| This Ph.D. dissertation reports novel structural design implementations for micromachined gyroscopes that provide inherent robustness against structural and environmental parameter variations. The emphasis is on investigating the paradigm of shifting the complexity from the control electronics to the structural design of gyroscope dynamical system. The general approach pursued in this dissertation is to explore the possibility of achieving wide-bandwidth frequency responses in the drive and sense-modes of the vibratory gyroscopes. Toward this goal, two major design concepts were investigated: expanding the dynamic system design space by increasing the degree-of-freedom of the drive and sense mode oscillatory system, and utilizing an array of drive-mode oscillators with incrementally spaced resonant frequencies.; In particular, three design concepts have been implemented and experimentally verified: utilizing 2-DOF oscillator in the drive-mode. 2-DOF oscillator in the sense mode, and multiple drive-mode oscillators. The prototype gyroscopes employing the explored wide-bandwidth design concepts were fabricated using a bulk-micromachining process developed in this thesis. A measured noise floor of 0.640/s/ Hz was demonstrated at 50Hz bandwidth, in atmospheric pressure. The sense-mode response in the wide-bandwidth operating region was experimentally demonstrated to be inherently insensitive to pressure, temperature and DC bias variations. Rate table characterization at 25°C and 75°C showed only 1.62% change in the sensitivity without active control, verifying the improved robustness of the design concept.; The results of this work introduce and demonstrate a new paradigm in MEMS gyroscope design, where disturbance-rejection capability is achieved by the mechanical system instead of active control and compensation strategies. The micromachined gyroscopes of this class could potentially yield reliable, robust and high performance angular-rate measurements leading to a wide range of applications including dynamic vehicle control, automotive safety systems, navigation/guidance systems, and interactive consumer electronics. |
