MTS Series 201 Actuators - Manual (Page 36)

Series 201 Actuator Product Information 36
Optional Displacement Transducer Operation
LVDT
The LVDT is an electromechanical device that provides an output voltage that is
proportional to the displacement of a moveable core extension. The core
extension is attached to a core mount that is secured inside the piston. The core
extension is axially oriented in the LVDT coil. The LVDT coil is connected to an
LVDT mounting that secures the LVDT assembly.
Temposonics sensors
Temposonics linear sensors use the time-based magnetostrictive position sensing
principle developed by MTS. Within the sensing element, a sonic strain pulse is
induced in a specially-designed magnetostrictive waveguide by the momentary
interaction of two magnetic fields. One field comes from a movable permanent
magnet that passes along the outside of the sensor. The other field comes from an
“interrogation” current pulse applied along the waveguide. The resulting strain
pulse travels along the waveguide and is detected at the head of the sensing
element. The position of the magnet is determined by measuring the elapsed time
between the application of the interrogation pulse and the arrival of the resulting
strain pulse with a high speed counter. Using the elapsed time to determine
position of the permanent magnet provides an absolute position reading that
never needs recalibration or re-homing after a power loss. Non-contact sensing
eliminates wear, and provides durability and output repeatability.