A Study of An Initial Alignment Method of Underwater Vehicle Dropped from Aircraft

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Journal of the Korea Institute of Military Science and Technology 2003;6(1):21-29.

항공기에서 투하되는 수중운동체의 초기정렬기법 연구

류동기, 김삼수

국방과학연구소

Abstract

The Strap Down Inertial Measurement Unit(SDIMU) is recently used for the sensor package of the modern underwater vehicles such as torpedoes and unmanned underwater-vehicles. For using SDIMU, an initial alignment must be carried out before the fire or navigation stage. The general initial alignment methods require that a mother vehicle Is a stationary condition or the Inertial Navigation System(INS) of vehicle is received the specific of data navigation from the mother vehicle. But an underwater vehicle dropped from aircraft is hard to satisfy above both necessary conditions of the general initial alignment. So, we suggest a new strap down initial alignment method of an underwater vehicle dropped from aircraft without using any aided sensors. The highlight point of this method is that a period of initial alignment is not before the fire but during running stage to fix alignment error. And we verify it by analyzing various data of S/W simulations, Hardware In the Loop Simulation(HILS) tests and sea trials.

Key Words: SDIMU, INS, Initial Alignment, Body frame, FOG(Fiber Optic Gyro), HILS(Hardware In the Loop Simulations), Navigation frame