Driving simulators provide unprecedented opportunities and advantages for driving research in terms of experimental control, flexibility, cost, and safety. Successful driving simulation, however, requires a good understanding of the mechanisms involved in the driver's perception and action. On the other hand, driving simulators can be used to study those same mechanisms.;A valid driving simulator must draw, from the human drivers, the same driving behavior that they would show in real world driving. In order to achieve this level of validity, an important requirement is that the simulated vehicle and environment should provide adequate sensory information (i.e., feedback) to the driver. Often this sensory feedback is primarily visual. However, depending on the driving task at hand, other forms of sensory feedback, such as motion and force feedback, can play important roles. The goal of this thesis is to investigate the role of different sensory cues in the operating of agricultural vehicles, which have significant differences with automobiles in virtually all major aspects.;A tractor driving simulator was developed to provide realistic visual feedback, yaw motion, and torque feedback on the steering wheel. The error of a GPS lightbar guidance system and the self-deviation of the tractor were measured in the field. The measurements were used to model the straight line driving of a tractor with a lightbar system and the model was implemented in the simulator.;Field tests and simulator experiments were carried out with experienced tractor drivers to investigate the role of motion and visual cues in common driving tanks associated with agricultural vehicles. Observations showed that drivers effectively use yaw motion feedback in steering the vehicle in parallel swathing mode. Steering effort significantly increased and performance deteriorated when motion feedback was eliminated. Visual feedback from the outside field was not used by the drivers in parallel swathing mode. Visual cues, however, were essential for turning maneuvers. Experienced drivers did not have a proper understanding of the relationship between their steering input and the vehicle motion. They needed visual feedback to complete maneuvers that required more than one steering input.;Torque feedback on the steering wheel was shown to be effective when the operator was engaged in a monitoring task as well as the steering task. Certain torque feedback schemes resulted in improved performance levels for both steering and monitoring tasks and reduced steering effort. These included a torque feedback that tends to move the steering wheel to the center position and a torque feedback that is proportional to the projected driving error.;When the operator performed the steering and monitoring tasks simultaneously, auditory signals were effective in reducing the load on the visual channel and thereby increasing the operator performance. Auditory signals were not appropriate for communicating the information regarding the steering task. However, they were very effective when used for the monitoring task. When the information regarding the steering and monitoring tasks were communicated to the operator through visual and auditory channels respectively, highest performance levels for both tasks were achieved.
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