ESTIMATION OF PRECISE ROAD GRADE USING TIME-DIFFERENCED SATELLITE NAVIGATION SYSTEM SIGNALS

摘要

Implementations described herein contemplate measuring the carrier phase (CP) of carrier signals transmitted by constituent satellites of a Global Navigation Satellite System (GNSS) to provide highly accurate calculations of a gradient of a road segment between different points at which the vehicle received carrier signals (from which CP measurements were made). The methods described herein are able to calculate the road grade with only an approximate estimate of the absolute altitude of the receiver. Similarly, the methods described herein are able to provide a precise estimate of road grade with only an approximate estimate of the absolute value of latitude or longitude. Furthermore, implementations described herein provide highly accurate calculations of road grade information with standard GNSS vehicle hardware and are thereby able to achieve a substantial increase in accuracy without increasing cost.

主权项

1. A method for determining a gradient of a road segment traversed by a vehicle from a first time to a second time, the method comprising:
receiving, by a transceiver located at the vehicle during a first epoch, at least four first carrier signals each transmitted by one of at least four satellite navigation system satellites; measuring a carrier phase (CP) of each of the at least four first carrier signals; storing the measured CP of each of the at least four carrier signals at processor readable media; receiving, by the transceiver during a second epoch, at least four second carrier signals each transmitted by one of the at least four satellite navigation system satellites; measuring a CP of each of the at least four second carrier signal; determining, for each of the at least four satellite navigation system satellites, a difference in the measured CP of the first carrier signal and the measured CP of the second carrier signal, providing, as an input into a change in carrier phase equation for each of the at least four satellite navigation system satellites, the difference in the measured CP of the first carrier signal and the measured CP of the second carrier signal for each of the at least four satellite navigation system satellites; obtaining a solution representing a change in location coordinates from the first epoch to the second epoch by solving a system of equations including the change in carrier phase equation for each of the at least four satellite navigation system satellites; and determining the gradient of the road segment from the solution.