Performance Analysis of a Planar Displacement Sensor With Inductive Spiral Coils

In this paper, a planar displacement sensor with inductive spiral coils is presented. The sensor is composed of two inductive coils of spiral shape. One coil is a stationary coil with input terminals, whereas the other coil is a moving (short-circuited) coil. The moving coil physically moves with respect to the stationary coil in x-z and y-z planes. The input inductance changes when the moving coil moves with respect to the stationary coil and it is measured between the terminals of the stationary coil. The inductive operating principle of the sensor was tested using the prototypes fabricated in printed circuit board technology. Two prototypes were designed and fabricated: the prototype without a gap in the stationary coil and the prototype with the gap inserted in the segments of the stationary coil.