Fiber Strapdown Inertial Navigation System Modeling And Parameter Identification Technology

With the development of the fiber optic gyro(FOG)and its relevant technologies,the fiber optical gyro strap-down inertial navigation system(FOG-SINS),of which core component is FOG,is more and more widely used in various areas such as aviation,spaceflight,ocean navigation,and civil applications.Parameter identification means calculating the parameters of error model of the inertial device.The accuracy of the parameters recognition would affect the precision of the inertial system directly.So it is necessary to research the methods of precise parameters identification of the FOG-SINS for improving the system accuracy.Based on the FOG-SINS,this paper discusses the parameter identification technology from two aspects of device level and system level.The identification schemes will be designed,and the related experiments will be conducted.The results of experiments will be compared and analyzed.Firstly,the paper introduces the development status of FOG-SINS and the basic principles of FOG and quartz accelerometer,presentes some basic knowledge of strap-down inertial navigation system(SINS)and relates mathematical foundations.This part provides theory support for the model establishment and parameter identification in the following sections.Secondly,the discrete parameter identification section analyzes the error model of FOG and accelerometer,presentes the identification schemes of the positive and negative turn rate method and the 24 positions method,analyzes the effect of turntable accuracy on parameter identification.Thirdly,the positions parameter identification section introduced two methods of parameter identification technology: four positions method and module method.Based on the two methods,corresponding position arrangement designs and experiments will be completed to identify the parameters.By comparing and analyzing the identification results,paper discusses the merits and demerits of the two methods.Finally,based on the error equation of the SINS,two methods of system level drift measurement,the least square method and the Kalman-filter estimate,will be introduced to estimate the gyro random constant drift and accelerometer zero offset error in static navigation state.With the least squares method,the output residuals of the navigation information under the static state were used to identify the system drift.The system drift were estimated by the designed the Kalman filter.Using the estimated drift to correct gyro bias and accelerometer zero offset caused by the turning on error each time and some other drift sources,the experimental results shown that the shift measurement and compensation provided a feasible method for improve the system precision.