一种减小微机械加速度计振动偏移的方案

Method for Reducing Vibration Deflection on Micromechanical Accelerometer

为降低敏感元件对称性较差的微机械加速度计的振动偏移,对加速度计振动偏移产生的原因和抑制方案进行研究。首先,分析了系统学模型,并得出对于不对称的敏感元件采用对称的电容检测电路时,检测电路输出和敏感元件动极板位移关系函数中存在明显偶次项系数,进而造成振动零偏;其次,讨论了力矩器的非线性,通过理论分析得出,外加静电力等效对称方案无法抑制力矩器环节的振动偏移,提出了敏感元件等效对称补偿方案以及静电力发生器等效对称化方案,通过理论分析得出该方案大大降低了敏感元件不对称带来的振动偏移;最后,对静电力对称方案和等效对称补偿方案进行了对比试验。试验结果表明,对于对称性较差的敏感元件,等效对称补偿方案在保证线性度的同时,大大减小了振动时输出均值的偏移。

In order to reduce the deflection of the accelerometers with asymmetric sensors,the reasons and the suppression methods for vibration deflection are studied.Firstly,the mathematical model of the system is analyzed.For the asymmetric sensor when symmetric capacitors detection circuit is used,even parameters will be existed in the relation equation between the circuit output and the displacement of the mobile plate inside the sensor,so the vibration deflection comes about.And then,the nonlinearity of the torquer is analyzed.The equivalent symmetric method through electrostatic force bias is discussed.It is obtained that the method cannot restrain the vibration deflection.Additionally,an equivalent symmetry compensating method for asymmetric sensor and an equivalent symmetry method for electrostatic torque are proposed.It is found that the method can improve the vibration deflection through theoretical analysis.Finally,contrast experiments are made.Results show that as equivalent symmetry method is used,the deflection of the accelerometer with poor symmetry sensor under the vibration is reduced,and the linearity is well kept.