Alternate of GPS for ballistic vehicle navigation

Integrated navigation technology, employing inertial navigation system (INS) and Global Positioning System (GPS), has attained the level of state-of-the-art for navigation of ground vehicles, ships, air and space vehicles. Very accurate navigation solution is achievable by employing data fusion techniques for optimal combination of navigation data from INS and GPS. The likelihood that GPS may be denied to the user for accomplishment of a specific mission is of great concern and thus motivates for exploring alternate means to substitute GPS. An integrated navigation system comprising INS and celestial navigation system (CNS), being immune to external interference, is envisaged to be more robust from the view point of external interference. Employing the notions of unscented transformation the CNS/INS integration scheme is analyzed. Celestial observations and the distinctiveness of free phase flight of a ballistic vehicle are utilized for improving the navigation performance. Simulation results reveal tremendous improvement in navigation precision