1
Robert W Levi, Thomas Judd: Dead reckoning navigational system using accelerometer to measure foot impacts. Point Research Corporation, Price Gess & Ubell, December 10, 1996: US05583776 (334 worldwide citation)

A microcomputer-assisted position finding system that integrates GPS data, dead reckoning sensors, and digital maps into a low-cost, self-contained navigation instrument is disclosed. A built-in radio frequency transponder allows individual positions to be monitored by a central coordinating facilit ...


2
Robert W Levi, Robert R Marshall: Navigation device for personnel on foot. Point Research Corporation, November 2, 2004: US06813582 (200 worldwide citation)

Performing dead reckoning navigation for persons on foot with improved accuracy. Accelerometers in a navigation device are used to deduce when abnormal steps are being taken and modify navigation calculations accordingly. Running and walking sideways or backwards are among the situations which can b ...