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ASC Paper Notes

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titleThe Neutral Steer Point

The distance of the NSP from the front axle is determined by the following equation

Assuming the tires in the front and back are the same model, and thus the cornering stiffness values are the same, the equation simplifies down to 1/3WB.

The location of the CG relative to the NSP determines the characteristic of the yaw response. This can be summarized in variables known as the static margin and the understeer coefficient

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F_b is the prescribed max braking deceleration, which in our case, is 1g minimum.

AppendixGlossary

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Note: Underlined terms have definitions in expandable sections above.

WB - Wheelbase, the distance between the rear and front axle

CG - Center of Gravity

HG - The height of the CG

TR - Track, the distance between the tires on the same axle

NSP - Neutral Steer Point, the point at which a lateral load can be applied to the vehicle without inducing rotation (yaw)

SM - Static Margin, the distance from the CG rearward to the NSP divided by the wheelbase

K - Understeer gradient, performance indicator indicating under and oversteer.

LG - Distance rearward from the front axle to the CG

LNSP - Distance rearward from the front axle to the NSP

C_f - Front TIRE cornering stiffness

C_r - Rear TIRE cornering stiffness

C_f bar - Sum of C_f for all tires on the axle

C_r bar - Sum of C_r for all tires on the axle

W_f - Weight on the front axle

WF_i - Weight on front inside wheel

WF_o - Weight on the front outside wheel

W_r - Weight on the rear axle

a_y - Lateral acceleration; can be present through an applied force OR the centrifugal force

δ - Delta, steering angle

Slip_F - front tire slip angle; the angular difference between the front tire’s direction and the actual velocity

Slip_R - rear tire slip angle; the angular difference between the rear tire’s direction and the actual velocity

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