Frequency split suppression of fused silica micro shell resonator based on rotating forming process

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TECHNICAL PAPER

Frequency split suppression of fused silica micro shell resonator based on rotating forming process Bin Li1 • Xiang Xi1 • Kun Lu1 • Yan Shi1 • Dingbang Xiao1 • Xuezhong Wu1 Received: 2 June 2020 / Accepted: 5 September 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract This paper demonstrates the impact of harmonic error on the natural frequency of micro shell resonator (MSR). Parameterized 3D model is established to analyze the frequency split of resonator with deviation along the circumferential and height direction. Both the n = 1 tilt mode and n = 2 wineglass modes are considered. The simulation results show that frequency split significantly increases as the growth of the 2nd and 4th harmonic errors. At the same time, the influence of frequency split on MSR output is analyzed. The increasing of frequency split will lead to the increasing of quadrature error and decreasing of mechanical sensitivity. The uniformity of the temperature field during processing is considered, a rotary platform is used to reduce the harmonic error of the resonator by improving symmetry of the shell structure. After measurement, the error of 2nd harmonic and 4th harmonic errors have been suppressed by using rotating platform. Finally, more than 10 samples are electrostatically characterized and well matched with the simulation results, the initial frequency symmetry of n = 1 and n = 2 modes is greatly promoted.

1 Introduction Vibration MEMS gyroscope is a kind of MEMS gyroscope with the best development prospect and the widespread application. In recent years, manufacturing high performance vibratory MEMS gyroscope through material and structural innovation is becoming a development trend. At present, micro hemispherical resonator gyroscope (MHRG) and disk MEMS vibrating gyroscope are the new vibratory MEMS gyroscopes with the most development potentials and many reports (Cho et al. 2014; Challoner et al. 2014; Ahn et al. 2014). Disk MEMS vibrating gyroscopes are limited to single crystal silicon as a material, and with the advancement of non-silicon which is based on 3D micromechanical manufacturing technology, MHRG have more preponderance in terms of potential performance. MHRG have the advantages of small size, low cost and high accuracy. Benefiting from the advancement of 3D micro-machining technology, the performance of fused silica (FS) micro hemispherical resonator gyroscopes (MHRG) has rapidly improved in recent years. The MHRG & Xiang Xi [email protected] 1

College of Intelligence Science and Engineering, National University of Defense Technology, Changsha, China

prototype developed by University of Michigan has a bias instability of 0.0103°/h, which is close to navigation-level precision (Cho et al. 2019). To achieve mode-matching and high quality factor of a hemispherical gyroscope, geometric uniformity and symmetry in combination with low thermoelastic damping structural material are critical. At present, three relatively mature micr