Inherently robust micromachined gyroscopes with 2-DOF sense-mode oscillator

Commercialization of reliable vibratory micromachined gyroscopes for high-volume applications have proven to be extremely challenging, primarily due to the high sensitivity of the dynamical system response to fabrication and environmental variations. This paper reports a novel micromachined gyroscope with 2 degrees-of-freedom (DOF) sense-mode oscillator, that provides inherent robustness against structural parameter variations. The 2-DOF sense-mode oscillator provides a sense-mode frequency response with two resonant peaks and a flat region between the peaks, where the amplitude and phase of the response are insensitive to parameter fluctuations. Furthermore, the sensitivity is improved by utilizing dynamical amplification of oscillations in the 2-DOF sense-mode oscillator. Prototype gyroscopes were fabricated using a bulk-micromachining process, and the performance and robustness of the devices have been experimentally evaluated. With a 5.8mum drive-mode amplitude, the tested unit exhibited a measured noise-floor of 0.64deg/s/radic(Hz) at 50Hz bandwidth in atmospheric pressure. The sense-mode response in the flat operating region was also experimentally demonstrated to be inherently insensitive to pressure, temperature and DC bias variations