Variables associated with the tire kinematics as well as the contact patch forces/moments are shown in the figure below.
Tire kinematics and force/moment calculations are performed with respect to ISO coordinates. The origin of the ISO coordinate system is the tire-surface contact point, C. The unit vector for the z-axis, e^zISO, aligns with the surface normal vector which in turn is a result of defined surface geometry as explained in Surface. The unit vectors for the x and y axes, e^xISO and e^yISO, are calculated using the following vector algebra equations:
where e^spin is the unit vector for the tire spin axis.
The inclination angle or camber, γ is
Tire revolution speed or spin rate Ω, which is needed for slip calculations, is derived using the following equation
where ω&conjugate0; is the angular velocity vector of the tire.
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