Indoor Navigation System for Mobile Devices

Overview: Airport travelers, retail shoppers and hospital visitors are a few of the millions of people who could benefit from improved indoor positioning. Yet even after decades of research, a simple and robust positioning system is lacking. Problems include high deployment overhead and inaccuracy.

One promising strategy exploits the unique frequency signatures of light fixtures, which are the result of manufacturing variations. A common cell phone camera may be used to detect these unique signatures and compare them with a database to determine one’s location. However, cameras have significant drawbacks such as limited bandwidth and low dynamic range, making it difficult to measure the signatures of individual light sources on a high ceiling, for example, in a warehouse store.

The Invention: UW–Madison researchers have developed an indoor navigation system using a mobile device equipped with two photodetectors. The system is able to determine the angular position of different light fixtures while avoiding the limitations in bandwidth and sensitivity associated with standard camera detectors. It is suitable for facilities with high ceilings more than three or four meters above the floor

Specifically, the new method can be illustrated in three steps: (i) identify multiple light source signals within the field-of-view according to known light source signatures; (ii) determine the angles of the multiple light sources; and (iii) identify the location of the mobile device based on the angle of the multiple light sources and a known mapping of light sources to locations.

Applications:

• Indoor localization software for a wide variety of location-based services
• Robotic navigation
• Physical analytics
• Virtual/augmented reality

Key Benefits:

• Accurate, reliable and easy to use
• Low-cost implementation
• Suitable in many indoor environments, even high ceilings