On-board unit for determining the route taken by a vehicle without the use of a global navigation satellite system for positioning

摘要

An on-board unit for a vehicle is arranged to determine the changes in position of the vehicle and thus its route taken. The on-board unit comprises a map database containing constraint information that describes possible vehicle routes, an inertial measurement unit, and a data processor. The data processor is arranged to process the output of the inertial measurement unit combined with relevant positional and motion constraints from the map database, and from these determine the actual route that has been taken by the vehicle. The unit may be arranged to receive GSM communications indicative of the coarse position of the on-board unit relative to known GSM transmitter locations. The unit is arranged to determine the route taken by the vehicle without the use of a global navigation satellite system (GNSS) for positioning, and may therefore be less vulnerable to jamming, blockage, and spoofing.