Measurement Method And Error Mechanism Analysis Of Hemisphrical Resonator Gyro

Hemispherical resonator gyro (HRG) has a wide application prospect in fields of satellite, submarine etc, which has the features of long life span, high reliability，small volume, light weight, high precision and being miniaturized. Studying hemispherical resonator gyro, improving the manufacturing process level and its application performance, are of great theoretical significance and practical value. This dissertation took a pre-research project as the background, and researched on the issues of model nonlinearity existing in HRG, error mechanisms of the system error affecting the accuracy of gyroscope, the identification of stochastic errors, the influence of three-axis turntable error on the calibrating error, test methods of measuring the specifications for HRG and identification methods of error model coefficients.Based on the review of Coriolis Vibratory Gyro, the domestic and foreign research and application situations of hemispherical resonator gyros which are developed by now were introduced. The stochastic error and systematic error sources of the hemispherical resonator gyro, error models, error analysis, and identification methods were reviewed. The significance of improving the hemispherical resonator gyro precision was pointed out.In order to fully reflect the impact of various error sources and the relationship among them, the hemispherical thin shell was simplified as a ring-shaped resonator, and the displacement and strain, stress relationships were given according to the Kirchhoff-Lyav hypothesis. The dynamic model of the ring-shaped resonator was derived according to the energy conservation principle and mechanical analysis. And the influence of the square term of angular rate and angluar acceleration was analyzed under both the parametric excitation and the positional excitation modes, respectively. The influence of parameter inconsistency on the solution accuracy was analyzed under both the parametric excitation and the positional excitation modes by using this linear model.Researches on the errors of resonator and error mechanisms that have influences on the accuracy of HRG were conducted. Two error sources were studied, namely the nonuniformity of resonator’s radius and the nonuniformity of quality factor. By calculating the effect on the standing wave drift rate from non-uniformity of radius and quality factor of HRG, the impact on the drift rate of HRG from the anisoelasticity and damping non-uniformity was given. According to the dynamic equations of hemispherical resonator, splitting of hemispherical resonator was derived which was caused by fourth harmonic of radius’ nonuniformity leading to the drift of gyro’s bias, it is also demonstrated that the fourth harmonic of radius’ nonuniformity leads to the anisoelasticity and damping non-uniformity simultaneously; while Q-factor’s nonuniformity only leads to the damping non-uniformity.Researches on the installing errors and error mechanisms that have influences on the accuracy of HRG were conducted, the misalignment of electrodes and displacement sensors, and the installing errors of resonator’s stead bar when the specific force existed, were studied. Gyro’s nonlinear output was caused by the misalignment of electrodes and displacement sensors, leading to the errors concerned with the square angular rate term and the cubic angular rate term, which were proved in experiment, at the same time bringing out scale factor and bias error. Because of the stiffness of resonator’s stead bar, existence of specific force brought out the misalignment error, leading to bias error. Tolerances towards part of error source that meet the accuracy of gyro were given. Finally the corresponding suppression method concerned with the related error sources was put forward.The problem about measurement methods of specification for HRG, was studied. Measurement method of misalignment angles was designed, turntable’s mouting errors, fixture error and misalignment errors were separated from one another, and the misalignment error was measured. The method of measuring the specifications concerned with the Q-factor was designed, the decay time was measured by making electrodes from the steady state to the power cut. The measurement method of hemispherical resonator gyro’s bandwidth was designed by using the uniform angular rate function of two axes of three-axis turntable. Measurement and identification method of frequency splitting and inherent rigidity shaft using two group of electrodes and displacement sensors was designed, and the optimal sample time was given too.Aimed at the problem of the identification methods of error model coefficients of HRG, some researches were done. The multiple-position test method based on D-optimal was designed. The method of calibrating the error model coefficients of HRG on the three-axis turntable was designed and the influence of three axis turntable error on the identification errors of hemispherical resonator gyro’s model coefficients was analyzed. Allan variance method was applied in determining the main components and error parameters of random error noise of hemispherical resonator gyro’s drift data. Measurement methods of specifications and identification methods of error model coefficients lay a foundation for precisional measurement of HRG and enhancing the accuracy of HRG.