机械应变测量调理电路的设计及其滤波特性分析

Design of Modulate Circuit of Mechanical Strain and Analysis of Its Filter Properties

结构发生机械形变时应变片阻值微小的变化不能直接被A/D进行模数转换,并且信噪较大,针对此问题设计了应变测量调理电路;对应变片选型作了详细的介绍;对电路惠斯通桥路、微弱信号放大电路、高阶滤波、二阶压控滤波电路等模块进行了理论分析和节点参数的计算。介绍的应变测量调理电路将应变片阻值的变化调理成一定范围内的电压信号输出,其幅值与变化趋势与对应被测结构件发生机械形变的真实情况基本一致,能够实现对应变的准确测量,并通过两级滤波有效地降低了信号噪声。

When the mechanical structure appears a minor deformation,the changing of the resistance value of strain gages is too small that can＇t be convert to digital signal by A/D conversion, as well as the signal-to-noise ratio is large. This article designs a regulation circuit based on the problem and has a detail introduction about the sdection of strain gages. The Wheatstone bridge circuit, amplifier,high-order filter and second voltage controlled filter circuit are analyzed and calculated for the node parameters. The regulation circuit for strain test introduced in this article introduces the changing of the resistance strain gages value of into voltage signal. Its amplitude and trend is consistent with the real mechanical deformation of the testing structure. The regulation circuit could test the strain accurate and effectively reduce the signal noise by two filter.