Engineers at the University of British Columbia have collaborated with the Japanese automotive company Honda to develop an e-skin for robotic prostheses that allows such devices to sense their environment in significant detail. The soft skin is highly sensitive, letting robotic hands to perform tasks that require a significant degree of dexterity and tactile feedback, such as grasping an egg or lifting a glass of water without breaking it. The elastomer skin contains fixed and sliding pillars that allow it to buckle and wrinkle, like real skin. The skin contains four deformable capacitators that let it distinguish between normal and shear forces, meaning that it can finely control its interaction with grasped objects. The researchers hope that the technology will enhance robotic prostheses and allow users to expand the range of daily activities they can perform using their prosthetic devices.
Robotic prostheses are evolving, and sensors are required to evolve in tandem. Grasping delicate objects with a robotic hand could spell disaster without a sensor that can measure how much force is being applied and determine the correct amount of force to apply. After all, our own skin is highly attuned to the subtleties of the objects we touch. Skin-like sensors continue to progress, with a variety of technologies emerging in recent years that can permit robots and robotic prostheses to sense their environment more comprehensively.
This latest e-skin is highly sensitive, expanding the types of activities that are possible. “Our sensor can sense several types of forces, allowing a prosthetic or robotic arm to respond to tactile stimuli with dexterity and precision,” said Mirza Saquib Sarwar, a researcher involved in the study. “For instance, the arm can hold fragile objects like an egg or a glass of water without crushing or dropping them.”
The technology may also be useful for medical or assistive robots, such as those that care for the elderly, or even surgical robots that interact with soft tissues inside the body. “Our sensor uses weak electric fields to sense objects, even at a distance, much as touchscreens do,” said John Madden, another researcher involved in the study. “But unlike touchscreens, this sensor is supple and can detect forces into and along its surface. This unique combination is key to adoption of the technology for robots that are in contact with people.”
The skin is easy to fabricate at scale, and can be made in large sheets that can cover significant areas. However, the researchers are keen to stress that this technology will evolve much further in the future. “Human skin has a hundred times more sensing points on a fingertip than our technology does, making it easier to light a match or sew,” said Madden. “As sensors continue to evolve to be more skin-like, and can also detect temperature and even damage, there is a need for robots to be smarter about which sensors to pay attention to and how to respond. Developments in sensors and artificial intelligence will need to go hand in hand.”
Study in journal Scientific Reports: Touch, press and stroke: a soft capacitive sensor skin