Engineers from the University of Washington (UW) and UCLA have developed a flexible sensor “skin” designed to accurately sense vibrations and shear forces.
This “skin” is designed with the ability to be stretched over any part of a robot’s body or a prosthetic, and accurately convey information about shear forces and vibration that are critical to successfully grasping and manipulating objects, notes a media release from University of Washington.
According to research funded by the National Science Foundation and recently published in Sensors and Actuators A: Physical, it can mimic a way a human finger experiences tension and compression as it slides along a surface or distinguishes among different textures, and measure this tactile information with similar precision and sensitivity as human skin.
The research team is a collaboration between the UW College of Engineering and the UCLA Henry Samueli School of Engineering and Applied Science.
“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,” says senior author Jonathan Posner, a UW professor of mechanical engineering and of chemical engineering.
“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,” he adds.
The skin, manufactured at the UW’s Washington Nanofabrication Facility, is made from the same silicone rubber used in swimming goggles. The rubber is embedded with tiny serpentine channels—roughly half the width of a human hair—filled with electrically conductive liquid metal that won’t crack or fatigue when the skin is stretched.
When the skin is placed around a robot finger or end effector, these microfluidic channels are strategically placed on either side of where a human fingernail would be, the release explains.
“Traditionally, tactile sensor designs have focused on sensing individual modalities: normal forces, shear forces or vibration exclusively. However,” states co-author and robotics collaborator Veronica Santos, “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,” continues Santos, an associate professor of mechanical and aerospace engineering at UCLA.
The researchers suggest that the skin has a high level of precision and sensitivity for light touch applications—such as opening a door, interacting with a phone, shaking hands, picking up packages, and handling objects—and can detect tiny vibrations at 800 times per second.
“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,” Posner concludes, per the release. “The sense of touch is critical for both prosthetic and robotic applications, and that’s what we’re ultimately creating.”
[Source(s): University of Washington, Science Daily]