Position Measurement in Three Dimensions using Magnetic Induction

A new method that utilizes magnetic induction to measure position in two and three-dimension is presented in this article. The method comprises one magnetic field excitation coil and four sensing coils for measurement. An alternating magnetic field is applied via the excitation coil and induced voltage is measured at four sensing coils. The synchronous detection method is used to demodulate the measured voltage signals; due to this the measurement system will not be affected by a stray magnetic fields. The method can measure displacements overs range of upto 3 mm, with a resolution of up to 200 nm in one dimension.
$\pm\sigma$
resolution of 200 nm over a sensing area of 500
$\mu \mathbf{m}\times 500\mu \mathbf{m}$
at a bandwidth of 1 kHz was achieved. The method is tested in three dimensions over a volume of 2 mm
$\times 2$
mm
$\times 2$
mm. The range and resolution of the setup can be adjusted by changing the size of the coil or signal conditioning parameters. The demonstrated method only uses such coils to measure displacement without any need of sophisticated sensors.