Architecture of torsional gyroscope having robust sense mode

Abstract

An architecture of a torsional gyroscope having robust sense mode is reported. The robustness is achieved by utilizing dynamic amplification of torsional oscillations in the sense oscillator. The frequency response of the sense oscillator, which essentially is a 2-degree-of-freedom (DOF) one, has two resonance peaks and a flat region between the peaks, where the amplitude is less sensitive to ambient damping resulting in the robust sense mode. The frequency response of the 1-DOF drive oscillator has one resonance peak, which is designed to fall within the flat region of the sense amplitude. This helps in reducing the effects of change in the geometry and material properties of the device, induced by inevitable fabrication imperfections, on the device performance. The device is modeled by deriving the equations for electrostatic moment, moments of inertia, and spring constants. The design concepts of antiresonance and zero-phase frequency, along with analytical expressions for resonance frequencies and 3-dB bandwidth are also presented. The design is then realized using an SU-8 based ultraviolet-lithographie, galvanoformung, abformung (UV-LIGA) process having 8-μm thick Ni–Fe as the key structural layer. A characterization technique is developed to extract the frequency response of the fabricated device.