A Dual-Mode Actuation and Sensing Scheme for In-Run Calibration of Bias and Scale Factor Errors in Axisymmetric Resonant Gyroscopes

This paper demonstrates a dual-mode actuation and sensing scheme for differential operation and self-calibration of axisymmetric Coriolis resonant gyroscopes. The proposed scheme actuates both modes of an axisymmetric gyroscope with two identical in-phase excitation signals, and senses both modes concurrently. This dual-mode actuation architecture utilizes the difference of the individual mode outputs to cancel out the common-mode bias terms, and provide rate-independent frequency split monitoring. The symmetry of the dual-mode architecture can be utilized to provide in-run scale factor calibration capability by mimicking the mechanical Coriolis force in the electrical domain, thereby providing a virtual electrical rotation to the gyroscope, to estimate the drift of the physical scale factor over time and temperature. The dual-mode architecture is demonstrated on a 2.625-MHz substrate-decoupled bulk acoustic wave gyroscope. The inherent bias cancellation provides sub10°/hr bias instability, with 1.4× improvement of angle random walk, as compared with the conventional single-mode actuation scheme. Benefiting from the in-run mode-matching capability, the dual-mode actuation scheme exhibits 45× reduction of bias drift over a temperature range of [10-80] °C. In-run scale factor calibration achieves 150× reduction of scale factor turn-on repeatability error down to 62 ppm, and over 100× reduction of the temperature drift of scale factor over [10-50] °C.