Magnetic Levitation by Composite Element of Two Active Materials

A magneto-electric composite element of functional materials, giant magnetostrictive (GMM) and piezoelectric materials, is developed for magnetic force control. This force control is based on the inverse magnetostrictive effect of GMM and realized by composing a closed parallel magnetic circuit with a permanent magnet in magnetic yoke. The magnetic force between two yokes can be adjusted by controlling the strain in the magnetostrictive rod. For the purpose of efficiently controlling the strain of the GMM rod, a magneto-electric composite element is constructed, in which two active materials, a magnetostrictive rod and a piezoelectric ring actuator, are mechanically coupled via strain. The magnetization in the magnetostrictive rod can be controlled by adjusting the voltage of the piezoelectric actuator. It is confirmed that this element works to adjust magnetic force and has wide frequency bandwidth. As an application of this element magnetic levitation system is proposed and movable yoke was levitated by simple PD control.