Study On The Outfield Calibration Technique For Laser Gyro Inertial Navigation System Of Missile Launching Vehicle

Laser gyro strapdown inertial navigation system (RLG-SINS) is suitable for dynamic circumstance and has good reliability, good anti-impact capability and high performance price ratio etc. In recent years,RLG-SINS is being widely used in many military applications.The inertial sensors in RLG-SINS include bias, scale factor error and installing error that can cause a very large effect on navigation accuracy. These errors can significantly be compensated by using calibration methods performed in laboratories with a high-precision turntable. However, after using for a long time some errors of RLG-SINS will deviate from the values calibrated in the laboratories. In order to make RLG-SINS have long-term stability and avoid dismounting RLG-SINS, these errors should be determined in the outfield condition before every mission.The outfield calibration method studied in this thesis is aimed at the missile launching vehicle. The missile launching vehicle is not able to maneuver freely in the condition of loading bomb. In static condition, the pitch angle and roll angle of the missile launching vehicle are no more than 10 . So performing of the outfield calibration and the position arrangements are restricted. In view of the features of missile launching vehicle above, the outfield calibration method of missile launching vehicle is performed on the basis of multi-position alignment to calibrate the most significant errors. This method does not require three-axis turntable or external instruments, and will be easy operation, less costly and, most importantly, can be applied in the field directly.First, the unstable errors of RLG-SINS are analyzed and a simplified RLG-SINS error model in outfield condition is established, then position arrangements are designed for outfield calibration of the missile launching vehicle, and the observability and observable degrees of RLG-SINS in different position arrangements are analyzed on the basis of Piece Wise Constant System (PWCS) theory and the singular value decomposition (SVD) theory. The influences different position arrangements and the changes of attitude angles have on the Kalman filter results are simulated. In order to analyze the efficiency of the outfield calibration method, real tests have been carried out to calibrate gyro drift and horizontal accelerometer bias and scale factor error. Gyro drift and horizontal accelerometer bias can be estimated by Kalman filter with good performance. But the horizontal accelerometer scale factor error can be estimated only when they deviate from the values calibrated in the laboratories significantly. The test results indicate that the outfield calibration method can calibrate the most significant RLG-SINS errors and improve the precision of RLG-SINS after error compensation.