Displacement Sensor Using Magnetostrictive Wire and Decrease of its Hysteresis Error

Abstract

A displacement sensor using magnetostrictive wire is a sensor which estimates the displacement from propagation time of an elastic wave that is caused and detected by using the magnetostrictive effect and the inverse-magnetostrictive effect. This sensor can be used for measurement up to 60 meters in simple structure, therefore it is appropriate for industry applications. This chapter describes the followings; In case of unipolar pulse current used until now, 1.3 millimeters hysteresis error is produced. Then, various methods for reducing the hysteresis error were proposed. Here, a method for reducing the error is introduced by the form of the pulse current. The bipolar pulse current is used instead of the unipolar pulse current. As the result, it is able to decrease the hysteresis error to 0.3 millimeters or less.