The Research Of SINS Damping And Gravity Aid Technology

The inertial measurement devices of SINS are attached to the vehicle directly,which make the system remove the complex mechanical structure of the stable platform.Therefore,SINS has the advantage of small volume,light weight,simple structure and so on.However,the system error cycle oscillation and longitude errors increasing with time of INS still exist in SINS.In order to eliminate system error cycle oscillation phenomena of SINS,the usual practice is to add damping network in SINS.However,there is an adjustment time for the damping system to reach a steady state.During the adjustment time,the system exists overshoot phenomenon,which affect the system performance seriously.In order to shorten the adjustment time of the system,and make the system reach the steady state quickly,this article will introduce the backward calculation which forms round-robin algorithm with the forward calculation into the damping strapdown inertial navigation system.Simulation results certificate that after the introduction of round-robin algorithm the adjustment time of the damping system has been greatly reduced.Meanwhile,in order to avoid the position error accumulation during the process of round-robin algorithm,this article also propose an improved algorithm,that is to correct velocity and position at the initial time of each forward calculate process,so as to achieve the purpose of further reducing the system position error.For the oscillation phenomenon of the system error in SINS,this article make use of modern control and estimate theory Kalman filter to achieve damping effect of traditional damping.In this article,the system error of SINS is estimated by the Kalman filtering and then correct the system through pulse using the estimated system error,so as to eliminate the system error periodic oscillation existing in SINS.Meanwhile,for the small amplitude oscillation caused by the rudimental system error after the pulse correction,this article further add the damping network after the pulse correction to improve the system accuracy.For the longitude error divergence over time of SINS,and under the condition of does not destroy the autonomy and disguised of SINS,this article use the Earth's characteristics-gravity anomaly to aid SINS,which can make the system achieve the purposes of restraining the longitude error divergence over time.Since gravity aided navigation and terrain-aided navigation system has great similarities,this article design the SITAN algorithm this is suitable for gravity aided navigation firstly.Then,for the periodic oscillations problem existing in state equation of the gravity aided SINS,this article design an scheme adding damping network to the gravity aided SINS,and re-establish the state equation and measurement equation.Simulation results certificate that the gravity aided damping SINS can greatly improve the accuracy of the system.After that,for the problem of nonlinear and linear error existing in the gravity aided SINS,this article design an nonlinear Bayesian filter based FPKE equation,and establish the state equation,measurement equation and FPKE equation of the state probability density function of the gravity aided strapdown inertial navigation system.