LAUSR

In this article, a new strapdown inertial navigation system (SINS)/ultrashort baseline (USBL) integrated navigation algorithm is proposed based on the Earth-centered Earth-fixed frame SINS mechanization. The dynamic model of the navigation system has proven to satisfy the “group affine” property. Using the Lie group theory to define the right group state error vector, a new SINS/USBL error model is developed to accurately describe the error propagation under error-polluted navigation parameters. The most significant advantage of this error model is its ability to handle large initial misalignment angles. Subsequently, considering the low update frequency of the USBL measurement update, a virtual observation equation is constructed to improve the convergence speed of the algorithm in the presence of large initial misalignment angles. Finally, for the sake of effectively suppressing the influence of acoustic outliers, the existing outlier Kalman filter based on statistical similarity measure is improved by adaptively adjusting the degree of freedom (DoF) parameters, so that inaccurate dof parameters have less impact on filter performance. The effectiveness and superiority of the proposed algorithm are verified by simulation and sea trial.