Aspects of pure and satellite-aided inertial navigation for gun-launched munitions

Pure inertial navigation and satellite-aided inertial navigation have become standards in many military applications. This standard or sensors, receivers, algorithms and their implementation can be used for a wide range of systems such as ships, airplanes and missiles. However, gun-launched munitions have special requirements due to the following restrictions: initialization and transfer alignment is impossible before launch; launch shock changes sensors which results in significant unknown errors; roll rates can exceed the range of gyros. The resulting system requirements can be met by special sensor concepts such as additional magnetometer sensors and special navigation algorithms. This paper presents an alternative sensor concept and navigation algorithm for gun-launched munitions. Navigation systems of gun-launched shells have to comprise g-hardened sensors and need to be initialized some time after launch. Using special algorithms based on Kalman Filters a sufficient and fast attitude initialization is possible. Additional stabilization of attitude can be achieved by incorporating magnetometer sensors in the navigation solution. The sensor concepts and algorithms are explained and results achieved in simulation, Hardware in the Loop and flight tests are presented.