2013 SSANGYONG TURISMO sensor

09-14
(2) Over steering
What is oversteering? ▶
ESP controls during oversteer ▶ Oversteer is a term of a condition in which the steering wheel is steered to a certain angle during
driving and the rear tires slip outward losing traction.
Compared to understeering vehicles, it is hard to control the vehicle during cornering and the vehicle
can spin due to rear wheel moment when the rear tires lose traction and the vehicle speed increases.
The ESP system recognizes the directional angle with the steering wheel angle sensor and senses the
slipping route that occurs towards the vehicle cornering direction during oversteer with the yaw rate
sensor and lateral sensor. Then the ESP system applies the braking force to the front outer wheel to
compensate the yaw moment value. In this way, the vehicle does not lose its driving direction and the
driver can steer the vehicle as intended.

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(3) ESP Control
The ESP (Electronic Stability Program) has been developed to help a driver avoid danger of losing
control of the vehicle stability due to understeer or oversteer during cornering. The yaw rate sensor,
lateral sensor and longitudinal sensor in the sensor cluster and the steering wheel angle sensor under
the steering column detect the vehicle conditions when the inner or outer wheels are spinning during
oversteer, understeer or cornering. The ESP ECU controls against oversteer or understeer during
cornering by controlling the vehicle stability using input values from these sensors and applying the
braking force to the corresponding wheels independently. The system also controls the engine power
right before the wheel spin synchronized to decelerate the vehicle automatically in order to maintain the
vehicle stable during cornering.

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3) HBA (Hydraulic Brake Assist System)
(1) Purpose
HBA (Hydraulic Brake Assist) system helps in an emergency braking situation when the driver applies
the brake fast, but not with sufficient pressure, which leads to dangerously long braking distance. ECU
recognizes the attempt at full braking and transmits the signal calling for full brake pressure from the
hydraulic booster. An inexperienced, elderly or physically weak driver may suffer from the accident by
not fully pressing the brake pedal when hard braking is required
under emergency. The HBA System increases the braking force under urgent situations to enhance
the inputted braking force from the driver.
Based on the fact that some drivers depress the brake pedal too soft even under when hard braking is
necessary, the HECU system is a safety supplementary system that builds high braking force during
initial braking according to pressure value of the brake pressure sensor and the pressure changes of
the pressure sensor intervals.
When the system is designed to apply high braking force when brake pedal is depressed softly by an
elderly or physically weak driver, the vehicle will make abrupt stopping under normal braking situation
due to high braking pressure at each wheels.

09-18
(2) Operation
The brake pressure value and the changed value of the pressure sensor are the conditions in which
the HBA System operates. There are 2 pressure sensors under the master cylinder. When the ESP
ECU system determines that emergency braking is present, the pump operates, the brake fluid in the
master cylinder is sent to the pump and the braking pressure is delivered to the wheels via the inlet
valves.
If the drive depress the brake pedal slowly, the pressure change is not high. In this case, only the
conventional brake system with booster is activated.

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4) ARP (Active Roll-Over Protection)
The ARP (Active Roll-over Protection) system is a safety assistant device that minimizes, by controlling
brakes and the engine, the physical tendency of the vehicle rollover during sharp lane changes or U-
turns. For the system, software is added to the existing ESP system and no additional device or switch
is needed. One must note that the ARP system, just as general assistant devices including the ABS, is
only a safety assistant device using the ESP system and its function is useless when the situation
overcomes the physical power. Following picture shows how the ARP compensates the vehicle
position by varying each wheel's braking power to overcome the physical tendency of the vehicle
rollover during sharp turns.
The vehicle driving condition is controlled by the internally programmed logic according to the input
signals from wheel speed sensor, steering angle sensor and lateral sensor.

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4. SCHEMATIC DIAGRAM
When equipped with ABS, the braking force at each wheel will be controlled with 3-channel 4-sensor
method. And when equipped with ESP, 4 wheels will be controlled independently with 4-channel
method. (When controlling ABS system only, it will be operated with 3-channel method.) When
compared to the vehicle equipped with ABS/EBD only, the internal hydraulic circuit has a normally-open
separation valve and a shuttle valve in primary circuit and in secondary circuit. When the vehicle brakes
are not applied during engine running or when applying the non-ABS operating brakes, the normally-
open separation valve and the inlet valve are open, whereas the normally-closed shuttle valve and the
outlet valve are closed. When the ESP system is operating, the normally-open separation valve will be
closed by the solenoid valve operation and the hydraulic circuit will be established by the shuttle valve.
Then, the inlet and outlet valves will be
closed or open depending on the braking pressure increase, decrease or unchanged conditions.
▶The warning lamp comes on and warning beep sounds when the ESP is operating
Driving feeling when the ESP is operating ▶
▶Noise and vibration that driver senses when the ESP is operating
1) Hydraulic Circuit Diagram
When the ESP operates during vehicle movement, the ESP warning lamp on the instrument panel
flickers and beep comes on every 0.1 second. The ESP operation shows that the vehicle stability is
extremely unstable and it is used to warn the driver. The ESP system is just a supplementary system
for the vehicle motion and it cannot control the vehicle when it exceeds the physical limits. Do not
solely rely on the system but be advised to drive the vehicle safely.
When the ESP system activates, the driving feeling can be different depending on vehicle driving
conditions. For example, you will feel differently when the ESP system is activated during when ABS
is operating with the brakes applied and when brakes are not applied on a curve. Thus, the ESP
system would make the driver feel more abruptly when the brakes are applied during the ESP
system activation.
The ESP system may transfer noise and vibration to the driver due to the pressure changes caused
by the motor and valve operations in a very short period of time. Extreme cornering will trigger the
ESP operation and this will make the driver feel noise and vibration due to sudden brake application.
Also, the ESP system controls the engine output. So, the driver may notice the engine output
decrease even when the accelerator pedal is being applied.

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(2) Hydraulic Circuit of HBA
The above figure shows one front and one rear wheel and the same hydraulic circuit forms as in the
ESP operation. When HECU recognizes that it is an emergency and it is required for hard braking,
depending on the pressure value of the brake pressure sensor and pressure changes caused by the
pressure sensor timing, it operates the pump immediately to apply the brake pressure at the wheels.
Then, the pressure in the pump increases until just before the corresponding wheel gets locked. The
motor still keeps rotating and the outlet valve and the separation valve will stay closed. When the wheel
starts to lock, the HBA function cancels and switches to ABS operation.

09-28
2) Electric Circuit Diagram
Wheel speed sensor, Stop lamp switch, Self diagnostic connector, Warning lamp (ABS/ESP) ▶