The team's new robotic gripper is precise, strong, delicate, and dexterous enough to handle objects. (Image Credit: North Carolina State University)
North Carolina State University researchers created a robotic gripper that possesses extreme delicacy, strength, dexterity, and precision when handling objects. In that case, it can pick up a drop of water, lift a 6.4 kg weight, partake in cloth-folding, and lift ultra-thin microfilms. The team believes the gripper could serve as a useful robotic prosthetic since a human's forearm muscles generate the essential electrical signals to control it.
"It is difficult to develop a single, soft gripper that is capable of handling ultrasoft, ultrathin, and heavy objects due to tradeoffs between strength, precision and gentleness," says Jie Yin, corresponding author of a paper on the work and an associate professor of mechanical and aerospace engineering at NC State. "Our design achieves an excellent balance of these characteristics."
The team's latest design for these grippers builds on kirigami-inspired grippers. Kirigami is the art of cutting and folding 2D material sheets to create 3D shapes. These new grippers have some significant improvements, including the fundamental structure and the gripper's trajectory. Additionally, it has high strength and gentleness due to its ability to distribute force evenly throughout the gripper's structure.
We typically measure a robotic gripper's strength using the payload-weight ratio. So since the NCU gripper weighs 0.4 grams and lifts 6.4 kg, it has a 16,000 payload-to-weight ratio. This is 2.5 times higher than the previous record with a 6,400 payload-to-weight ratio. Combining all the important characteristics like strength, precision, and gentleness allows the grippers to be used in different applications.
Even better, the grippers' characteristics are driven by their structural design rather than the materials used to fabricate them. That's more practical because they can be fabricated out of biodegradable materials, like sturdy plant leaves. This makes them useful for short-term applications like biomedical materials or handling food. And the team showed that the grippers can handle sharp medical waste like needles.
The gripper turns pages of a book when connected to a myoelectric prosthetic hand. (Image Credit: North Carolina State University)
In addition, they connected the gripper with a myoelectric prosthetic hand, which is controlled via the wearer's muscle activity. "This gripper provided enhanced function for tasks that are difficult to perform using existing prosthetic devices, such as zipping certain types of zippers, picking up a coin, and so on," says Helen Huang, co-author of the paper and Jackson Family Distinguished Professor in the Joint Department of Biomedical Engineering at NC State and the University of North Carolina at Chapel Hill.
While this new gripper can't take over all the prosthetic hands' functions, it can supplement the other ones. Also, wearers won't need to replace or augment the motors already installed in robotic prosthetics because they can simply take advantage of existing motors when using the grippers.
During their tests, the team demonstrated that these grippers plucked grapes from a vine or turned book pages. "We think the gripper design has potential applications in fields ranging from robotic prosthetics and food processing to pharmaceutical and electronics manufacturing," Yin says. "We are looking forward to working with industry partners to find ways to put the technology to use."
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