Characterization, Control and Compensation of MEMS Rate and Rate-Integrating Gyroscopes.

Inertial sensing has important applications in navigation, safety, and entertainment. Areas of active research include improved device structures, control schemes, tuning methods, and detection paradigms. A powerful and flexible characterization and control system built on commercial programmable hardware is especially needed for studying mode-matched gyroscopes and rate-integrated gyroscopes. A gyroscope can be operated in a mode-matched rate-mode for increased sensitivity or rate-integrating mode for greatly increased dynamic range and bandwidth, however control is challenging and the performance is sensitive to the matching of the modes. This thesis proposes a system built on open and inexpensive software-defined radio (SDR) hardware and open source software for gyroscope characterization and control. The characterization system measures ring-down of devices with damping times and automatically tunes the vibration modes from over 40 Hz mismatch to better than 100 mHz in 3 minutes. When used for rate-gyroscope operation the system provides an FPGA implementation of rate gyroscope control with amplitude, rate and quadrature closed-loop control in the SDR hardware which demonstrates 400% improvement in noise and stability over open-loop operation. The system also operates in a RIG mode with hybrid software/firmware control and demonstrates continuous operation for several hours, unlike previous systems which are limited by the gyroscope ring-down time. The hybrid mode also has a simulation module for development of advanced gyroscope control algorithms. Advanced controls proposed for RIG operation show over 1000% improvement in effective frequency and damping mismatch in simulation and 25% reduction in drift due to damping mismatch in a test RIG. By tuning the compensation, the drift can be reduced by almost 90%, with worst case drift decreased to -41 deg/s and RMS drift to -21 deg/s. Harmonic analysis of the anisotropy in a rate-integrating gyroscope measured with this control system is presented to guide development of new error models which will further improve performance.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/96121/1/jagregor_1.pd