Initial Alignment Algorithm Based on the DMCS Method in Single-Axis RSINS with Large Azimuth Misalignment Angles for Submarines

Since the inertial sensor error has been modulated effectively by the Rotation Modulation Technique (RMT), the Rotation Strapdown Inertial Navigation System (RSINS) has been widely used for submarines in order to satisfy the requirement of high-accuracy and long working duration. The performance of the initial alignment is main factor affecting the accuracy of the Strapdown Inertial Navigation System (SINS). The traditional initial alignment algorithm based on the compass method has bad performance when the misalignment angle is large, which will make the submarine SINS fail to launch properly in a complex operating environment. Since the RSINS uses the mathematical platform to calculate the navigation information, it allows multiple algorithms to run simultaneously, and different algorithms do not interact with each other. Thus, to improve the alignment accuracy, an initial alignment algorithm based on the Dual Mathematical Calculation System (DMCS) is proposed; moreover, to solve the problem of large azimuth misalignment angle, an improved DMCS-based alignment algorithm is also presented in this paper. Both simulations and experiments showed that the novel algorithm can effectively improve the initial alignment performance under the large misalignment angle environment, enhancing the environmental suitability of the RSINS.