BMW G12 - Active Lane Keeping Assistant; Active Lane Keeping Side Collision Warning

G12�Driver�Assistance�Systems
22.�Lane�&�Traffic�Jam�Assistant
142
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.