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Self-Steering Tractor Offers More Precision in Field

26 September 2011

A farmer rising at the crack of dawn to till his fields in a tractor all day? This could soon become a thing of the past. Flanders’ Mechatronics Technology Centre (FMTC), together with the Mechatronics, Biostatistics and Sensors (MeBioS) division of K.U.Leuven’s Biosystems Department, has engineered a fully automated, self-steering robotic tractor.

The tractor adapts itself to terrain conditions and adjusts its speed and turning radius automatically. It can complete a pre-programmed route with exceptional precision…and without the intervention of a driver. The researchers behind the machine will unveil a first prototype at the 30th Annual International Agriculture and Horticulture Days of Mechanisation, on 24 and 25 September in Oudenaarde.

Erik Hostens, project engineer for FMTC, described the tractor’s navigation system: “We started by installing a linear propulsion system to press the gas pedal down and steer. Then we equipped the tractor with a computer and various additional positional sensors, including a GPS system.” The most important challenge came after these modifications were complete: engineering a steering system that effectively takes over the role of the operator.

“Only experienced tractor operators have the skills needed to work a field with precision. The job of an operator is really quite complex: he observes the tractor’s current position, makes a judgement based on terrain conditions and the route to be followed, and, based on all this, decides the speed and orientation of the tractor. All these actions had to be integrated into the automated steering system. The system registers positional changes in real-time with a GPS and adjusts itself accordingly.”

Traction control

The constantly changing ground conditions in the field present a particularly sticky challenge when developing an automated tractor. Gregory Pinte, of FMTC, explains: “The tractor must be capable of driving in both hard and wet terrain. Traditional navigation systems are unable to handle multi-terrain conditions.

Instead, a different setting must be calibrated for each terrain type. That’s why we developed a steering system that intuits terrain conditions and estimates the expected wheel slippage. Based on a model of the tractor, the optimal speed and turning radius is calculated, in real-time, for the current terrain type. This ‘smart steering’ allows for precision down to the centimetre.”

Higher precision and low operator costs

What is the benefit of an automated tractor? “The importance of precision steering for agricultural machines has increased significantly, particularly with the arrival of organic farming,” says Professor Wouter Saeys, of the MeBioS division. “The accurate positioning of the machine is essential.”

Another important trend in agriculture is automation. Vincent Theunynck, of New Holland, explains: “By putting automated agricultural machines in the fields, ever-increasing operator costs can be significantly reduced. On top of that, thanks to the ‘smart steering’ capability of the robot, changes in terrain type have become superfluous.”

The tractor-robot is an example of the successful cooperation within the IWT-SBO project Learning Control of Production Machines (LeCoPro) between participating academic knowledge centres and a Flemish industrial partner.

As part of the project, the FMTC partnered with the Flemish universities K.U.Leuven, VUB and UGent to establish a knowledge base geared toward developing smart steering strategies for use in production machines. The techniques developed in the course of this program will allow Flemish industry to bring the ‘smart machines’ of the future to the market.

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