[Credit: UCLA Engineering]
Researchers from the University of Washington and UCLA say they ahve developed such a flexible sensor skin that can be stretched over any part of a robot’s body to allow it to gain information on shear forces and vibration that could help it more accurately grasp and manipulate objects.
A report on the skin was recently published in the journal Sensors and Actuators A: Physical.
The skin reportedly mimics the way a human finger feels tension and compression as it strokes a surface and interprets different textures, according to the report, and measures tactile information with precision close to that of skin.
“Robotic and prosthetic hands are really based on visual cues right now — such as, ‘Can I see my hand wrapped around this object?’ or ‘Is it touching this wire?’ But that’s obviously incomplete information. If a robot is going to dismantle an improvised explosive device, it needs to know whether its hand is sliding along a wire or pulling on it. To hold on to a medical instrument, it needs to know if the object is slipping. This all requires the ability to sense shear force, which no other sensor skin has been able to do well,” UW mechanical and chemical engineering professor and senior author Jonathan Posner said in a press release.
Traditional tactile skins have not provided a full range of sensory information, and often the ability of fully instrumented fingers on robots to detect touch is limited to just that appendage, according to the report.
“Traditionally, tactile sensor designs have focused on sensing individual modalities: normal forces, shear forces or vibration exclusively. However, dexterous manipulation is a dynamic process that requires a multimodal approach. The fact that our latest skin prototype incorporates all three modalities creates many new possibilities for machine learning-based approaches for advancing robot capabilities,” UCLA mechanical & aerospace engineering associate professor and co-author Veronica Santos said in a prepared statement.
The skin was manufactured at UW’s Washington Nanofabrication Facility and is made from the same silicone rubber used in swimming goggles. The material can be embedded with conductive liquid metal that can stretch with the surface without the fatigue associated with solid wires.
As the filled channels in the ‘skin’ changes in geometry, the amount of electricity flowing through it is altered and can be measured to correlate with shear forces and vibrations.
“It’s really following the cues of human biology. Our electronic skin bulges to one side just like the human finger does and the sensors that measure the shear forces are physically located where the nailbed would be, which results in a sensor that performs with similar performance to human fingers,” lead author Jianzhu Yin said in prepared remarks.
The skin has been shown to be sensitive enough for light touch applications including opening a door, interacting with a phone, shaking hands, picking up packages, handling objects and can detect vibrations at 800 times per second, according to the report.
“By mimicking human physiology in a flexible electronic skin, we have achieved a level of sensitivity and precision that’s consistent with human hands, which is an important breakthrough. The sense of touch is critical for both prosthetic and robotic applications, and that’s what we’re ultimately creating,” Posner said in a press release.
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