Getting autonomous vessels and underwater vehicles to work together
An international team of researchers has recently succeeded in getting several autonomous vessels and underwater vehicles to communicate and work together as part of one and the same operation.
What is extraordinary about this is that although all the vessels were equipped with different electronic and guidance systems, they nevertheless succeeded in working together to complete a task prepared for them by a major international team of researchers. The task was to detect a discharge of contaminated water in a Norwegian fjord. In fact, the aim was to test the feasibility of using the vehicles for many different kinds of tasks, such as the effective mapping and clearing of harbour floors, monitoring of vulnerable ecosystems and inspection of subsea installations. However, the technological systems required for such tasks are hardly “off-the-shelf”.
“The vehicles we’ve now succeeded in getting to work together, without any human assistance, are equipped with different sets of software and technologies”, says SINTEF’s Gorm Johansen, who is a Research Scientist and responsible for the tests carried out in Trondheimsfjord. “We have adopted a cross-disciplinary and international approach in order to tackle the many challenges this provides. The team is made up of researchers, suppliers and end users with backgrounds in cybernetics, software development, communications, underwater acoustics and marine operations”, he says.
Its own “command centre”
The project is known by the acronym SWARMs – an abbreviation of “Smart and Networking Under Water Robots in Cooperation Meshes”.
In order to coordinate the interaction of a large number of different vehicles, the researchers have established a command centre and developed so-called “middleware”. From the command centre, the operator can plan, simulate and monitor the operation. The centre contains map-based information and other relevant data needed to plan the operation, and can be located either on land or at sea.
The middleware is specially tailored software that enables the different vehicles to communicate with the command centre, and is installed both in the centre itself and in all of the vehicles. In simple terms, we can say that it acts as a translator that converts incoming signals from the different vehicles into a common language.
One of the project’s challenges has been to identify effective systems that make it possible to transmit signals between the different vehicles both above and below the water surface.
“When a vehicle is on the surface, we use WiFi to facilitate rapid communication”, explains Johansen. “Below the surface, we have to rely on ‘slow’ acoustic waves, which makes it something of a challenge to transmit large volumes of data under water. The Norwegian company Water Linked has developed software and electronics that enable us to achieve optimal exploitation of acoustic waves so that data volumes can be increased, providing us with more data and shorter delays”, he says.
The vehicles can be equipped with cameras, sonar and a variety of sensors used to measure parameters such as salt concentration, currents and temperature. Some of the vessels can also be equipped with robot arms.
An international project
The team of researchers has been made up of 30 partners from 10 countries. Five of the project partners are from Norway. As well as being responsible for the final demonstration in Trondheimsfjord, SINTEF has developed a methodology for carrying out marine operations involving several vehicles, and the factors that must be considered during the development of autonomous vessels of this type.
“The methodology describes all the factors that have to be considered during such a complex operation”, says Johansen. “This is expensive equipment, the fjord is large, and the risk of losing a vessel is high if the software fails or procedures are not followed. An advanced underwater vehicle such as an AUV (Autonomous Underwater Vehicle) easily costs hundred thousand euros”, he says.
There are four Norwegian partners involved in the project together with SINTEF. NTNU led the marine operations in Trondheimsfjord, as well as the integration of the middleware into two of the underwater vehicles. Maritime Robotics has integrated the middleware into one of its own unmanned surface vessels. Water Linked has supplied a high-speed underwater communication system. Inventas has been working with the development of user interfaces and user experience to enable the operators to achieve optimal communication with the system. Inventas also developed and demonstrated an intuitive input device for controlling an underwater vehicle with a robotic arm.
The implementation of both prior simulations and the tests themselves has been very thorough. The large number of partners from different countries has provided an additional challenge. This was resolved by establishing a separate lab containing simulated vehicles in which the participants were able to connect themselves remotely to the machines and carry out the necessary tests prior to the demonstration in the fjord. During the last two months of the project, approximately 20 documented tests were carried out before a single vehicle had even entered the water.
Using the Trondheimsfjord as a lab
The demonstration was carried out in Trondheimsfjord which, according to Johansen, is one of the world’s best test environments for autonomous vehicles. “NTNU’s test station is equipped with everything from offices to its own landing stage and workshops. Moreover, Trondheimsfjord has suitable water depths and is protected from swells and breakers, which makes it an excellent and realistic test environment”, he explains.
The autonomous vehicles succeeded in completing the task set by the research team. They combined to sweep an area measuring 300 by 300 metres and succeeded in detecting the discharge, while the researchers made sure that none of the vessels went astray.
In the future, researchers envisage that vehicles collaborating in this way will be used more frequently in marine operations. A key factor is that the technology becomes less expensive because it is possible to use equipment supplied by a variety of different owners and manufacturers.
“It becomes a self-reinforcing loop – more frequent use leads to less expensive equipment, which in turn promotes more use”, says Johansen.
The SINTEF researchers are now launching a new EU-funded project called AFarCloud, which will be looking into collaborations between robots and drones in the agriculture sector.
“We’re transferring our methodologies and technologies from maritime operations to the agriculture sector. All our experience from SWARMs will be applied in the new project, which will boost its usefulness to society”, concludes SINTEF’s Gorm Johansen.