On-line Calibration Technology For Shipborne Single-axis Rotating Fiber Optic Strapdown Inertial Navigation System

The fiber optic SINS that has specific performance has been widely used in the field of navigation. And the errors of its inertial measurement units (IMU), including fiber optic gyro(FOG) and accelerometer, can effect the precision of navigation directly. Before the SINS is used,the parameter of IMU is calibrated by using tri-axis turntable to finish a series of experiments in laboratory. For long time application of FOG and accelerometer in SINS, their parameter values of IMU may be different from the values identified by calibration in laboratory as time passed. For example, FOG drift and accelerometer bias are random when the system is start-up. At the same time, the scale error of FOG and accelerometer is different from the values identified by calibration. This will lead to the precision of alignment and navigation decreasing, and can't satisfy the request of high-precision navigation .Currently, we calibrate the SINS termly to improve the precision of SINS in the processing of application. Namely, we also remove the SINS from the transport and take it to laboratory to calibrate the SINS again. But this method lead to great inconvenience in the actual use and maintenance, and it really costs much. Aiming at the above circumstances, we should take measures to estimate and compensate the parameter errors of IMU during the voyage, and improve the precision of navigation. As the development of the technology of shipborne fiber optic SINS, it can satisfy the request of high-precision navigation when be used for a long time in the field of navigation.This paper is mainly about the on-line calibration technology for shipborne fiber optic strapdown inertial navigation system(SINS). The main contents of this paper are as following:1) Based on the property of the coarse alignment of single-axis rotating fiber optic strapdown inertial navigation system(SINS), the expressions relating gyro drift and accelerometer bias to misalignments are derived. And the observability methods of analytic method is used to analyze the observability of FOG drift and accelerometer bias. During the voyage, the method of Lie derivative is used to analyze the observability of the parameter errors of IMU. The ways of optimal error incentives are designed to stimulate the parameter errors completely.2) The three-position on-line calibration method that use misalignment angles to estimate gyro drift and accelerometer bias is designed. And then, the computer simulation should be designed to validate the algorithm of the three-position on-line calibration.3) The ways of optimal error incentives are designed to stimulate the parameter errors completely. And then, the strong tracking cubature Kalman filter (CKF) is used to estimate the parameter errors under the conditions of more accurate information which provided by global position system (GPS),Doppler velocity log (DVL) and star sensor. And then,the computer simulation should be designed to validate the algorithm of the on-line calibration.4) Using the Phins and shipborne single-axis rotating fiber optic SINS, the experimentations in Songhua River are designed based on the analyzing the theory of on-line calibration, proving the simulation experimentation. We introduce the processes of the experimentations in Songhua River in detail, analyze and compare the results of many experiments.