Abstract
The scale factor drifts and other long-term instability drifts of Micro-Electro-Mechanical System (MEMS) inertial sensors are the main contributors of the position and orientation errors in high dynamic environments. In this paper, a novel high dynamic micro vibrator, which could provide high acceleration and high angular rate rotation with integrated optical displacement detector, is proposed. Commercial MEMS inertial sensors, including 3-axis accelerometer and 6-axis inertial measurement unit which is about 3 mm * 3 mm * 1 mm with 19 mg, could be bonded on the vibration platform of the micro vibrator to perform in-situ during the self-calibration procedure. The high dynamic micro vibrator is fabricated by a fully-integrated MEMS process, including lead zirconate titanate (PZT) film deposition, PZT and electrodes patterning, and structural ion etching. The optical displacement detector, using vertical-cavity surface-emitting laser (VCSEL) and photoelectric diodes (PD), is integrated on the top of the package to measure the 6-DOF vibrating displacement with the detecting resolution of 150 nm in the range of 500 μm. The maximum out-of-plane acceleration of the z-axis vibrating platform loaded with commercial 3-axis accelerometer (H3LIS331DL) achieves above 16 g and the maximum angular velocity achieves above 720°/s when the driving voltage is ±6 V.
Highlights
The Micro-Electro-Mechanical System (MEMS)-based micro-inertial measurement unit (MEMS-IMU) can provide the multi degree-of-freedom (DOF) inertial information required for inertial positioning
The operational accuracy of micro inertial sensors is approaching the level of macro inertial sensors, the long-term drifts of zero and scale factor still limit their potential in high accuracy strategic and navigation applications, and the calibration validity duration based on traditional calibration methods is quite short [3]
This proposed platform can potentially be adapted as a universal system-in-package solution to provide precise on-chip physical reference inputs and in-situ self-calibration of scale factor drifts for multi-types and multi-structures of MEMS inertial sensors including accelerometers, gyroscopes, and other IMUs
Summary
The MEMS-based micro-inertial measurement unit (MEMS-IMU) can provide the multi degree-of-freedom (DOF) inertial information required for inertial positioning. The system architecture is simple without the need for an additional sensor section, but the detection accuracy and repeatability are not high Another method of motion detection for MEMS-IMU is based on capacitive sensing, which provides a threshold point with very high precision in the case of skillfully imbedding the capacitor plate electrodes at the bottom side of the vibratory stage and substrate [11,14]. This proposed platform can potentially be adapted as a universal system-in-package solution to provide precise on-chip physical reference inputs and in-situ self-calibration of scale factor drifts for multi-types and multi-structures of MEMS inertial sensors including accelerometers, gyroscopes, and other IMUs. 2.
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