The Effect of Changes in some Vehicle Handling Variables on Driver Steering Performance

Abstract

The literature on vehicle handling is summarized. Experiments were carried out to determine the effect of vehicle response time, steering gear ratio, and near- and far-sight distances on driver performance on a tracking task consisting of driving through a narrow winding course marked by traffic cones. The vehicle response time was found to affect greatly the number of cones touched by the vehicle during a set testing time. On the particular track used in these tests, the driver performed best when the vehicle response time was 0.20 seconds. The near and far distances over which the driver could see the test course were also found to be of importance. Increasing near-sight distance, with no limit on the far-sight distance produced poorer driver performance. This also occurred for the case of decreasing far-sight distance with fixed near-sight distance. Tests with variations of steering ratio and steering torque produced little change in driver performance, although there was a weak minimum in cone scores at a steering ratio G = 24. In some of the experiments reported here, spare mental capacity was measured during the test period. For this indirect measurement of task difficulty, changes in the spare mental capacity of the driver were found to have the same sensitivity to changes in the vehicle, as did the change in the number of cones touched by the vehicle.