The challenge

AUVs are playing an ever-greater role in the naval warfare playbook. Their ease of mobilisation is making them a go-to technology across survey, security and mine countermeasures. But navies still want accurate positioning and look to USBL-aided navigation to support their AUV and unmanned underwater vehicle (UUV) operations.

Using USBL position aiding to support underwater vehicle inertial navigation is key way to underpin accurate vehicle operations, reduce errors margins and improve efficiency. Regular, accurate position updates from a USBL system ensure the vehicle’s INS maintains accuracy, which can be critical in challenging environments.

This is just what a customer of L3Harris wanted. The customer chose our Mini-Ranger 2 USBL positioning system to aid the third-party INS on their L3Harris Iver3 AUV. The customer had already used Mini-Ranger 2 with another UUV and had been impressed with its performance and ease of use.

The solution

Mini-Ranger 2 is the ideal USBL system for coastal operations, supporting high-elevation tracking of up to 10 targets simultaneously down to 995 m water depth (extendable to 4,000 m), as well as data harvesting. It offers performance without the cost and complexity of a deepwater USBL system. To provide INS aiding on their Iver3, L3Harris’ customer chose to integrate our AvTrak 6 OEM Nano into their Iver3.

AvTrak 6 OEM Nano is the smallest variant of our AvTrak transceiver, designed for use on small underwater vehicles. It combines the functions of a transponder, transceiver and telemetry link, enabling communications, tracking and USBL aiding for subsea robotics. It’s also based on our 6G hardware platform, which means it’s interoperable with all our USBL, LBL and INS systems. This provides flexibility, but also performance enhancement, for example when combined with a Sonardyne INS.

USBL-aided navigation with a third-party INS – not a problem

Although L3Harris AUV Systems was only tasked with integrating the AvTrak 6 OEM, it decided to go a few steps further, making sure it spoke the right language as the third-party INS. Specifically, that meant making sure the AvTrak 6 OEM Nano would be able to send out a PSIMSSB telegram, instead of our proprietary SPOS, to the vehicle’s INS. Our engineers here at Sonardyne were able to support this change, simplifying the integration for the L3Harris AUV Systems team.

AvTrak 6 OEM Nano is designed with no housings, so that it’s easy to install for vehicle integrators. However, our engineers also provided the AvTrak 6 transducer on a special Iver3 mounting post design, so it was easy to plug and play into the Iver3. This is now available for the Iver3 vehicles going forward, as standard.

The results

Following integration, L3Harris AUV Systems carried out successful performance testing, validating the ability of the Mini-Ranger 2 to aid the third-party INS via our AvTrak 6 OEM Nano. The team at AUV Systems was also impressed with our Ranger 2 software, allowing them to easily visualise where the Iver3 was subsea both relative to the vessel and its absolute positioning.

“The support from Sonardyne’s engineering team, applications group and the Sonardyne Inc. team has been a great bonus to this project for us and our client. Because of this support, we were able to go ahead and perform a full integration and validate the performance, which more than met our expectations. Aiding an AUV INS with a USBL is now a real customer requirement and through Sonardyne we’re able to offer this on our Iver3 vehicles.” – Morgan Eash, Project and Applications Engineering Manager – L3Harris AUV Systems.

Deeper integration, further improving performance

What’s more, L3Harris is now also exploring deeper integration to allow the vehicle to utilise the AvTrak 6’s diagnostics capability. By providing the vehicle with information of the acoustic environment the vehicle’s autonomy could make decisions to adjust the AvTrak 6 OEM Nano’s power and gain settings to improve acoustics without a human in the loop.

Using Mini-Ranger 2’s optional Robotics Pack software, the customer also has the option to track up to 10 vehicles on one common interrogate, providing absolute position of all ten vehicles and the surface vessel to each vehicle.  This allows for better situational awareness for each vehicle enabling swarms.

Get in touch if you would like to know how will can support your AUV and UUV operations.