PLCs, Autosteer, & ISOBUS: The Beginnings of Farm Machinery Autonomy
By Chris Hunsaker, Co- Founder / CEO at Acuitus Ag and guest panelist at the 2023 Marketing & Distribution Convention. This article continues a series where we’ll explore different aspects of technology and how they might shape the future of ag machinery.
Tractors saw a shift towards computer control in the 1990s, incorporating the programmable logic controller (PLC) for tasks like electronic engine control and transmission shifting. This integration was facilitated by networking systems via CAN bus, mirroring advancements in the automotive industry.
PLCs revolutionized tractor controls, replacing mechanical linkages with digital interfaces. Real-time kinematics (RTK) emerged, enabling sub-inch positioning accuracy and paving the way for autosteer technology. Deere introduced proprietary RTK/autosteer, while Trimble offered aftermarket solutions compatible with various brands.
Simultaneously, specialty crop implement manufacturers were creating their own operator control interfaces out of necessity. Tractor-attached specialty crop implements had evolved to have more functions/adjustments than native tractor controls supported, while self-propelled or stationary implements required dedicated operator controls interfaces. At first, these controls consisted of simple analog switches/relays.
The controls were expensive, proprietary, and could not be updated economically or easily to support new functionality because they were hardware focused. PLC integration transformed these controls, making them more versatile and cost-effective. The introduction of PLCs also spurred innovation and faster updates because of the increasing use of software in controls logic.
The International Organization for Standardization (ISO) established ISOBUS in 1991 to govern communication between tractors and implements via CAN bus. A decade later, tractors and implements started to offer communication between them based on the ISOBUS standard.
ISOBUS offered dual potential benefits: integrating implement controls into native tractor controls (like the Greenstar display in a Deere tractor) and enabling the automatic optimization based on the operational data exchange between these machines.
This sounds promising, doesn’t it? Unfortunately, ISOBUS integration has been slow due to tractor technology limitations and high development costs for implement manufacturers adapting to various tractor systems. In my previous company, we struggled to justify investing in ISOBUS integration when we could offer superior control interfaces and features independently. We’ll explore these challenges next!
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