A swing online calibration method of ship-based FOG-IMU

The system error parameters of fiber optic gyroscope inertial measurement unit (FOG-IMU) may change due to various disturbances, especially when the ship is in long-term sailing. Therefore, the independent online calibration is particularly important. In this paper, a swing online calibration method is designed, making full use of the swing motion caused by the waves on the sea, and the system parameters of the inertial device are calibrated in real time. First, the model of the inertial device is established. Then the Kalman filter based state equation and observation equation are determined. Finally, system error parameters are estimated and compensated according to the ship swing calibration path. The calibration errors are updated as well. At this time, the system parameters can be calibrated and iterated repeatedly. So the filter updates the data once again to improve the navigation accuracy, which makes it possible to recalibrate the FOG-IMU without disassembling the inertial device.