HEXA

ELECTRONIC STABILITY PROGRAM (ESP)

INTRODUCTION

Electronic Stability Program

(ESP)

with Traction

Control system

(TCS)

and Hydraulic Brake Assist

(HBA)

has evolved from the Anti lock Braking

System

(ABS).

Where the ABS only aids the driver

during braking the TCS will apply control to support

the driver when accelerating, and the ESP will

provide control supporting the driver when a critical

situation such as skidding is detected. This could

occur as a result of making a sudden emergency

evasive swerve to avoid an object in the road or

when cornering on a slippery road or trying to turn

at higher speeds.

ESP will only be able prevent the vehicle from

skidding away as long as the vehicle remains

within its physical limits.

The ESP integrates with the ABS using a common

hydraulic unit with attached ECU and containing a

pressure sensor. The wheel speed sensors are

common and in addition ESP has a steering wheel

angle sensor and a combined yaw rate and lateral

acceleration sensor. The system is also connected

to the engine management system via the

integrated vehicle network (IVN) or High speed

CAN BUS.

The ESP monitors the vehicles’ dynamic behavior

and driver inputs and when it detects a situation

where the vehicle is starting to understeer

(moving

straight ahead without responding to the steering)

or oversteer

(breaking away from the rear)

. It will

support the driver by applying individual brake

controls combined with engine torque reductions to

counter the under or oversteer behaviour.

The TCS prevents the driven wheels from spinning

when the driver is accelerating via a combination

of individual brake interventions and engine torque

reductions. This way it improves the vehicle

traction and stability.

The HBA monitors how the driver applies the brake

by monitoring the brake pressure increases. If the

system detects an emergency brake application it

assists the driver by building up the brake pressure

in the wheels to achieve full ABS braking.