Architecture and System Performance of SPAN - NovAtel's GPS/INS Solution

摘要

As a GPS receiver manufacturer, NovAtel is in a unique position to build a GPS/INS navigation system. The Synchronized Position Attitude Navigation (SPAN) system is based on OEM4 receiver technology combined with an Inertial Measurement Unit (EMU). The IMU integration is tightly coupled with access to the GPS receiver core. The integrated system provides real time position, velocity and attitude. GPS outages can be seamlessly bridged, enabling more reliable navigation through challenging environments like urban canyons. Additionally, GPS performance is improved with the integration of inertial measurements, allowing for faster signal reacquisition and faster return to a fixed integer carrier phase solution after signal outage. The real time solution is computed on board the receiver and raw data can be simultaneously logged for post-processing. Post processing is performed by NovAtel's Waypoint Inertial Explorer package. This paper discusses NovAtel's approach to INS/GPS system architecture. To demonstrate the performance of the SPAN system, data will be collected under real world conditions in a land vehicle. Test results will show system performance with various levels of GPS aiding and with wheel sensor aiding. The real time solution will be compared to the post-processed solution. Methods to deal with the constraints of real time will be discussed. The accuracy benefits of a post-processed solution will be demonstrated as well.