BMW F12 2011 Technical Training Manual page 43

F12￿Chassis￿Dynamics
5.￿Steering
Overall,￿lane￿changes￿and￿steering￿maneuvers￿can￿be￿mastered￿with￿a￿greater￿degree￿of￿stability￿by
coordinating￿steering￿interventions￿at￿the￿front￿and￿rear￿axle￿-￿without￿compromising￿agility￿and￿con-
trol.
The￿combination￿of￿the￿active￿steering￿with￿the￿rear￿wheel￿steering￿gives￿the￿driver￿advantages￿in￿all
speed￿ranges.
Stabilization￿when￿understeering
When￿changing￿lanes￿quickly,￿all￿vehicles￿have￿a￿tendency￿to￿produce￿a￿significant￿yaw￿response￿and
can￿sometimes￿start￿to￿oversteer.
If￿the￿ICM￿dynamic￿handling￿controller￿detects￿a￿difference￿between￿the￿response￿desired￿by￿the￿driv-
er￿and￿the￿reaction￿of￿the￿vehicle,￿it￿initiates￿coordinated￿steering￿interventions￿on￿the￿front￿and￿rear
wheels.￿The￿speed￿of￿the￿stabilizing￿intervention￿is￿such￿that￿it￿is￿hardly￿perceptible￿by￿the￿driver.
Decelerating￿DSC￿brake￿interventions￿can￿largely￿be￿dispensed￿with￿which￿improves￿the￿stability￿and
damping￿of￿the￿vehicle.
F12￿Possible￿driving￿dynamics￿interventions￿during￿understeering
Index
A
B
1
2
3
4
M
If￿the￿driver￿misjudges￿a￿bend￿when￿driving￿fast￿on￿a￿country￿road,￿the￿vehicle￿may￿understeer.
Explanation
Prevention￿of￿understeer￿by￿individual￿brake￿modulation￿(DSC)
Prevention￿of￿understeer￿by￿rear￿axle￿steering￿intervention￿(IAL)
Individual￿brake￿modulation￿(DSC)
Rear-wheel￿steering￿intervention￿(IAL)
Course￿of￿an￿understeering￿vehicle
Course￿of￿a￿vehicle￿with￿neutral￿drivability
Yaw￿moment￿acting￿on￿the￿vehicle￿due￿to￿an￿intervention￿by￿the￿driving
dynamics￿control
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