A.A. Levitskiy, P.S. Marinushkin

Piezoelectric gyroscopes are low-cost, low power consuming and relatively small. They find applications in game consoles, image stabilization in cameras and inertial navigation systems. However technological imperfections, which are always present during the fabrication process of piezoelectric gyroscope reduce the measurement accuracy. Such technological imperfections include deviations from the ideal mass, stiffness and damping distributions. Resonators with imperfections show splitting of natural frequencies, location of the two mode shapes and different damping factors associated with each vibration mode. Another reason for the errors of piezoelectric gyroscopes is the presence of temperature-induced errors due to the temperature sensitivity of mechanical and electrical material properties of piezoelectric ceramics. The change of material properties leads to imbalance and a change in the dynamic characteristics of the gyroscope resonator. This article is devoted to the study of the temperature-induced errors in previously reported tubular piezoelectric gyroscope. To evaluate the effect of temperature-induced errors on the output signal of the gyroscope, the finite elements method in three-dimensional formulation was used. Practical implementation of the method is executed using ANSYS environment. The analysis procedure was carried out in two steps. The first step is a static solution of the thermoelastic deformation problem. Second step include prestressed modal analysis. The transient analysis was also performed to calculate the trajectories of the gyroscope resonator motion. It was concluded that the wall thickness variation, leads to imbalance of the resonator. Thus, the displacement along the Y axis of the resonator under the influence of the Coriolis force is distorted by the projection of the drive on the same axis, which leads to an error in the measurement of angular velocity. As a result, at the output of the piezoelectric vibrating gyroscope the spurious output signal in the absence of angular speed will be observed. The conclusion was drawn from the calculations that with the increase of the wall thickness error, the scale factor variation also increase. Also analysis of the obtained dependences allow to make a conclusion the scale factor variation increases as the frequency split decreases. The obtained results allow making the following conclusions that should be considered during design process. 1) Geometric heterogeneity is the source of spurious signal at the output of the gyroscope in the absence of angular velocity 2) The uniform heating of the imperfect resonator with a geometric and mass distribution inhomogeneity leads to a change of the angular position of the vibrations planes of the resonator and, consequently, an increase of the parasitic signal. 3) To reduce the thermal drift induced by these reasons, the change of vibrations planes must be suppressed using different methods. First method employs additional mechanical adjustment of the resonator (longitudinal and transversal grooves on the surface of the resonator) to eliminate geometry errors and mass imbalance. Second method utilizes mechanical trimming to introduce frequency split and, in turn to fix vibration planes. Methods for temperature stabilization and temperature compensation also can be implemented.