Mazda 2007 CX-9, Service Highlights

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DYNAMIC STABILITY CONTROL/ROLL STABILITY CONTROL
04-18–23
04-18
DSC CONTROL OUTLINE
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•
While a vehicle normally turns safely in response to steering operation, there are instances when the limits of
tire lateral grip is surpassed due to road surface conditions or vehicle speed, and the influence of evasive
steering to avoid an accident or similar situations.
•
Tires surpassing lateral grip exhibit one of the following conditions:
—
Strong oversteer tendency: The rear wheels are relatively losing their grip as compared to the front wheels
—
Strong understeer tendency: The front wheels are relatively losing their grip as compared to the rear
wheels
•
Dynamic stability control (DSC) operates at vehicle speeds of 10 km/h {6.2 mph} or more in the conditions
described above, controlling engine output and wheel braking to suppress oversteer and understeer
tendencies.
Vehicle Condition Determination
•
The vehicle speed, steering angle, lateral-G, forward-G and yaw rate are detected by the sensors and used in
calculations by the DSC/roll stability control (RSC) hydraulic unit (HU)/control module (CM) to determine the
vehicle condition. Then, depending on the difference between the target yaw rate, calculated with the values
input from each sensor, and the value detected by the yaw rate sensor, an oversteer or understeer tendency
can be determined.
Oversteer Tendency Determination
•
When turning, if the actual vehicle yaw rate is larger than the target yaw rate (the yaw rate that should normally
be formed as determined by the steering angle and vehicle speed), it means that the vehicle is in or about to be
in a spin. Therefore the vehicle is determined to have an oversteer tendency.
Understeer Tendency Determination
•
When turning, if the actual vehicle yaw rate is less than the target yaw rate (the yaw rate that should normally
be formed as determined by the steering angle and vehicle speed), it means that the vehicle is not properly
turning. Therefore the vehicle is determined to have an understeer tendency.
End Of Sie
YAW MOMENTUM
UNDERSTEER CONDITION
LINE OF TRAVEL
TARGET YAW RATE
LINE OF TRAVEL
OVERSTEER CONDITION
LINE OF TRAVEL
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