A New Polar Rapid Transfer Alignment Method Based on Grid Frame for Shipborne SINS

A polar grid rapid transfer alignment method for shipborne strapdown inertial navigation system (SINS) is studied. The basic framework and the specific process of grid rapid transfer alignment are built. The grid equations of attitude error, velocity error and position error of SINS are deduced. The math model of alignment with velocity plus attitude quaternion method is established. The velocity plus attitude quaternion method and velocity plus attitude angle method are derived and compared. On this basis, the Kalman filter algorithm is used to design grid alignment filter. The ship trajectory is designed and generated, and the researched alignment method is simulated and verified by MATLAB. Simulation results show that the proposed method can accurately estimate the attitude error angle, velocity error, deflection deformation angle and installation error angle, except at the poles, whether in mid latitude or high latitude, and regardless of the sea state level. The horizontal estimation accuracy of attitude error angle is 0.8’, the azimuth estimation accuracy is within 1.8’, the velocity error is within 0.03m/s, and the estimation accuracy of deflection angle and installation error angle is within 1.2’. Finally, the ship experiment is carried out, and the experimental results show that the actual application effect of the proposed method was as satisfactory as in the simulation experiment. During the estimation time of 20 s, the attitude misalignment angle error is 0.2 ’, the velocity error is 0.05 m/s, and the estimation accuracy of deflection deformation angle and installation error angle is less than 1’.