Engineers in Stanford University’s Biomimetics and Dextrous Manipulation Lab have long been focused on biomimicry—especially related to geckos. Building on its gecko-inspired adhesive, which has been used on drones, former grad student Wilson Ruotolo, current grad student Dane Brouwer and Mark Cutkosky, Fletcher Jones Professor in the School of Engineering, set their sights on using the technology to create a multi-fingered, anthropomorphic gripper that is more versatile.
“You’ll see robotic hands do a power grasp and a precision grasp and then kind of imply that they can do everything in between,” Ruotolo said. “What we wanted to address is how to create manipulators that are both dexterous and strong at the same time.”
The duo’s research, published in Science Robotics, was inspired by biology. They created a human hand-like gripper with four fingers. Each finger features the innovative gecko-like adhesives. Of course, nothing is quite that simple. The research had two main challenges: creating the right tendons to control farmHand, and ensuring the adhesive would properly work on differently shaped objects.
“The first applications of the gecko adhesives had to do with climbing robots, climbing people or grasping very large, very smooth objects in space, but we’ve always had it in our minds to use them for more down-to-earth applications,” Cutkosky said. “The problem is that it turns out that gecko adhesives are actually very fussy.”
Following how gecko toes work, the adhesive has microscopic flaps that create a weak intermolecular force at the surface touching an object. While the adhesive is non-sticky and strong with only minimal force required, the adhesive has to precisely connect to a surface to activate the force. That is especially difficult when the surface is not flat.
Since the researchers aimed to test their gripper on various items, including eggs, plates, basketballs, and an angle grinder, their focus turned to the finger pads. They were designed with a collapsible rib structure that easily buckles. Regardless of the angle or area of contact, the pads are able to apply equal force.
“If you move these ribs, the buckling results in a similar force no matter where you start,” Brouwer said. “It’s a simple, physical behavior that could be deployed even in spaces outside of robotics, perhaps as shoe tread or all-terrain tires.”
The other challenge was the tendons. Instead of developing a traditional gripper, which typically pinch using a C shape, the farmHand uses the ends of its fingers, pressing the finger pads towards each other, which provides extra surface area for the adhesives to grip.
Making all of that happen provided the researchers an opportunity to explore other facets of engineering in addition to robotics. Their unique design wasn’t compatible with existing computer simulations. Instead, they used 3D modeling and 3D printing to test different parts of the gripper, which was an immeasurable time benefit.
While the initial research proved successful, the project itself isn’t necessarily done. The researchers hope to further enhance the gripper via user feedback and start to delve into how the gripper could be used in various industries.
Interested in other ways next-gen engineers are paving the way for the future? Check out Student Inventors Share Innovations in Healthcare, Solar Panels and More and The University of Texas Focuses on Ethical Artificial Intelligence in New Robotics Program.