Fuzzy adaptive Kalman filter for marine SINS initial alignment

Ship rocking disables marine strapdown inertial navigation system (SINS) to complete initial alignment using Kalman filter In order to overcome the disturbance caused by ship rocking, a robust filter should be designed to complete marine INS initial alignment. In the paper, a fuzzy adaptive Kalman filter is presented to complete marine INS initial alignment in condition of ship rocking. The state space model of the fuzzy adaptive Kalman filter is established and the Takagi-Sugeno fuzzy system is used to continually adjust the measurement noise strength during the filtering procedure, and tune the filter as well as possible. Simulation results show that fuzzy adaptive Kalman filter presented in the paper can overcome the disturbance caused by ship rocking to complete marine INS precise alignment in less than 4 minutes, and the estimation error of the horizontal misalignment angle is less than 0.01 degree and the estimation error of the heading misalignment angle is less than 0.1 degree.