How The Vdc System Works - Alfa Romeo GT Owner's Manual

VDC SYSTEM
(Vehicle Dynamics Control)
(on request for versions/
markets where applicable)
The VDC is an electronic system that con-
trols car stability, intervening on the driving
torque and braking the wheels in a differ-
entiated manner, in the lack of grip, it helps
to bring the car back to the correct direction.
When travelling the car is subjected to lat-
eral and longitudinal forces which can be
controlled by the driver as long as the tyres
offer adequate roadholding; when this falls
below the minimum level, the car begins
to divert from the course required by the dri-
ver.
Especially when travelling on an uneven
surface (such as paving, or due to the pres-
ence of water, ice or soil), changes in speed
(acceleration or braking) and/or course
(bends or the need to avoid obstacles) may
cause the tyres to lose grip.
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When the sensors detect the conditions
that would lead to skidding, the system in-
tervenes on the engine and on the brakes
producing a stabilising torque.
The performance of the
system, in terms of active
safety should not induce
the driver to take pointless and un-
necessary risks. The style of dri-
ving must in any case always be
adapted to the conditions of the
road surface, visibility and traffic.
The responsibility for road safety
is always and in any case the dri-
ver's.
System helps the driver to keep the car un-
der control in the event of a loss of tyre grip.
The forces induced by the system to con-
trol the loss of car stability always depend
on the grip between the tyre and the road
surface.
HOW THE VDC
SYSTEM WORKS
System is engaged automatically when the
car is started and cannot be switched off.
The basic components of the system are:
– an electronic control unit that process-
es the signals received from the various sen-
sors and brings about the most appropriate
strategy;
– a sensor that detects the position of the
steering wheels;
– four sensors that detect the turning
speed of each wheel;
– a sensor that detects rotation of the car
around its vertical axis;
– a sensor that detects lateral acceleration
(centrifugal force).
The heart of the system is the control unit,
which with the data supplied by the sensors
installed on the car calculates the centrifugal
forces generated when the car is cornering.
The yawing sensor, which originates from the
aeronautical industry, detects the rotations
of the car around its own vertical axis. The
centrifugal forces generated when the car
is cornering are detected by a highly sensi-
tive lateral acceleration sensor.