Collaborating underwater ‘drones’ offer good possibilities for the inspection of wind farms and other objects at sea. They must be able to communicate underwater. TNO has developed technology to use sound waves as an efficient means of communication.
Working with underwater drones, in jargon ‘Autonomous Underwater Vehicles’ (AUVs), requires accurate preparation, says Quincy Martina, Project Manager at TNO Acoustics and Sonar. “You usually work from a ship and you have to plan the mission well in advance. What are the environmental conditions, what risks are expected, but above all: what result has to be achieved and what is needed for this?”
Maurits Huisman, Business Development Manager at TNO: “Ultimately, the result counts. Underwater drones can increase the efficiency and safety of offshore inspections and monitoring. Divers who carry out inspection and monitoring can end up in hazardous situations and you want to avoid that as much as possible. Other inspection systems, for example, require cables, which limits the deployment possibilities of those systems.”
“Wireless communication in seawater is problematic because radio signals do not carry that far. The solution is that we do not use radio signals, but sound waves.”
Still, there were concerns about the use of AUVs, says Martina: “Wireless communication in seawater is problematic because radio signals do not carry that far. The solution is that we do not use radio signals, but sound waves. Actually, just like with sonar. With this form of communication below sea level, TNO has already gained extensive experience, especially in applications for Defense.”
Sound enables underwater communication with drones. “Both to send them and to send (measurement) data”, says Martina. “It is not as fast as with 4G on land, but the data speeds are sufficient to be practical. The range varies – depending on the environmental conditions and frequency bandwidth – from a few hundred meters to tens of kilometers.”
In the meantime TNO is also working on further improvements of the AUVs. “We make the drones more autonomous,” says Huisman. “You can then give them assignments that they perform together without human interference. We also work on the cooperation of the various systems. With this cooperation you can think of taking over tasks when a member of a team of AUVs fails. You can also equip the underwater drones with different types of sensors, so that they provide data that complement each other. The AUV teams can then decide for themselves what data they need to collect in order to carry out their assignment and where they do it. “This is not the case yet, but TNO is working on the development of a system including an acoustic modem and software for autonomous applications. decision.
TNO is now looking for partners with whom the system for autonomous decision-making of AUVs in a consortium can be further developed and demonstrated. Huisman: “Such a demonstration can lead to a breakthrough of this technology in the maritime sector.” As possible partners Huisman mentions contractors from the offshore industry who provide inspection and monitoring work: “But other interested parties are also welcome. Together we can bring the expertise and technology of TNO to the market. We are ready for it anyway.” Source: TNO