Gps - navigation system with a local speed - and direction sensing and with pdop - accuracy evaluation.

摘要

GPS present position and/or speed sensor distance data corrective coefficient are updated depending on accuracy evaluation, minimum speed, system independency, uninterrupted data flow from satellite and statistical error:A GPS (Global Positioning System) navigation system for a vehicle determines the present position from GPS radio waves (1) and from direction (6) and speed (7) sensor system (2).A data processor (9) selects updating of present position from the GPS device (1) and/or corrects a distance corrective coefficient for the speed sensor (7) data if five conditions are fulfilled:a) if a PODP accuracy evaluation value of GPS (1) data is equal or smallerb) if GPS speed data are equal or greaterc) if the difference between GPS and sensor speed data is equal or smaller than respective predetermined values andd) if GPS data were obtained within three consecutive time intervals of predetermined lenght ande) if these three consecutive GPS data are equal or smaller than a predetermined value.