The twin-hull AUV with its innovative pitch and yaw thrusters.
A Newfoundland sonar company, in partnership with NRC and Memorial University, has developed a robotic vehicle that can navigate in any direction underwater without human intervention — all while carrying out complex missions.
Marport Deep Sea Technologies’ autonomous underwater vehicle (AUV) is suited for use in offshore energy, defence and ocean science applications, such as surveying underwater oil and gas pipelines or power cables, hunting for underwater mines, and mapping the seabed.
Marport’s first commercial AUV was completed in July 2012 for Geodetic Offshore Services Limited, which will use the robot vehicle to survey existing underwater pipelines or new pipeline routes out of West Africa. “The oil and gas industry is an obvious market for our vehicle because oil and gas companies are required to do video or sonar surveys of their pipelines every six months to a year,” says David Shea, Engineering Manager for the Marport subsidiary, Marine Robotics Inc. (MRI).
Engineering Manager of Marine Robotics Inc, launching the AUV.
Such surveys are normally done using a tethered underwater vehicle, which requires a surface ship, human pilot and operator. “We wouldn’t be where we are without NRC. To stay ahead of the competition, we need to keep developing, innovating and maintaining our relationship with NRC.” – David Shea, Marine Robotics Inc. “It costs about $30,000 to 50,000 a day just to support the ship,” says Shea. “But with an AUV, the surface ship can do other work while the AUV surveys the underwater pipeline.” An AUV can not only save survey companies tens of thousands of dollars per day, on average, but also produce higher quality, more accurate surveys.
To operate the AUV, “you program the mission, which consists of telling the vehicle what path it should take, at what depth and speed, and using which sensors,” adds Shea. “You load the plan, drop the vehicle into the water, push the start button and away it goes. Once the AUV completes its mission, it comes to the surface and calls you to pick it up, using either an RF (radio frequency) link or a satellite modem.”
Conventional torpedo-shaped AUVs feature a single hull and simple thrusters to propel them. The Marport AUV has a twin-hull design, which provides an optimum separation of sonar transmitters and receivers, so they provide higher resolution images.
The vehicle’s most innovative feature, however, is its thrust-vector propulsion system, for which a joint patent has been filed by Marport, NRC and Memorial University. “Our propulsion system allows the AUV to drive equally well forwards or backwards, move sideways like a crab, or hover in place like a helicopter,” says Shea. Unlike torpedo-shaped AUVs, which have a typical turning radius of 10 to 15 metres, the Marport vehicle can turn 360 degrees within a radius of just two metres, at top speed, or stop completely and rotate in place.
Besides surveying pipelines, “our AUV could also be used for mine-hunting applications,” says Shea. “Most torpedo-shaped AUVs need to keep moving to maintain stability, like an airplane. Our vehicle is more like a helicopter, since it can stop, hover and inspect an object.”
For this application, the AUV would do an “aerial” underwater survey, searching for mine-like objects from a certain “altitude” above the sea floor. “If it identifies anything suspicious, our vehicle could dive down and video the potential mine from close up,” says Shea. “By comparison, using other AUVs, you would have to survey the area, bring the vehicle to the surface, process the data, and then launch a tethered underwater vehicle from a surface vessel.”
Behind the scenes of a successful partnership
Marport’s underwater vehicle grew out of meetings between the company and NRC in 2006. “Their business involved the development of sonar equipment, mostly for the commercial fishing industry,” says Dr. Chris Williams, the NRC project coordinator. “Marport had heard that NRC has expertise in underwater vehicles, so they asked if we could combine our skills to produce an AUV to help them demonstrate and sell new and existing sonar equipment.” The company applied for an Atlantic Initiative Fund grant and was awarded $2.2 million in January 2008.
Development of the AUV began later that year. “In 2008, I was the second employee of Marport’s AutonomousSystems department,” says David Shea. “By January 2011 — with the injection of funds and NRC’s ongoing support — we had spun off the department into MRI (Marine Robotics Inc.), which currently employs 12 people in St. John’s.”
While the Marport/MRI team developed the actual AUV, NRC’s “one-stop shop” provided the company most of the services it needed. “We started off at the concept design level,” says Dr. Williams. “We did model testing in our towing tank and wave basin. And we designed a custom propeller to give the AUV the highest possible propulsion efficiency.” Further testing was conducted at Memorial University’s flume tank facility and their Holyrood Marine Base.
NRC experts fabricated the vehicle’s fibreglass shell, which covers the hull, nose and tailpieces. NRC researchers, led by Dr. Moqin He, also developed a hydrodynamic model of the AUV’s behaviour, from which a vehicle simulator was built. This allowed the company to predict how the vehicle would perform under real-world conditions, including strong ocean currents. In addition, NRC provided Marport with financial and technical support via the Industrial Research Assistance Program.