System reset for underwater strapdown inertial navigation system

Conventional system reset methods establish the relationship between measurements such as position or heading and gyro drifts by the Psi equation, following which, they iteratively calculate the gyro drifts. However, these methods have some limitations in practice. First, the process of system reset takes a long time, and usually, the interval between two samples is a few hours. Second, the position information of multiple points is generally difficult to obtain for an underwater vehicle. In order to solve the above problem, a system reset method suitable for underwater strapdown inertial navigation system (INS) is proposed in this paper. This method uses external velocity as aiding information, which relates the measurement velocity to gyro drifts, position, and heading by the intermediate vector on the geographical frame and then calculates the gyro drifts and the errors of position and heading. The results of simulation and trial show that the proposed system reset method only spends 2 min on correcting system errors including gyro drifts, position errors, and heading error, only using the aiding velocities from a Doppler velocity log.