A precise reciprocating two-position alignment method for vehicular fiber SINS

In order to accomplish a rapid precise initial alignment for vehicle fiber strapdown inertial navigation system (SINS), a reciprocating two-position alignment approach is proposed to decrease the alignment error caused by the inertial sensors´ ramp errors just after power-on. The mechanism of the stochastic ramp errors contributing to the alignment error is analyzed. The reciprocating two-position rotating scheme is presented and the aligning Kalman filter is designed and the observability is discussed. Simulation results show that the azimuth error with the proposed method could be half of that with a common two-position alignment procedure in case of ramp errors, and the estimation of the horizontal inertial sensors stochastic ramp errors can be over 40%, constant drift errors over 90%.