Distance Measurement With Inductive Coils

Distance measurement is an important tool in several applications. This article describes the development of a resonant inductive sensor for short (few centimeters) distance measurement. The sensor uses the principle of inductive coupling, where a transmitter coil (TX) induces a voltage in receiver coil (RX). The distance between TX and RX coils is determined as a function of the amplitude of the induced signal. Both coils are controlled by processing circuits and a microcomputer performs information processing and stores the measured data. In a setup for distances between 100-240 mm, experimental results showed a maximum standard deviation (σ) of 2.56 mm at 235 mm.