Audi Q7 - Function A

26
If the driver applies the brakes, a target braking maneouvre may be
performed in all of the phases described above (pre-charging of
the brake system, reconfiguration of hydraulic brake assist, driver
warning, warning jerk, partial braking operations I and II)
1)
.
During the target braking manoeuvre, Audi pre sense front com-
putes whether the driver is applying enough brake force to be able
to avoid a collision. If this is not the case, the required brake
pressure is increased depending on the situation.
If Audipresensefront detects that an accident is likely to be
unavoidable, the ABScontrol unit J104 can initiate automatic
emergency braking
1)
.
Emergency braking can be performed immediately up to a defined
maximum speed or after partial braking operation II. If the vehicle
has automatically brought the vehicle to a halt without driver
input, further audible signals will sound. These signals alert the
driver to the fact that he/she must actively take control of the
vehicle (e.g. by braking).
Function A
When the vehicles approaches another vehicle which is moving
much more slowly or is stationary, the control unit in the dash
panel insert J285 issues visual and audible warnings to the driver if
certain pre-defined limits are exceeded.
These warnings are given within a certain time frame ahead of the
last braking opportunity for braking or collision avoidance before
the actual collision occurs.
The timing of warnings depends on the driver's degree of activity.
Depending on steering, pedal and turn signal inputs, the system
classifies the driver as active or inactive and, consequently, as
attentive or inattentive. If the driver is classed as attentive, the
warning will be issued later than a warning for a driver classed as
inattentive. At the same time, the ABS control unit J104 prefills
the brake system and changes the deployment algorithms for
hydraulic brake assist. This means that hydraulic brake assist starts
to build up brake pressure even at low brake pedal actuation
speeds.
If the driver does not respond to the warnings or, for example,
eases o the accelerator, the ABS control unit J104 produces a
warning jerk. The warning jerk is a very brief but easily noticeable
braking impulse and does not serve to reduce speed. It alerts the
driver to the trac situation and indicates to the driver that he
must react immediately in order to prevent an impending collision.
Depending on how attentive the driver is considered to be, the
warning jerk will be produced within a certain time window ahead
of the last opportunity to brake or take evasive action to avoid a
collision. If the driver still fails to react or only eases his foot o
the accelerator, the system will initiate partial braking opera-
tionI
1)
, which involves applying up to 35 % of maximum brake
force. If the front camera for driver assistance systems R242 has
also detected the obstacle, partial braking operation II
1)
is initiated
by applying up to 60 % of maximum brake force.
1)
Not available in all countries.
Precharging of the braking system, hydraulic
brake assist reacts more sensitively
Audible and visual driver warnings
(rear collision warning)
Warning
jerk
Partial braking
operation I or
partial braking
operation II
(if the front camera
has confirmed pres-
ence of a vehicle)
Emergency braking
(if collision is prob-
ably unavoidable).
Collision
Target braking
637_001
Flowchart
637_041
Audi pre sense
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