Long-Range Position Sensor Using Magnetoelastic Waves in Amorphous Magnetic Wires.

A large magnetostriction in FeSiB realizes strong magnetoelastic coupling, and allows efficient driving and pickup of magnetoelastic waves. Owing to the high electrical resistivity of amorphous FeSiB, the eddy current loss of the propagated magnetoelastic waves is low. Only a longitudinal mode of the waves is propagated in the onedimensional shape of the wires. Because of these characteristics, the attenuation constant of the waves is low (0.18 m-1 at 500 kHz), and they are propagated over a long distance. As an application of the waves, a long-range position sensor was fabricated. The output signal, whose period is proportional to the sensing distance, was obtained for the detection range from 0 to 5.0 m.:with an resolution of 1 mm. The analyses of the reflection factor of the magnetoelastic waves and reflecting methods for the sensor are discussed. A high reflection factor was obtained by successfully using a wheel-type reflector in the sensor.