GPS (Global Positioning System) is a well known technology used for tracking and navigating. Everyone that have used GPS knows that the signal is blocked when you are inside a house, in a garage or surrounded with tall buildings. IPS (Indoor Positioning System) is a technology used for positioning were GPS can not be used. The most common technologies for IPS are radio, infrared or ultrasound signals.
Lets have a quick look at the three different IPS technologies.
IPS based on radio signals can use WLAN or Wi-FI. Advantages using this: Low cost, exists a lot of places and covers large areas and could work across multiple buildings. The disadvantage is low accuracy.
RFID can also be used, higher costs than WLAN or Wi-Fi but this is more accurate. But still with RFID it’s hard to separate the rooms in a building since the radio signals travels through the walls. The radio signal also reflects off metallic or ceramic objects and can be picked up by multiple sensors (earlier post about RFID/EPC).
Ultrasound is picked up by microphones and the short wavelength ensures that the signal stays in the room. This can be used to accurately tell if a object is in a specific room of the building.
Most known for heat seeking or infrared homing (used by passive missile guidance systems). Many objects such as people, vehicle engines and aircraft generate and retain heat,and as such, are especially visible in the infra-red wavelengths of light compared to objects in the background.
Sonitor Technologies AS are working with Ultrasound based IPS and are shaping the sensitivity on the detectors so they can pick up specific signals. Sonitor have installed their solutions in several hospitals to identify and track doctors and patients.
Ultrasound based IPS have a tendency to overlook pieces of equipment when the number of items in a room grows large. Therefore some hybrid Ultrasound/RFID IPS have been tested. These systems combines the best of RFID and Ultrasound.
I would really like to do a research project on this technology combining RFID, Ultrasound and mobile devices. If you have an idea for a cool research project case please leave a comment on it.