grain weevil robot

The inside of a grain bin is one of the most dangerous places for farmers and other ag workers involved in the handling and storage of grain. One ag tech start-up has built a robot that can do pretty much anything a worker can do inside a grain bin with a shovel — keeping workers out of grain bins and harm’s way.

It takes less than five seconds to become helplessly trapped in flowing grain and less than 30 seconds to become fully engulfed and overwhelmed. Learn more about grain bin hazards.

It began with a challenge

Before Chad Johnson became CEO of Grain Weevil, he and his son Ben gained valuable robotics experience as a mentor and competitor on robotics teams in Nebraska. This experience provided the opportunity to start working on a grain bin robot following a challenge from a local farmer to build him a robot to keep his family out of the grain bin.

“So we started messing around with a whole bunch of ideas for a small package that can do the right amount of work to keep grain from crusting inside a bin.” said Johnson. “And we’ve been tweaking the grain bin management robot ever since.”

How the Grain Weevil works

The Grain Weevil — around 2 feet long and 1 ½ feet wide — employs two augers or “screws” to propel it along the surface of stored grain. In the process, the drive system disrupts the grain’s surface. The result is a “controlled avalanche” that employs gravity to enable the grain’s surface to flow and even out naturally. The Grain Weevil can also be programmed to level out peaks in stored grain to ensure even distribution inside a bin. If need be, the robot can be used to break up any crust that’s formed over time from the presence of moisture or quality degradation.

“The ultimate goal is no boots in the grain. The Grain Weevil can do the work that no farmer should,” Johnson said. “It knows exactly where it's at inside the grain bin and all the slopes and angles in the grain. It is programmed so it knows its tasks and specific patterns that it travels for those tasks. So if I'm leveling grain, it will run a specific pattern so it’s operating efficiently. It’s a very intelligent machine.”

“No boots in the grain” is strongly echoed by Nationwide®, the founders of Grain Bin Safety Week, an annual safety campaign to reduce the number of preventable injuries and deaths associated with grain handling and storage.

“If you and your workers can avoid entering a bin, that’s always the best, safest option,” said Nationwide Risk Management Sr. Consultant Paul Stevenson. “Nationwide is proud to be a key stakeholder of Grain Weevil to help keep farmers out of harm’s way.”

Future Grain Weevil improvements

Current versions of the Grain Weevil have run times of around two hours and require around 20 minutes to completely charge. It operates via a remote control, though Johnson said future versions will be autonomous. Evolving battery technology will also help cut down on the cost (currently estimated near $10,000 per machine), weight and operating efficiency of future versions of the Grain Weevil once it’s commercially available.

“We’re working on being able to pinpoint the location of each Grain Weevil inside a bin; and once we can do that, its autonomous capabilities will be ready to go. True autonomy is difficult inside such a large steel structure filled with grain, an organic material, that eliminates the possibility of GPS communication,” Johnson said. “Then, we will have a machine that can do anything a human can do inside a grain bin, helping keep the farmer or worker safe.”

To learn more about Grain Weevil, visit

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