When operators need to interact with an Unmanned Underwater Vehicle (UUV) that is busy running a mission, they typically rely on a laptop and a “deck box” with an acoustic modem from a chase boat. Additionally, due to the range limits of the acoustic modem, they need to be within range of the UUV, typically within roughly 1,000m.
Placing an Unmanned Surface Vehicle (USV), or an Autonomous Surface Vehicle (ASV), within range of the UUV provides a live communication link between the UUV and a remote operator. This enables the UUV to stay on task without having to surface to communicate, saving time and power onboard the UUV. It also provides the operator live feedback from the UUV to make real-time decisions based on up-to-date information. If new information comes to light, the operator can alter the existing mission while the UUV is underway.
As part of the Navy’s 2018 Advanced Naval Technology Exercise (ANTX) hosted at the Naval Undersea Warfare Center (NUWC) Newport, SeaTrac worked with the Naval Oceanography Special Warfare Center (NOSWC) and with Ocean Server to demonstrate the concept.
The SeaTrac ASV was fitted with a Teledyne Benthos C-Band acoustic modem to communicate with one of NOSWC’s Ocean Server Iver UUVs. With assistance from the team at Ocean Server, the SeaTrac team performed the integration work needed to access the “back seat driver” functionality in the Iver through the Benthos acoustic modem.
For the demonstration, the team programmed the NOSWC UUV and launched it from a small chase boat off the NUWC Narragansett Bay Test Facility (NBTF). The UUV followed a standard “mow the lawn” pattern, simulating a surveying mission. Throughout the mission, the SeaTrac ASV received position and status updates from the Iver, and relayed those updates back to shore, allowing the operator on shore to see in real time how the Iver was progressing.
– Hunter Brown , L3 Technologies
The SeaTrac ASV followed its mission to the UUV survey area, and established communications with the UUV, and the Iver started its survey mission.
The image below shows the operator’s live view on shore during the mission, at a time just after the Iver has completed its survey pattern. At this point, the Iver is drifting on the surface (the yellow icon), and the SeaTrac ASV is station-keeping at its programmed waypoint (the blue icon). The red dashed lines represent the ASV’s mission. The green path shows the path of the Iver: this data was transmitted from the Iver to the ASV with the acoustic modem (roughly every 15 seconds), and then relayed from the ASV to shore over the RF link.
During the mission, spectators in the booth were able to watch the progress of the Iver as it made its way through its survey.
Power and Speed: The acoustic modem draws very little power and has little impact on the SeaTrac ASV’s speed: ongoing communications with the UUV has little impact on overall power use.
RF Communications: The demonstration at Newport took place within sight of the booth on the NBTF pier, and so the direct line of sight RF link was sufficient. Cellular coverage was also good in the area, providing a second reliable link as a backup.
Acoustic Communications: The conditions in and around the NBTF are sufficient for undersea communications. For the demonstration, data was reliably sent and received between the ASV and the Iver.
An ASV equipped with an acoustic modem provides a cost-effective data relay between an operator and a UUV. This link provides real-time status back to the operator and can also enable the operator to redirect the UUV to perform a different task, without the need for the UUV to surface.
Hunter Brown from L3 Technologies adds: "Work with the SeaTrac team progressed efficiently. The team was able to integrate acoustic communications between the SeaTrac boat platform and the Iver UUV. Very minimal support was needed from the Iver team because of the combination of SeaTrac’s efforts and the user-customizable, open system Iver platform.”