“…Combined with fuzzy inference system (FIS), the initial alignment schemes based on fuzzy adaptive filters, such as the fuzzy adaptive Kalman filter [ 37 ], fuzzy simplified UKF [ 38 ] and fuzzy strong tracking UKF [ 39 , 40 ], etc., were proposed to improve the performance of SINS initial alignment under large alignment angles and disturbance. In [ 41 , 42 , 43 , 44 , 45 ], the SINS initial alignment methods utilizing neural networks were researched, which could be applied for the application scenarios with disturbances, for example, Shipborne, guided projectiles, and so on. In [ 46 , 47 ], two machine learning methods were proposed to achieve the nonlinear initial alignment of SINS under the condition of large misalignment angles, of which one was based on Gaussian process regression (GPR) [ 46 ], the other utilized a combination of Gaussian mixture model (GMM), expectation–maximization (EM), and UKF filter [ 47 ].…”