Coming when it’s called, an operator-less tractor and grain cart transit a Manitoba field, pull in beside the rolling combine, and farmer Matt Reimer unloads his grain on-the-go.
Reimer touches the screen on a laptop application he created; the tractor then pulls to the left and stops, waiting to be called again.
“This will save us about $5,000 in labour this fall,” said the 2,500 acre, grain producer from 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.”
“I didn’t have an RC aircraft or anything like that,” he said.
“There are jobs that we do that don’t really take a person, or that you could have a robot do in the same field with you. The grain cart was the obvious one for me,” he said.
The robotic tractor and grain cart saves the farm a person in the field and allows the combine to keep rolling.
“We’ve used it on 600 acres so far. It worked right off,” he said.
Reimer got the idea at Christmas time, last winter.
“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 “can barely remember my first year college (computer programming) class.”
He found a company called 3D Robotics that builds an autopilot system that is generally used for RC aircraft, however is found in a variety of unmanned enthusiast vehicles.
It features processor and sensor technology from ST Microelectronics and uses a NuttX real-time operating system that can be harnessed for any autonomous vehicle, not just aircraft 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’s cab. The CVT gearbox in the machine allows it to run through the field and come to a stop without any range or gear changes and without risk of stalling the machine.
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 now includes checking for tractor related issues, as well as its 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,” said Reimer.
Early in development the producer found that using a wheel angle sensor was necessary to take the edge off the Pixhawk’s guidance signals and make turns more gradual.
The farmer did have to develop some programming skills to get the grain cart to pull up to the combine and receive the grain.
He 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 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 into the machine 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 2 kilometers and will disable the unit, bring the tractor to a stop if it should 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, failing safe and stopped.
An actuator also operates the brake.
Four, wireless key-fobs are distributed among those who are in the field. Any of these, short-range devices can interrupt the signal to the controller and will bring the machine to a stop or prevent it from starting to move.
When loading the trucks from the cart, drivers use these to make the tractor and cart immobile.
The operator that once ran the cart is now heavy harrowing the field while the combine is rolling.
“That operator can shut the tractor (and cart) down if it is in his way. And can start it 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,” he said.
This winter Reimer plans to study the CANBUS system in the tractors to learn how to tap directly into those feeds and hopes to be able to improve on the work he can get the machines to do for themselves.
“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,” he said.
Additional video of Reimer’s robotic tractor in action: