Highly dynamic strapdown inertial navigation attitude updating algorithm based on sine function fitting

In order to improve the attitude solution accuracy of the strapdown inertial navigation system under high dynamic conditions, a high dynamic attitude updating algorithm based on sine function fitting is proposed according to the Taylor series expansion method of the equivalent rotation vector. The angular velocity of the carrier motion is fitted with the sine function. Considering the effect of the higher order terms of the Bortz equation, the rotation vector represented by the gyroscopic angular increments is expanded by Taylor's sixth order, and the error compensation coefficient is obtained by comparing different expressions of the rotation vector. Based on the MATLAB platform, the proposed algorithm is simulated and analyzed in comparison with the conventional algorithm by using the environment of cone motion and large angular rate rotation co-existed as the simulation conditions. The simulation results show that the performance of the proposed algorithm is better in the case of low-frequency cone motion with small half-cone angle accompanied by high-speed angular rate rotation, where the error of the three subsample algorithm based on fitting of sine function proposed in this paper is reduced by 2 orders of magnitude compared with the traditional three subsample cone algorithm based on extended form frequency series or three subsample cone algorithm based on extended form explicit frequency at half-cone angle 0.5 °, angular frequency 2.26π rad/s, constant angular rate 5.30 rad/s and attitude solution period 0.02 s. © 2024 Editorial Department of Journal of Chinese Inertial Technology. All rights reserved.