Analysis of DOV estimation in initial alignment based on Single-axis rotating SINS

Abstract

The Strapdown inertial navigation system (SINS) requires the precise attitude, whereas the deflection of the vertical (DOV) is normally ignored in alignment. To solve the issue of orientation and position errors caused by DOV, a novel DOV calculation method, estimated by misalignment angles based on single-axis rotating modulation, is proposed. The theoretical limit error equation of attitude angle, affected by the coupling of inertial measurement units (IMU) errors and DOV, has been specifically derived based on the inertial frame alignment theory. It is pointed out that the DOV components directly affect the values of misalignment angles, coupling with horizontal accelerometer errors. Moreover, the specific process of combining coarse alignment of inertial frame and fine alignment of Kalman filter method is presented. Finally, the experiment analysis validates the performance of the proposed method and correctness of the theoretical analysis, where the estimation accuracies of DOV components are 0.349′′ and 0.479′′ respectively.