Cruise control
Adaptive Cruise Control
Modern commercial vehicles are equipped with cruise
The limitations of conventional cruise control systems are
control. Cruise control maintains a set, constant vehicle
overcome by Adaptive Cruise Control (ACC).
speed under varying road conditions and thus is a great relief
If the vehicle catches up with a preceding vehicle, ACC
for the driver, at least on not too busy motorways.
reduces engine throttle and (if necessary) applies braking
force to maintain a safe distance as preset by the driver. Even
in dense traffic and with other vehicles crossing or joining his
lane at various speeds, the driver is relieved from frequent
manual intervention.
What are the benefits of ACC?
Above all, Adaptive Cruise Control reduces the strain on the
driver. Because ACC maintains a safe distance to the vehicle
immediately ahead, the driving is much more relaxed, with
reduced symptoms of fatigue.
ACC includes a Forward Collision Warning (FCW) function
to alert the driver if manual intervention is required.
In dense traffic, however, the driver must continually adjust the
Advanced Emergency Breaking System (AEBS) further
vehicle speed to the traffic flow. The benefit of conventional
reduces the risk of a rear-end collision by applying up to the
cruise control systems diminishes as the traffic gets heavier.
maximum available brake power if appropriate.
How does ACC work?
A radar sensor behind the grille detects objects
ahead of the vehicle and checks their relative speed
and distance. Three radar beams together with an
integrated yaw rate sensor enable the system to
differentiate between vehicles in the same lane and
those in other lanes.
When will ACC react?
ACC will react on:
• moving objects ahead that are coming closer,
like preceding vehicles driving at a lower speed.
• stationary objects that have been detected
moving before, like a slowly moving queue that
comes to a full stop.
The driver sets a desired cruise speed and
following distance to a vehicle ahead.
ACC will not react on:
• objects that are moving away from the vehicle,
like overtaking vehicles.
• stationary objects, like a traffic jam that is already
at complete stand-still when first detected.
• opposing traffic.
To maintain the set distance the vehicle speed will
be adapted by active intervention from ACC in the
vehicle systems:
engine throttle
engine brake
automatic gear shift down
secondary retarder
service brakes
• ACC is intended for use on main roads and
• The field of view of the radar sensor is limited. In
some situations (for example a motorcycle, or a
vehicle driving far off centre) other traffic can be
detected later than expected or not be detected
at all.
• ACC is a supporting system that will contribute
to more relaxed and safer driving. However,
ACC is not an autopilot. The driver himself will at
all times remain fully responsible for his vehicle.
How will ACC react?
Maintain a preset distance
If a preceding slower vehicle is detected, ACC
will maintain a safe distance by decelerating the
vehicle. If the lane ahead is clear again, the vehicle
will accelerate to the set cruise speed.
ACC alerts the driver if manual intervention is
needed to avoid a collision, Active intervention by
FCW and AEBS in the vehicle systems will follow if
the driver does not react properly.
ACC distance alert
• audible distance alert and yellow warning on the
central dashboard display
FCW distance alert
• audible distance alert and red warning on the
central dashboard display
FCW partial braking phase
• max. deceleration 3 m/s2
AEBS full braking emergency phase
• max. decelaration 6 m/s2
ACC and AEBS can be switched on and off by the
driver. FCW will remain active, even with ACC off.