Dynamic steering model of a tractor-implement system for navigation applications

The determination of dynamic response of tractor trajectory, to a steering action is essential for achieving accurate guidance of agricultural tractors. This research investigated the dynamic response of a tractor-implement system via a dynamic model of the system. To provide sufficient details without loss of generality, this model, implemented in the MATLAB environment, consists of a tractor bicycle model and a pulling-wheel implement model based on a John Deere 7700 tractor and a pulling cultivator. The simulation results obtained from this model was validated visas field tests. The cornering stiffness of the wheels was found to be the critical system parameter in this model. The values of the cornering stiffness were determined by conducting a series of circling tests at different speeds on the testing fields. Field validation test results indicated that the developed tractor system dynamic trajectory model could accurately estimate the trajectories of a tractor-implement system at various traveling speeds. The results also indicated that the developed model could provide useful information to determine optimal steering angle and traveling speed to guide a tractor-implement system following crop rows accurately.