Real-Time Indoor Geolocation Tracking for Assisted Healthcare Facilities

Background

The ability to identify the geographic location of an individual residing outside of a building by latitude, longitude, and altitude is easily accomplished using a relatively inexpensive GPS receiver. Typical commercially available receivers for under $100 can provide coordinates within a sampling time of 30 seconds to an accuracy of 3m. For example, the Copernicus II 12-channel GPS module from Trimble is under $70 and can provide updated coordinates with a period of 3s. GPS receivers typically use a carrier wave in the L1 band at 1575.42 MHz on which navigation messages are modulated. Unfortunately, such microwave signals are significantly attenuated by building roofs and walls, rendering GPS unusable in indoor setups.

Indoor position measurements can be accomplished using different mechanisms such as radio signals, magnetic fields, and sound waves. Newer, emerging technologies employ computer vision to identify objects in a camera field of a view. A vision system can measure distances in between recognized objects, and between a user and recognized objects. These measurements provide a system with depth perception and can identify how far a user is away from a surface or other rigid body in a field of view.