An Inductive Linear Displacement Sensor With Complementary Resonant Coupling Units

This paper presents an inductive linear displacement sensor with complementary resonant coupling units. The sensor is mainly composed of a stator and two identical movers. The two movers are symmetrically arranged on both sides of the stator, forming a complementary coupling with the stator. The stator contains excitation coils and pickup coils, which generate magnetic field and output induction signals respectively; The movers also contain pickup coils, which are in series with resonance capacitors to generate a secondary magnetic field that reacts on the stator after receiving the excitation magnetic field, rather than outputs induction signals. The structure of this sensor makes the pickup coils on the stator directly receive the magnetic field on the movers in a complementary way, and avoids using leading wires on the movers, which is helpful to improve measurement accuracy and ensure the environmental adaptability of the sensor. The comparison experiments of the sensor prototypes show that the newly designed sensor is insensitive to the change of the gaps between the movers and stator. By improving the sensor prototype, the short-period measurement error is
$9 ~\mu \text{m}$
, and the long-period measurement error is not more than
$14 ~\mu \text{m}$
within 300mm.