Stretchable skin-like robot crawls and convey objects
In a paper titled “All-Soft Skin-Like Structures for Robotic Locomotion and Transportation” published in the journal of Soft Robotics, the researchers led by Professor of Robotics Jonathan Rossiter developed what they describe as ElectroSkin robots, consisting of dielectric elastomer actuators (DEAs) and soft electroadhesives (EAs) in a fully compliant multilayer composite skin-like structure.
regions powered for electroadhesion and actuation.
The dielectric elastomer actuators were simply made of deformable dielectric membranes sandwiched between two compliant electrodes (made of conductive silicone), in effect, forming soft and variable parallel capacitors that can be deformed under the application of an electric field due to Maxwell pressure.
The soft-stretchable electroadhesives consist of compliant planar electrodes embedded in a soft dielectric, they behave like variable coplanar capacitors which produce controllable adhesion (as electrostiction) under a voltage. Applying an electric field between the electrodes causes polarization in any object in direct contact and induces electrostatic attraction forces.
The paper describes how through a careful timing of electroactivation, the actuation of the DEA pairs and the adhesion and release cycles of the EA pairs can be sequenced into a grip-move-release-relax cycle that will incrementally move the soft robot skin across a surface or alternatively, acting as a thin conveyor belt, move an object across its surface. More simply explained, moving in a fashion similar to soft organisms like snails and slugs, the soft robot crawls across the surface by alternately contracting its artificial muscles and gripping the surface using electrical charges.
To prove the concept, the authors designed a soft self-actuating conveyor belt able to transport small objects at a speed of 0.28 mm/s. Since the active areas can be exploited as electromechanical actuators or as electrostatic gripper elements, or both simultaneously, the ElectroSkin robot can be driven in many different modes and future optimized designs could enable such robots to crawl up walls and across ceiling, explore difficult to reach environments including collapsed buildings.
The researchers also demonstrated an untethered ElectroSkin conveyor, based on a miniature microprocessor, a Li-Po battery, and two small and lightweight high-voltage amplifiers. Next they plan to integrate stretchable triboelectric nanogenerators to aim for self-powered ElectroSkin robots.
“ElectroSkin is an important step toward soft robots that can be easily transported, deployed and even worn. The combination of electrical artificial muscles and electrical gripping replicated the movements of animals like slugs and snails, and where they can go, so could our robots!”, commented Professor Rossiter.
University of Bristol – www.bristol.ac.uk
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