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Deere Takes Next Step Toward Driverless TractorDeere Takes Next Step Toward Driverless Tractor

February 4, 2008

8 Min Read
Deere Takes Next Step Toward Driverless Tractor

In the labs of the world’s biggest farming equipment manufacturers, engineers are working on a “killer app” that could one day rival the ox, the reaper and the modern-day combine in historical significance.

That killer app — an automated tractor — is already capable of turning, shifting gears and seeing through darkness and dust. It can follow a crop line with sub-inch precision in moonlight, can make decisions to raise and lower heavy farming implements on its own and can save thousands of hours and countless dollars for farmers.

And it may one day be capable of doing its job without need of an operator.

“Everybody in our market has an eye on this as the end game,” says Aaron Senneff, manager of hardware and systems engineering for John Deere Agricultural Management Solutions. “Autonomous tractors — ones that operate without a human in the loop — are definitely what we’re all trying to do. It’s the next great frontier for the ag equipment market.”

Deere, which will release its iTEC Pro automated guidance product this spring, has been a leader in development of autonomous technology. But it’s not alone. Case IH and New Holland have teamed with Trimble, an expert in GPS and optics, to develop automated tractor guidance systems, as well.

“This has huge implications for farmers,” says Michael Boehlje, professor in the Dept. of Agricultural Economics at Purdue University’s Center for Food and Agricultural Business. “It profoundly increases the number of acres that can be done using the same equipment.”

To be sure, no one has developed a completely autonomous tractor yet. Operators are still needed, mainly for safety reasons. Engineers fear today’s sensing technologies aren’t reliable enough to ensure an autonomous tractor will stop if a child runs in front of it.

But the new breed of self-guided tractors can do virtually everything else. They can precisely follow a line of crops, turn around at the end of the field and keep doing it for hours on end.

“The operators are there just to be aware of what’s going on around them and act accordingly,” Senneff says. “Beyond that, there is very little for them to do.”

Overcoming Overlap

The question — even among many career farmers — is why do it? Why put an automatic guidance system on a tractor when you’re perfectly capable of driving a straight line without help?

Equipment builders, of course, have the answer. “If you’re doing it day-in and day-out, at night and under all sorts of weather conditions and field conditions, fatigue starts to take its toll, no matter how good an operator you are,” says Barry Nelson, a spokesman for Deere. “But if you have the satellite to keep you in line, it doesn’t matter if it’s nighttime or the conditions are dusty or if the crop is overlapping the row. You can still get more work done in less time.”

Indeed, agricultural industry experts cite so-called “overlap” as a key problem for farmers. Studies show that when driving a tractor from row to row, operators often overlap the last row by an average of 10 percent. That means they use 10 percent more fertilizer and chemicals and they do 10 percent more work.

“Whether you are spraying or planting, you can get a significant amount of overlap because the biggest error is to leave ground uncovered, rather than double-covered,” says Boehlje of Purdue.

For that reason, ag equipment makers began trying satellite-based global positioning systems (GPS) shortly after the technology hit the general market in the 1990s. They linked the GPS units to dashboard-mounted displays and steering gears, usually with good results. New Holland worked with Trimble to develop its version, known as Intellisteer, while Deere rolled out GreenStar Auto Trac.

Global positioning clearly helped farmers by enabling them to precisely follow designated rows, sometimes at a resolution of less than an inch. In some cases, manufacturers accomplished that by showing the crop lines on the displays and allowing operators to manually follow them. In other cases, suppliers tied the GPS to the steering system, enabling the steering to automatically stay on course.

But Deere’s iTEC Pro, due out this spring, takes the process a step farther. It employs a series of controllers, linked by a CAN (controller area network) bus operating at 250 Kbits/sec. While the operator drives the tractor, the network enables the controllers to “talk” to one another and therefore share information on where the tractor is and where it should be. At the same time, iTEC’s display controller communicates with the tractor’s electronic control unit (TECU), which, in turn, sends messages to the vehicle’s hitch, transmission, steering system and selective control valves (SCV). In that way, the tractor controls its own ground speed and steering, as well as its ability to raise and lower various implements, such as planters and sprayers.

The process of decision-making starts with the John Deere StarFire GPS receiver, which is located on the roof of the cab. Built by a Fargo, ND-based Deere subsidiary known as Phoenix International, the receiver uses a satellite-based network maintained by NavCom Technology, Inc., also a Deere subsidiary. By communicating with the GPS satellite, the receiver determines where the tractor is. It then sends a message to the display controller — the main brain of the system — which houses a map of the farmer’s field. By comparing that map to the actual location of the tractor, the display controller determines whether course correction is needed.

“It does the basic math comparisons between where it is and where it should be,” Senneff explains. “Then it determines, ‘Am I too far left? Am I too far right?’”

If it’s too far in either direction, the display controller can signal the TECU, which talks to the steering, hitch, SCV and transmission. In effect, it closes the data loop by actuating the electro-hydraulic system that re-orients the tractor’s wheels to the left or right. To correct its course, it sends a signal to a hydraulic steering valve, which pressurizes hydraulic cylinders (from Deere’s Cylinder Div.) on either side of the front wheels, thus turning the tractor in the desired direction.

ITEC Pro’s real feat, however, is its use of its software smarts to lift its implements and perform a U-turn when it reaches the so-called “headlands.” The headlands — the open area at the end of the crop rows — have up to now been the province of the driver’s manual abilities. With iTEC Pro, however, that changes. Using the operator’s stored map and GPS data, it calculates when it’s reaching the end of a row. Then it communicates with the TECU, telling the transmission to slow the vehicle and ordering the hitch or SCV controls to lift whatever implements it’s pulling. When it reaches the headlands, it executes a lightbulb-shaped U-turn, much like a car turning around in a parking lot. Finally, it re-orients itself, lowers the implement and moves on to the next row.

Although Deere engineers won’t give details on the processing power that’s needed to make all of that happen, they do admit it’s considerably more than their tractors used previously.

“The processing power in a GreenStar display is equivalent to what you’d find on your desktop,” Senneff says. “There’s a great deal of intensive computation needed to make a system like this work.”

Pursuit of Autonomy

With systems such as the iTEC Pro, experts say the results can be astounding. Because GPS is not dependent on daylight, farmers are suddenly able to work at night, sometimes keeping their machines in use for most of the day.

“Potato farmers can schedule their machines for 22 hours a day, allowing two hours a day for maintenance,” says Boehlje of Purdue. “That couldn’t have been done in the past. Even with the best lighting systems, they couldn’t operate their equipment in the dark.”

Moreover, the ability to reduce overlap is seen as a boon for farmers. Assuming 10 percent overlap in a manual application, the automated systems can eliminate every 10th pass. “It’s not just a matter of physical work,” Boehlje says. “If you’re spraying chemicals, you’re saving money. That’s why GPS has been so dominant in spraying applications.”

Operatorless tractors, however, are another matter. For now, experts say such tractors could be used in fleets of three, with an operator in the front machine and two driverless vehicles on the wings. Some researchers have experimented with such fleets in South America, but the technique has not spread to the agricultural industry in any meaningful way. There are also reports of a 40-acre alfalfa field in California being harvested by a lone operatorless tractor, but farmers are understandably reluctant to make broader use of the technology.

“There’s technology out there that can enable driverless operation,” Senneff says. “But the big question is, how good and reliable will that technology be? Then there’s a separate question: How reliable will it have to be before customers will accept it?”

History suggests such barriers will fall in time. And acceptance of GPS has already begun.

“People started by adopting manual guidance, then they adopted automatic steering and soon they’ll be accepting technologies like the iTEC Pro,” Senneff says. “There’s no doubt there will be a day when they will adopt autonomous tractors, as well.”

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