In-flight coarse alignment for aerostat strapdown inertial navigation system aided by single GPS antenna

To meet the need of attitude initialization for an in-flight aerostat strapdown inertial navigation system (SINS), three coarse alignment methods aided by single GPS antenna were investigated: Specific Force Integrating Method (SFIM), Quaternion Based Analytical Method (QBAM), and Freeze Inertial Body Frame method (FIBFM). Theories of the methods were illustrated and the aerostat motion characteristics in stratospheric was analyzed. Then simulations were carried out to evaluate the performance of the methods. Comparison results showed that, the SFIM and the QBAM would not perform as expected in the presence of aerostat heading rotation, while the FIBFM could afford the disadvantage from the angular motion and obtain an acceptable coarse alignment result, which was proved by 50 times Monte-Carlo simulations.