Landmine detection in Cambodia

Anstelle des Tragschraubers setzte das AMLS in Kambodscha ein Trike ein.
© Photo Fraunhofer FHR

In Cambodia, AMLS used a trike instead of the gyrocopter.

Das Messprinzip: Das von den Pflanzen reflektierte Sonnenlicht wird aus der Luft spektral aufgelöst aufgezeichnet.
© Photo Fraunhofer FHR

The measuring principle: the sunlight reflected by the plants was recorded spectrally resolved from the air.

The scientists at Fraunhofer AMLS investigate airborne sensor systems. The idea emerged that the internally developed hyperspectral systems could be used for the detection of buried landmines. In November 2015, the team flew to Cambodia to support the aid organizations and carry out first tests.

It all started with a competition to gather ideas entitled »Projects for People« within the framework of the Netzwert Symposium 2015. The competition had the following aim: »Utilization of Fraunhofer competencies and technologies in the solution of social problems«. Due to personal contacts with the aid organization Kleine Hilfsaktion e.V., Cambodia quickly became the focus of the AMLS group: 20 years after end of the civil war (1970-1998) the country is still suffering from the devastating effects. It is one of the poorest countries in the world and all of the buried mines have not yet been cleared. But typically, over half of the areas cordoned off as mine fields are not contaminated with mines. Measurement flights with the new technique were carried out to classify areas so that the mine clearance teams could be deployed in a more purposeful manner. This also facilitated the earlier reopening of uncontaminated areas.

The project idea developed by AMLS concentrated on the utilization of existing airborne, multi- and hyperspectral imaging for the detection and classification of mine fields. The technology was originally developed for plant observation in the agricultural sector. The measurement principle uses plants as bio-indicators for pollutants in the earth. Landmines that have been in the ground for up to 30 years gradually release their explosive material into the surrounding soil. This material, which is absorbed by the plants, disturbs the metabolism of the plants and changes the way they reflect sunlight. The spectral sensors from AMLS can detect this change. The measuring principle was confirmed under laboratory conditions in the USA. Field measurements under real-life conditions had, however, not yet been carried out.

The project paper submitted within the framework of the competition convinced the members of the jury and AMLS was among the 8 candidates invited to the final in Munich in January 2015. In Munich, the team presented the project to an audience of experts at the Netzwert Symposium in an elevator pitch. Thankfully, the research group got second place – just 1.6 points behind the winner – and received funding in the amount of € 25,000. A sum of € 3,000 was also donated to Kleine Hilfsaktion e.V.

Following the success of the competition, the team was determined to carry out a measurement flight campaign in Cambodia. As the cost of transporting the gyrocopter to Cambodia would have exhausted the budget right from the start, the team set about finding a suitable ultralight aircraft in the locality. After some Internet research, the researchers found a solution: they came across a pilot who flies tourists over the temples in Cambodia with a trike similar to a motorized hang-glider. A joint campaign was agreed for November 2015.

The vegetation has its most active physiological phase after the rain period, thus leading to better measurements. The AMLS technology was adapted to the trike using an identical model from the Netherlands. The owner of the trike, the Microlight Aero Team at the airfield in Budel, supported the AMLS mission: in addition to examining and dismantling the aircraft, they were also able to carry out some free test flights.

In various discussions during the project preparation phase, the team was regularly referred to Peter Willers, who managed a mine clearance platoon in Cambodia for the Foreign Office for over six years. A fortunate coincidence: the expert lives just 20 km from the RheinAhrCampus and was immediately interested in the project. With his good contacts, Peter Willers was able to open important bureaucratic doors in Cambodia and also agreed to come to Cambodia, together with Roland Debschütz from Kleine Hilfsaktion e.V., as an advisor, which later proved to be extremely important.

In the course of the measurement campaign the researchers successfully gathered 40 GB of data, which now has to be evaluated. The flights in Cambodia took place in a region in which mine clearance is currently being carried out. These clearance measures will be complete in a few months. Of relevance in this respect is the fact that the team will be provided with the final clearance maps which show where the mines were actually found. By comparing this information with the results from the measurement flights, the scientists will then be in a position to identify the important spectral indicators for landmine-induced plant stress.

More details relating to the trip in November 2015 can be read in a blog in the Internet (amls-cambodia.blogspot.de).