Page 292 - Understanding Automotive Electronics

2735 | CH 8 Page 279 Tuesday, March 10, 1998 1:19 PM

VEHICLE MOTION CONTROL 8

Figure 8.13
Forces During
Braking

FPO

slips relative to the road surface. The amount of slip (S ) determines the braking
force and lateral force. The slip, as a percentage of car speed, is given by

UwR
–
S = ------------------ × 100%
U
Note: A rolling tire has slip S = 0, and a fully locked tire has S = 100%.
The braking and lateral forces are proportional to the normal force (from
the weight of the car) acting on the tire/road interface (N in Figure 8.13) and
the friction coefficients for braking force (F ) and lateral force (F ):
b
L
F = Nµ b
b
F = Nµ L
L
where
µ is the braking friction coefficient
b
µ is the lateral friction coefficient
L

UNDERSTANDING AUTOMOTIVE ELECTRONICS 279