Research On Dual-axis Rotating Inertial Navigation System On-line Calibration Technique

With the use of the indexing mechanism,which makes inertial navigation system rotated regularly,the effects of the inertial navigation devices on the navigation system can be significantly decreased or restrained by its periodic rotation-modulation.Moreover,the navigation accuracy and working hours of the rotating inertial navigation system can be improved greatly without increasing the accuracy of the inertial navigation devices.Thus a rapid development has occurred in the fields of the investigation of the rotating inertial navigation system.Using the dual-axis turntable carried by rotating inertial navigation system,system can be calibrated without horizontal reference or azimuth reference in carrier,no matter the carrier is Static or moved.Because of avoiding gyro being disassembled and carried to test site for calibration,lots of considerable manpower and material resources can be saved.This paper is mainly focused on the investigation of the calibration process of dual-axis turntable and the research work can be listed as follows:1.The device errors of the gyro and accelerometer are introduced in the paper and the relevant error models are also established for the purpose of analysis.Based on the dual-axis rotating SINS error equation and device error model,in particular,the relationship between the attitude error,velocity error and position error of the SINS and the device bias,scale factors and installation errors are deeply analyzed and simulated in the paper.2.At present,the discrete calibrate technique,which holds the advantages of adequate research background and flexibility for error modeling,has been widely applied as the calibrate method in the laboratory environment.However,the accuracy of the discrete calibrate is dependent on the testing equipment,especially the turntable that affects the navigation accuracy directly,which brings much more errors into the calibration results of the dual-axis turntable with low accuracy.By dual-axis turntable,this paper will make the system stop in different six positions to calibrate accelerometer' error and analyze the relationship between turntable error and the residual error of the calibration result.3.Therefore,this paper makes a comprehensive investigation on the calibration techniques at the system level.The principle of systematic calibration method is to deduce the device errors utilizing the navigation errors.For details,the relationship between navigation errors and device errors is established at first,and then the calibration results can be obtained by filter method or other methods.Thus it cuts down the dependences of calibration results on the high accuracy turntable.With the system turned 18-times to cause device error by dual-axis turntable,this paper will adopt fitting method of systematic calibration to get the error of gyro under the static base condition.4.The global observability analysis method holds the function that it can make a prejudgment for the estimate results of the state vector before the filter period just like other common observability analysis methods.What's more,the linearization of the system equation can be avoided in the global observability analysis method,which comprehensively reflects the particular situations inside the system.As a result,this paper utilizes the global observability analysis method to solve the calibration problem of a single axial optical gyro with a dual-axis turntable.Consequently,the changes of the observability of the navigation system are analyzed when the optical gyro rotates around the dual-axis turntable,and then by the principle which can get as more as gyro error by using little time the rotation scheme is established to solve the practical problems.