谐振式液体密度传感器压电激励与检测的实现

本文利用正压电效应和逆压电效应，实现谐振式液体密度传感器的压电激励与压电检测，原理简单、功耗低、检测方便。设计了基于该激励和检测方式的自动增益控制(Automatic Gain Control，AGC)电路，当传感器的输出信号发生较大变化时，激励信号的增益可随输出信号的幅值进行自动调节，使输出信号的幅值保持稳定。该电路具有结构简单，适应性好，可靠性高，调节速度快等优点。同时，对所设计的谐振式液体密度传感器进行了标定实验，该密度传感器的精度约为±1.0kg/m³，重复性约为±0.05%，可以实现液体密度的高精度实时在线测量。

Implement of Piezoelectric Excitation and Piezoelectric Detection on the Resonant Sensor for Liquid Density Measurement

The sensor for liquid density measurement based on the resonance theory is driven and detected based on the piezoelectric effect and inverse piezoelectric effect in this paper. The automatic gain control （ AGC） circuit based on piezoelectric excitation and piezoelectric detection with simple struc-ture and low power consumption is designed, when the output signal of sensor changes large, the gain of excitation signal can be automatically adjusted with the output signal amplitude so that the output signal amplitude remains stable. The circuit has many advantages, for example simple structure, good flexibility and reliability, fast speed of response and so on. Meanwhile, the calibration experiments are taken, and results conform that the repeatability error is about ±0. 05% and the accuracy is about 1. 0kg/m3 . In a word, the sensor designed in this paper can achieve liquid density measurement online with high precision in real-time.