Research On Displacement Measurement System Based On Eddy Current Sensor

Intelligent sensor system is the mainstream direction of the current sensor research,which aims at improving accuracy while pursuing higher stability and wider applicability.The use of eddy current sensors to measure displacement has gradually become the focus of modern scientific research,not only has the common advantages,but also has its own unique advantages,Therefore,this paper carried out in-depth study of the displacement measurement system based on eddy current sensor,the main contents are as follows:Firstly,the influencing factors of the displacement measurement accuracy of the eddy current sensor are analyzed,and the main reasons affecting the measurement accuracy are the non-linear relationship between the input and output characteristics and the temperature drift.For the nonlinear relationship between the input and output characteristics of the displacement measurement system,a model of the relationship between the input and the output is established by means of curve fitting.After nonlinear correction,the linearity increased from 10.38%to 1.33%.Non-linearity has been significantly corrected to achieve the desired goal.For the temperature drift problem of eddy current sensor,a temperature compensation model based on binary regression and a temperature compensation model based on least square support vector machine?LS-SVM?are proposed.Firstly,the eddy current sensor experiment to get the original sample data to measure the displacement.Secondly,by using the least square method to determine the coefficient to be determined of the binary regression equation,to obtain the binary regression equation,and establish the temperature compensation equation based on binary regression.Then,The LS-SVM is trained to obtain the optimal kernel function and its parameters though using the sample data,and then the temperature compensation model based on the LS-SVM algorithm is obtained.Finally,after temperature compensation,the zero temperature coefficient of temperature compensation by binary regression is raised from4.81?10^-3/?C under the initial condition to the present2.24?10^-4/?C,and the sensitivity temperature coefficient is raised from8.67?10^-3/?C at the initial condition to 1.48?10^-3/?C at present.LS-SVM temperature compensation for the zero temperature coefficient from the initial condition of4.81?10^-3/?C to upgrade to the present1.185?10^-4/?C,the sensitivity temperature coefficient from the initial conditions of8.67?10^-3/?C to the current5.33?10^-4/?C.After analysis,both models can play a role of temperature compensation for eddy current sensor displacement measurement,but the LS-SVM algorithm is more effective.In order to apply the nonlinear correction algorithm and the temperature compensation model to the practical measurement system,in this paper,an intelligent sensor system of eddy current displacement measurement including data measurement,signal processing,output display and wireless transceiver is designed,which realizes the accurate measurement after real-time correction by using the STM32 single-chip microcomputer.