Anti-Lock Braking System (Abs) (06.09); Dynamic Stability Control; Concept - Aston Martin V8 Vantage Workshop Manual

Brake system (06.00)

Anti-lock Braking System (ABS) (06.09)

The anti-lock braking system (ABS) is a four-channel system
having independent inputs from all four-wheel speed
sensors.
The ABS module, monitors signals from the sensors to
calculate, brake slip and the acceleration / deceleration of
individual wheels. When the brake pedal is depressed, and
the ABS module detects incipient wheel lock-up from the
incoming signals, it triggers the re-circulation pump inside
the module's hydraulic modulator, and the solenoid valves
for the wheel(s) concerned. Brake pressure, is then
modulated to increase / decrease or remain constant at the
wheel(s) concerned until wheel lock-up is eliminated. The
ABS provides self-diagnosis and any malfunction within the
system will be indicated to the driver by the illumination of
the brake warning light and 'ABS FAULT' displayed in the
message centre right. Should a fault develop within the ABS,
the brake system will operate conventionally and with the
same standard of performance as a vehicle not equipped
with ABS.

Dynamic Stability Control

Dynamic Stability Control (DSC) is a closed-loop system
designed to enhance driving safety by improving vehicle
handling when the tyres are at the limits of their grip
capabilities. This is achieved through instantaneous,
electronically controlled, reduction of engine torque and
strategic application of the brakes at individual wheels.
By using the principle that by controlling the brakes
individually it is possible, to an extent, to steer the vehicle.
This principle can be used to enhance driving safety by
correcting the vehicle's yaw moment (turning force), when
the vehicle fails to follow the driver's steering inputs.
October 2005
Anti-lock Braking System (ABS) (06.09)

Concept

Satisfactory handling is determined according to whether a
vehicle maintains a path, which accurately reflects the
driver's input (steering wheel angle) while at the same time
remaining stable.
The ABS / DSC module measures the vehicle's motion using
the sensors below and processes the information to maintain
vehicle control and stability within its ultimate control limits,
which are determined by the physical limits set by the tyre's
grip.
Wheel speed sensors - Longitudinal acceleration.
lateral acceleration sensor - Lateral acceleration.
Yaw rate sensor - Yaw rate, defined as the rotation around
the vertical axis.
When there is insufficient tyre grip for the driving situation
(for example, the driver has entered a corner too fast) the
DSC will maintain stability and optimise the cornering and
stopping performance, but cannot always prevent the
vehicle from running wide.
Driver demand is measured by using the steering wheel
angle sensor and vehicle speed to calculate the optimum
yaw rate. This is compared to the actual measured yaw-rate
and a yaw-rate calculated from the lateral acceleration and
the vehicle speed. If the deviation between these
measurements is too great, an understeer or oversteer
correction is made.
The first step in this process is to determine how the vehicle
should respond to driver demand (ideal response) and how
it actually does respond (actual response). Hydraulic control
valves can then be activated to generate brake pressure and
/ or engine torque reduction can be used to maintain the
Workshop Manual
Brake system (06.00)
6-6-1