Over the summer, the U.S. Navy began deploying underwater charging stations for unmanned undersea vehicles (UUVs). This technology is completely devoid of cables, making it easier for drones to charge out at sea. Wireless charging (also known as inductive charging), was originally developed for smaller electronics like smartphones and tablets. The process simply involves setting your phone down on a flat charging mat, during which the charger emits an alternating magnetic field that induces an alternating current in a receiver coil to the device.
Due to its slowness compared to conventional methods, wireless charging has struggled to become ubiquitous. This isn’t discouraging the U.S. Navy, which has been expanding their research and development into unmanned underwater vehicles. One of the Navy’s projects is focusing on the development of torpedo-shaped robots programmed to do a variety of tasks from reconnaissance and mine hunting, to ocean floor mapping and being capable of engaging in anti-submarine warfare. These crafts are electrically powered, quiet, and can travel great distances.
The Navy’s projects on wireless charging of unmanned crafts started with a simple demonstration, after Project Manager Wayne Liu ably ran a proof-of-concept using his cellphone that still charged on a pad while being placed inside a plastic bag.
“Currently, if the Navy buys one underwater vehicle and some sort of charger, it will only work that that brand or that particular type,” says Alex Phipps of U.S. Department of Defense’s Space and Naval Warfare Systems Center Pacific (SPAWAR). “What we’re looking to do is capture the common elements that can be reused for vehicles, and create a standard that we can give to industry.”
The demonstration was a success, prompting SPAWAR researchers to look into setting standards for underwater wireless power transfer devices. In July, researchers from the Naval Surface Warfare Center’s Carderock Division transferred two kilowatts of electricity from a submerged wireless charging station to a section of the Navy’s mid-sized autonomous research vehicle. While these preliminary tests have been encouraging, there are two main issues scientists and engineers are facing.
The first is how the current recharging methods require the unmanned crafts to land or dock via a surface ship. This exposes the underwater vehicles, which limits their capabilities on remote autonomous operations. Another issue is the difficulty of these vehicles plugging themselves into charging stations. Sea drones must currently return to their base and be manually connected by humans in order to recharge. One of the approaches researchers are taking is aiming to make charging stations wireless, so these unmanned robots can simply land on top to start. Not only would this remove the human element from the recharging process, but it would also enable these stations to be remotely deployed in areas where UUVs operate.
Unscrewed underwater vessels are being relied upon in operations like surveillance, but must either land or surface to properly recharge, which is something SPAWAR wants to change. One of the ways they hope to achieve this task is by deploying underwater charging systems, and establishing a standard in the process, so all such systems work in this manner.
