Research On LVDT Signal Conditioning Circuit Design And Neural Network Calibration

Displacement sensors include inductive,capacitive,hall-type,eddy current,potentiometer and other analog structure types.The inductance sensor is based on the electromagnetic induction principle and converts the measured physical quantities such as displacement,flow,pressure into the change of coil self-induction coefficient L or mutual inductance M,then converts them into the changes of voltage or current through the signal conditioning circuit,thus achieving conversion of non-electric quantity to electric quantity.It is widely used in aerospace,construction,machinery,railway,coal,textile,chemical and other national economic sectors,and is used to measure the object length,vibration frequency,thickness of accurate data.Therefore,the study on LVDT and its performance has very important significance.This paper takes the ordinary AC non-standard linear output rebound type LVDT as the research object,and develops a set of LVDT signal conditioning circuit system.The AD698 is used as the excitation source to drive LVDT,and processes the LVDT output AC signal into DC voltage signal by using the signal conditioning circuit system.The voltage value is displayed by single chip and OLED.At last,the RBF neural network algorithm is used as the LVDT calibration algorithm to determine the relationship between the output and the input of the sensor.The dual phase orthogonal lock-in amplifier is the core of signal conditioning circuit system.MATLAB/Simulink is used to build the principle simulation model of dual phase quadrature lock-in amplifier,and its principle is simulated and analyzed.Then Tina software is used to build the circuit model of dual phase orthogonal lock-in amplifier,and the circuit simulation is analyzed.The circuit being modified repeatedly,the performance of the circuit is improved.Then,the Altium Designer is used to draw the system circuit board for the system experiments.Finally,through collection,processing and analysis of the experimental data,the output of LVDT shows to be linear basically,and the error of the simulation experiment of LVDT calibration is in the allowable range.From the above experiments,a conclusion can be drawn that LVDT signal conditioning circuit system and the calibration algorithm design is reasonable,and they can be applied on the LVDT output signal processing and calibration.