Numeral eddy current sensor modelling based on genetic neural network

This paper presents a method used to the numeral eddy current sensor modelling based on the genetic neural network to settle its nonlinear problem. The principle and algorithms of genetic neural network are introduced. In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network （GNN） according to measurement data. So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network. The nonlinear model has the advantages of strong robustness, on-line modelling and high precision. The maximum nonlinearity error can be reduced to 0.037% by using GNN. However, the maximum nonlinearity error is 0.075% using the least square method.

A New Modeling Method Based on Genetic Neural Network for Numeral Eddy Current Sensor

In this paper,we present a method used to the numeral eddy current sensor modeling based on genetic neural network to settle its nonlinear problem.The principle and algorithms of genetic neural network are introduced.In this method, the nonlinear model parameters of the numeral eddy current sensor are optimized by genetic neural network (GNN) according to measurement data.So the method remains both the global searching ability of genetic algorithm and the good local searching ability of neural network.The nonlinear model has the advantages of strong robustness,on-line scaling and high precision.The maximum nonlinearity error can be reduced to 0.037% using GNN.However,the maximum nonlinearity error is 0.075% using least square method (LMS).

Parameter Optimization and Precision Enhancement of Dual-Coil Eddy Current Sensor

To enhance the measurement precision of eddy current sensor in particular environments such asextreme temperature changes and limited available space in aerospace, we optimized the structural parameters ofthe traditional dual-coil eddy current sensor probe by electromagnetic field analysis and finite element simulationmodeling, and further presented the criteria for determining the optimal coil distance of the dual-coil probe. Thesimulation results are verified by setting up an experimental platform. For the extreme temperature environment,the displacement measurement error caused by the full range temperature variation of the dual-coil sensor underthe optimal distance is less than 21.0% of that of the single-coil sensor. On this basis, we analyzed and verified thethermal stability of the structurally optimized dual-coil eddy current sensor. After temperature compensation,the displacement measurement accuracy can reach 14.9 times more accurate than that of the single-coil sensor.The method proposed in this paper can provide a design reference for the structural optimization of the axialdual-coil eddy current sensor probe.

HIGH TEMPERATURE DISPLACEMENT SENSOR

A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90-350 mV at 550 ℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2-3 V at 550 ℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550 ℃ in a magnetic bearing system for more than 100 h.

Investigating Averaging Effect by Using Three Dimension Spectrum

The eddy current displacement sensor＇s averaging effect has been investigated in this paper, and the frequency spectrum property of the averaging effect was also deduced. It indicates that the averaging effect has no influences on measuring a rotor＇s rotating error, but it has visible influences on measuring the rotor＇s profile error. According to the frequency spectrum of the averaging effect, the actual sampling data can be adjusted reasonably, thus measuring precision is improved.