Farming technology: robotic weeding machines

By: Chris McCullough

The technological advances of agricultural machinery and equipment is rapidly evolving, with self-drive tractors, autonomous spray units, drones, and planting machines already playing a role.

FarmDroid has 50 robots working in fields across Europe at the moment

Technology for robotic weeding machines used in agriculture has come a long way over the past two decades, but there still is a huge journey to travel for them to completely take over from manual labour or using chemicals.

Today, weeding and seeding robots are working in fields all over the world but with a number of restrictions as to where they can work most efficiently. Although these robotic weed warriors come in various sizes and cost, they still depend heavily on unpredictable inputs such as sunshine to recharge the batteries or a strong wireless connection to run operational programmes or even steer the unit.

The robotic weeding machines need near-perfect ground conditions to operate

However, more importantly, these robots need near-perfect ground conditions in which to operate, otherwise, their efficiency levels fall dramatically. Some robots can only work in level fields or with gradients less than 10 degrees while others cannot run if fields become wet.

The size of the field can also be a prohibitive barrier, as most robots have a maximum area working capacity before a second unit is required to continue on​​ a bigger farm. These were some of the attributes of robotic weeders discussed during a recent webinar organised by the German Agricultural Society, the DLG, addressed by a number of experts from the robotic world.

Danish technology

Rene Jannick Jorgensen, CEO of FarmDroid ApS based in Denmark

One of the expert panellists was Rene Jannick Jorgensen, chief executive officer of FarmDroid ApS based in Denmark. FarmDroid ApS was founded in 2018 by Jens Warming and his brother Kristian Warming, together with Innovation Environment, Syddansk Innovation A/S, and robot expert Esben Ostergaard.

The company has produced one robot, the FD20, to assist farmers with weeding and seeding, with the capability to work in fields up to 20 hectares. Currently, there are more than 50 FarmDroid robots working in fields across Europe, mostly on farms in Germany with both good results and some challenges as well.

The FarmDroid FD20 was designed to be left in a field up to 20 hectares in size for the entire season

"Our robot was designed to help crop farmers with weeding. It has a capacity of working in up to fields of 20 hectares, but it can be moved across smaller fields, for example, four fields of five hectares each," says Rene.

"Our concept dates back to 2011 when we had a solar-driven unit that was later developed into the main unit running in Denmark in 2018. Version two of that robot is running in six different European countries, and we have seeded and weeded more than 1000 hectares this spring with our units."

The FarmDroid FD20 is an automatic seeding and weeding robot powered by four solar panels. A battery back-up bank can run the machine for 24 hours without any external charging.

Four solar panels power the FarmDroid FD20

"We seed using a system that provides millimetre accuracy and it makes a very fine seeding pattern where you can see the lines in all directions," says Rene.

"The weeding that’s performed with the same high position navigation both between the rows and in the rows minimises the need for supplementary manual weeding."

Rene says the FD20 was designed to be left in a field up to 20 hectares in size for the entire season and it would take care of the entire field during that time, or it can be moved to wherever necessary.

The robot has six seeding rows and travels at a rate of 450 to 950m per hour

Initially designed for sugarbeet, the FD20 is already working in four different crops. This robot has six seeding rows but more can be configured and travels at a rate of 450 to 950 metres per hour. It uses an RTK GPS system that gives an accuracy of eight millimetres and costs around €65,000.

Robotic challenges


There are, of course, many obstacles that farmers and robot developers have to overcome before the popularity of these autonomous machines can increase. "Farmers have already proven they are ready to adopt technology and they are the first movers in overcoming the challenges," says Rene.

"In terms of setting up, yes, robots can be used in one field but they can also be moved to a different field by a tractor to improve their optimisation. The more hectares a robot manages, the better the business case for the farmer.

"In terms of integration into farms, even though robots are robotic and autonomous, they still require attention, as agriculture does wear parts and all machines need attention.

"However, on a robot, if a part is not operating as it should, the farmer will get a notification from our remote support centre and will know exactly what area of the robot needs attention."

Robots can mostly only run on certain fields and it’s up to the dealer to visit the farmer to investigate whether the unit will suit his farm.

"The dealer and the customer will discuss the ground conditions," says Rene. "We have specifications that the robot is designed to run within. If the slopes are above 10 degrees, then we would not recommend a robot right now.

"To have a decent return on investment from a robot, the farmer requires at least 10 hectares. If a farmer uses it for 20 hectares, for example, spring season organic sugarbeet and autumn season where it could be rapeseed then the business case or return on investment is less than two years."

Robot versus chemicals

The big question from crop and cereal growers is whether robotic weeding will ever become as effective as weeding using chemicals and what obstacles will they need to overcome for this.

"That’s a very difficult comparison because on conventional chemical fields you are used to seeing a very clean field under all circumstances," says Rene.

"However, organic farmers are used to seeing some weeds in the field and that requires support from manual hand weeding.

Our objectives with using mechanical weeding is to remove as many weeds as possible but it can be difficult to remove them very close to the crop mechanically without harming the crop, especially in the early growth phases.

"Our take on it is to actually start weeding before the crop emerges through the surface to get a head start. Later in the season, getting close to the crop is, without doubt, the biggest challenge for a robot," he adds.

The panel also pointed out that there are robots applying chemicals to crops in terms of autonomous sprayers and other units.  

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