Seamless Navigation through a Locata-enhanced GPS and INS Integrated System

The Global Positioning System (GPS) can provide centimetre-level positioning accuracy in “open-sky” environments. However, GPS coordinates become unavailable in difficult urban, suburban and rural environments because the GPS signals may be partly or completely blocked by trees and buildings. In an attempt to address the demands for continuous high accuracy navigation to support ground-vehicle imaging systems, this paper describes an integrated system based on the “tripleintegration” of GPS, inertial navigation systems (INS) and the recently developed RF-based navigation system “Locata”. Although traditional GPS/INS integrated systems can bridge relatively short GPS gaps, its capability is heavily dependent on the accuracy (and ultimately the cost) of the INS. The Locata system can broadcast strong time-synchronised ranging signals over an area where GPS satellite geometry is poor or the signal availability is limited. This paper describes the triple-integration of GPS/INS/Locata, and tests its suitability for the precise continuous navigation when the GPS solution is unavailable or its accuracy is decreased.