Mechanically Dithered Laser Gyro Strapdown Inertial Navigation System Calibration Method

Laser gyro strapdown inertial navigation system (LSINS) has been an important development direction in recent years which is fit for high dynamic circumstance and low cost , good reliability, high capability etc. Most of the currentely manufactured ring-laser gyros undergo dithering motion.Calibration, aliagnment, state initialization and the calculation of current state are the 4 phases of the inertial navigation. Differentiating and analysing the inertial instrument(gyro and accelerometer) error models and compensating by software is efficacious to improve the accuracy of navigation.In these paper, the error models of laser gyros and accelerometers are studied. The mechanical dithering of laser gyro bring the error in the output of the accelerometer and gyro. The principle and characteristic of the error is analyzed in the paper. Removing the dither-error is necessary to improve the calibration precision.The continuous automatic calibration technology is a new way to calibrate the strapdown inertial navigation system, which uses the high accuracy three-axis turntable to calibrate the errors of gyros and accelerometers. It has the advantages such as high accuracy, high efficiency, flexibility of the calibration trajectory. The result of kalman filtering and compensation indicate that the system precision has been improved. At the same time, turning off gyro ang running gyro to calibrate the accelerometer gained the same result.