Research On A High-performance Displacement Sensor Based On The Principle Of Eddy Current

Eddy current displacement sensor is a sensor based on the principle of eddy current effect.It can measure the static and dynamic relative displacement changes between the probe and the metal conductor to be measured in a non-contact,high linearity and high resolution,and is widely used in industrial field and laboratory research.The performance of the eddy current displacement sensor has a crucial impact on the displacement measurement results.How to optimize the detection coil,design the sensor circuit system,and improve the linearity and stability of the sensor are the difficulties in designing a high-performance eddy current displacement sensor.Aiming at the design difficulties of the above-mentioned high-performance sensors,this paper conducts corresponding research from the following aspects:1)The detection coil of eddy current displacement sensor is studied.The equivalent circuit model and finite element simulation model of the eddy current sensor are established to study the relationship between the coil impedance and the measured conductor displacement,analyze the influence of the parameters of the detecting coil on the sensor performance,and provide theoretical basis for the coil design and optimization of the eddy current displacement sensor.2)The hardware system of eddy current displacement sensor is studied.This paper proposes a specially designed AC bridge circuit to complete the impedance measurement of the sensor coil.An active temperature-compensated crystal oscillator with excellent frequency stability is used to design the excitation signal source of the sensor.The phase sensitive detection circuit is used to demodulate the displacement of the measured conductor.Finally,the microcontroller is used to complete the sensor signal acquisition and processing.Reasonable circuit design and device selection have effectively improved the sensitivity and stability of eddy current displacement sensors with small probes.3)The compensation system of eddy current displacement sensor is studied.The nonlinear and temperature drift problems of the eddy current displacement sensor are studied and analyzed.A multiple regression compensation model is established to compensate the nonlinear and temperature of the sensor system.The specific data of the sensor range,linearity,temperature characteristics,resolution,hysteresis error and stability are given through the experimental test,which provides the basis for evaluating the performance of the eddy current displacement sensor developed in this paper.The research results show that the linear range of the eddy current displacement sensor with 5mm probe designed in this paper is 2.05 mm,the sensitivity temperature coefficient is 0.0085%/?,the measurement error is within 5?m,and the nonlinear error is less than ?0.24%.Each performance index has reached the expected goal.Compared with the mainstream products with a probe diameter of 5mm produced by domestic manufacturers,the linear range of the eddy current displacement sensor studied in this paper is increased by 100%,the nonlinear error is reduced by 76%,and the sensitivity temperature coefficient is reduced by 84.8%.It has reached the research level of highperformance eddy current displacement sensor,and has certain application value and reference value.