Mow 'em, Cowbot! University of Minnesota working on autonomous mower for pastures

The Cowbot would be a way to mow down thistles as a way to control the spread of weeds, "like a Roomba for a pasture," says Eric Buchanan, a renewable energy scientist at the West Central Research and Outreach Center in Morris, Minnesota.

Parikshit Maini works on programming the Cowbot, a robotic mower, for a test run near Morris, Minnesota, Wednesday, June 15, 2022.
Jeff Beach / Agweek
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MORRIS, Minn. — Cows don’t like to eat thistles. Farmers don’t want to let thistles take over a pasture.

A new possible solution to the problem is the “Cowbot,” a weed-mowing vehicle that can operate without a driver.

“It’s kind of like a Roomba for a pasture, except a smart one,” said Eric Buchanan, a renewable energy scientist at the West Central Research and Outreach Center in Morris, Minnesota.

Mower sitting among thistles in a pastures
Thistles, like those seen in the foreground, are a problem in pastures. The Cowbot mower is a possible solution to the thistle problem.
Contributed / West Central Research and Outreach Center

Buchanan and others with the University of Minnesota are thinking futuristically about farm management, like a robot that can mechanically weed rows of corn.

“We’re also looking at possibilities of using drones in addition with ground vehicles like the Cowbot to actually herd the cows,” Buchanan said.


Modified Toro

For the Cowbot, the researchers have partnered with Toro, a Minnesota company with a long history of making lawn mowers.

Closeup of Toro logo
Toro partnered with the University of Minnesota to help develop the Cowbot, a robot to mow pastures. A Toro mower designed for golf courses was modified for the project.
Jeff Beach / Agweek

A Toro diesel golf course mower was converted to electric and the mower blade changed to a flail mower. A flail mower has flails or blades attached to a rotating drum or axle.

The flail mower “can mow a little more aggressively and would be better for thistles and bigger weeds,” Buchanan said.

It also is less likely to throw out material from beneath the mower.

A trailer for the mower also has been equipped with solar panels to recharge the electric vehicle.

This version of the Cowbot still requires some human help to get started. Parikshit Maini, a post-doctoral researcher with the University of Minnesota, said the Cowbot is driven manually around the perimeter of a pasture to be mowed, establishing a boundary for the GPS steering.

Two men standing alongside large mower
Parikshit Maini, left, and Eric Buchanan, chat on June 15, 2022, in Morris, Minnesota, as the Cowbot pasture mower was being prepared for a test run.
Jeff Beach / Agweek

Then the Cowbot can map out a plan for the most efficient way to mow the area. Unlike a Roomba in a living room, a pasture-mowing robot has to account for things like slope and obstacles and how thick the weeds are.


Maini said that on a flat open field, a spiral pattern starting on the outside and working in is the most efficient, but a back-a-forth pattern, perhaps skipping row to account for space needed to make turns might be needed in some cases.

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“We have multiple planners and those planners have different aspects as to when one should be used or another should be used,” Maini said.

The next level for the Cowbot would be the ability to seek and destroy weeds rather than mowing a whole pasture. While the Cowbot has cameras, it may need help from drones to get to that next level.

“Now the computer science researchers from our sister campus in the Twin Cities are working on methods where we might uses drones to fly over the pasture ahead of time, identify weeds, and then cameras on the Cowbot itself would take that map and kind of ground truth it, if you will,” Buchanan said.

Weeding in corn rows

Also in the beginning stages of development is a smaller robot.

Small four-wheeled robot sitting in the grass
The plan for this small robot is to equip it with tools to mechanically weed between corn plants. It is part of University of Minnesota research on using robots to control weeds.
Jeff Beach / Agweek

“So we’re working on a robot now we’re calling the ‘Weed Terminator’ to actually go down a cornfield and find weeds and kill them," Buchanan said.

This rover robot would be taught to recognize corn and weed out anything that is not corn.

“There will be a mechanical arm … that will eliminate the weed,” said Pratik Mukherjee, a postdoctoral researched with the University of Minnesota.


That will involve the challenge of coordinating cameras with the drive function and the mechanical arm.

While the most immediate real-world application for the Cowbot might be on organic farms that don’t spray herbicides for weeds, Buchanan said he hopes it can be useful on any kind of farm.

“It's difficult at the beginning, things start off slowly, but they ramp up fast,” Buchanan said. “Think about Tesla, people thought they were crazy when they started making electric cars, and they’re in high demand now.”

Reach Jeff Beach at or call 701-451-5651 (work) or 859-420-1177.
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