Porsche Stability Management (Psm) - Porsche Boxster Owner's Manual

Porsche Stability Management
(PSM)
PSM is an active control system for stabilization of
the vehicle approaching the performance limits of
driving maneuvers.
Warning!
Risk of an accident, resulting in serious per-
sonal injury or death.
The increased control that is provided should
not induce you to take greater risks with your
safety. The limits dictated by the laws of
physics cannot be overcome, even with PSM.
The risk of accidents due to inappropriate
speed cannot be reduced, even by PSM.
The driver bears the responsibility for all
driving maneuvers.
f Adapt your driving style to the prevailing road
and weather conditions.
f Obey all traffic laws.
Sensors at the wheels, brakes, steering system
and engine continuously measure:
– Speed
– Direction of travel (steering angle)
– Lateral acceleration
– Rate of turn about the vertical axis
– Longitudinal acceleration
PSM uses these values to determine the direction
of travel indicated by the driver.
PSM intervenes and helps to correct the course if
the actual direction of motion deviates from the
chosen course (steering-wheel position):
It brakes individual wheels as needed. In addition,
the engine power may be manipulated in order to
stabilize the vehicle.
The events below inform the driver of PSM control
operations and warn him/her to adapt his/her
driving style to the road conditions:
– The multifunctional information light on the
instrument panel flashes.
– Hydraulic noises can be heard.
– The vehicle decelerates and steering-wheel
forces are altered as the PSM controls the
brakes.
– Reduced engine power.
– The brake pedal pulsates and its position is
changed during braking.
In order to achieve full vehicle deceleration,
foot pressure must be increased after the
brake pedal has begun vibrating.
Examples of PSM control operations
– If the front wheels of the vehicle drift on a
bend, the rear wheel on the inside of the bend
is braked and the engine power is reduced if
necessary.
– If the rear of the vehicle swings out on a bend,
the front wheel on the outside of the bend is
braked.
Additional braking functions
– Pre-filling the brake system:
The brake system is prepared for possible
subsequent emergency braking if the acceler-
ator pedal is released suddenly and quickly.
The brake system is prefilled and the brake
pads are already applied gently to the brake
discs.
– Brake booster:
In the event of an emergency braking operation
where the pedal force is insufficient, a brake
booster provides the braking pressure neces-
sary for maximum deceleration at all 4 wheels.
Advantages of PSM
– Best possible traction and lane-holding ability
in all driving situations – even on road surfaces
with varying friction.
Operation, Safety
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