第18卷第11期 2010年11月
文章编号
1004-924X(2010)11-2430-07
光学精密工程
Optics and Precision Engineering
Vol.18No. 11
Nov.2010
力反馈式微机械加速度计刚度的自适应调整
李童杰，刘云峰，董景新，范达
（清华大学精密测试技术及仪器国家重点实验室，北京100084）
摘要：为了提高模拟力平衡式电容微机械加速度计的鲁棒性和分辨率，对系统的非线性进行了研究。通过分析系统的数学模型，认为力发生器的非线性会引人一个可变负刚度。在传统方案中，为保证加速度计满量程时总刚度大于0，预载电压要小于失稳预载的0.707，这就造成在加速度输人较小时其总刚度较大，从而影响其阅值以及小输人时的分辨率。为弥补传统方案中力矩器非线性对系统分辨力的影响，本文应用自适应理论，提出一种基于总刚度不变的变预载自适应调整方法来提高闭环系统的鲁棒性和分辨率。设计了一种基于DSP的数字式微机械加速度计并进行了试验。试验结果表明，采用自适应调整方案后，加速度计在0g附近的分辨率由43.2μg提高到11.3μ，1g附近的分辨率由36.4g
提高到12.1，这些数据验证了自适应调整方案对系统性能的改进。关键调：微机械加速度计；自适应控制；刚度；变预载；分辨率
中图分类号：TH824.4
文献标识码：A
doi:10. 3788/OPE. 20101811.2430
Adaptingadjustmentofstiffnessforforcefeedbackmicroaccelerometer
LI Tong-jie,LIUYun-feng,DONG Jing-xin,FANDa
(StateKeyLaboratoryofPrecisionMeasurementTechnologyandInstruments,
Tsinghua University,Beijing 100084,China)
Abstract: To improve the roborant capacity and the resolution of a micromechanical accelerometer, the nonlinearity of the system was studied. The mathematic model of the system was discussed and the variable electrostatic stiffness brought by the nonlinearity of a electrostatic torque was analyzed.Ana lytical results show that the preload voltage is used to be less than O. 7o7 time of crippling load voltage so as to make total stiffness greater than zero, which will cause a poor resolution when the input is near Og. In view of the nonlinear effect, an adaptive adjustment method in which the total stiffness was kept a constant and the preload voltage and the feedback voltage were renewed every sampling cy cle was proposed to improve the stability and resolution of the system. Finally, a digital micro acceler ometer based on DSP was developed,then it was tested by using the adaptive adjustment method. Ex perimental results indicate that the resolution of the accelerameter is improved from 43. 2 μg to 1l. 3 μg near Og and from 36.4 μg to 12.1 μg near 1g.These data prove the system performance has been improvedgreatly
Key words: micro accelerometer; adaptive control;stiffness; variable preload; resolution
收稿日期：2010-02-26；修订日期：2010-04-26.
基金项目：国家十五"预研项目（No,51308050208）