In the underwater domain, the US Navy (USN) has been testing its first XLUUV test asset system (XLE0) – delivered by Boeing in December 2023 – in the Southern California operational area. “These tests are intended to find issues to allow us to develop solutions and implement lessons learnt for the future XLUUV vehicles,” Capt. Scot Searles, Programme Manager, Unmanned Maritime Systems, said. Thus far, the main areas of learning and improvement have been battery function and vehicle software. These tests also provide an opportunity to develop training and standard operating procedures for sailors and civilians to support the future XLUUVs.
For the unmanned surface vehicles (USV) domain, Capt. Searles also provided detailed statistics on the performance of the USVs’ autonomy systems. “In the last 2 years we’ve collected nearly 10,000 hours of autonomy data on our prototype vessels, which travelled over a 100,000nm steered by autonomous control,” Capt. Searles explained. “In all that 10,000 hours of autonomous operations there has not been a single collision (real or simulated).”
More specifically, Capt. Searles explained how USVs performed under the supervision of crews during the Integrated Battle Problem (IBP) 23.2 multi-domain unmanned capabilities exercise under U.S. Pacific Fleet’s Experimentation Plan. During the exercise, which concluded in January 2024, four USVs – Mariner, Ranger, Seahawk, and Sea Hunter – traveled a combined 46,651 nautical miles to make port visits to Pearl Harbor, Papua New Guinea, Yokosuka (Japan), and Sydney (Australia).
IBP 23.2 has allowed the USN to identify 157 distinct human interventions – I.e., crew stopping the USV – due to on vessel issues. That is equivalent to one intervention every 28 hours. However, of those interventions over two thirds were related to issues with Government Furnished Equipment (GFE) C4I systems (reloading crypto or losing crypto synchronization) or were done for operator convenience (take control of the system to go faster or slower than autonomous navigation). Of the remaining 48 human interventions, only 17 interventions were done for sensing and perception issues, and of those only 9 related to concerns with maneuvering decisions from the autonomous system.
“This all puts the meantime between human interventions for autonomy at once every 4 days but under good weather conditions (I.e., not chasing false contacts) it is more like once every 12 days,” Capt. Searles concluded.
“As such, autonomy reliability requires interventions only once every 12 days and HM&E only once every 17 days, so we are very pleased with performance of systems but also happy that we are finding limits and getting those limits addressed.”
Capt. Scot Searles, Programme Manager, Unmanned Maritime Systems
Over the coming months, the USN will continue testing its autonomy software to increase its levels of maturity. This will include also work on defining clearer engineering operations autonomy, that is, understanding how autonomous systems can retain continued awareness of their systems’ functioning – normally a watch stander’s role on a manned ship. Capt. Searles also explained that the Medusa system, which bring the payload delivery capability to the submarine torpedo tube, continues apace, with a contract award by this summer. The programme, however, will take a few more years than a normal UUV/USV programme because it will include weapon system and delivery certification.
