Robotic hand dexterous enough to use tweezers

Humanoid robots are a staple of science fiction, from C-3PO in Star Wars to Data in Star Trek, and they’re also now used widely in today’s world of medicine and biotechnology.

But these robots still face some problems – they have never really been very good at using their hands. Human hands are amazingly complex, capable of a range of tasks from picking up delicate objects to manipulating large tools. These fine motor skills in particular have been challenging for robots to replicate.

Now, in research published in Nature Communications, Korean engineers have developed a robotic hand capable of tasks like picking up an egg, using scissors and manipulating tweezers.

“Interpreting the extremely complex functioning of the human hand remains an unresolved challenge in the field of robotics,” writes the research team, led by Uikyum Kim from Ajou University in Korea.

“Out of the 206 bones in the human body, 54 bones are in the hands, corresponding to a quarter of the total number of bones; the muscle structure driving them is also extremely complex.

“In addition, the tactile corpuscles, which enable tactile sensation, are mostly distributed in the hand, and they help in performing delicate tasks.”

Called ILDA (integrated linkage-driven dexterous anthropomorphic), the new hand solves some of these problems. It’s 22 centimetres long and has five robotic fingers, each tipped in a fingertip sensor. It consists of 20 joints (including three for each finger, matching a human’s finger), allowing for 15 degrees of freedom in movement.

Other robotic hands have similar degrees of freedom, but have a weak gripping force in the fingertips. This new hand is capable of exerting 34 Newtons of force, so it has the best of both worlds, while weighing only 1.1kg.

The researchers tested ILDA with a variety of tasks that seem very simple but are difficult for robots.

For example, it crushed an aluminium can; delicately grasped an egg; cut paper with scissors; and used tweezers to manipulate small objects.

Crucially, ILDA integrates all the parts needed for responsive movement, sensing and dexterity, so it can be mounted onto existing commercial robot arms without the need for additional parts such as forearms.

This is a step forward for the field, according to the researchers.

“Developing integrated hands without additional actuation parts while maintaining important functions such as human-level dexterity and grasping force is challenging,” they explain in their paper. “The actuation parts make it difficult to integrate these hands into existing robotic arms, thus limiting their applicability.”

But by being mounted on a commercial robot arm, this new hand can better perform useful manipulation tasks using real-world tools. The next step: bringing down the cost. And maybe learning to coordinate two hands at once.

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