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What is Magnetostrictive Position Sensing?

In a Gemco position sensor, a current pulse is sent down a Magnetostrictive wire in a specially designed waveguide (Figure A)

The interaction of this current pulse with the magnetic field created by a movable magnet assembly produces a torsional strain pulse on the wire, which travels at sonic speed along the wire (Figure B)

The strain pulse traveling up the wire is sensed by a small induction pickup coil in the head assembly of the LDT. The position of the movable magnet is determined with high precision by measuring the time between the launching of the current pulse and the arrival of the torsional strain pulse (Figure C)

As the moving magnet is placed on top of the cylinder piston, the result is highly accurate non-contact position sensing with absolutely no wear on the sensing element.

In general, this is how the signal is created, in the head of the magnetic position sensor the signal is calculated and transferred to the controller of the cylinder. 

Application Note: Magnetostrictive Control in Rugged Applications on Hydraulics Cylinders

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