The Tire-Force Ellipse (Friction Ellipse) and Tire Characteristics¶
Authors: Raymond Brach, Matthew Brach
Published: 2011 (Conference Paper)
Source: SAE Technical Paper Series
Algorithm: Tire-force ellipse
DOI: 10.4271/2011-01-0094
Summary¶
Examines the popular friction-ellipse abstraction against simple and measured tire-force behavior. The paper is a useful caution that the ellipse is a qualitative force-limit picture, not a faithful model of nonlinear combined-slip tire dynamics.
Abstract¶
The tire force developed over, and acting tangent to, the tire contact patch plane provides directional control of a vehicle as well as braking and acceleration traction. For analysis and modeling, this force is usually broken into its components, Fx and Fy. The former is the force component along the heading axis of the tire and supplies traction, whereas the latter is the force component perpendicular to the heading axis of the tire and controls steering. The resultant of these two forces is limited in magnitude by the tire characteristics, the tire-surface sliding friction and the normal force. Comparisons of the idealized tire-force circle/ellipse using a simple bilinear tire force model and using actual tire data show that it provides only a limited, simplified notion of combined tire forces due to its lack of dependence upon the slip angle and traction slip. Furthermore, these comparisons show that the idealized tire-force circle/ellipse does not represent actual tire behavior, even approximately, since it is incapable of modeling the nonlinear behavior of tires.
Links¶
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Tags¶
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Vehicle dynamics
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Tire model
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Friction ellipse
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Combined slip
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Simulation
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Road vehicles