electronic stability program (esp) - ja505

 Electronic stability control (ESC), also
referred to as electronic stability
program (ESP) or dynamic stability
control (DSC), is a computerized
technology that improves the safety of
a vehicle's stability by detecting and reducing
loss of traction (skidding)
Operation of the ESP
 When ESP detects loss of steering control, it
automatically applies the brakes to help "steer"
the vehicle where the driver intends to go.
 Braking is automatically applied to wheels
individually, such as the outer front wheel to
counter oversteer or the inner rear wheel to
counter understeer.
 Some ESP systems also reduce engine power
until control is regained. ESP does not improve a
vehicle's cornering performance; instead, it helps
to minimize the loss of control.
Electronic Stability Program
ESP Control Modes
Normal modes
 During normal driving, ESP works in the
background and continuously monitors steering
and vehicle direction. It compares the driver's
intended direction (determined through the
measured steering wheel angle) to the vehicle's
actual direction (determined through measured
lateral acceleration, vehicle rotation (yaw), and
individual road wheel speeds).
ESP Off Mode
 Many ESP systems have an "off" override
switch so the driver can disable ESP, which
may be desirable when badly stuck in mud or
snow, or driving on a beach, or if using a
smaller-sized spare tire which would interfere
with the sensors
ESP with sport mode
 The Electronic Stabilization Program (ESP)
adds to that reassurance without numbing
the performance thanks to its Sport mode.
The system will brake wheels individually and
modulate the engine’s power output to
rescue the situation if it detects you have lost
control. So you can enjoy the car’s supreme
handling to the full.
ESP With ASR Mode
(acceleration slip regulation)
 ASR improves traction and can help the driver
maintain control even if the limit of adhesion
is inadvertently reached while cornering. In
addition, it reduces tire wear. ASR activation,
is indicated by a flashing light in the
instrument cluster; it works with the
electronic differential lock (EDL) and it is also
part of the electronic stabilization program
(ESP). ASR can be deactivated with the ESP
ESP With ABS Mode
 ESP also uses traction control for driving safety.
If the traction control system is detecting wheel
slippage, the electronic stability control sensor
will pick up on the direction of the slide. If there's
a difference between the angle of the steering
wheel and the direction the car is sliding, the ESP
will work with the traction control system to
engage the ABS at the proper wheel (or wheels)
and control the throttle to reduce the speed of
the vehicle.
ESP with EBR mode
 ESP complements the familiar functions of
the engine braking regulation (EBR).
 EBR reduces brake slip at the drive wheels
during deceleration and ensures directional
Adaptive Brake Light
Adaptive Brake Light
 During heavy braking from a vehicle speed
greater than 50km/h, the Electronic Stability
Program ESP® activates the new "Adaptive
Brake Light" safety function, which makes the
brake lights flash instead of just lighting up
 Once the danger has passed and the brake pedal
is only held or slightly released by the driver,
ESP® deactivates the "Adaptive Brake Light" and
the brake lights light up continuously as usual.
These flashing brake lights ensure a higher level
of attention on the part of following traffic.
Components of ESP
1.ESP-Hydraulic unit with integrated
2.Wheel speed sensors
3.Steering angle sensor
4.Yaw rate sensor with integrated
acceleration sensor
5.Engine-management ECU for
Electronic Sensor:
 Wheel-speed sensors: One wheel-speed sensor at
each wheel measures the speed of the wheel which
the computer can then compare to the speed of the
 Steering-angle sensors:This sensor, in the steering
column, measures the direction the driver intends to
aim the car. If it's different than the direction the car
is actually traveling, the ESP system will kick in.
 Rotational-speed sensor:This is also known as the
yaw sensor. It's the one in the middle of the car that
measures the side-to-side motion of the vehicle.
Hydraulic Component
 ESP uses a hydraulic modulator to assure that
each wheel receives the correct brake force. A
similar modulator is used in ABS. ABS needs
to reduce pressure during braking, only. ESP
additionally needs to increase pressure in
certain situations and an active vacuum brake
booster unit may be utilized in addition to the
hydraulic pump to meet these demanding
pressure gradients.
Yaw Rate Control
 ESP incorporates yaw rate control into the antilock braking system (ABS). Yaw is a rotation
around the vertical axis; i.e. spinning left or right.
Anti-lock brakes enable ESP to brake individual
wheels. Many ESP systems also incorporate
a traction control system (TCS or ASR), which
senses drive-wheel slip under acceleration and
individually brakes the slipping wheel or wheels
and/or reduces excess engine power until control
is regained. However, ESP achieves a different
purpose than ABS or Traction Control
 An Electronic Stability Program system on
Mercedes Benz S550
Different between vehicle using
ESP and without using ESP
 Vehicle without ESP ®
 Vehicle approaches an obstacle
 Vehicle goes off course, enters oncoming traffic lane and
driver loses control
 Counter steering causes the vehicle to go into a skid
 Vehicle with ESP ®
 Vehicle approaches an obstacle
 Vehicle threatens to break away. ESP intervenes and
restores full steer ability
 Counter steer results in threat of renewed breakaway, ESP
intervenes again
 Vehicle is stabilized
 ESP has made driving easier and less likely to
end in a serious accident.
 Essentially it prevents your car from skidding
out of control.
 Automatically adapts the engine torque
to the respective wheel-to-roadsurface traction possibilities if the
driver accelerates too heavily
 Increases the level of active driving safety since
only non-spinning wheels provide optimum
traction without impairing side stability.
 Reduces the braking distance in corners or on
roads with a smooth surface
 Significantly improves the directional stability of
the vehicle when cornering -up to the limit
 ESP cannot prevent a crash if the vehicle exceeds
its physical limits, but it helps to make sure that
the driver does not lose control of the vehicle
under extreme conditions.ESP monitors such
things as the driver's steering and braking
decisions, engine speed, and individual wheel
speed and slippage. It then reduces engine speed
and/or applies the antilock brakes of individual
front of rear wheels to correct understeer or
oversteer until stable control has been regained.

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