A new drone developed in collaboration with the Royal Danish Navy and the country’s space research agency could mean safer demining and cheaper mineral surveys
The ground-breaking nature of military technologies means that many may find their way into equally ground-breaking industrial applications. It is with great interest then, that InnovOil views a new Danish project to use drone-mounted magnetometers to map leftover mines in former war zones. The plan would use a so-called Smart unmanned aerial vehicle (UAV), in combination with an underhanging frame outfitted with magnetometers capable of identifying and locating the magnetic steel used in some marine and land-based mines. Beyond ordnance, however, the same technology could be invaluable to future mineral and resource surveys. The scheme involves a number of prominent Danish innovators, including national space research centre DTU Space, Center for Energy Resources Engineering (DTU CERE), the Royal Danish Navy, drone developer Sky-Watch, utility and upstream firm DONG Energy and geotechnology firm Geo, and thanks to a recent award of 11 million kroner (US$1.6 million) in backing from Innovation Fund Denmark, it will soon be ready for take-off.
Flipping the bird “The plan is for our drone and its unique magnetometer module to make demining more precise than the current method of using off-road vehicles on land and special divers in coastal areas. It will also minimise the risk of injuries for the people involved, as the drone can be operated from a safe position outside the mined areas,” explains DTU Space senior researcher Arne Døssing, who heads the project. It was Døssing who originally came up with the concept of a drone-mounted magnetometer array. Having worked on processing gravity and magnetic airborne surveys in Greenland, he was aware of the limitations of the current methods, especially in remote areas such as the northern Greenland Shelf. In areas like these, simply transporting enough fuel for a survey can be up to 90% of the total cost, he says. Even then, high resolution surveys are extremely difficult, as the areas of investigation may be too far from land for a small plane or helicopter to fly over in detail during a single mission. The future, as Døssing saw it, would be to conduct these surveys using hybrid vertical take-off and landing (VTOL) and fixed-wind drones, which can fly further and longer and do not have to be deployed from a conventional airstrip. However, the magnetometers and associated instruments required for these surveys – batteries, GPS, sensor arrays and altimeters – have previously been too heavy to be deployed by anything other than a plane or helicopter. Døssing’s idea was to use a very light underslung frame – a so called “magnetometer bird” – which would be carried well below the drone and would only be equipped with the magnetic sensors and their electronics. The weight of additional equipment (GPS, altimeter, etc.) is removed by using the systems already in place in the UAV. The magnetic sensors (Caesium or Potassium-type) are embedded within the lightweight “bird” frame – Døssing says he expects a frame of about 1.5 m, weighing only 2 kg in total – which is suspended about 5 m below the UAV. Magnetometer readings from the bird are recorded and communicated back to the drone, which also logs position, attitude and altitude of the UAV using its onboard GPS and flight systems. By projecting the UAV positional information onto the bird using 3D tracking of retroreflective mirrors placed on top of the bird, the team can reduce its weight significantly compared with the traditional frames towed by a helicopter. With processing, this enables surveyors to build up an accurate map of the location of mines and/or minerals. “It will be the first drone in the world to fly with a lightweight ‘bird’ underneath it. The bird construction is absolutely necessary to ensure the ultra-sensitive magnetometers are as close to the surface as possible, at the same time as minimising exposure to magnetic disturbances from other instruments and from the flying drone,” says Døssing.
Mines and minerals The space agency will oversee the development of the frame, while Sky-Watch will work on refining its Smart UAV, design and extending its flight range – itself a relatively pioneering piece of kit. With a 4.5m wingspan, it is sizable, but is still able to be dismantled and transported in two containers. Although the aircraft has a fixed wing, rotors within the main body of the drone also allow it to perform vertical take-off and landing (VTOL). That means it can be deployed from difficult-to-access or remote locations, or even from offshore vessels, for example, in relation to surveys in hydrocarbon exploration areas or for marine surveillance. As its name may suggests, the Smart UAV can also be tasked with flying missions autonomously, following a series of set waypoints. The difficulty of launch from rough terrain or a vessel means that VTOL take-off is likely to remain manual, but the possibility of even partially unmanned missions, perhaps even using multiple UAVs, could dramatically change the time expected to conduct a full survey. Døssing has said that such a system could more than halve the cost and time of mapping these mined or remote areas.
As the team sees it, initial research and deployment will be focused on locating and clearing WWII mines in the North Sea, ahead of the laying of power cables for a new offshore wind farm developed by project partner DONG. It is estimated that there are still more than 5,000 unexploded mines from this period remaining in Danish waters and on land, and encountering just one can slow the development of new power or oil and gas sites by months. The drone will also be tested in West Greenland, where the team hopes to improve the surveying of mineral deposits and military waste. It will also undergo a test deployment from a vessel, in order to qualify the detection of larger mines in deeper waters and the flexibility of the aircraft’s VTOL capabilities. With the support from the Danish Innovation Fund, the project is now set to begin in earnest in April 2017. Døssing expects to have a prototype system by late Autumn this year, before the first test campaign planned for Spring 2018. “The global market for flexible, efficient, and precise mapping of, for instance, mines, military waste, and minerals is big. So the project will allow Danish technology companies to take a strong position in this area,” Døssing added.