Mexican-Hat-Like Response in a Flexible Tactile Sensor Using a Magnetorheological Elastomer

• Published in: Sensors (Basel, Switzerland) Vol. 18; no. 2; p. 587
• Main Authors: Kawasetsu, Takumi, Horii, Takato, Ishihara, Hisashi, Asada, Minoru
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 14.02.2018; MDPI
• Subjects: Compressibility; Deformation mechanisms; Elastomers; flexible materials; force and tactile sensing; Incompressibility; magnetic flux measurements; Magnetic transducers; magnetorheological elastomer; Maintainability; Noise levels; robotic skin; Sensitivity; Sensors; tactile sensor; Tactile sensors (robotics); force and tactile sensing; magnetic flux measurements; tactile sensor; flexible materials; magnetorheological elastomer; robotic skin
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s18020587

A significant challenge in robotics is providing a sense of touch to robots. Even though several types of flexible tactile sensors have been proposed, they still have various technical issues such as a large amount of deformation that fractures the sensing elements, a poor maintainability and a deterioration in the sensitivity caused by the presence of a thick and soft covering. As one solution for these issues, we proposed a flexible tactile sensor composed of a magnet, magnetic transducer and dual-layer elastomer, which consists of a magnetorheological and nonmagnetic elastomer sheet. In this study, we first investigated the sensitivity of the sensor, which was found to be high (approximately 161 mV/N with a signal-to-noise ratio of 42.2 dB); however, the sensor has a speed-dependent hysteresis in its sensor response curve. Then, we investigated the spatial response and observed the following results: (1) the sensor response was a distorted Mexican-hat-like bipolar shape, namely a negative response area was observed around the positive response area; (2) the negative response area disappeared when we used a compressible sponge sheet instead of the incompressible nonmagnetic elastomer. We concluded that the characteristic negative response in the Mexican-hat-like response is derived from the incompressibility of the nonmagnetic elastomer.