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Sensors already used by unmanned underwater vehicles were tested for use on unmanned surface vehicles in support of missions in coastal waters. It was part of the UK’s DASA program to fast-track autonomous vehicle capability in challenging or harsh conditions.

Loss of satellite-based timing signals needed for navigation and positioning can occur in ports and harbors around tall structures or close to cliffs or inside fjords, where GPS or GNSS receivers may not have a clear line of sight with the sky. It can also happen through deliberate signal jamming or degrading of performance, known as spoofing.

Most USVs rely on uninterrupted GPS or GNSS signal updates to inform their situational awareness and plot a course safely. When there’s no signal, or what’s called spoofing or jamming, USVs must consider alternative navigation sensors and instruments or they need to be remotely piloted adding expense and risk to over-the-horizon operations.

Sonardyne’s SPRINT-Nav hybrid inertial navigation instrument was integrated into a 2 m-long SEA-KIT X and tested against local real-time kinematic (RTK) GPS positioning. The sensor is already proven as a reliable navigation instrument for unmanned underwater vehicles, which operate in what is effectively a GPS or GNSS denied environment. Now it will also be used to provide a high-integrity, continuously available navigation solution for a USV, like SEA-KIT X, operating in littoral zones in water depths up to 150 m, according to thedigitalship.com.

SEA-KIT is a 10,000 nautical mile-range vessel able to carry up to 2.5 tonnes of payload and deploy and recover autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs). This capability, and flexibility, means it is well suited to support naval missions including intelligence gathering, hydrographic survey and as a communications gateway.