Calibration of a 3-axis hemispherical resonator gyro assembly

Abstract

The paper presents an approach to calibration of inertial measurement units (IMU) for space application based on hemispherical resonator gyroscopes without accelerometers on a two-axis calibration turntable. The conventional sensor instrumental errors include bias and scale factor, temperature variations of the factors above and misalignment of sensitive axes. Also, additional quantities associated with the alignment error of the IMU to the turntable are to be estimated along with the parameters of sensor error model. Traditional methods of calibration usually involve different special set of operations for every parameter to be resolved. The main idea of the proposed approach is to avoid the requirement of any rigorous complicated sequence of operations in calibration experiment, and make the calibration procedure uniform, simple and non-strict to a feasible extent. The work is primarily focused on analysis of observability in the underlying estimation problem. The approach under consideration has previously proved its efficiency for traditional 6-axis inertial measurement units of different accuracy grades in real applications. The results of our study show that for a 3-axis gyro assembly all desired quantities, including conventional sensor error parameters, temperature variation coefficients and misalignment between turntable and sensor assembly, can be estimated simultaneously in one simple calibration experiment.