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The effect of an artificial feel steering device providing a synthetic torque feedback to the driver is studied for a transit bus operating in an urban drive cycle. Driver workload is greatly reduced and the results are shown to be statistically valid for a wide range of transit bus routes.

This paper reviews activities relating to understanding, and improving the on-center performance of heavy truck steering systems. Initially, the on-center steering performance characteristics for commercial vehicles were quantified. Steering wheel torque and angular position were the prime measurables. Graphical analyses of the on-center handling data were performed. To better understand the data, and to insure statistical significance, an algebraic model of the analyzed data was developed, with confidence intervals determined. The calculated system stiffness, as determined from the steering wheel data, was found to be a key discriminator between steering gears. System stiffness is a function of several component values, which were measured in the laboratory. Finally, to test the above findings, a correlation study of subjective driver impressions with measured steering gear characteristics and objective vehicle measures was performed.

With the expectation that means of redundant steering will be necessary for highly autonomous vehicles, different methods of providing redundant steering can be considered. One potential for redundancy is to steer the rear axle for directional control of the vehicle in the event of a failure in the primary steered front axle. This paper will characterize the dynamics of directional control of a three-axle vehicle when steered at the rear, and compare it to a conventionally steered three-axle vehicle. Several compensators are suggested that allow similar vehicle dynamic behavior when steering the rear axle as a driver would expect when steering the front, giving hope that a steerable rear axle can provide acceptable redundancy for a failed primary steering system on the front axle.