Creepy robotic hand detaches at the wrist before scurrying away to collect objects

Engineers have built a detachable robotic hand that can crawl into hard-to-reach spaces to retrieve objects.

The spider-like device can be fitted with multiple fingers and is reversible, meaning it can grip objects in both directions and operate as though it has two functional palms.

In a study published Jan. 20 in the journal Nature Communications, scientists at the Swiss Federal Technology Institute of Lausanne (EPFL) said the robot was designed to combine two capabilities that are usually kept separate in robotics: manipulation and locomotion.

The hand can also operate without a full, mobile robot base. Instead, it simply detaches itself from a robotic arm and scuttles off to wherever it is needed, picks up the object and returns to reattach itself.

This could make it useful in situations where robots need to reach or retrieve objects from spaces that are too tight or too dangerous for human arms to access, such as industrial or exploratory environments and areas affected by disasters, the researchers noted.

"We can easily see the limitations of the human hand when attempting to reach objects underneath furniture or behind shelves, or performing simultaneous tasks like holding a bottle while picking up a chip," study co-author Aude Billard, head of the Learning Algorithms and Systems Laboratory in EPFL's School of Engineering, said in a statement.

"Likewise, accessing objects positioned behind the hand while keeping the grip stable can be extremely challenging, requiring awkward wrist contortions or body repositioning."

Handy robotics

Robotic appendages, like hands, have been built before. The human hand is, after all, considered a biological marvel; it's given humans the dexterity needed to make tools, prepare food and build shelter, all of which have proved key to our survival as a species.

Still, human hands do have some distinctly biological limitations, the scientists noted. For example, our asymmetrical thumbs and our hands' permanent attachment to our arms.

EPFL's robot is essentially a self-contained system that can either act like a normal "gripper" on the end of an arm or detach itself and scurry about on its own. The design draws inspiration from nature, with the researchers likening it to how an octopus uses its arms to move across the seafloor and open shells, or how a praying mantis uses its spiked forearms to both move around and catch prey.

In experiments, the researchers demonstrated the hand performing various standard gripping and grasping exercises, as well as accomplishing more fiddly feats of dexterity that humans routinely struggle with. These included holding multiple objects at once or gripping objects without using the thumb or forefinger.

Not only can the robotic hand grasp up to four objects simultaneously, it can also crawl across the floor while carrying items on its "back."

Each of the robot's fingers is driven by small electric motors and linked by lightweight 3D-printed joints, allowing them to curl and spread much like human fingers. Unlike a human hand, however, each finger joint can bend both forward and backward, allowing it to grab objects in both directions and "flip" its working orientation without needing to rotate at the wrist.

The fingertips are capped with a soft silicone layer to add friction, making it easier to hold objects securely and maintain traction when crawling. "There is no real limitation in the number of objects it can hold; if we need to hold more objects, we simply add more fingers," Billard said.

The hand reattaches itself to the arm using a "snap-and-lock" system. Magnets help align the connectors, and a small motor drives a locking bolt that secures the joints.

The system could eventually be adapted for human prosthetics or "extra limb" augmentation, the team said, though this isn't the focus of the current prototype.

"The symmetrical, reversible functionality is particularly valuable in scenarios where users could benefit from capabilities beyond normal human function," Billard said.

"For example, previous studies with users of additional robotic fingers demonstrate the brain's remarkable adaptability to integrate additional appendages, suggesting that our non-traditional configuration could even serve in specialized environments requiring augmented manipulation abilities."