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How Autonomous is a HUGIN AUV?

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16. August 2017 by Richard Mills
This week I was reminded of an old rumour that has floated about the industry for many years. It concerns the ability of HUGIN to operate autonomously. There is a misconception that HUGIN AUVs only work if they are followed around with an expensive ship.

No-one disputes HUGIN is the most successful commercial AUV ever built. They have covered almost 1,000,000 line kilometres of contracted commercial survey work. HUGINs can carry a class-leading suite of payload sensors, and operate them all concurrently. These sensors include synthetic aperture sonars, multibeam echosounders, sub-bottom profilers, cameras, lasers, sniffers and so on.

The data set produced by HUGIN is simply unrivalled and can be collected without any input or supervision from an operator. The vehicle is designed to follow a mission plan on its own. This was a key requirement from the outset and continues to be the way the vast majority of our defence customers use their vehicles.

Why is Supervision Important for Data Quality?

The majority of commercial work that HUGINs perform requires a level of position accuracy that is unattainable by running autonomously. Even with a class-leading performance of 0.08% of distance travelled in a straight line for unaided navigation. Hence, the majority of commercial operators supervise their missions using a HiPAP positioning and communications system.

During supervised work, the AUV is running autonomously. We simply augment its performance by sending a position update very regularly. This limits the error budget of the navigation system making the data position as accurate as possible. After all, beautiful data is worthless if you do not know where it is.

In this configuration, we use a rule of thumb that real-time position accuracy will be approximately 1 metre for every 1000 metres of depth. Post-mission processing can bring that down further, making the data positioning the most accurate available today.

This level of supervision also provides other benefits. For example, real time sidescan imagery and bathymetry is transmitted to the operator for quality control purposes. Obviously, as there is an acoustic link we also have access to vehicle status and the ability to change settings or send commands directly to the HUGIN via the same HiPAP link.

In the last few years some commercial operations have required a different approach. HUGINs have been used autonomously in very shallow water. For example, running in less than 30 metre depth surveying plastic pipelines utilizing our own pipe tracking capabilities. Autonomous commercial missions have also used UTP (Underwater Transponder Protocol) which is our version of single beacon, or sparse LBL, navigation.

What is the Difference between Autonomy and Following a Mission Plan?

Just because an AUV can follow a mission plan does not make it truly autonomous. In this mode the vehicle is simply adhering to a complex "if – then" decision tree. Every action is determined in advance, be it heading and speed, or aborting if something goes wrong.

True autonomy comes from instinctively learning from the environment and changes around the vehicle. For example, we have demonstrated a HUGIN AUV equipped with in-mission autonomy that detected and classified mine-like objects. It then used this data to create a new mission plan to photograph the highest priority targets. This was completed without operator input.

Conclusion

So when considering AUV performance, please remember that HUGINs are truly autonomous. To optimize their performance for very strict commercial requirements, it can be necessary to provide external position updates. This flexible capability makes the HUGIN AUV System the most capable in the world today.

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About the author

Richard Mills

Director Subsea Solution Sales, Kongsberg Maritime

Richard has been with Kongsberg Maritime for 5 years, the majority of which has been as the Director of Sales for the Marine Robotics department. He specialises in the commercial application of Marine Robotics technology and is a board member of Eelume.

Prior to joining Kongsberg, Richard held a similar position at International Submarine Engineering Ltd based in British Columbia, Canada. Before joining the subsea world, he was a military helicopter pilot.