If we want androids to perform human-like tasks as good (or better) than the rest of us, they need to accurately sense shear forces (unaligned forces pushing the body in two separate directions). Engineers from the University of Washington and UCLA may have finally bridged this gap – they’ve developed a flexible sensor "skin" that could help our artificial brethren successfully grasp and manipulate objects.
The ability to detect shear forces is a fundamental requirement for androids that can perform everyday tasks we take for granted. If an object – say, a fragile item like an egg – begins to slip from our grasp, our innate ability to sense its vibrations and shear forces tells us what’s happening without us seeing it.
"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," said Jonathan Posner, a UW professor of mechanical engineering and of chemical engineering.
Our human skin allows us to handle objects with varying degrees of care and without more obvious visual cues. Science Daily defines shear stress as a “stress state in which the shape of a material tends to change (usually by "sliding" forces -- torque by transversely-acting forces),” an evolutionary reaction within our bodies.
Robots haven’t, as of yet, achieved that level of precision.
"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,” said Posner.
The new stretchable skin – made from the same silicone rubber used in swimming goggles – can be fitted around a robot’s body or even a prosthetic hand (cue the sounds of ecstatic Sci-Fi fans), and this imparts the ability to detect vibrations and shear forces, and according to the researchers, perform tasks like opening a door, interacting with a phone, shaking hands, picking up packages, and handling objects, while “feeling” the light-touch applications.
Tiny serpentine channels – half the width of a human hair – within the rubberized skin include electrically conductive liquid metal (again with the jubilant Sci-Fi fans) that allows the skin to maintain its elasticity. Its sense of touch is actually superior to humans’ (uh oh…), with the ability to detect vibrations at 800 times per second.
Advancements like this – and not necessarily aesthetic concerns like the “uncanny valley” – will help clear the final hurdles to functional androids that can interact with and benefit humanity.