Volvo XC90 Owner's Manual page 357

Subfunctions for City Safety
76
Function overview .
Audio-visual warning signal in the event of a
collision risk
Distance measurement with the camera and
radar unit
City Safety carries out three steps in the follow-
ing order:
1. Collision warning
2. Brake support
3. Auto Brake
The following text explains what happens during
the three steps:
1 - Collision warning
The driver is first warned of a potentially immi-
nent collision.
NOTE: The illustration is schematic - details may vary depending on car model.
76
City Safety can detect pedestrians, cyclists or
vehicles that are stationary or moving in the same
direction as the car and are ahead. City Safety
can also detect pedestrians, cyclists or large ani-
mals that are crossing the road in front of the car.
In the event of a risk of collision with a pedes-
trian, larger animal, cyclist or vehicle (including
vehicles described in the "City Safety in cross
traffic" section), the driver's attention is alerted by
means of a visual, acoustic and brake pulse warn-
ing. There is no brake pulse warning at lower
speeds, sudden driver braking or acceleration.
The brake pulse frequency varies according to
the car's speed.
2 - Brake support
If the risk of collision has increased further after
the collision warning then the brake support is
activated.
Brake support reinforces the driver's braking
action if the system considers that the braking is
not sufficient to avoid a collision.
3 - Auto Brake
The automatic brake function is activated last.
If in this situation the driver has not yet started to
take evasive action and the risk of collision is
imminent then the automatic braking function is
deployed - this takes place irrespective of
whether or not the driver brakes. Braking then
takes place with full brake force in order to
DRIVER SUPPORT
reduce collision speed, or with limited brake force
if it is sufficient to avoid a collision.
In connection with automatic braking the seatbelt
tensioner may also be activated. For more infor-
mation see the "Seatbelt tensioner" section.
In some situations, the action of Auto-brake may
begin with light braking and then progress to full
brake action.
When City Safety has prevented a collision with a
stationary object, the car remains stationary in
anticipation of positive action by the driver. If the
car has been braked to avoid collision with a
slower vehicle in front, its speed is reduced to
match that of the vehicle in front.
NOTE
On cars with manual gearbox, the engine
stops when the Auto-brake function has stop-
ped the car, unless the driver has managed to
depress the clutch pedal beforehand.
The driver can always interrupt a braking inter-
vention by firmly depressing the accelerator
pedal.
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