Abstract
This paper focuses on structural optimization of a Butterfly vibratory gyroscope (BFVG). An oblique suspension beam adopting polygonal cross-section is proposed in order to enhance the sensitivity and robustness. The operation principles of the BFVG are introduced. The suspension beam, which was found to be the key component, is selectively stressed. Varying cross sections of the suspension beam, including parallelogram, pentagon, hexagon, platform of pentagon, L-shaped and convex shapes are compared with each other. In particular, in order to show the advantages of the proposed polygonal cross-section, the convex cross-section is used as a reference. The influence of fabrication imperfections, which includes alignment error, silicon thickness error, etching depth error, upper width error, bottom width error and deep reactive-ion etching (DRIE) verticality error, on the oblique beam’s spindle azimuth angle of the two cross-sections is analyzed. Further, the quadrature error of two cross-sections with a fabrication defect is analyzed. The theoretical arithmetic results suggest that a polygonal cross-section beam is much more stable than a convex cross-section beam in most cases. The robustness of the fabrication imperfection is improved nine-fold and the quadrature error due to fabrication defect is reduced by 70 percent with a polygonal cross-section. It could be a better candidate for BFVG’s oblique beam, which would provide a gyroscope with good robustness and repeatability.
Highlights
A gyroscope is a sensor that measures the angular motion of a vehicle
It is important to design a strong, robust oblique beam cross-section which is flexible enough to be regulated at the spindle azimuth angle
We found that a larger spindle azimuth angle was associated with a more sensitive gyroscope
Summary
A gyroscope is a sensor that measures the angular motion of a vehicle. It is the core device in inertial navigation systems. The hexagonal oblique beam is produced using precision, time-controlled multilayer pre-buried masks This design can increase the spindle azimuth angle to reduce the mismatch between the excitation and detection frequencies. The NUDT presented a pentagon cross-section with AWE and DRIE-combined fabrication technology [33] In this design, the spindle azimuth angle of the oblique beam can be flexibly changed by adjusting the width of the etching dimension. Due to the inconsistent etching depth on both sides of the oblique beam, the internal etching occurs on the asymmetric side This will affect the spindle azimuth angle and the performance of the gyroscope. The shape of the convex cross-section beam was obtained by two DRIE process [34] This design can reduce the internal etching effect on the oblique. That can give the BFVG has stronger stability and reach the goal of optimization design
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