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Directional Dynamics of Steering the Third Axle

Journal Article
ISSN: 1946-391X, e-ISSN: 1946-3928
Published September 29, 2015 by SAE International in United States
Directional Dynamics of Steering the Third Axle
Citation: Williams, D. and Nhila, A., "Directional Dynamics of Steering the Third Axle," SAE Int. J. Commer. Veh. 8(2):323-331, 2015,
Language: English


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.