Error Analysis And Measurement Technology For Hemispherical Resonator Gyro

Hemispherical Resonator Gyro (HRG) is a kind of Coriolis vibration gyroscope, it is a promising sensitive device used in SINS which is fixed on aeronautics and aerospace flying vehicle, it has the features of longevity and high-precision which is the trend of gyros'development. HRG has a wide application in military arms, aeronautics, and aerospace fields etc, especially in the field of deep space exploring because of its structural characteristics and outstanding specifications, so it is the optimum option for gyroscopes which will be used in environment satellites, communications satellites, lunar probe astronomical telescopes and deep space exploring etc.The structure and the advantages of HRG over other kinds of gyro were presented; practical application examples of HRG in space tasks were introduced. The domestic and foreign research history, present research status, and development trend of HRG were summarized. Research on the error models, the identification methods and the calibration methods of HRG was conducted.Firstly, under the Kirchhoff-Lyav hypothesis, the strains and stress of an arbitrary point on mean camber of the hemispherical resonator were deduced by means of theory of curved surface. After that the strains and stress of a point whose normal displacement to the mean camber is known, is calculated, through integrating these strains stress, the forces and torques on the micro unit of hemispherical thin shell were computed, thus the force and torque equilibrium equations were established, which lay a foundation for the dynamics analysis of hemispherical resonator.Secondly, supposed the HRG to be subjected to 3-D angular velocity and 3-D angular acceleration, the dynamics equations of hemispherical resonator were achieved by the force equilibrium equations and the Bubonov-Galerkin method which resolved the differential equations, so the dynamic error model of HRG was established. The error models concerned with the specific force and the angular velocity were introduced at meantime. The influence of resonator's thickness nonuniformity on the gyro's accuracy was analyzed. The resonator's mass nonuniformity on the the gyro's accuracy was also analyzed while the gyro was subject to the linear vibration environment.Thirdly, the elementary parameters including scale factor, bias, linearity, asymmetry of the scale factor, threshold, etc. were measured using a two-axis turntable. The method for identifying the static error model coefficients was designed; the error model concerned with specific force was identified using pole-axis tumble test method on a two-axis turntable. The single-axis angular velocity and two-axis angular position method, namely the outer axis was in the uniform velocity state, while the middle axis and the inner axis were in the angular position state, was designed for identifying the error model coefficients about the angular velocity. The composite test plan on double spheres, that is the outer axis of the three-axis turntable is exerted two different angular velocities, was discussed to solve the rank descending problem of the information matrix. The dual-axis velocity and single-axis test plan, that is the outer axis and the middle axis were in the uniform angular velocity state while the inner axis was in the angular position state, was designed for identifying the dynamic error model coefficients. The three-axis uniform angular velocity test plan, that is the three axes of the turntable were in the velocity state simultaneously, was put forward for identifying the dynamic error model coefficients. The optimum velocity ratios of middle axis and inner axis were designed. By way of these methods, the sequential measurement method for identifying the different error model coefficients can be realized on the three-axis turntable through one-time mounting of the gyro.Finally, aiming at the stochastic noise features of HRG, Allan variance analysis was used for identifying the zero-drift features of HRG. The schemes including sampling the outputs of different HRGs at the same sampling frequency, sampling the outputs of the same HRG at the different sampling frequencies were designed for measuring Allan variance coefficients of domestic HRGs. The power density spectrum analysis was applied in the outputs of the HRGs, it is proved that the Allan variance can evaluate the static accuracy of HRG. The specifications for the random error was analyzed aiming at HRGs manufactured at different periods, the shortcomings of HRGs were determined, the contrast of the random error coefficients was made. It is proved that the accuracy of HRGs was enhanced greatly, but the manufacturing technology and craft need to be raised further.