Three-freedom-degree weak coupling resonant accelerometer based on modal localization effect

Abstract

The invention discloses a micro resonant accelerometer based on the principle of modal localization, which belongs to the field of micro-electromechanical systems (MEMS). The accelerometer consists oftwo identical movable masses and three resonators connected together through a mechanical coupling beam. According to the invention, the three-freedom-degree weak coupling resonators are used to further improve the sensitivity of the resonators, and the sensitivity of the accelerometer is improved; capacitor plates are arranged on inner and outer sides of each resonator; amplitude differential detection is carried out on a single resonator, which can enhance the signal intensity and eliminates feedthrough capacitor signal interference caused by the potential difference between a drive electrode and a detection electrode; the stability and accuracy of a measurement signal can be greatly enhanced; a stiffness adjustment electrode is added; and flexible working point selection and linear working scope adjustment are realized.

Description

[0001] Field: [0002] The invention relates to an acceleration sensor, in particular to a miniature resonant accelerometer based on mode localization effect, and belongs to the technical field of sensors. Background technique: [0003] The accelerometer is an instrument used to measure the acceleration of the carrier. It is the basic core component of the inertial navigation system. It has important application value in aerospace, automotive industry, consumer electronics, construction machinery and other fields. With its many advantages such as small size, light weight, low cost and easy mass production, MEMS accelerometer has become the main development direction of accelerometer. The working principle of most MEMS accelerometers is based on Newton's second law, which uses a movable mass to generate inertial force, and converts the inertial force into voltage, current or frequency changes through electrostatic, piezoresistive, piezoelectric or resonance sensing mechanisms ...

AI Technical Summary

Problems solved by technology

However, there are still many aspects to be improved in terms of structural design of the accelerometer.

For example, the differential detection method is not used for a single resonator, resulting in the output signal of the test will be interfered by the feedthrough capacitance signal between the resonator drive electrode and the detection electrode, which greatly reduces the effective signal amplitude; the weak accelerometer The coupled resonator consists of a double-ended fixed tuning fork structure, which is driven from both ends of the resonator at the same time. This design makes the resonator structure have four operating modes, which gives the choice of operating modes and the design of closed-loop circuits It has brought great difficulties; due to the structural mismatch caused by the processing error to the two weakly coupled resonators, the initial working point of the accelerometer cannot be determined, and it is difficult to flexibly adjust the working point and the linear measurement range

More importantly, the core sensitive structure of the accelerometer is a two-degree-of-freedom weakly coupled resonator, and its mode localization is limited, which limits the further improvement of the accuracy of the accelerometer.

Images