Design and Theoretical Analysis of a Resonant Sensor for Liquid Density Measurement

Sensors

Dezhi Zheng²  Jiying Shi¹ 

[1]School of Instrument Science and Opto-Electronics Engineering, New Main Building B504, Beijing University of Aeronautics and Astronautics, Beijing 100191, China

关键词: liquid density measurement;    resonant sensor;    tuning fork;    natural frequency;   

DOI  :  10.3390/s120607905

来源: mdpi

【 摘 要 】

In order to increase the accuracy of on-line liquid density measurements, a sensor equipped with a tuning fork as the resonant sensitive component is designed in this paper. It is a quasi-digital sensor with simple structure and high precision. The sensor is based on resonance theory and composed of a sensitive unit and a closed-loop control unit, where the sensitive unit consists of the actuator, the resonant tuning fork and the detector and the closed-loop control unit comprises precondition circuit, digital signal processing and control unit, analog-to-digital converter and digital-to-analog converter. An approximate parameters model of the tuning fork is established and the impact of liquid density, position of the tuning fork, temperature and structural parameters on the natural frequency of the tuning fork are also analyzed. On this basis, a tuning fork liquid density measurement sensor is developed. In addition, experimental testing on the sensor has been carried out on standard calibration facilities under constant 20 °C, and the sensor coefficients are calibrated. The experimental results show that the repeatability error is about 0.03% and the accuracy is about 0.4 kg/m³. The results also confirm that the method to increase the accuracy of liquid density measurement is feasible.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.