Relative Estimation Method of DOV Based on Double-Alignment of SINS

Deflection of the vertical (DOV) has become a significant error source in inertial navigation systems (INSs) and meantime widely used in geodesy, exploration, geoid refinement, and so on. Hence, an efficient and reliable method for DOV estimation is crucial for those fields. In this letter, an ingenious and efficient method, the relative estimation means based on double alignment (RE-DA), is proposed, which mainly includes attitude tracking of normal and orientation for plumb line two processes. First, the influence mechanism of DOV in initial alignment based on the inertial method was briefly introduced and the conclusion was clarified that the alignment result, attitude matrix, was with respect to the plumb line. Moreover, the method for attitude tracking of normal based on the strapdown INS and odometer (SINS/OD) integrated navigation using the Kalman filter was investigated. Finally, the process of the proposed RE-DA method was specifically introduced. In verifying the proposed method, several repeated land-vehicle experiments were conducted, where the statistical results show that the root mean square (rms) of the estimation values are 0.73^{\prime \prime } and 0.69^{\prime \prime } respectively, which provides a novel means for DOV high-efficient estimation.