Role of Visual Cues from the Environment in Driving an Agricultural Vehicle

Driving is an interactive process in which the driver receives information regarding the state of the vehicle and the environment in which the vehicle is moving through visual, motion, haptic and auditory cues. The driver needs this information for successful guidance or navigation of the vehicle. A good understanding of this process requires knowledge of the sensory cues used by the driver in performing different driving tasks. This knowledge is also necessary in the development of driving simulators which are emerging as useful research tools. The goal of this research was to test whether drivers of agricultural vehicles use visual cues from the environment when performing common driving tasks such as parallel swathing and simple turning maneuvers. Experiments were performed using a tractor in the field and using a tractor driving simulator in the laboratory. The results show that in straight line driving with a lightbar guidance system, the steering behavior and performance of most drivers does not change with varying level of visual information from the environment. However, it seemed that approximately 33% of the subjects in our experiment used an aiming cue on the field boundary, when available. Visual cues from the environment played a significant role in maneuvers which included more than one phase of steering input. Drivers were able to successfully complete those maneuvers that consisted of only one phase of steering input, such as turns, even when complete visual cues from the environment were not provided. However, maneuvers which required multiple phases of steering input could not be completed when the visual information from the environment was incomplete. A driving simulator for agricultural vehicles, therefore, should include these cues. Also, cabs of agricultural vehicles should be designed in such a way that these features can be easily seen by the operator.