Multi-axis chip-scale MEMS inertial measurement unit (IMU) based on frequency modulation

摘要

A multi-axis microelectromechanical-systems (MEMS) inertial measurement unit (IMU) is fabricated in a vacuum sealed single packaged device. An FM vibratory gyroscope and an FM resonant accelerometer both for generating FM output signals is fabricated in the silicon chip using MEMS. A signal processor is coupled to the an FM vibratory gyroscope and to the FM resonant accelerometer for receiving the FM gyroscopic output signals and the FM accelerometer output signals. The signal processor generates simultaneous and decoupled measurement of input acceleration, input rotation rate, and temperature and/or temperature distribution within the IMU, self-calibration of the biases and scale factors of the IMU and its support electronics against temperature variations and other common mode errors, and reduction of the cross axis sensitivity by reducing acceleration errors in the gyroscope and rotation errors in the accelerometer.

主权项

1. A multi-axis microelectromechanical-systems (MEMS) inertial measurement unit (IMU) in a vacuum sealed single packaged device comprising:
a single silicon chip; an FM vibratory gyroscope for generating frequency modulated (FM) gyroscopic output signals fabricated in the silicon chip using silicon MEMS technologies as part of the vacuum sealed single packaged device; an FM resonant accelerometer for generating frequency modulated (FM) accelerometer output signals fabricated in the silicon chip using silicon MEMS technologies as part of the vacuum sealed single packaged device; and a signal processor coupled to the an FM vibratory gyroscope and to the FM resonant accelerometer for receiving the frequency modulated (FM) gyroscopic output signals and the frequency modulated (FM) accelerometer output signals, the signal processor generating simultaneous and decoupled measurement of input acceleration, input rotation rate, and temperature and/or temperature distribution within the IMU, self-calibration of the biases and scale factors of the IMU and its support electronics against temperature variations and common mode errors, and reduction of the cross axis sensitivity by reducing acceleration errors in the gyroscope and rotation errors in the accelerometer, wherein the FM resonant accelerometer comprises:
a tuning fork resonator having two tines with an anti-phase and in-phase mode of vibration; anda plurality of variable gap parallel plate electrodes coupled to the two tines to produce a negative electrostatic spring, where external acceleration causes a shift of both tines with in-phase motion, which changes an effective gap in the parallel plate electrodes thereby changing the effective stiffness for each tine, where the change of stiffness induces a change of an anti-phase resonant frequency, and where the change of the anti-phase resonant frequency is an FM measure of the input acceleration.