BMW G12 Product Information page 148

G12￿Driver￿Assistance￿Systems
22.￿Lane￿&￿Traffic￿Jam￿Assistant
22.1.5.￿Steering￿interventions
If￿the￿current￿course￿of￿the￿vehicle￿deviates￿too￿much￿from￿the￿target￿trajectory￿(path￿curve),￿a￿steering
correction￿is￿initiated.
The￿steering￿intervention￿is￿a￿corrective￿measure.￿This￿means￿the￿driver￿is￿not￿relieved￿of￿his￿duty￿to
steer￿the￿vehicle.￿As￿the￿corrective￿steering￿interventions￿are￿limited￿to￿approximately￿1.5 m/s²￿based
on￿the￿lateral￿acceleration,￿the￿system￿cannot￿navigate￿curves￿above￿the￿respective￿speed-dependent
curve￿radius￿without￿the￿driver's￿assistance.￿The￿driver￿must￿therefore￿steer￿the￿vehicle￿at￿the￿same
time￿in￿order￿to￿stay￿on￿the￿roadway.
The￿target￿trajectory￿and￿required￿steering￿corrections￿are￿calculated￿based￿on￿the￿driving￿speed￿as
follows:
Speed￿range￿0￿to￿70￿km/h:
• The￿position￿and￿previous￿movements￿of￿the￿vehicle￿driving￿ahead￿are￿given￿priority￿when
determining￿the￿appropriate￿steering￿corrections.
• Detected￿lane￿markings￿are￿taken￿into￿account￿to￿avoid￿unwanted￿steering￿corrections￿that
would￿result￿in￿leaving￿the￿lane.
• Corrective￿steering￿interventions￿in￿the￿direction￿of￿the￿center￿of￿the￿lane￿are￿initiated￿if￿the
vehicle￿detects￿there￿is￿not￿a￿vehicle￿driving￿ahead.
Speed￿range￿70￿to￿130￿km/h:
• Corrective￿steering￿interventions￿in￿the￿direction￿of￿the￿center￿of￿the￿lane￿are￿initiated.
• It￿is￿possible￿to￿bridge￿the￿gap￿for￿a￿limited￿time￿where￿lane￿markings￿are￿not￿detected￿by
estimating￿the￿course￿of￿the￿lane￿based￿on￿the￿vehicle￿driving￿ahead.
Speed￿range￿130￿to￿210￿km/h:
• Corrective￿steering￿interventions￿in￿the￿direction￿of￿the￿center￿of￿the￿lane￿are￿initiated.
• For￿safety￿reasons￿above￿a￿driving￿speed￿of￿approximately￿130 km/h￿the￿course￿of￿the￿lane￿is
not￿estimated￿using￿the￿vehicle￿driving￿ahead.
The￿vehicle￿driving￿ahead￿is￿given￿priority￿as￿the￿"correction￿target"￿at￿speeds￿ranging￿between
approximately￿0 and￿70 km/h￿due￿to￿the￿limited￿detection￿of￿lane￿markings.
In￿traffic￿jams￿or￿slow-moving￿traffic￿following￿distances￿are￿often￿extremely￿small￿(< 10 m)￿due￿to
tailgating￿and￿lanes￿ahead￿are￿often￿partially￿covered￿due￿to￿staggered￿driving.
This￿means￿the￿KAFAS￿stereo￿camera￿is￿unable￿to￿correctly￿interpret￿the￿lane￿markings￿in￿some￿cases.
When￿classifying￿the￿object￿driving￿ahead,￿vehicles￿such￿as￿motorbikes￿are￿not￿used￿as￿the￿"correction
target".
Steering￿torque
The￿driving￿dynamics￿function￿software￿in￿the￿Dynamic￿Stability￿Control￿(DSC)￿control￿unit￿calculates￿a
target￿steering￿torque￿based￿on￿the￿curve￿nominal￿value.￿The￿target￿steering￿torque￿is￿then￿converted
to￿an￿engine￿torque￿by￿the￿Electronic￿Power￿Steering￿(EPS),￿which￿finally￿results￿in￿a￿steering￿wheel
movement￿at￿the￿wheels.
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