Researchers from Harvard University and the City University of New York (CUNY) have developed soft robotic grippers that can be used for the non-destructive sampling of fauna from the ocean floor. In doing so, they demonstrated a new fabrication technique to rapidly create soft actuators.

Robotic hands that are standard issue on underwater remotely operated vehicles (ROVs)—designed for undersea construction and to install and repair submerged pipelines—are generally ill-suited to collecting delicate coral, sponge and other samples.

As such, Robert Wood, Harvard engineer and roboticist, and David Gruber, associate professor of biology and environmental sciences at CUNY, set out to design two types of hands to replace the ROV’s factory-furnished metal gripper. Each gripper needed to be capable of recovering objects of different sizes and shapes. One, inspired by the coiling action of a boa constrictor, can access tight spaces and clutch small and irregularly shaped objects. The other, a bellows-style model, features opposing pairs of bending actuators.

The soft robotic gripper is attached to the remotely operated vehicle. Image credit: Kevin Galloway/Wyss Institute.The soft robotic gripper is attached to the remotely operated vehicle. Image credit: Kevin Galloway/Wyss Institute.Harvard's Office of Technology Development has filed a patent application on the method devised for the manufacture of the bellows-type soft actuators. The method is scalable, potentially opening a range of commercial, biomedical and industrial applications.

The biggest design challenge, Wood says, was a lack of precise specifications. The team had no way of knowing the size, shape or stiffness of the objects they would be sampling on the ocean floor. To approximate likely specimens, they purchased an assortment of vegetables, tied them to a metal grate and dropped them into a test tank. After tank tests, the devices were tested in the northern Red Sea in May 2015. The researchers conducted more than a dozen dives ranging from 100 to 170 meters. They used the grippers to retrieve samples of delicate red soft coral, as well as difficult-to-snag coral whips, and bring them to the surface undamaged in the ROV’s cargo tray.

Wood has several performance enhancements he intends to develop for the technology, including applying his lab’s expertise in soft sensors to let an operator “feel” what the gripper is touching and experimenting with bilateral, rather than single-arm, manipulation to achieve improved dexterity. Ultimately, the team hopes to conduct field work up to 6,000 meters underwater.

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