Study Of Alignment Techniques On The Strap-down Inertial Navigation System

Strap-down inertial navigation system (SINS) is a kind of advanced inertial navigation technology, which is the developing direction of inertial navigation. Due to a series of advantages of SINS, it has become a trend that SINS will take the place of platform inertial navigation system in new century. One of the key technologies of SINS is the initial alignment, whose accuracy influences on the precision of SINS, the weapons' response time and the accuracy of attack.At present, the Kalman filter is rounded and widely used filter. The main purpose of the initial alignment of SINS is to initialize the attitude matrix. Through the state space model Kalman filter estimates the initial misalignments and revises the attitude matrix.The initial alignment of SINS divides into two aspects: the quiet initial alignment and the transfer alignment.On the static base, the error model and measurement model were deduced in detail according to the basic principle of the SINS and the alignment; the observability of the system was analyzed by the PWCS theory; the system performance influenced by the inertial sensor errors was simulated and analyzed; the estimation method of the orientation error was improved and simulated to overcome the disadvantage of the one-order digital filter.On the moving base, the differential equation of velocity and attitude errors between the MINS and SINS were derived and the filter model was formed; both the velocity matching and the attitude matching methods were respectively simulated and analyzed in the condition of the constant speed and swing base; the velocity plus attitude matching method was simulated in the case of the second-order Markov model of deck deformation considered, and the results was compared with the former model.