The control of agricultural tractors carrying out draught cultivations

The subject area of tractor automation, tractive efficiency and traction is well researched with numerous papers and concept vehicles developed worldwide. Current in-tractor systems display performance attributes such as work rate and pass-to-pass accuracy but not factors such as cultivation quality, consistency of operation and utilisation of power. The significant research in this area relies on quasi-static systems using field calibrations or staticmathematical models. Dynamically, tillage causes variation in implement depth and wheel power. Little research exists in this area and forms the basis of the study here within.In this study, three point linkage force resolution and tractor dynamic kinematic models were developed and integrated with an instrumentation system to measure the force and positional parameters required. This allowed the resolution of draught and vertical forces acting on the tractor, prediction of implement tillage depth and tractor pitching and field energy performance calculations. Initial field and laboratory experiments concluded that existing linkage control systems are too complex to achieve a consistently energy efficient field operation. The models developed were integrated into a three point linkage position controlling algorithm based on three selectable work modes: field work rate; tractor and fuel efficiency; consistent cultivation depth and quality; whilst displaying real-time field performance to the tractor operator. The study demonstrates an improvement in energy usage of 3.5% is achievable through accurately controlled tillage depth in real-time.The study contributes significantly to knowledge through the novel integration of the developed models and instrumentation system into a control algorithm which has significant future potential. A commercialised version of the system can be retrofitted to tractors as an add-on or through manufacturer integration. Recommendations are made for further work and how the system could be utilised for field mapping and spraying and fertiliser application consistency and rate monitoring in real-time.

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