Abstract
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.
Highlights
The sense of touch provides essential information for robots working in an unknown environment, handling unknown objects and interacting with humans
We developed a magnetorheological elastomer tactile sensor [6] that overcomes the issues described in the previous sections
We proposed a flexible tactile sensor using a dual-layer elastomer and magnet and investigated the sensor responses with different contact speeds and the spatial responses
Summary
The sense of touch provides essential information for robots working in an unknown environment, handling unknown objects and interacting with humans. A number of researchers has been proposing various types of flexible tactile sensors with safe, flexible and protective coverings intended to provide tactile sensations for robots, e.g., [1,2,3]. Various technical issues remain, such as a large amount of deformation that causes the sensing elements to fracture, deterioration in the sensitivity caused by the thick and soft coverings and a poor maintainability. (2) the sensor has high sensitivity and extremely low rigidity with respect to the surface deformation of its flexible covering; (3) the electronic and fragile elements in the sensor are completely separated from the parts to which the contact forces are applied; and (4) the flexible covering can be replaced when it becomes damaged and requires no precise positioning.
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