A Robust Linear Inductive Position Sensor With High Accuracy Absolute Positioning Capability Based on Eddy Current
Liang Wu, Hanxu Zou, Xuhan An, Yuan Tan, Liang Fang · IEEE Sensors Journal · 2025
To enhance the absolute positioning capability and accuracy of conventional eddy current sensors, this article presents a robust absolute linear inductive position sensor (IPS) that features high accuracy and strong anti-interference capability. The sensor integrates the stationary ruler equipped with rectangular reflective metallic conductors (RMRCs) and the moving ruler carrying spiral copper coils, including both excitation and induction coils. RMRCs consists of two measurement channels with M and 2M + 1 pitches. When high-frequency alternating current is injected into the excitation coils, eddy currents are generated on the surface of the RMRCs located beneath the moving ruler, and a radiative magnetic field is induced. Dual-channel induced electromotive forces (EMFs) are induced in the induction coils owing to alterations in the coupling area between the spiral coils and the RMRCs. Absolute position can be acquired by processing two induced EMFs. The structure of the sensor and its measurement principle are described in detail. A sensor prototype is fabricated and its performance experimentally characterized. The experimental results demonstrate that the sensor prototype exhibits high precision and robust anti-interference capabilities, enabling it to achieve absolute positioning. The peak-to-peak value of measurement error is 12.5 μm during the full measurement range of 204 mm.