Khairi Abdulrahim and colleagues at the University of Nottingham in the UK are following an alternative approach to shoe-based navigation. Their new device complements the one recently developed at Carnegie Mellon University and North Carolina State University. (See: Radar in your shoe: The reasoning Improbable Research, December 1st, 2010).
But rather than rely on radar, the team from the Institute of Engineering Surveying and Space Geodesy (IESSG) at Nottingham use ZUPT (Zero Velocity Update) to correct for errors in an inertial measurement unit (IMU) (normally three accelerometers and three gyroscopes) strapped to a shoe.[see pic. above]
“In walking pedestrian navigation, ZUPT was used successfully by strapping the IMU on foot/shoe. This has the advantage that when walking, the foot has to be briefly stationary (zero velocity condition) while it is on the ground. It is during this period that ZUPT is used to correct the IMU velocity.”
ZUPT has already been battle-tested in series of real-world trials carried out by the university :
“… position error is consistently kept below 5 metres while walking for periods as long as 40 minutes while walking a distance of approximately 2700 metres.”
And in the future, say the researchers, low cost IMUs with ZUPT –
“… could even be integrated with shoes itself [sic] especially for emergency personnel, army or even for blind pedestrian [sic] for navigating and tracking purposes and navigation could be done in real time.”
Details of the device and its associated computational algorithms will be presented at the 2011 International Technical Meeting of the Institute of Navigation, Inc. Jan 24-26th in San Diego.
In the meantime, a full technical description can be found here: Using Constraints for Shoe Mounted Indoor Pedestrian Navigation