Abstract:

 Due to the long alignment time of the traditional method,a novel forward-forward backtracking alignment method is proposed to faster the alignment procedure. Firstly, the fundamental of the navigational inertial-frame coarse alignment is described, and the effect of the navigational inertial-frame coarse alignment is analyzed. Secondly, the principle of the initial alignment method of SINS is deeply explored. Based on the navigational inertial-frame error model, the time-varying error attitude estimation is transformed into a time-invariant error attitude estimation, then the forward-forward backtracking alignment method can be devised by this transformation. Moreover, the fundamental of the forward-forward backtracking alignment method is investigated in detail. Finally, the simulation and turntable test are conducted for validating the performance of the proposed method, and the results show that the errors of yaw are less than 0.1° when the whole alignment procedure lasts for 303 s. Thus, the proposed method has the advantages of high computational efficiency, short alignment time, and high alignment accuracy.

Key words:  Strapdown inertial navigation system (SINS), Forward-forward backtracking alignment, Error model with initial navigation frame, Initial alignment on swaying base