Study On Absolute Linear Displacement Sensor Based On Eddy Effect

Precision measurement technology plays an indispensable role in the development of modern industrial technology,widely used in fields such as aerospace,national defense and military,processing and manufacturing,and automatic control.Its level has become one of the important indicators to measure a country’s scientific and technological development level.Eddy current displacement sensors,using non-contact measurement methods,have advantages such as high sensitivity,fast speed response,strong anti-interference ability,and good reliability.However,eddy current displacement sensors are mainly used for measuring small axial displacements.This paper proposes a large range absolute linear displacement sensor to address issues such as the small range of traditional eddy current displacement sensors.It utilizes the eddy current effect and low manufacturing process to achieve large range and high-precision absolute linear displacement measurement.The main research work is as follows:(1)According to the eddy current effect,the action and reaction mechanism of field coils,eddy current field and inductive coils are studied,and the direct mapping relationship between eddy current field distribution and time-varying magnetic field distribution is studied.The eddy current distribution is discussed with the electromagnetic field simulation software.The second order vector method is used to establish the eddy current distribution model under the energized rectangular excitation coil.(2)By studying the existing absolute linear measurement method,the eddy current large range absolute linear displacement measurement model is established by using the measurement method of combining fine measurement channel and coarse measurement channel.The sensor structure is established and designed according to the sensing mechanism and signal transmission sequence,and the measurement model is simulated and verified with the electromagnetic field simulation software.(3)According to the sensing mechanism,the measuring system is designed,mainly including hardware circuit,software program and sensor prototype.The hardware circuit mainly includes excitation signal generation module and induction signal acquisition module.The software program mainly includes the lower computer program based on ARM and the upper computer program based on data acquisition and analysis.(4)The sensor experimental platform is built to test the static indicators such as sensor linearity and dynamic indicators such as speed fluctuation;The error components are analyzed and the sensor structure is optimized.The final experimental results show that the sensor prototype has good absolute positioning ability and time stability,and the linearity of the full scale(500 mm)is 0.136 ?.。In a word,the theoretical model of the sensor is deduced and analyzed firstly.Then the electromagnetic field simulation is carried out to verify the feasibility of the sensor.And the sensor prototype is fabricated and the supporting electrical system according to the sensing mechanism is designed.Finally,an experimental platform is built up to test and evaluate the performance of the sensor prototype.The sensor prototype is optimized after error analysis.The experimental results show that the sensor in this paper can realize large range absolute linear displacement measurement with high accuracy.