Up Close and Personal With Automated Ag Equipment
Our Control Automation engineering staff got the chance to visit a commercial farm in North Dakota and learn the hardware and software making these huge automated tractors ready for high-tech ‘field’ work.
It took a while of driving, but we finally arrived at the farm of Paul Zook, outside the small town of Beach, North Dakota, just east of the Montana border. Agriculture is the livelihood of generations of farmers, with many of them working the same land cultivated by fathers and grandfathers of the innovators running the farms today.
Figure 1. Case IH Steiger tractor with air seeder and Coulter drill. Author’s image
We’ve heard all about the possibilities of autonomous farm equipment, but I really wanted to get to the source, climb into the cockpit, and trace the wires for all these sensors that claim to provide technology breakthroughs in all aspects of agriculture.
Sure enough, it was more impressive than I imagined.
Meet the Equipment
I’m no stranger to farm equipment, but I grew up driving much smaller tractors, meant for plowing or baling up just a few acres. The rigs used in commercial farming applications dwarf anything on the hobby farm scale around which my perspective is based.
The system that particularly caught my attention was a Bourgault Independent Coulter Drill. The purpose of this machine is to cut a small trench in the ground, laying the proper amount of seed, and often fertilizer, then covering it gently back up. All of this is accomplished in back-and-forth driving passes, covering up to 70 ft in width per pass (for large models).
The drill machine is paired with a Bourgault Air Seeder, responsible for storing and delivering the seed and fertilizers to the drill, and also the tractor, a Case International (Case IH) Steiger series, used for pulling and controlling both the seeder trailer and the drill trailing behind.
The Automation Technology
Before discussing what the tractor can accomplish, it may be worth noting what they are designed to accomplish. The technologies automate many previously manual functions, but these are not driverless. The operator is still required to respond to any alarms displayed on the various heads-up screens in the cockpit.
Reverse-engineering from the end of the implement forward, the cutter disk and seed applicator must maintain a constant depth of push into the ground. This is not easy with a row width of up to 70 feet, so the applicators are controlled by hydraulic cylinders, all of them operating with the same constant pressure and therefore pushing with equal force into the ground.
Figure 2. The point of seed and fertilizer application, depth controlled by hydraulics. Author’s image
The seeds are delivered to the ground with the flow of air. The applicators are maintained in groups, with the seeds delivered to each group by solenoid-controlled hydraulic gates. Each applicator hose has an optic sensor detecting proper flow. If any become clogged, a remote data collector transmits the alarm condition to a tablet inside the cockpit.
Figure 3. Optic sensors on towers provide feedback if any line becomes plugged, prompting the driver in the cab. Author’s image
If the tractor path crosses over an area already seeded, the automation controls can shut down various groups of seed applicators, optimizing the consumption of both seed and fertilizer.
Figure 4. Hydraulic lift gates allow material flow or clean air flow for thorough cleaning of the lines post-usage. Author’s image
Moving ahead to the storage and delivery of the materials, an air handler is responsible for maintaining the flow of seed and fertilizer in ducts leading from the storage tank trailer. A hydraulic motor turns an auger, providing a carefully controlled velocity of ingredients. A metal sensor measures the rotation to provide feedback to the variable control valve for the hydraulic motors. A set of optical sensors are also visible, providing low alarm information for any of the on-board tanks.
Figure 5. Hydraulic motor with a gear encoder for rotational speed monitoring. A sensor is visible on the tank to provide feedback for empty tank levels. Author’s image
In order to maintain a proper feed rate that consumes the correct amounts from each of the differently-sized tanks, the weight is an indicator of how much ingredient is on board. A load cell (weight sensor) provides that weight information and ensures a proper rate of consumption. All of the sensors are connected by Fieldbus protocols that facilitate reliable communication.
Figure 6. Load cells measure the filled weight to optimize the feed rate of each tank, ensuring they will become empty at the same time, extending the time between filling. Author’s image
The flow of air not only carries the seed and fertilizer to the applicator at the end, but the air pressure is also delivered into the top of the storage tanks to ensure that the seed is actually pushed down into the auger. A set of sensors monitors the air pressure to ensure the tank tops are properly sealed and secured.
The Software Inside
As the tractor navigates the field, it is able to pilot itself for much of the routine operation, requiring minimum amounts of human intervention. An on-board computer receives sensor feedback, either wired (for standard vehicle options) or wireless (for many aftermarket add-ons), and provides alarms to the driver if any system reports failure. Air pressure, material flow, cargo weight and balance, depth pressure, and many other values are continually monitored.
Figure 7. Distributed IO blocks using M12 connectors to receive signals from the tank load cells. Author’s image
Case IH uses software called AFS (Advanced Farming System) which is similar to many industry-standard control and acquisition systems. A few exceptions designed for agriculture are a historical crop yield over years, custom mapping for various implements that allow the self-guidance benefits, and an automated data transmission system with cellular data connectivity to send information to a central control station. This is a huge benefit for operations with many vehicles operating over many square miles of land.
Many other options for software advance the computer benefits into the cloud. This includes obtaining daily satellite maps with color-ranging indices to indicate crop health from seedling to harvest. Many years of data can be used to predict how much fertilizer and other parameters must be adjusted based on similarity to previous years. Using these tools, it is easier to optimize a year based on data.
Figure 8. Sample of AFS Connect mapping software. Image used courtesy of Case IH
One example of how this software can be used is a previous year for Mr. Zook when grasshoppers devoured part of a field. Satellite images showed the exact days on which the infestation appeared and grew, and from what direction. The weather data, matched with other farm information can be used to predict if this could happen again. Countermeasures can be taken only if and when required, saving material cost and harm to the environment, should chemicals be absolutely necessary.
I really appreciate the time and expertise shared with me by Mr. Zook. His enthusiasm for agriculture technology and his knowledge of the art of farming was truly contagious. I was excited when I first saw the rigs, but far more so once I began to learn how they worked, and what systems were used to accomplish each part of the puzzle.
Autonomous vehicles, whether for commercial, personal, or agricultural reasons have seen a lot of publicity in recent years. But there is no comparison between reading information about these vehicles versus the experience of climbing into the cockpit and examining the sensor and hydraulic subsystems in order to learn exactly how these innovations are driving today’s technology.