Active combine speed control for relative positioning of a grain cart

Nykamp, Alex
Major Professor
Matthew Darr
Committee Member
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Agricultural and Biosystems Engineering

In the past, optimizing the efficiency of crop production focused on one single machine. Today, machine manufacturer's focus has shifted to optimizing the performance of a complete field operation through coordinated machine operations.

The focus of this project was on the harvest operation, where resource usage is typically the highest. With modern grain harvest systems, combine operators often unload grain while continuing to harvest crop (unloading-on-the-go). In order to achieve this, the combine operator must coordinate machine speed and placement with the grain cart operator for accurate placement of grain into the cart. The combine operator manages on/off control of the unloading auger with in-cab controls as the well as the placement of the grain by changing the speed of the combine relative to the cart.

This project developed an autonomous machine positioning system that controlled the relative position of a combine to a grain cart during unloading-on-the-go. This was achieved by developing a control model which made small adjustments to the ground speed of the combine to achieve relative position shifts.

The control system was able to consistently achieve the desired accuracy of à ±40 cm while limiting the differential engine loading due to position shifts to less than 10% of the rated engine power. In addition, the system was tuned to make position shifts at a similar rate as that of an operator during traditional operation.

Analysis was performed on the step response characteristics of the system across treatment factors of ground speed, allowable range of speed, and engine load. The results showed a statistically insignificant impact of ground speed and engine load, while range of speed did have a statistically significant impact on response time.

This result of this project was a system that allowed the combine operator to completely remove attention from the combine's relative positioning to the grain cart during a grain unloading cycle.