Browsing by Subject "Stress sensor"

Now showing 1 - 2 of 2

Open Access
A MEMS vibrating ring gyroscope with on-chip capacitive stress sensors for drift compensation
(2022-07) Uzunoğlu, Baha Erim
MEMS gyroscopes are commonly used for rotation measurement in navigation. Even though the noise performance of these sensors has improved in the last few decades, the long-term drift problem is still prominent for these sensors. Longterm drift error is caused by external factors such as temperature and induced stress on the MEMS chip. With this work, we present an on-chip solution for the compensation of long-term drift. Due to its compact and singular anchor morphology, a vibrating ring gyroscope design was employed. Eight bridge-type capacitive stress sensors were placed periodically at the inner section of the ring surrounding the inner anchor, which adds localized stress measurement capability to the design. Another eight stress sensors were placed at the outer section of the ring surrounding the electrodes of the device. Tensile stress was applied on a testbed, and the output of the stress sensors and the gyroscope were recorded. Then, the gyroscope was subjected to a zero rate output(ZRO) test in mismatch and matched frequency configurations. The compensated output of the device was able to reach 0.008 /h in mismatched mode and 0.003 /h in matched mode without any signs of drift. The stress and the gyroscope output were partitioned into 12 hour blocks to increase the performance of the least squares fitting algorithm. We have observed a decrease in the compensation performance due to possible nonlinear and hysteresis effects generated during the long-term operation. Finally, we were able to show that the change in temperature wasn't sufficient enough to explain the frequency change of the drive and sense modes.
Open Access
A ring gyroscope with on-chip capacitive stress compensation
(Institute of Electrical and Electronics Engineers, 2022-08-18) Uzunoğlu, Baha Erim; Erkan, Derin; Tatar, Erdinç
We present long-term stress compensation results for a 3.2mm diameter ring gyroscope integrated with 16 capacitive stress sensors for the first time in this work. A bridge-type capacitive sensor is preferred due to its compact size and temperature insensitivity for on-chip stress measurements. The ring design enables a high level of integration and stress sensor-gyroscope output correlation. We first demonstrate the stress sensor operation on a stress test-bed. The drift test for sixteen days at mismatched mode and the drift test for eight days at matched mode in room temperature reveal that the stress compensation can eliminate the gyroscope drift. The stability of the stress compensated gyroscope output can reach 0.008°/h in mismatched mode and 0.003°/h in matched mode at an averaging time of two days with no signs of long-term drift. High gyroscope stability is achieved with a partial least-squares fitting algorithm; however, we believe that stress and gyroscope output relation might be linear time-variant with possible nonlinear and hysteresis effects. Analysis of the drive and sense mode frequencies shows that only temperature cannot explain the frequency variations, and the inclusion of stress can comprehensively describe the frequency changes.