A Method to Guarantee the Measurement Accuracy of Plane Displacement with a Hole Using Eddy Current Sensors in Mechatronics Applications

Eddy current sensors are widely used in high precision displacement measurement in mechatronics systems, but the measurement result misalignment caused by hole plane seriously restricts its accuracy. To solve this problem, this paper proposes a method of error correction that integrates theoretical modeling and data-driven. Firstly, the distribution law of eddy current density in the plane with a hole was analyzed based on the equivalent eddy current ring model, and the quantitative relationship between hole size, position and coil inductance was derived. Secondly, the virtual eddy current sensor model was constructed by combining finite element simulation and sensor processing circuit characteristics, and the sensitive parameters of the virtual model were calibrated by global-local optimization strategy. Finally, Using the discrete data points of the virtual sensor output combined with the interpolation algorithm, the sensor output characteristic relationship is calibrated. The results show that after the calibration of the output characteristic relationship, the range error of the sensor in different measuring scenes and different measuring positions is greatly reduced, and the maximum absolute error is reduced from 507 μm to 21 μm, which is more than 95.9% lower than before calibration. The proposed method can accurately predict the variation trend of the sensor output voltage under hole interference. The displacement measurement error is effectively corrected, which breaks through the dependence of traditional calibration methods on a large number of measured data, and effectively helps the accuracy guarantee and reliability improvement of intelligent manufacturing equipment.