A guide to … Stability Control

div align="center">wheel sensor, a throttle sensor and a sensor which
Stability Control has been touted as the mostdetects how much pitch or lean the car is experiencing
important automotive safety device since the seatbelt.in a corner.
Governments in North America, Europe and AustraliaEngineers also found a way to apply the brakes to
have plans to make the technology compulsory on alleach individual wheel, to help bring the car under
new vehicles because studies have shown it cancontrol in the safest and most effective manner
reduce the likelihood of single-vehicle crashes andpossible.
prevent roll-overs.Modern versions of the technology is so good, a race
It is designed to prevent cars from an unintended skiddriver in a car without Stability Control would unlikely
in a bend. In most cases the technology works withoutout-manoeuvre the same car with a well-calibrated
the driver knowing that he or she has had a brush withStability Control system, because the system can do
danger.what the driver can’t: brake individual wheels.
In essence, Stability Control protects drivers from minorAll this requires an incredible amount of computer
indiscretions, such as when suddenly findingpower.
themselves on wet or slippery pavement, or in anStability Control systems constantly monitor and
unexpectedly tight corner.process hundreds of times per second the following
However, Stability Control does not (and nor does itinformation:
promise to) over-rule the laws of physics. If Vehicle speed (wheel sensors)
you’re travelling way too fast for a corner or Steering input (steering wheel sensor)
for the conditions, you may still run off the road. Acceleration (throttle sensor)
Stability Control is an extremely worthwhile technology, Braking (brake sensor)
but it is important to note that some systems are Pitch or ‘lean’ of the car
more effective than others.(yaw sensor)
Car makers use different names to describe theThanks to complex algorithms and thousands of hours
technology; there are more than 20 acronyms acrossof tests and calibrations, engineers develop Stability
the industry.Control systems to suit each vehicle’s
Stability Control was originally called ESP, for Electroniccharacteristics, such as weight, mass, engine power
Stability Program, a deliberate pun on Extra Sensoryand tyre grip.
Perception because the technology uses sensors toSome cars are programmed for conservative drivers
monitor driving conditions and driver behaviour.and so the Stability Control system is prone to
Stability Control first appeared on a production car inintervene at the earliest hint of a skid.
1995, on the luxury flagship sedan, the Mercedes-BenzSome cars, particularly performance vehicles, often
S Class, although the technology was developed on itshave a slightly higher threshold because they have a
behalf by electronics company Bosch and appearedhigher level of grip.
on other vehicles soon after.Despite the varying levels of effectiveness, Stability
Today, the technology is most commonly called ESC,Control is still proven to be a life-saver.
for Electronic Stability Control, although in recent timesOverseas studies of crashes involving cars equipped
it has simply been called Stability Control.with Stability Control claim there have been reductions
To understand in the simplest terms how Stabilityof between 35 and 50 per cent in serious injury
Control works we need a brief history lesson.single-vehicle collisions.
The roots of Stability Control started with anti-lockThis is one of the reasons that the European New Car
brakes, or ABS (Anti-lock Braking System).Assessment Program (ENCAP) and the Australian
In an emergency stop, ABS systems automaticallyNew Car Assessment Program (ANCAP) recently
clamp and release the brakes up to 20 times perdecided that only vehicles with Stability Control could
second while the driver is applying full brake pedalbe awarded a Five Star safety rating.
pressure.As with its European affiliate, ANCAP is an
Once again, this often occurs without the driverindependent body that crash tests vehicles to higher
necessarily knowing that the technology is at work.standards than those imposed by Governments.
The benefit is straightforward: ABS prevents theIt is intended to be a consumer guide to car safety
brakes (and therefore the tyres) fromand most top-selling models are tested.
‘locking’ and gives the driver theANCAP is supported by Australian and New Zealand
ability to steer around an obstacle. It is especially helpfulautomobile clubs, the State government road and
in wet weather braking.transport authorities of NSW, Victoria, South Australia,
For ABS to work, cars had to be fitted with extraQueensland, Tasmania, Western Australia, the New
sensors to monitor the speed of each of the fourZealand Government, the Victorian TAC, NRMA
wheels.Insurance and the FIA Foundation.
Engineers eventually found a new use for theseWhen checking the safety rating of a new vehicle on
sensors and created what became known asthe ANCAP website be sure to check if a vehicle has
Traction Control.Stability Control (some older Five Star ratings
This is where the speed of the driven wheels isdidn’t require the technology).
constantly compared to the speed of the other twoMost importantly, though, when you’re looking
wheels.to buy your next car, check with the vehicle
When one pair of wheels is travelling faster than themanufacturer that the exact model you are buying has
other, the system intervenes and applies the brakesStability Control.
and/or automatically cuts engine power until theMost modern luxury cars have Stability Control as
vehicle’s speed is reduced, and all fourstandard, but on more affordable vehicles the
wheels are again travelling at the same speed.technology may be standard on some variants and
For example, in a rear-drive car, if the rear wheelsoptional or not available on others.
started to spin at a faster rate than the front wheelsNRMA Insurance is a provider of car insurance, home
(which indicate the real speed the vehicle is travelling),insurance, motorcycle insurance, business insurance,
then traction control would be activated in milliseconds.health insurance, travel insurance, boat insurance and
The same thing happens if the front wheels spin fastercaravan insurance in NSW, ACT & TAS.
than the rear wheels in a front-drive car (whenReport this article
equipped with Traction Control).This article is free for republishing
Traction Control is typically most useful at detectingSource:
unintended wheelspin when accelerating from aRepublish this article
standstill, such as when trying to drive up a steep wet
slope, or when accelerating aggressively out of aAsk a Question About this Article
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in place, it was simply a matter of adding a steering