AxFEM

Fast simulation of near-axisymmetric resonant MEMS

• BitBucket
• Tutorials

Summary

AxFEM is a semi-analytic finite element code designed to simulate axisymmetric and nearly-axisymmetric vibrating structures, with a special emphasis on micro-scale solid-wave gyroscopes. It was written by Erdal Yilmaz (Ph.D., 2016) and myself. Our work was motivated by analysis of micro-scale versions of the Hemispherical Resonator Gyro (HRG) developed under the DARPA MRIG program and successors, which had the goal of producing micro-machined versions of vibrating structure. Our goal was to understand what aspects of the design and fabrication process would make such sensors most resistant to damping, drift, and other infelicities.

While micro-machined solid wave gyroscopes promise cost savings of several orders of magnitude over their conventional counterparts, typical MEMS processing leads to significantly larger variations in fabricated devices than one sees in standard HRGs. Fortunately, these variations are not completely arbitrary, but have structure inherited from the nature of the fabrication steps. Part of our goal with AxFEM was to provide detailed understanding of how breaking the idealized axisymmetric shape of the devices due to fabrication variation would affect the ultimate performance of the device. Performing such computational studies with fully-resolved three-dimensional finite elements is prohibitively expensive, so combine an analytic group-theoretic approach with finite element analysis to obtain an accurate “2.5d” simulation framework. Our results provided not only predictions of the quality factors, gain factors, and design sensitivity of several devices, but also a better understanding of the qualitative features of different fabrication errors that would lead to performance issues in devices.

Links

• White paper on HRGs
• YouTube video describing HRGs

Papers

@article{2016-sensors,
  author = {Yilmaz, Erdal and Bindel, David},
  title = {Temperature Sensitivity and Shape Optimization of
             Solid-State Wave Gyroscopes},
  journal = {IEEE Sensors},
  volume = {16},
  number = {6},
  pages = {6213--6221},
  year = {2016},
  doi = {10.1109/JSEN.2016.2580670}
}

@inproceedings{2016-hh-workshop,
  author = {Yilmaz, Erdal and Bindel, David},
  booktitle = {Proceedings of the Hilton Head Solid-Sate Sensor and
                 Actuator Workshop 2016},
  title = {Temperature Sensitivity of Solid-Wave Gyroscopes (Late News)},
  month = jun,
  year = {2016}
}

@inproceedings{2013-sensors,
  author = {Yilmaz, Erdal and Bindel, David},
  title = {Effects of imperfections on solid-wave gyroscope dynamics},
  booktitle = {Proceedings of IEEE SENSORS 2013},
  month = nov,
  year = {2013},
  doi = {10.1109/ICSENS.2013.6688462}
}

Talks