Robot tractor handles heat of harvest

Manitoba farmer says driverless drone pulls grain cart to where it’s needed while combines keep on rolling

A driverless tractor and grain cart travel across a Manitoba field, pull up beside a rolling combine where farmer Matt Reimer unloads his grain on-the-go.

Reimer presses a key on his laptop and the tractor pulls to the left and stops, waiting to be called again.

“This will save us about $5,000 in labour this fall,” said Reimer, who farms 2,500 acres near Killarney, Man.

“I have had thoughts about using robotics on the farm for a while. But this was the first time I’ve actually built anything.”

He said there are jobs around the farm that have to be done, but they don’t really require a person.

“Grain cart was the obvious one for me.”

The robotic tractor and grain cart saves the farm from having to tie up a person in the field while also allowing the combine to keep rolling.

“We’ve used it on 600 acres so far. It worked right off,” he said.

Reimer got the idea last Christmas.

“My folks gave me some money at Christmas and rather than put it into the grocery budget, I thought we should do something fun with it this year — robotics,” he said.

Reimer’s background isn’t in computers and he said he can barely remember his first year college computer programming class.

But he found a company called 3D Robotics. It builds an autopilot system generally used for RC aircraft, but is also found in a variety of unmanned recreational vehicles.

It contains processor and sensor technology from ST Microelectronics and uses a NuttX real-time operating system that can be harnessed for any autonomous vehicle and costs about $260.

“It’s all open-source, so you can easily adapt it to whatever you want it to control,” said Reimer.

The guidance unit controls actuators, including air cylinders and servo units, that operate mechanical controls in the John Deere 7930 tractor cab.

The CVT gearbox in the machine allows it to run through the field and stop without any range or gear changes and without risk of stalling.

The tractor runs at 1500 r.p.m. the whole time, the way it would with an operator in the cab.

Other than an oil leak and some overheating at the start of harvest, the system has worked better than expected.

A new morning checklist for the drone tractor includes checking for tractor related issues, as well as robotics. Steering is provided by an Outback, hydraulic control valve, about $1,000, making it the most expensive part of the unit.

“It’s the best I could find for this and one of the cheapest.”

Reimer’s cart rivals designs from major equipment makers John Deere and Kinze that have been shown to producers, but not widely placed into the market.

Early in development, Reimer found that using a wheel angle sensor was necessary to take the edge off the Pixhawk’s guidance signals and make turns more gradual.

He had to develop programming skills to get the grain cart to pull up to the combine and receive the grain.

Reimer took a free online course offered by the Massachusetts Institute of Technology in Python programming language.

“I had to write about 600 lines of code that works on top of some great programming for the (follow-me) software that controls the tractor when it comes to the combine,” he said.

“The Pixhawk and everything else I used is all open-source, (open-machine) and the folks who created it documented everything really well. It would take two weeks of reading that stuff to get the tools I needed,” he said.

Failsafe systems are built in and the Reimers keep the unit within view whenever they call it to the combine or in from the field.

The 3D Robotics digital radio system that controls the tractor, the Pixhawk, has a range of about two kilometres and will disable the unit and stop the tractor should it run out of range of its RC master control in the combine.

Reimer attached springs to the clutch that keep it disengaged when not pushed back by an air cylinder actuator. This makes its operation similar to a braking system on a big truck.

An actuator also operates the brake.

Four, wireless key fobs are distributed to those in the field. Any of these short-range devices can interrupt the signal to the controller and stop the machine or prevent it from starting to move.

When loading the trucks from the cart, drivers use the key fobs to make the tractor and cart immobile.

The system can free up time and a person who previously would have been tasked to drive the cart can now take on other duties, such as heavy harrowing while the combine is rolling.

“That operator can shut the tractor (and cart) down if it is in his way. And the (unit) starts back up after he has passed,” said Reimer.

“We have taken the labour we have saved and put it to work harrowing and doing other jobs that make the farm work better.”

This winter, Reimer plans to study the CANBUS system in the tractors to learn how to tap directly into those feeds to improve on the remote operation work he has started.

“I can see having a second seeding unit in the field with you. Harrowing and rolling soybean and pulse crops are other jobs that a robotic tractor could accomplish,” he said. “You have to be out there to supervise, but you can really increase your capacity.”

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