through walls and objects; therefore avoiding troublesome issues encountered with BLE and WiFi. The main challenge with magnetic positioning is the size of the copper coil used to generate the magnetic field: it must be large enough to create a strong field, yet small enough for integration as a beacon into building infrastructure. The ELF beacon is rectangular-shaped for placement above doorways to tag users upon entering a room. Tagging occurs when the user’s smartphone magnetometer detects the dipole magnetic field of the beacon. The field is generated using a set-up that mimics a signal generator: Arduino Uno connected to Arduino Motor Shield, running C-code to create an ELF square wave, powered by batteries. By setting each beacon frequency to a distinctive value, user location can be determined based on unique identification. The prototype beacon’s coil was wound by hand; therefore the largest gauge wire could not be used due breakage risk and the prototype is not fully optimized in terms of size. Future plans include winding a 40 gauge copper wire by machine with multiple layers for further size optimization.