修正非线性误差的宽量程多电桥电阻测量电路设计

利用电桥测量电阻是各种自动控制和检测系统中广泛使用的一种方法,其测量精度和范围成为测量电路设计的关键技术。为解决传统单电桥电阻测量电路在宽量程范围内进行高精度测量的问题,通过对单电桥待测电阻与输出电压之间变化关系的分析,指明了等效电压与实际电压之间的非线性误差,提出了一种查表式修正非线性误差的方法,并给出了在线性公式基础上修正非线性误差的计算公式以及测量精度计算公式,在此基础上设计了一种基于单片机控制的可根据待测电阻值区间自动进行切换的多电桥电阻测量电路。该电路能够在较宽的量程范围内取得较高的测量精度,与传统的手动档位仪表相比较具有更好的便捷性和准确度。

Design of multi bridge resistance measurement circuit with wide range based on non linearity errors correction

Using bridge to measure the resistance is widely applied to various automatic control and detection systems, and its measurement accuracy and range are the key technique for the design of measurement circuit. In order to solve the problem of high accuracy measurement within wide range for the traditional single arm bridge circuit, the non linearity error between equivalent voltage and actual voltage is pointed out by analyzing the relation between the measured resistance and the output voltage of the bridge. Then we put forward a method to correct the non linearity error through look up table. At the same time, this paper gives a formula to correct the non linearity error on the basis of linearity equation as well as measurement accuracy calculation formula. Finally, we design a multi bridge resistance measurement circuit controlled by a MCU, which can automatically switch the bridge arm resistance according to the range of the measured resistance. This circuit has higher measurement accuracy and more convenient compared with the traditional manual instruments in a wide range.