Audi q7 2017 - Page 33

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Warnings against a possible collision
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 classies the driver as active or inactive and, conse-
quently, 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, ABS Control Module J104 prells the
brake system and modies 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 driver does not respond to the warnings, however, J104
generates an acute warning by jolting the brakes. The
warning jolt is a very brief but easily noticeable braking
impulse which does not serve to slow the vehicle down. 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 jolt will be produced
within a certain time window ahead of the last opportunity
to brake or take evasive action to avoid a collision.
Braking intervention phase
If the driver does not respond to the warning jolt, J104 will
automatically initiate braking. If the vehicle automatically
comes to a halt without driver input, further audible signals
will sound.
These signals alert the driver to the fact that he must
actively take control of the vehicle (for example, by apply-
ing braking). If the driver fails to take control of the vehicle,
the system will release the brake and the vehicle will start
to move.
The following preconditions must be met in order to
activate the system:
• presensecity responds to pedestrians who are standing
in the same lane as the vehicle or moving towards same
lane as the vehicle.
• presensecity is active upwards of a speed of about
6.2 mph (10 km/h).
Response to pedestrians
Collision warning phase
If the vehicle is traveling at a speed of about6.2 mph
(10 km/h) and a pedestrian crosses the lane in front of the
vehicle or is standing in the same lane as the vehicle creat-
ing a critical driving situation, the instrument cluster issues
audible and visual advanced warnings to the driver.
• presensecity can warn against pedestrians up to a
speed of 52.8 mph (85 km/h).
• presensecity can initiate braking up to a speed of 52.8
mph (85 km/h).
637_041
Audi pre sense
Flowchart
Precharging of the braking system, hydraulic
brake assist reacts more sensitively
Audible and visual driver warnings
(early warning)
Warning jolt
Emergency or full braking Collision
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