A fast alignment method for SINS with large misalignment angles based on ADRC

Alignment accuracy and alignment time are two important indexes of the initial alignment procedure of a strapdown inertial navigation system (SINS). However, large misalignment angles will bring nonlinear problems of SINS error models and prolong the convergence time of the initial alignment procedure. In this paper, an innovative control scheme is proposed for the initial alignment of SINS on stationary base, which is implemented by active disturbance rejection control (ADRC). Compared with the conventional compass method, the proposed method has a lower requirement on high accuracy of the coarse alignment. Therefore, the total alignment time is decreased, meanwhile the interferences caused by the system errors are decreased and the stability of the closed-loop system is enhanced. Simulations and experiments show that the alignment procedure has been greatly hastened and the accuracy has been improved.