A new robotic gripper can “feel” what it’s holding, much like natural human skin. Developed by researchers from the City University of Hong Kong (CityU), Carnegie Mellon University, and the Southern University of Science and Technology, the tactile sensor could give prosthetics a more human sense of touch.
Human skin naturally senses shear force: the direction, magnitude, and subtle changes in how an object slips and slides across the skin’s surface. When grasping an object, the skin on the hands and fingers provide feedback allowing the brain to make subtle adjustments in the hand’s grip to keep the object stable and safe, without holding it too tightly.
The research team replicated the ability to sense shear force by creating a flexible, artificial skin with multiple layers, similar to natural skin. The artificial skin’s top layer is made of a thin, supple magnetized film; it depresses when in contact with an object. Measuring the change in the magnetic field within the depression allows the sensor to detect the object’s shear force. It also measures normal perpendicular force separately from shear force.
Furthermore, the tactile sensor works with a deep learning algorithm that provides “super-resolution.” This feature enables the sensor to precisely locate the object’s position. This level of precision may give engineers the ability to create tactile sensor arrays using minimal sensing units, reducing electronic hardware and increasing response time.
Mounted on the robotic gripper’s fingertip, the tactile sensor helped the robot grasp fragile objects, such as an egg. The gripper also performed delicate tasks, such as threading a needle. The same gripper held a bottle still while a researcher increased its weight by filling it with liquid. An identical gripper without the new sensor dropped the bottle because it couldn’t adjust its grip to accommodate the heavier amount of liquid.
The researchers recently published their findings in the journal Science Robotics. The team believes their work could lead to tactile sensor arrays incorporated into continuous electronic skin. That could give robotic prosthetics surface-wide sensing capability. That kind of artificial skin may even cover domestic robots eventually, enabling them to perform everyday tasks with human-like precision.