Research On Key Technology Of Platform Gyrocompass With Four-frequency Differential Laser Gyroscope

The platform gyrocompass system is an important kind of shipborne navigation systems, and the electromechanical gyros are widely used in classical platform gyrocompass systems. Considering the substaintial characteristics and excellent performance of the RLG (Ring Laser Gyro), the possible ways and methods, applying RLGs in a platform gyrocompass system, are researched and discussed in this dissertation, the navigation and control models of the platform gyrocompass system based on four-mode differential laser gyro are established, a simplified dual axis experimental platform gyrocompass system is designed and developed, simulation analyses and related experiments are carried out to research the azimuth loop and horizontal loop. The main work and innovations of this dissertation are as follows:1. The applicability using RLGs in a platform gyrocompass system is discussed and studied. Based on theoretical analyses, experimental tests, and simulation with experimental data, the feasibility using RLGs in a platform gyrocompass system is verified, and the influence of RLGs'drift on the platform gyrocompass's accuracy is summarized.2. The servocontrol and navigation theoretical models of the four-mode differential laser gyro platform gyrocompass system are studied and developed. The correction and stabilization of four-frequency differential RLG platform are realized by the servocontrol system, whose stabilization reference is digital.3. A simplified dual axis four-mode differential laser gyro experimental platform gyrocompass system is designed and developed. By properly setting the sensors, the platform gyrocompass system can work at the azimuth loop state and horizontal loop state independently, which verified the gyrocompass's north finder and plumb line stabilization capability.4. The key technologies and control parameters of the RLG platform gyrocompass system are specially studied. Some problems caused by the grating angular encoder are hurdled; the electric parameters and frictional characteristic are tested; the transfer functions of the control system are identified; and a rate-position double loops platform stabilization control system is designed as well.5. The calibration methods of the RLG platform gyrocompass are investigated. Based on the separate calibration thought, the calibration reference and sensor error models are presented. The self-calibration is realized by rotating the platform system with its own axes, by which RLGs and accelerometers'scale-factor errors, bias errors and installation error can be calibrated, and the verticality degree between the two rotating axes are identified as well.6. System experiments and simulation analyses are carried out. The servocontrol system's static and dynamic experiments, the static experiments of azimuth loop and horizontal loop are completed, the influence of RLGs'drift on the platform system's performance accuracy is simulated using the experimental data. The experiment results coincide with the theoretical analyses, which verified the servocontrol, control and navigation theoretics'correctness in four-frequency RLG platform gyrocompass.