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Due to restrictive tolerancing in microfabrication, structural imperfections that reduce performance of fabricated micro devices are typical. In microelectromechanical vibratory gyroscopes, feedback control is a common strategy in attempting to correct the imperfections. However, a purely feedback control can be insufficient for compensation of all the errors, requiring post processing in the form of laser trimming to achieve higher levels of performance. In this paper, we explore another alternative: the design and implementation of a dual stage control architecture with self-calibration and feedback capabilities. The self-calibrative portion of the control identifies and electronically "trims" large imperfections, while the feedback control compensates for remaining small nonidealities and in-operation perturbations. Presented here is an algorithm for in-situ imperfection identification based on the dynamic response of the device. A realization of the dual stage control architecture is proposed for a gyroscope using nonlinear electrostatic parallel plate actuators. Modeling and simulation results which demonstrate successful compensation of imperfections with the proposed architecture for a device with 10% fabrication error appearing in the form of stiffness nonidealities and subjected to further 1% in-run perturbations are presented.Index Terms-Error suppression, microelectromechanical systems (MEMS), rate integrating gyroscopes, smart MEMS.

This paper reports the experimental analysis of commercially available variable-capacitance MEMS accelerometers, characterized under standardized tests. Capacitive MEMS sensors of the same low-level input acceleration range with various mechanical sensing element designs, materials, fabrication technologies and price ranges were selected for evaluation. The selected sensors were characterized using ANSI and NIST certified testing equipment and under the same testing conditions; and their sensitivity, resolution, linearity, frequency response, transverse sensitivity, temperature response, noise level and long-term stability were tested and compared. The experimental results are then interpreted to provide an insight to advantages and disadvantages for using a particular mechanical design, fabrication technology, sensor material and the techniques for electronics integration and packaging of each specific sensor design.

We present a long-term bias drift compensation algorithm for high quality factor (Q-factor) MEMS rate gyroscopes using real-time temperature self-sensing. This approach takes advantage of linear temperature dependence of the drive-mode resonant frequency for self-compensation of temperature-induced output drifts. The approach was validated using a vacuum packaged silicon Quadruple Mass Gyroscope (QMG), with signal-to-noise ratio (SNR) enhanced by isotopic Q-factors of 1.2 million. Owing to the high Q-factors, measured frequency resolution of 0.01 ppm provided a temperature self-sensing precision of 0.0004 • C, on par with the state-of-the-art MEMS resonant thermometers. The real-time self-compensation yielded a total bias error of 2 • /h and a scale-factor error of 700 ppm over temperature range of 25-55 • C. The presented approach enabled repeatable long-term rate measurements required for MEMS gyrocompassing applications with a milliradian azimuth precision.