HEXA

ELECTRONIC STABILITY PROGRAM (ESP)

19.2 WORKING OF ESP

During normal operating conditions the ESP

controller will be monitoring the inputs made by

the driver through the steering wheel brakes and

accelerator pedals. It will also be monitoring the

vehicles response to these inputs through wheel

speed sensors and a yaw rate sensor.

The driver inputs are used by the system to

understand where and how the driver intends the

vehicle to manoeuvre. Using the wheel speed and

Yaw rate sensors the system calculates how the

vehicle is actually manoeuvring, and by

comparing the driver’s intentions with the actual

vehicle response it determines if it has to

intervene to maintain the vehicle on its intended

path.

The TCS part of ESP reacts to the vehicle

spinning one or more of its driven wheels. When a

wheel breaks traction and spins the drive force is

lost. The driver cannot accelerate, and the vehicle

stability is affected. The TCS is able to counter

this via 2 control strategies; firstly it can brake the

spinning wheel reducing the drive torque being

delivered at that wheel. By preventing the drive

torque from escaping at the spinning wheel more

torque will be delivered to the wheel which is free

to rotate. If all driven wheels are spinning or the

level of torque being delivered to the wheels is so

high it cannot be controlled by the brakes only the

system will reduce the engine torque to a level

that can be transmitted to the road.

The ESP is a development beyond the TCS and

reacts when it detects that the vehicle is starting

to skid (under steering or over steering).

ESP: Drive Modes MT Vehicle

Drive Modes is an innovative feature associated

can choose the vehicle dynamics as per driving

Requirements for comfort, safe and sporty drive.

This feature, which is associated with engine and

seven

Other systems in the vehicle, offers the optimum

blend of performance, refinement, fuel economy

and Excitement to the driver, Drive modes are

selected through the Rotary Switch. The switch

will have different drive modes namely Auto,

Dynamic, Off Road and Comfort.

A. Auto Mode:

In Auto Mode system will adapt to the prevailing

surface conditions automatically and enables

control settings based on the condition

sensed.This mode is designed to react more

sensitively to support a regular driver to the

available physical limit. Vehicle performance

optimized to support all surface condition.

B. Comfort Mode:

In Comfort mode vehicle performance will be

identical to Auto Mode i.e. system will adapt to the

prevailing surface conditions automatically and

enables control settings based on the conditions

sensed. The Engine power output is reduced

(320Nm) as compare to Auto Mode (400Nm), this

mode is designed to cruise in more relax manner.

C. Dynamic Mode:

The intent is to offer a stable drift through dynamic

mode selection for sporty driver. A sporty driver

wants to have more body slip angle than a normal

driver. Therefore the interventions by the Vehicle

controller in dynamic mode is more focused to

provide that extra freedom to test physical limit

aggressively.

D. Rough Road:

Rough Road Mode optimizes the vehicle behavior

for driving over rough road or other unyielding

obstacles. Such condition causes wheels to be

unloaded or to lift off the ground, causing a risk of

them to spinning up. This mode is focused to

improve

grip

and

vehicle

composure,

predominantly when wheels may be up against

steep obstacles and the vehicle is also going up

on inclined surface or rough roads, torque

optimization is specifically tuned for this condition.

Braking performance is also tuned to support

Rough road surfaces as compared to other drive

modes, it also benefits in to better stopping

distance and pedal feel for Rough Road surfaces.

The EMS internal calibration and ABS/ESP

operation modes change as per user selected

drive modes as

Described in Table below:

Visual Indication of Drive Mode selection:

The EMS and ABS/ESP will receive the switch

status on CAN and after reaching the required

drive mode,

These ECUs will send drive mode state signal to

the IPC, BCM and rotary switch to perform

functions as Described below:

1. Instrument Panel Cluster and Infotainment

system: will display the current drive mode

2. The rotary drive mode switch: It will give the

appropriate function ON LED activation to

indicate the Mode change.