大量程微机械加速度计非线性的弱闭环修调

Weak closed-loop adjusting of wide-range micro-machined accelerometer's nonlinearity

大量程微机械加速度计在制导炮弹等大动态武器的组合导航系统上具有重要的应用需求。开环工作的大量程微机械加速度计由于敏感单元的大变形,支撑梁机械刚度的非线性、差动电容器的非线性以及电容检测电路的非线性等会造成较大的全量程测量误差。设计提出一种利用静电力进行弱闭环修调的简单方法,改善大量程加速度计的非线性,有利于提高其测量精度和动态范围。Simulink仿真和原理性验证实验证明了该方法的有效性。基于该弱闭环修调的方法研制了一种单5 V供电的大量程微机械加速度计,其分辨率优于2 mg,2 h偏置稳定性5 mg,±200g范围内的非线性度为0.68%。

Wide-range micro-machined accelerometer is in urgent demand for high dynamic integrated navigation system such as guided projectiles. Due to sensing element's large deformation at open-loop status, the nonlinearity of the beam's stiffness, differential capacitor and capacitance detection circuit would lead to large full-scale measurement errors. This paper presents a simple method by using electrostatic force of weak closed-loop to improve the nonlinearity of wide-range accelerometer, which could improve the measurement accuracy and dynamic range. Simulation and principle proof test have demonstrated the effectiveness of the method. Based on this method, a wide-range micro-machined accelerometer using+5 V supply is designed, in which the resolution is superior than 2 mg, the 2 h bias stability is 5 mg, and the nonlinearity within ± 200 g input is 0.68%.