A Microactuation and Sensing Platform With Active Lockdown for In Situ Calibration of Scale Factor Drifts in Dual-Axis Gyroscopes

This paper presents the design and experimental results of a microvibratory actuation and sensing platform to provide on-chip physical stimulus for in situ calibration of long-term scale factor drifts in multiaxis microelectromechanical systems (MEMS) inertial sensors. The platform consists of a three degrees-of-freedom micromotion stage that can provide piezoelectric actuation for X/Y-tilting reference stimuli, compensation of undesired off-axis motion, integrated sensing of applied periodic stimulus, and electrostatic position lock-down for shock protection. A dual-axis MEMS gyroscope is mounted on top of the microplatform, and its electrical interconnects are provided through microfabricated highly flexible parylene cables with virtually zero-loading. The piezoelectric stage is measured to provide up to 280°/s angular ac excitation to a 25-mg inertial sensor payload at an expense of <;100 μW, while providing an analog sensing signal (11 mV/°/s) to determine the applied rate with a precision of 1.2 °/s. The estimated scale factor has <; 0.8% deviation from rate-table characterized values on the same-model gyroscope samples. With further improvements in control precision and angular velocity estimation, the introduced platform is expected enable on-chip self-calibration of long-term scale-factor drifts to <; 100 ppm.