Shearer SINS Self-Alignment Method Based on Gravitational Acceleration Spatial Mapping Model Without Latitude

The initial alignment technique is essential for the start-up time and attitude measurement accuracy of the strapdown inertial navigation system (SINS). Aiming at the problem that the traditional initial alignment method cannot obtain the reference information in the navigation coordinate frame to complete the initial alignment under the unknown latitude condition, this study proposes an initial alignment method of shearer shaking base based on gravitational acceleration spatial mapping model (GASMM) of the inertial frame. First, an objective function in the form of acceleration integration and the integral dynamic window (IDW) algorithm were designed to suppress noise. Second, the objective function is constructed using the geometric relationship between the gravity acceleration vector in the inertial frame and the Earth frame, and the quasi-Newton optimization alignment (QNOA) method is utilized to estimate the local geographic latitude. Subsequently, the problem of self-alignment on a shaking base under unknown latitude conditions is regarded as the Wahba attitude determination problem, and the eigenvalue decomposition quaternion method is utilized to solve the attitude and complete the self-alignment of the shaking base. Finally, the initial alignment simulation of the SINS shaking base and the shaking base experiment of the vehicle and shearer is performed. The simulation and experimental results indicate that the mean error of the heading angle error can attain 0.6° in 300 s in the coarse alignment process without utilizing local latitude, which provides a more accurate initial attitude for subsequent fine alignment.