Abstract:
MEMS based inertial sensors have found many applications in recent years and demand for robust
and accurate sensors is increasing rapidly. MEMS gyroscopes in particular have found many
applications from mobile phones to navigation systems and precision robotics, also, there is a need
for highly accurate, robust and low-cost sensors. Resonant MEMS gyroscopes utilize the
phenomenon of mode matching to achieve high sensitivity but are susceptible to environmental
changes and fabrication imperfections. For achieving, the desired performance resonant
gyroscopes need error compensation circuitry. Non-resonant gyroscopes use another approach in
that they sacrifice the response sensitivity but remain accurate and robust even with drastic
environmental changes and fabrication imperfections. Non-resonant gyroscopes can be further
categorized based on the number of degree of freedoms in the operational modes and the different
transduction mechanisms used. This work proposes a multi DoF non-resonant gyroscope design
using electrostatic actuation and capacitive sensing based on the SOIMUMPs commercial
microfabrication process. The non-resonant gyroscope was found to be robust in a temperature
range of -40 to 100 C, it is also robust to fabrication imperfections and pressure changes. The
sensitivity of the gyroscope is found to be 198.9 µV/(◦/s) with a low noise of 0.00328 rad/s/√Hz.
In addition to the non-resonant gyroscope, this work also presents the design of resonant
gyroscopes with error compensation techniques to minimize the performance loss. The resonant
gyroscope has mechanical elements incorporated in the design to minimize frequency mismatch
error, scale factor error and the quadrature error. These compensation mechanisms allow the
gyroscope to maintain high performance in the presence of error source. Finally, a resonant MEMS
gyroscope utilizing the concept of mode localization is presented. The design uses a novel
technique for sensing the angular rate to achieve high resolution and is capable of measuring
angular rates in micro degree per second which is much better compared to the previously reported
designs. The design is also capable of angular rate measurement in the range of ±500 °/s.
