Low-Cost, Precise Railroad GPS Vehicle Location System Final rept. (Aug 05-Aug 06)

摘要

If the precise location of both train and track maintenance vehicles and equipment could be determined automatically at central dispatch, it could significantly improve the safety and efficiency of train movements through track maintenance areas. This could be achieved using an automatic precise location system on the train and on the maintenance vehicles that automatically transmit their respective locations to central dispatch. This study focuses on the feasibility of automatically and precisely determining the location of maintenance vehicles and equipment using a GPS Vehicle Location System (GVLS). GVLS uses a GPS receiver augmented with dead reckoning sensors, in order to provide the vehicle location when GPS coverage is interrupted. The GVLS achieves the required position accuracy by using a sophisticated carrier differential GPS (CDGPS) position algorithm. This algorithm compares the GPS carrier phase measurements from the GVLS receiver with GPS carrier phase measurements from a nearby reference receiver at a known (surveyed) location. Using these measurements, the algorithm estimates and removes line-of-sight slant range errors, such as the unknown carrier (integer) biases, and determines the relative position between the two receivers. The reference receiver measurements are obtained from a High Accuracy -