Precision relative navigation solution for autonomous operations in close proximity

The ability to provide highly accurate and reliable relative navigation information in real time is a key enabling technology for autonomous operations between moving platforms in close proximity. Northrop Grummanpsilas Navigation Systems Sivision (NSD) has developed an innovative approach to relative navigation that fuses Global Positioning System (GPS) pseudorange and carrier phase measurements with Inertial Navigation System (INS) data and implements a innovative approach to resolving the GPS carrier phase integer ambiguity to satisfy accuracy, integrity, continuity, and availability requirements. This capability was recently demonstrated as part of the Air Force Research Laboratorypsilas Automated Aerial Refueling (AAR) program. During the final flight test phase, a Learjet-25 test aircraft autonomously performed station keeping and transitioning between various positions in close proximity to a KC-135R tanker, in a fashion typical of refueling maneuvers. The relative and absolute vehicle navigation data used by the autonomous flight control system were calculated using NSDpsilas relative navigation algorithm and sensor data from two LN-251 Embedded GPS/INS (EGI) systems with embedded 24-channel GPS receivers, one on each vehicle. This paper will present and discuss the flight test results and performance.