Abstract
A new surface acoustic wave (SAW)-based rate sensor pattern incorporating metallic dot arrays was developed in this paper. Two parallel SAW delay lines with a reverse direction and an operation frequency of 80 MHz on a same X-112°Y LiTaO3 wafer are fabricated as the feedback of two SAW oscillators, and mixed oscillation frequency was used to characterize the external rotation. To enhance the Coriolis force effect acting on the SAW propagation, a copper (Cu) dot array was deposited along the SAW propagation path of the SAW devices. The approach of partial-wave analysis in layered media was referred to analyze the response mechanisms of the SAW based rate sensor, resulting in determination of the optimal design parameters. To improve the frequency stability of the oscillator, the single phase unidirectional transducers (SPUDTs) and combed transducer were used to form the SAW device to minimize the insertion loss and accomplish the single mode selection, respectively. Excellent long-term (measured in hours) frequency stability of 0.1 ppm/h was obtained. Using the rate table with high precision, the performance of the developed SAW rate sensor was evaluated experimentally; satisfactory detection sensitivity (16.7 Hz·deg·s−1) and good linearity were observed.
Highlights
There has been great interest in surface acoustic wave (SAW) rate sensors because of their many unique properties such as superior inherent shock robustness, a wide dynamic range, low cost, small size, and long working life compared to other current gyroscope types [1]
When the Coriolis force from the external rotation acts on the vibrating particles along the SAW propagation path, a pseudo running wave shifted by a quarter of a wavelength will be induced, that couples with the initial SAW generated by the interdigital transducers (IDTs), resulting in the change of trajectory of the wave particles, and the acoustic wave displacement was deviated, leading to the acoustic wave velocity shift, the so-called SAW gyroscopic effect [3]
The pre-rotated SAW propagation on X-112°Y LiTaO3 substrate considering the mass loading contribution from the copper (Cu) dots distributed in the SAW propagation path is analyzed
Summary
There has been great interest in surface acoustic wave (SAW) rate sensors (so called gyroscopes) because of their many unique properties such as superior inherent shock robustness, a wide dynamic range, low cost, small size, and long working life compared to other current gyroscope types [1]. When the Coriolis force from the external rotation acts on the vibrating particles along the SAW propagation path, a pseudo running wave shifted by a quarter of a wavelength will be induced, that couples with the initial SAW generated by the IDTs, resulting in the change of trajectory of the wave particles, and the acoustic wave displacement was deviated, leading to the acoustic wave velocity shift, the so-called SAW gyroscopic effect [3]. A SAW gyroscope with similar structure based on a Y112°X
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