Research status and development trend of micro-mechanical resonance accelerometer
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摘要: 微机械谐振式加速度计(MMRA)是通过检测加速度施加前后谐振器谐振频率变化实现对加速度检测的。该传感器具有频率信号输出、稳定性好、灵敏度高、精度高等优点,己成为MEMS传感器的重要发展方向之一。详细讨论了微机械谐振式加速度计设计中的关键技术,难点及对应解决方案、发展趋势。其中,关键技术包括机械结构、激励与检测方式以及谐振器刚度改变方式。分析了谐振器的三种机械结构以及微杠杆工艺误差造成的不对称性;根据谐振器材料的压电特性,可将MMRA分为压电MMRA和非压电MMRA,压电MMRA的激励与检测方式都是压电激励/压电检测,非压电MMRA主要为静电激励/电容检测;讨论了轴向应力和静电刚度这两种谐振器刚度改变方式的原理和适用范围。微机械谐振式加速度计主要存在四个技术难点:机械耦合、温度特性、工艺误差、组装与封装,并针对这四点给出了相应的解决方案。集成,静电刚度,新材料,多轴以及更高的性能指标将是今后微机械谐振式加速度计的主要发展趋势。Abstract: The micro-mechanical resonance accelerometer(MMRA) is used to measure the acceleration by detecting the change of resonant frequency of the sensitive element.This kind of sensor has become one of the important development direction of micro-sensors because it has many advantages such as frequency signal output,high stability, sensitivity and precision.This paper describes the key technologies, difficulties and corresponding solutions, development trends of MMRA. The key technologies include mechanical structure, excitation and detection methods, and methods of changing the resonator stiffness. The three mechanical structures of the resonator and the asymmetry caused by the error of the micro-lever process are analyzed; according to the piezoelectric properties of the resonators materials, MMRA can be divided into piezoelectric MMRA and non-piezoelectric MMRA, piezoelectric MMRA employs piezoelectric excitation/piezoelectric detection and non-piezoelectric are mainly electrostatic excitation/capacitance detection; there are two main methods to change the stiffness of the resonator: axial stress method and electrostatic stiffness method, whose principles and scopes are analyzed and compared. Development of MMRA mainly includes four technical difficulties: mechanical coupling, temperature characteristics, process error, assembly and packaging, and the corresponding solutions are given. Integration, static stiffness, new materials, multi-axis and higher performance will be the main development trends for MMRA in the future.
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Key words:
- micro-mechanical resonance accelerometer /
- resonator /
- resonant frequency /
- sensitivity
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