Modeling of Farm Tractors



This project consists of deriving numerous analytical models that can be used to describe the steering angle to yaw rate motion of a tractor. The best of these analytical models has been chosen with the purpose of quantifying the effects of different hitched implements and their changing conditions (such as depth) on the behavior of the tractor. The chosen analytical model is called the “3 wheeled” bicycle model seen in Figure 1. For this model, the implement is modeled as a third wheel at the hitch. Current work is validating that the hitched implement can indeed be represented by the linear tire model. The linear tire model used for the hitched implement is Fyh = -Cαh•αh. System identification (experimental) data taken on a Deere 8520 with different hitched implements at different depths is being used to quantify the Cαh term through comparisons of the analytical model with empirical (experimental) models. Figure 2 shows a nine tine cultivator during an experiment.

Figure 1:


3-Wheeled Bicycle Model

Figure 2:


Deere 8520 with Cultivator