Fast two-position initial alignment for SINS using velocity plus angular rate measurements

•Angular rates are incorporated as measurements to speed up alignment convergence of the SINS.•Measurement equation in full 3 channels is derived in both navigation and body frames.•Cross-correlation between the process and measurement noises are analyzed and addressed in KF.

An improved two-position initial alignment model for strapdown inertial navigation system is proposed. In addition to the velocity, angular rates are incorporated as measurements. The measurement equations in full three channels are derived in both navigation and body frames and the latter of which is found to be preferred. The cross-correlation between the process and the measurement noises is analyzed and addressed in the Kalman filter. The incorporation of the angular rates, without introducing additional device or external signal, speeds up the convergence of estimating the attitudes, especially the heading. In the simulation study, different algorithms are tested with different initial errors, and the advantages of the proposed method compared to the conventional one are validated by the simulation results.