Mower with a mind of its own

Robotic Mower
August 12, 2020

Originally appeared in the Legacy Magazine

About 250 crossbred Holsteins graze on grasses and cover crops at the West Central Research and Outreach Center (WCROC) near Morris, Minnesota. The herd is part of the center’s ongoing research on dairy production.

But the cows don’t eat everything, and the weeds left behind will spread unless cut. That’s when the cowbot goes to work.

The little 25-horsepower tractor-like machine works something like a combination of a robotic vacuum cleaner and a lawn mower. Weighing in at nearly a ton, it has four-wheel drive and can “think” and navigate on its own. When power runs low, it returns to its charging station, a trailer with solar panels.

The mission of the cowbot is to explore a new way to reduce agriculture’s carbon footprint—a priority at donor-supported WCROC, which is committed to using renewable energy to reduce fossil-fuel consumption in agriculture. In addition, the cowbot aims to lessen the use of herbicides and save farmers’ time.

The cowbot is the result of a collaboration between WCROC, part of the U of M College of Food, Agricultural, and Natural Resource Sciences; the College of Science and Engineering; and Bloomington-based Toro Co.

Toro was interested in converting its diesel-powered GM3280 mower to electric for testing as a quiet vehicle on parks and golf courses. When WCROC contacted the company about an earlier project, the mower project found a home. Toro contributed the original mower plus more than $124,000 for parts and engineering design, software, fabrication, and assembly labor to create the prototype. The company continues to provide engineering support through testing.

“Toro’s mower was designed for more formal turf, not pastures, but it works great here,” says WCROC lead researcher Eric Buchanan, who received a grant from Minnesota’s Environment and Natural Resources Trust Fund to study the use of autonomous vehicles for weed control.

The three-year project began in 2018 with a focus on pasture mowing. This summer, it branched into early weeding of row crops, specifically corn and soybeans. The final year will be devoted to fine-tuning hardware and software, and developing and testing safety protocols.

“Our goal is not to develop a new commercial vehicle. Our overall mission is to take things that are available and see if they will work in new ways,” Buchanan says.

Field tests resumed this summer. With different mowing patterns developed in 2019, the U of M robotics team is flying a drone to spot weeds, collecting images for a database that allows the cowbot to recognize them. Weed identification will become more important as testing moves into weeding row crops.

“The terrain is very bumpy so we’re mowing very slowly, less than two miles an hour,” says Jack Gust, a chief engineer in research and development for Toro. “But if you’re a robot, time is not that big of a deal.”

See the mower on the move