Unmanned, Under the Sea
Unmanned underwater or undersea vehicles (UUV) are typically used to detect mines and map out the ocean floor. There are two very different groups of UUVs: Remotely operated underwater vehicles (ROVs) are controlled through a tethered line, while autonomous underwater vehicles (AUVs) operate independently. Since 2008, most AUVs have been designed to mimic nature in both appearance and movement. These vehicles, commonly known as biomimetic vehicles, are sought after because they look natural.
The Robotic Jellyfish – The U.S. Navy, alongside researchers from Virginia Tech and the University of Texas at Dallas, have spent months studying the mechanics of jellyfish propulsion and redesigning the Robojelly, a reconnaissance robot resembling a jellyfish.
The Robojelly, created with Bio-Inspired Shape Memory Alloy Composites (BISMAC) actuators, is fabricated to mimic real locomotive behaviors of jellyfish. It’s coated with multi-walled carbon nanotubes in a nano-platinum catalyst powder, which creates heat when exposed to hydrogen and oxygen. Then the nanotubes are wrapped around a nickel-titanium shape memory alloy. The exothermic reaction between the metal and the water sparks the shape memory alloy to change its shape, contracting and moving forward. “To our knowledge, this is the first successful powering of an underwater robot using external hydrogen as a fuel source,” says Yonas Tadesse, assistant professor of engineering at the University of Texas at Dallas.
The BIOSwimmer™ – The U.S. Department of Homeland Security (DHS) relies on unmanned underwater vehicles to combat criminal activity in and around American waterways. Its Science and Technology Directorate is funding the development of a UUV designed to resemble tuna called the BIOSwimmer. According to the DHS, tuna have a natural body framework ideal for UUVs, which solves some propulsion and maneuverability problems that plague conventional UUVs.
“We’re using nature as a basis for designing and engineering a system that works exceedingly well,” says David Taylor, program manager for the BIOSwimmer at the DHS. In 2009, Boston Engineering Corporation’s Advanced Systems Group (ASG) in Waltham, Mass., was awarded the contract to develop the BIOSwimmer. The UUV uses an onboard computer suite for navigation, sensor processing and communications. “It’s designed to support a variety of tactical missions and with its interchangeable sensor payloads and reconfigurable operator controls can be optimized on a per-mission basis,” says Michael Rufo, director of the ASG.