ESP: A NECESSITY OR A GIMMICK?
WHAT IS ESP?
ESP(Electronic Stability Program) is a piece of technology used in automobiles which helps in overall improvement in the stability of vehicle by continuous monitoring on vehicles' traction(grip) levels with the road. Level of traction or grip with road can vary due to different factors including road conditions, weather, tire, etc. This system prevents the loss of traction by cutting the power to that specific wheel(s) which shows lack of grip. It also 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 over-steer, or the inner rear wheel to counter under-steer. ESP does not improve a vehicle's cornering performance; instead, it helps to minimize the loss of control.
An ESP system in present-day automobiles typically consists of two operating modes: Yaw Stability Control (YSC) and Roll Stability Control (RSC). YSC helps the driver maintain the desired heading of the vehicle even when the vehicle is operating at the limits of traction. RSC on the other hand, reduces the possibility of single vehicle, un-tripped rollovers.
COMPONENTS OF ESP:
YAW STABILITY CONTROL
This mode of ESC is used for lateral (or directional) stability of the vehicle. When
the vehicle is operating in sub-limit conditions (slip angles are very low) and has neutral steer, there is an approximately linear relationship between yaw rate and steering wheel angle given by: Yaw rate = (steering wheel angle) X (yaw rate gain). Further for a neutral steer vehicle with negligible slip angle, the yaw rate and lateral acceleration are related as follows: Yaw rate = (Lateral Acceleration) / (vehicle speed).The actual yaw rate is measured using the yaw rate sensor on board the vehicle.The difference between actual and ideal yaw rates (sometimes called ‘vehicle slip rate’) is used as the control variable for yaw stability.
(Vehicle slip rate) = (actual yaw rate) - (ideal yaw rate). If vehicle slip rate has a positive value i.e. the actual yaw rate is higher than ideal, then the vehicle is said to be ‘oversteering’. If vehicle slip rate is negative, the vehicle is said to be understeering.
DIFFERENT NAMES, SAME THING?
We should keep in our mind that our car may have ESP but it might be called something else. Car makers trademarked different names and acronyms for the system but they all do the same job. Along with ESP and ESC(Electronic stability control), you might also see VDC (vehicle dynamic control), VSA (vehicle stability assist) or DSC (dynamic stability control) in an equipment list.Some brands like to give the system their own stamp: Volvo uses the name Dynamic Stability & Traction Control (DTSC), while Porsche calls it PSM (Porsche Stability Management – not to be mixed up with PASM, which stands for Porsche Active Suspension Management and describes Porsche’s adaptive suspension system.
The once-common initials TCS (traction-control system) or ASR (Antriebsschlupfregelung, ‘drive slip control’, in German) are used for wheelspin-preventing technology and were more common before being integrated into electronic stability control in most models.
EFFECTIVENESS
A number of studies from around the world have confirmed that ESC is pretty much effective in helping the driver maintain control of the car, thereby saving lives and reducing the probability of occurrence and severity of crashes(if it somehow, occurs).
source:BOSCH
ESC is described as the most important advance in auto safety by many experts
including Nicole Nason, administrator of the NHTSA, Jim Guest and David Champion of Consumers Union of the Federation Internationale de I'Automobile(FIA), E-Safety Aware,Csaba Csere, former editor of Car and Driver, and Jim Gill, long time ESC proponent of Continental Automotive Systems.
The European New Car Assessment Program (EuroNCAP) "strongly recommends" that people buy cars fitted with stability control. The IIHS requires that a vehicle must have ESC as an available option in order for it to qualify for their Top Safety Pick award for occupant protection and accident avoidance.
CONCLUSION
How important is it?
In short, very important.Statistics in the UK have shown that ESP can reduce the chance of drivers being in a fatal accident by 25%. Similarly, studies in Sweden show up to 32% less chance of fatal accidents occurring in bad weather when the car is equipped with ESP. Infact, from 2014, European Union made it mandatory that all (mainstream) cars have ESP installed.
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