Inspired by jellyfish, this tentacle robot could grasp fragile objects delicately

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new type of soft, robotic gripper that utilizes thin tentacles to grasp fragile or priceless objects.

The team of researchers turned to nature to take some inspiration from while designing the gripper and avoided complex mechanisms such as embedded sensors feedback loops or advanced machine learning algorithms along with the skill of an operator.

Tentacles alone are not that strong to get the job done; however, the filaments grasp and hold heavy or irregularly shaped objects together –just like jellyfish collect stunned prey. It takes simple inflation for the gripper to wrap around the desired object; it doesn’t need sensing, planning, or feedback control.

“With this research, we wanted to reimagine how we interact with objects,” said Kaitlyn Becker, former graduate student and postdoctoral fellow at SEAS and first author of the paper, in a press release published by the institution. “By taking advantage of the natural compliance of soft robotics and enhancing it with a compliant structure, we designed a gripper that is greater than the sum of its parts and a grasping strategy that can adapt to a range of complex objects with minimal planning and perception.”

The handy gripper

The foot-long filaments are made of rubber tubes, and there's nothing in them. One side of the tube is thicker than the other; this way, the tube curls easily when it's pressurized, and wraps around the object.

To put the gripper to test, the researchers had it pick up various objects such as houseplants and toys. It could be used while picking up fruits and vegetables in agricultural applications, or in settings where delicate tissue operations are needed.

“Entanglement enables each highly compliant filament to conform locally with a target object leading to a secure but gentle topological grasp that is relatively independent of the details of the nature of the contact,” said Professor L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics in SEAS, and of Organismic and Evolutionary Biology, and Physics in FAS and co-corresponding author of the paper.

“This new approach to robotic grasping complements existing solutions by replacing simple, traditional grippers that require complex control strategies with extremely compliant, and morphologically complex filaments that can operate with very simple control,” said Wood, the Harry Lewis and Marlyn McGrath Professor of Engineering and Applied Sciences and co-corresponding author of the paper. “This approach expands the range of what’s possible to pick up with robotic grippers.”

The research has been published in the Proceedings of the National Academy of Sciences (PNAS).

Abstract:

Grasping, in both biological and engineered mechanisms, can be highly sensitive to the gripper and object morphology, as well as perception and motion planning. Here, we circumvent the need for feedback or precise planning by using an array of fluidically actuated slender hollow elastomeric filaments to actively entangle with objects that vary in geometric and topological complexity. The resulting stochastic interactions enable a unique soft and conformable grasping strategy across a range of target objects that vary in size, weight, and shape. We experimentally evaluate the grasping performance of our strategy and use a computational framework for the collective mechanics of flexible filaments in contact with complex objects to explain our findings. Overall, our study highlights how active collective entanglement of a filament array via an uncontrolled, spatially distributed scheme provides options for soft, adaptable grasping.