Research on the Trajectory Measurement Method of Underwater High-speed Attack Weapons in the Geodetic Coordinate

When evaluating the shooting accuracy of underwater attack weapons against the surface target, we need to transform various coordinates into a unified coordinate. Typically, the surface target track uses the geodetic coordinate and under-water weapon trajectory uses the navigation coordinate. Therefore, trajectory data in the navigation coordinate need to be converted to the geodetic coordinate. Using an inertial measurement unit can only get the trajectory data in the navigation coordinate. Because of the Doppler effect, acoustic reverberation, range ambiguity, and low data refresh rate, the methods based on the cooperative acoustic beacon or the baseline positioning cannot meet the trajectory measurement requirements of the underwater high-speed attack weapon. In this paper, a method combining baseline positioning with an inertial measurement unit is proposed to solve the problem of trajectory measurement in the geodetic coordinate of the underwater high-speed weapons. The system composition, working principle, and measure results are introduced, and the measure errors are analyzed.