Robot Weed Killer Reduces Herbicide Use

Nov. 2, 2006 — A solar-powered weed killer could help farmers pinpoint and destroy unwanted plants amidst their crops and significantly reduce the use of herbicides.

The autonomous agricultural robot — or AgBot — designed by engineers at the University of Illinois at Urbana-Champaign, uses cameras and vision recognition software to seek out weeds, cut them down and apply a precise amount of herbicide to the root.

The targeted approach requires fewer chemicals and minimizes the risk that they will get into the environment, whether carried by wind or water.

According to the EPA, more than one billion pounds of pesticides and herbicides are used in the United States each year to control weeds, insects and other organisms.

Farmers typically apply herbicide to the entire field, making no distinction between crop and weed. The herbicide can become airborne or, if it rains, leech into ground water. If inhaled or ingested in large quantities, some herbicides can be harmful to people.

Hong Young Jeon, a PhD candidate in agricultural and biological engineering, and Nathanael Gingrich, a master’s student at the university, saw an opportunity to address the problem.

Working under the direction of agricultural engineer, Lei Tian, the team built a robot five feet long and 28 inches wide.

A curved solar panel mounted to the top gathers solar energy to charge a battery. The battery powers two small cameras, sensors, GPS for navigation and an electric motor that drives the robot about 3 miles per hour. The panel also serves as a canopy to protect the machine from the elements and provide shade for the vision system.

The vision system, although still in the beginning stages of development, will be designed to recognize the shape and structure of plants and be able to distinguish between a weed and a corn plant.

When a weed is spotted, a robotic arm attached to the front of the machine cuts the weed and then squirts herbicide onto the root.

Currently an operator controls the robot, but eventually it will work autonomously. The vision system will allow the machine to recognize when it has arrived at the end of a cornrow and to turn down the next lane.

A wireless connection between the robot and a laptop computer could make it easy for the farmer to operate the machine from the comfort of his house.

"The farmer could control everything from the living room," said Jeon.

According to Søren Marcus Pederson, a senior research fellow at the Royal Veterinary and Agricultural University in Frederiksberg, Denmark, surveys show that farmers are generally receptive to new technologies. But there has to be an economic advantage.

For example, using a small machine might require less fuel and would not compact the soil the way heavy machinery does. There is a cost associated with the labor needed to undo the compacting that occurs each year, said Pedersen.

But a cost advantage may be hard to see on low-value crops such as rice and corn.

"It’s difficult for me to see a huge breakthrough in cereal crops. You have to start to focus on vegetables, potatoes, and sugar beets — crops that have a relatively high value," said Pedersen.

And the robot’s safety system would have to be reliable enough for it to operate autonomously.

"It’s relatively costly to implement safety features on these robotic systems," he said. "In principal, they can work the whole day, but if there is a requirement that it has to be attended, then you have to limit your time for using these systems."