Porsche Cayenne Owner's Manual page 183

Porsche Stability Management (PSM)
PSM is an active control system for stabilization of
the vehicle during extreme driving maneuvers. It
operates together with the Porsche Traction
Management (PTM) system.
PSM makes use of both the ABD and TCS
systems, as well as the known functions of the
anti-lock brake system (ABS) and engine drag
torque control system (MSR).
Warning!
In spite of the advantages of PSM, it is still the
driver's responsibility to adapt her/his driving style
and maneuvers in line with road and weather
conditions, as well as the traffic situation.
The increased safety that is provided should not
induce you to take greater risks with your safety.
The limits set by the physics of driving cannot be
overcome, even with PSM.
Risks of accident due to inappropriate speed
cannot be reduced by PSM.
Advantages of PSM
– Best possible traction and lane-holding ability
in all driving situations – even on road surfaces
with varying friction.
– The system compensates for undesired vehi-
cle reactions (load-alteration effect) when the
driver releases the accelerator pedal or brakes
on bends. This compensation functions up to
the maximum lateral acceleration.
– PSM actively stabilizes the vehicle as required
during dynamic driving maneuvers (e.g. rapid
steering movements, during lane changes or
on alternating bends).
– Improved braking stability on corners and on
different or varying road surfaces.
– Improved brake functioning and reduced
stopping distance in the event of emergency
braking.
Readiness for operation
PSM is switched on automatically every time you
start the engine.
Function
Sensors at the wheels, brakes, steering system
and engine continuously measure:
– Driving speed
– Direction of travel (steering angle)
– Lateral acceleration
– Longitudinal acceleration
– Rate of turn about the vertical axis
PSM uses these values to determine the direction
of travel desired by the driver.
PSM intervenes and corrects the course if the
actual direction of motion deviates from the
desired course (steering-wheel position):
It brakes individual wheels as needed. If neces-
sary, PSM additionally influences the engine power
or the gear-changing characteristic of the
Tiptronic in order to stabilize the vehicle.
Driving and Driving Safety
183