Page 369 - Mechatronics with Experiments

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JWST499-c06
JWST499-Cetinkunt
SENSORS 355 254mm×178mm
Interrogation electric pulse
forms magnetic field along
entire waveguide for 1 to 3
microseconds
Magnetic field from
position magnet
Sensor
element head
Sensor element Interaction of magnetic fields
protective tube generates torsional strain pulse
Waveguide

Position magnet
(a)

Null Measured length range Inactive

Magnet

Piston head &
rod assembly Sensor rod

Non-ferrous spacer

(b)

(c)
FIGURE 6.26: Operating principle of magnetostriction absolute position sensor: an industry
standard sensor used for cylinder position measurement in electro-hydraulic motion control
systems. (a) Operating principle of the sensor; (b) in-cylinder mechanical placement of the
sensor; (c) cut-away picture of a hydraulic cylinder with a magnetostriction sensor.