Digital Control Technology For Force To Rebalance Mode Hemispherical Resonator Gyro

The hemispherical resonator gyro (abbreviated as HRG) is a vibrating inertial instrument which works on the Coriolis Effect. It plays an important role in the civil and military areas for its several advantages such as high precision, high reliability, and longevity and so on. Presently, analog circuit is a major way of implementation for the measure and control of HRG, which has many inheret disadvantages. This paper focuses on digital method, the digital control key technology is studied, the digital control loop for force to rebalance mode HRG is designed. Based on the correlation between the temperature and the natural frequency, the HRG's temperature drift is compensated.The main works and innovation points are as follows:1. HRG's digital control circuit which contains amplitude-control loop, reference phase loop, quadrature-control loop and rate loop is implemented based on FPGA platform. After the implemention, the performance of the four control loops is tested.2. Aiming at reference phase loop, the frequency characteristic of HRG is analyzed, and the control project by the phase-locked loop is designed. Then the problem that the input and output signal of HRG has different frequency is solved.3. Aiming at amplitude-control loop, the oscillating process of the resonator in force to rebalance mode is studied. Based on the studied results, the theory is deduced and the control project of the amplitude-control loop is designed. Then the amplitude of the resonator is kept constant.4. Aiming at quadrature-control loop, the model of HRG's quadrature drift is built up. Based on the model, the phase error of the 0-degree and 45-degree vibration signals are employed as the error signal for quadrature control loop. Then the frequency split of the resonator is eliminated, the quadrature drift is reduced.5. Aiming at rate loop, the principle of the resonator's pocession is analyzed, the equation between the vibration's position and the force is deduced, and the problem that the vibration will be process because of the rotating carrier is solved.6. The influence of temperature effort on HRG's control circuit is analyzed and the temperature compensation method of HRG is studied. Aiming at the problem of HRG's temperature measurement, the method of getting temperature by measuring the resonator's frequency is designed. Based on the method, the temperature drift model of HRG is built up to compensate the temperature drift. Experiment proves that after temperature compensation, the temperature drift has fall to 30% of the before when the temperature change from -10 centigrade to 40 centigrade, the temperature drift is suppressed and the HRG precision is increased.