Designing Airgap-Stable Magnetic Linear Position Systems

This work addresses the topic of magnetic linear position detection, a common method used in modern industries to determine linear displacement by magnetic means. One major shortcoming of this method is the inherent airgap instability, which puts strong constraints on mechanical construction tolerances and limits resolution and sensitivity. We propose a method to improve the airgap stability by adding a second magnet, which makes the field and by extension the system output (locally) independent of the distance from the source. It is shown that the measurement error for 1-D systems can be reduced by a factor of ~14 and for 2-D systems by a factor of ~5 by application of this method for a realistic example.