The main driving force to integrate these two navigation systems as an integrated GPS/INS system in different architectural forms to provide robust positioning. The complementary advantages of GPS and INS have been extracted. The loosely coupled and tightly coupled GPS/INS systems have been in existence for more than two decades and performed reasonably well, nevertheless, the tracking performance was still a problem to be addressed in non-benign environments such as dynamic scenarios, indoor environments, urban areas, under foliages etc., where the GPS tracking loops lose lock due to the...