Airborne Alignment Method for Missile-Borne Inertial Navigation System Aided by GNSS

To satisfy the combined demands for rapidity, accuracy and robustness in missile-borne in-flight alignment, we propose a GNSS-aided airborne alignment framework. During flight, GNSS measurements are used to generate attitude and position observations for coarse alignment; in the fine-alignment phase a reduced-order state model and bidirectional filtering suppress dynamic errors, while RTS smoothing is applied to improve consistency and stability. Hardware-in-Loop Simulations show that the scheme completes transfer alignment in about 30 s and converges to a steady-state attitude accuracy of better than 0.05°, with a maximum 76.5% reduction in the relative baseline misalignment angle vector norm.