A fast and high-accuracy transfer alignment method between M/S INS for ship based on iterative calculation

There are two viewpoints in the transfer alignment process given as follows: (1) the information used for matching in strapdown inertial navigation system (SINS) originates from the mathematical frame which cuts off the direct relationship between sensor measurement and misalignment angles; (2) in close correction mode, the estimated parameters from data fusion filter are used to participate in SINS navigation solution. Based on the above viewpoints, a novel transfer alignment method based on iterative calculation is designed, and in this method the alignment time is shortened and alignment accuracy is improved and the real-time property of alignment result is ensured with the following two methods: (1) during every data fusion period, sensor data and external reference navigation parameters are stored, and the backward and forward navigation solution and data fusion are executed once or several times with the help of high performance computer; (2) with the help of multi-tasking method, the operations for storing sensor data in the current fusion period, iterative calculation for the previous fusion period, and navigation solution for the current fusion period based on the stored data and real-time data are run in parallel but with different priorities. The simulation and turntable test under ship swinging condition indicate that alignment time of the proposed method is shortened compared with that of classical method when the data fusion times of two methods are equal; and alignment accuracy is improved when the alignment times are equal.