Video: Drone monitors fields to spot weeds

Spot the weeds (Image: Kacper Kowalski/Panos)

UNLEASH the robot weedkillers. A drone zipping over fields in Denmark can spot the tiny colour variations that give away the presence of weeds in amongst the crops. Logging the coordinates, it can then send a ground vehicle in to spray the densest patches, reducing the need to spray whole fields.

This is the ASETA project, led by Anders La Cour-Harbo of Aalborg University in Denmark. It aims to reduce herbicide use by concentrating weedkiller only in places where it is needed most.


The drone aims to reduce weed killer use by concentrating it only where it is needed most

The project uses a camera attached to a UAV to survey the fields. The camera is tuned to pick up parts of the light spectrum that correspond to the reflective signatures of the weeds and crops it is looking for – for example, thistle sticks out because it absorbs yellow light more than surrounding beet plants. Information is sent back to a central computer, where it is used to update previous flight maps of the fields.

The system then identifies areas that could be dense with weeds, and sends the ground vehicle in for a closer look and possible spraying. It’s all automatic: the only human input is defining the boundaries of the field to be surveyed. The drone system is currently being trialled in Denmark (see video above).

La Cour-Harbo and his colleagues plan to add further sensors to their drone, which along with better processing capabilities will allow the system to build maps that include soil nutrition levels, plant growth stages and pest infestations. The ASETA team presented a paper describing the system at the Intelligent Autonomous Vehicles Symposium in Gold Coast, Australia, last week.

One problem with the system is that operating it may be difficult for farmers who aren’t familiar with the technology. Future versions could be simplified – or other designs might prove more user-friendly.

“I think it makes a lot of sense to have a fairly rapid movement towards autonomous vehicles,” says Ken Giles at the University of California, Davis, who is working on a human-controlled helicopter for spraying. But putting herbicides on aerial drones brings its own challenges, he says. “On one hand the regulatory folks say this is five gallons of flying pesticide with no one on board. On the other hand they see that it’s a very efficient technique.”