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Run-Time Inputs |
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Run-Time Inputs |
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»Click here to display Table of Contents«
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Run-Time Inputs |
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Run-Time Inputs |
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The first set of inputs which are computed by MotionSolve during the multi-body simulation are: the position vector (R), velocity vector (V), angular velocity (W), and the direction cosine matrix [DC] of the wheel. MotionSolve computes the inputs described in the table below and makes them available to the tire model:
Quantity |
Type |
Description |
|---|---|---|
R[3] |
Double Precision Vector |
Position of tire I marker relative to the road reference marker expressed in ground RM marker coordinate system. |
V[3] |
Double Precision Vector |
Translational velocity of rim in the inertial frame relative to road reference marker. |
W[3] |
Double Precision Vector |
Rotational velocity of rim in the inertial frame relative to road reference marker. |
DC[9] |
3 by 3 Matrix |
DC matrix of rim relative to road reference marker. |
These quantities, together with the road normal unit vector obtained from the road surface geometry, are used to compute a series of tire kinematic states (see Ref[2]) such as:
Name |
Description |
Formula |
Definition |
|---|---|---|---|
sLon |
Longitudinal Slip |
svx/vx |
Ratio between the contact patch longitudinal velocity and the wheel center longitudinal velocity. |
sLat |
Lateral Slip |
ATAN(svy, ABS(vx)) |
Angle between lateral slip velocity of the contact patch and the longitudinal velocity vector of the rim. |
sTrn |
Slip Turn |
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Currently not used. |
aInc |
Inclination angle |
ASIN(DOT(Uspn,Uz)) |
Angle between the contact patch Z vector and the projection of the spin axis vector on the CP Z vector. |
Svx |
Longitudinal Slip Velocity |
DOT(ucpx, Vcp) |
Unit vector lying in the road plane and wheel plane (intersection), projected along the contact patch velocity vector. |
Svy |
Lateral Slip Velocity |
DOT(ucpy, Vcp) |
Unit vector lying in the road plane and perpendicular to the road normal and ucpx, projected along the contact patch velocity vector. |
wFre |
Free Rolling angular velocity |
Vx/Re |
Wheel center longitudinal velocity divided by the effective rolling radius. |
The kinematic states are used in the force and moment computation as outlined in the following topics: