ASSIST is a navigation application designed for visually impaired users, capable of tracking the position of the user within an indoor environment and providing turn-by-turn directions to a location (i.e. elevator, room 52, cubicle 7) using BLE Beacons, Tango, or hybrid infrastructure depending on infrastructure availability.
The hybrid Beacon-Tango localization system designed is capable of highly accurate, robust, real-time multi-floor indoor localization. Bluetooth Low Energy (BLE) Beacons, which are excellent at coarse location detection are used for approximating the user's general location (i.e. floor or section within a large indoor environment). A vision-based approach, utilizing a Google Tango RGBD + 6-degrees-of-freedom visual inertial odometry enabled device (phone & phablet available), allows us the software to detect the fine location (position and orientation) of the user. The Tango device allows us to effortlesly and quickly record a 3D feature map of the environement in a compressed format, called an Area Description File (ADF), which allows for real-time re-localization within that environment. Although the Tango device was prone to small errors during the estimation of each camera position, the average error was 3 cm and the maximum error recorded was 0.4 m. A limitation experienced was the size of the ADF able to be recorded, which was found to be approximately a floor of a building. A Tango device is therefore used to record an ADF for each floor (or each section in a large building) and BLE Beacons can be used to detect the coarse location and load the corresponding ADF to be localized against for that section of the building. The software designed also has modules for being used by those without access to a Google Tango device, in which case it will only use BLE Beacon based localization.
Furthermore, an adaptable interface is designed which allows the position of the user to be tracked on a 2D floor plan of the environment - accomplished by aligning the 3D Area Description File to the 2D floor plan. An annotation module is also included which allows for waypoints to be placed on the 2D map associated with the 3D ADF.
