Autonomous weed control research

'Where we are going, we don't need drivers!'

By Michael Reese, Renewable Energy Director

November 2018

Toro mowerThe West Central Research and Outreach Center is leading a new collaboration with the University’s Department of Computer Science and Engineering, Department of Bioproducts and Biosystems Engineering (BBE), and The Toro Company (Toro) to develop autonomous vehicles for controlling weeds in pastures and row crops.  The project has been recently funded through a $750,000 grant from the Minnesota Environmental and Natural Resources Trust Fund.   This is an interdisciplinary project at the WCROC utilizing staff from the crops, dairy, and renewable energy programs.   

Autonomously controlled vehicles are quickly entering agricultural markets with the appearance of drones, tractors, and small robots.  The concept of this project is to enable weed control with minimal human supervision and with vehicles powered by the sun’s energy.  Farm operations typically compete for limited labor resources.  Weed control in pastures is usually a lower priority and using herbicides can be challenging if pastures contain both grasses and legumes.  For row crops, getting out in the field early after planting can aid in controlling weeds.  Weeding robots have the potential to be operating while human labor is still focused on spring planting and other activities.  Row crop robots also may enter fields in which crops are too mature for other equipment.  Similar to robotic vacuums now used in homes, a row crop weeding robot can be programed to move throughout a field by itself, and can also remove weeds either by mechanical methods or by directly applying a small amount of herbicide.       

An electrically-powered mower with manual and autonomous controls will be developed for weed control in WCROC pastures and a second electrically-powered manual and autonomous utility vehicle will be developed for weeding row crops.  Both autonomous vehicles will be refueled, or rather charged, in-part utilizing a portable solar charging trailer which is being developed at WCROC.  In addition to the charging station, WCROC staff will custom fabricate and test small-scale row crop weeding implements that will be attached to an electric utility vehicle.  Department of Computer Science and Engineering is responsible for developing autonomous control of both vehicles while BBE will focus on safety controls and mechanisms. 

Toro mowerThe Toro Company, headquartered in Bloomington, is retrofitting a large diesel-fueled mower with electric motors and drive-by-wire capabilities and will assist in the integration of the autonomous controls and safeguards.  Drive-by-wire is essentially the process and systems which enable vehicles to be sent an electronic or digital signal to steer, accelerate, stop, engage mower, etc.  Today, many vehicles already utilize this drive-by-wire function thereby making them easier to convert to autonomous operation.   For example, whereas an old car would have mechanical connections such as rods and cables, your new car most likely has a wire connected to the accelerator and then to the electronic fuel injection system.  The ‘gas pedal’ then sends a signal to a module in the fuel injector to increase fuel flow or the ‘brake pedal’ sends a signal to an actuator which then applies the brakes.  In addition to the drive-by-wire capabilities, a flail mower will be retrofitted on the front and autonomous controls such as GPS and LIDAR will be added.  The sensors and mower control systems will be interfaced with a computer and software directing its operation.  Safety protocols and mechanisms will be built into the mower.  During the spring and summer of 2019, the autonomous mower will be tested at Toro’s research facilities.  It will be field-tested within WCROC pastures during the summer of 2020.

This winter, WCROC staff will begin retrofitting an existing cargo trailer with solar panels, batteries, and a charger system.  Staff will also begin fabricating small-scale weeding implements that can be attached to an electric UTV.   The weeding implements will be tested under manual operations to test and refine weed control effectiveness.  Concurrently, an electric utility vehicle platform will be selected and retrofitted to drive-by-wire.  The same autonomous sensors, hardware, and software used for autonomous mower control, will also be utilized in the UTV row crop weeding system. 

Agriculture is moving evermore quickly towards high technology applications.  The autonomous weed control project represents an exciting and new direction for the WCROC and the Renewable Energy Program into autonomously-controlled and renewably-fueled vehicles.  In addition to the benefits of powering these autonomous systems utilizing energy produced on farms, lowering pesticide use, potentially more effective weed control, and helping producers better manage limited labor resources; autonomous farm vehicles may also offer new opportunities for young producers to participate in a paradigm shift affecting future farm operations.  Just as horse-power gave way to small tractors and then small tractors to large tractors, farmer-driven tractors may soon give way to autonomously-controlled, robotic vehicles ranging from very large to very small; on the ground and in the air.  To paraphrase a quote from the movie “Back to the Future”, ‘Where we are going, we don’t need drivers!’