扭摆式高g值微机械加速度计的设计优化与冲击校准

陶永康，刘云峰，朱科引,董景新

(清华大学精密仪器系，北京100084)

摘要：设计实现了一种扭摆式高g值微机械加速度计。微结构采用十字形扭梁减小横向效应，摆片两侧使用梳齿结构作为止档和阻尼器，6个敏感单元并联的方式提高基础电容量。有限元仿真得到表头谐振频率约为56 kHz，前两阶模态分离比大于4，高过载能力10 万g，微结构灵敏度为8.94E-6pF/g，基于玻璃-硅(Silicon On Glass,SOG)工艺流片后单侧基础电容约为3.6 pF。分析了环形二极管电容检测电路的检测带宽问题，并设计了高g值加速度计的检测电路。搭建了霍普金森杆实验系统进行高g值的冲击校准，2万g范围内非线性度2%，5 V供电下标度因数约为24.5 μV/g。

关键词：高g值微机械加速度计；扭摆式加速度计；检测读出电路；霍普金森杆；冲击校准

中图分类号:TH 7;U666.1文献标志码：A

Optimizationdesignandshockcalibrationofpenduloushigh-gmicro-machinedaccelerometer

TAO Yong-kang, LIU Yun-feng, ZHU Ke-yin, DONG Jing-xin(DepartmentofPrecisionInstrument,TsinghuaUniversity,Beijing100084,China)

Abstract:A kind of pendulous high-g micro-machined accelerometer was designed. Cruciform torsion beam was applied to reduce cross-axis sensitivity, and comb structure was used as stopper and damper. The micro-structure parallels 6 sensing units to improve initial capacitance. Based on finite element analysis, the micro-structure’s natural frequency is about 56 kHz with modal separation ratio more than 4. It can resist 1E5 g shock acceleration and the micro-structure’s sensitivity is 8.94E-6pF/g. The accelerometer’s fabricated by silicon on glass (SOG) technology, and its single-side initial capacitance is about 3.6pF. The measurement bandwidth of ring diode capacitance detection circuit was analyzed and a high g accelerometer’s detection circuit was designed. Calibrated by Hopkinson bar, the accelerometer’s nonlinearity is 2% of 2E4 g range, and the scale factor is about 24.5μV/g with 5V supply.

Keywords:high-gmicro-machinedaccelerometer;pendulousaccelerometer;detectivereadoutcircuit;Hopkinsonbar;shockcalibration

目前微机械加速度计的一种重要应用需求是高g值测量，获取高冲击过程中的加速度，用于冲击过载实验和某些特殊的军事应用场合。例如侵彻钻地武器的弹药在侵彻硬质界面的过程中，需要测量几万乃至十几万g的加速度[1-3]。高g值加速度计是侵彻过程惯性测试与控制的关键技术之一，研究高g值微机械加速度计对于推动国内侵彻武器研究、爆炸和冲击测试等实验手段的发展具有重要的实用价值。

考虑微尺度效应和材料特性的影响，基于微机械工艺制造的加速度计具有天然的抗冲击优势。电容式微机械加速度计具有工艺相对成熟、温度特性良好和冲击前后性能稳定性好等优势，是发展潜力较大的一种高g值加速度计类型[4-6]。……