An Innovative Polar Rapid Transfer Alignment Aided by Doppler Velocity Log For Marine Vessels

Under the severe condition of polar region, the information of master strapdown inertial navigation system(MINS) is inaccurate and systematic state model becomes abnormal. Then, the traditional transfer alignment(TA) algorithm, using the information measured from MINS, is ineffective. In this paper, an innovative polar rapid transfer alignment, aided by Doppler Velocity Log and modeled under a large misalignment angle, is proposed to solve the problems. Because of the imprecise measurement information of MINS, the velocity obtained from Doppler sensor is applied as observation information, whose error is not calculated over time. Adopting "velocity +attitude" matching method and considering a large misalignment angle, nonlinear transfer alignment equations are derived with the compensation of lever-arm effect and error model of Doppler velocity log. Due to the nonlinear TA algorithm, an extended Kalman filter(EKF) is introduced to estimate the misalignment angle and then compensate it. By designed experiments, a new TA algorithm with aid of Doppler velocity log performs better than the traditional TA algorithm without any external sensors. Therefore, an innovative rapid transfer alignment algorithm introduced in this paper, accurately and effectively, improves the performance of transfer alignment in polar region.