Improvement on the Pitch and Roll Output of Rotation Inertial Navigation System

Experiments show that the rotation inertial navigation system has better position and velocity accuracy compared with the nonrotation inertial navigation system. But the pitch and roll output accuracy of the former is worse. This paper proves that the vortex motion of inertial measurement unit, an unexpected angular motion along other two directions perpendicular to the rotation direction, is the key cause of attitude accuracy loss. Detailed studies are done on vortex motion and an improved algorithm of horizon attitude based on gyro data analysis and Fourier fitting is proposed. Experiments show that the proposed attitude compensation method can improve pitch and roll output accuracy from
$60^{\prime \prime }$
less than
$10^{\prime \prime }$
.