Electronic Stability Control: The Next Great Safety Advance
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See Also: ESC Tutorial How Electronic Stability Control Works
By Les
Jackson
AIADA Contributing
Editor
The seat belt – a simple, inexpensive piece of
equipment – has saved huge numbers of lives and limited serious
injuries in crashes since they were mandated in all passenger vehicles in
the mid-60s. Since 1975, when only about 20% of people used them, seat
belts have been documented by NHTSA (the National Highway Traffic Safety
Administration) to have saved over 135,000 lives and prevented countless
serious injuries. It has been only recently that seat belt use reached the
80% level – an impressive statistic,
nonetheless.
Now poised to enter into automotive history as
what most experts consider the second most beneficial safety device: ESC,
or Electronic Stability Control, is a device that makes skilled drivers out
of everyday operators of motor vehicles. Think of it this way: imagine
driving down a winding road in the rain and suddenly encountering a tight
turn. You’re going too fast for the conditions and any attempt to
brake or turn is going to result in loss of control and a dangerous skid
sideways. Now imagine that you’re in the same vehicle with a NASCAR
or Formula 1 race driver at the wheel. He/she can easily bring the vehicle
into control because race drivers have extensive training and practice in
recognizing changing vehicle dynamics while the vehicle is at the limits of
adhesion. The driver would easily be able to make the correct adjustments
to steering, braking and power to safely negotiate the situation.
Electronic Stability Control (ESC) takes the
place of that highly skilled driver in any vehicle. It utilizes the
technology inherently available in ABS (Anti-lock Brake System) and
Traction Control systems to control a vehicle’s tendency to lose
directional stability. Using a system of sensors that detect lateral
acceleration, yaw and wheel speeds, ESC computer software determines the
degree to which the vehicle is plowing (understeer) or fishtailing
(oversteer) and selectively applies braking pressure to individual front or
rear wheels and reduces engine power to bring it under control. All this
happens so quickly that most drivers wouldn’t notice that anything is
wrong.
The effectiveness of ESC in helping the driver
maintain control of the car has been confirmed by many studies in the
Enter the
SUV
According to current safety data, over 10,000
people each year die in rollover crashes and nearly half of the fatalities
involve SUVs and light trucks. This is a growing safety issue, since SUVs
and light trucks are three times more likely to roll over in a single
vehicle crash than a passenger car. Several years ago NHTSA started
compiling data on rollover crashes, primarily involving SUVs and light
trucks. As these vehicles gained popularity with the buying public; the
incidence of such crashes dramatically increased because drivers
weren’t familiar with the different handling characteristics of high
center-of-gravity vehicles. Some of the very things that drew people to
SUVs and minivans – tall "greenhouse," stiff suspensions, 4-wheel
drive, high ground clearance, heavy and strong construction – also
made these vehicles more prone to loss of control and rolling over. Clearly
something had to be done…
Rulemaking
Now that SUVs and minivans comprise nearly half
of all new vehicle purchases it falls upon NHTSA to mandate safety systems
that will make operation of these vehicles and passenger cars more
predictable and directionally stable in all conditions. A NHTSA NPRM
(Notice of Proposed Rulemaking) is now at the Office of Management and
Budget and is expected to get through the review process as early as the
end of this congressional session. The NPRM will encompass the minimum
rollover/loss of control safety standards that will be mandated for new
models. These standards will be based upon predictable test models in which
repeatable data can be demonstrated (one such model is the "J" turn, in
which radical steering input is introduced to cause a vehicle to fishtail).
After the NPRM is issued all auto manufacturers
will have at least 60 days to comment before a final rule is issued. When
the rule becomes law (presumably, by spring 2007) a phase-in schedule for
SUVs and light trucks is most likely to begin in 2008. Ultimately, all
vehicles will be required to be equipped with some form of ESC. NHTSA
estimates the costs will range from $300 to $800 per vehicle, depending
upon model and drivetrain configurations.
What Do Automaker
Say?
Vehicle manufacturers welcome this new standard.
In fact, nearly all manufacturers already offer ESC on some of their
product lines and three (Hyundai,
Addendum
ESC is currently not retrofittable to older
vehicles, unfortunately, because its complex software and sensor
integration must be done during the initial design of the vehicle’s
architecture. This doesn’t preclude some company from eventually
marketing a "semi-ESC" device for older vehicles, but there is no way of
predicting if/when such technology will be developed. Meanwhile, below is a
worldwide listing (provided by Continental Automotive Systems) of which
vehicle manufacturers use electronic stability control systems under
different marketing names:
Acura: Vehicle Stability Assist (VSA)
Audi: ESP - Electronic Stabilization Program
Buick: StabiliTrak
BMW: Dynamic Stability Control (DSC), including Dynamic
Traction Control
Cadillac: All-Speed Traction Control &
StabiliTrak
Chevrolet:StabiliTrak (except Corvette - Active Handling)
Chrysler: Electronic Stability Program (ESP)
Dodge: Electronic Stability Program (ESP)
Ferrari: Controllo Stabilita (CST)
Ford: AdvanceTrac and Interactive Vehicle Dynamics (IVD)
Honda: Electronic Stability Control (ESC) and Vehicle
Stability Assist (VSA)
Infiniti: Vehicle Dynamic Control (VDC)
Jaguar: Dynamic Stability Control (DSC)
Jeep: Electronic Stability Program (ESP)
Kia: Electronic Stability Program (ESP)
Land
Rover: Dynamic Stability Control (DSC)
Lexus: Vehicle Dynamics Integrated Management (VDIM) with
Vehicle Stability Control (VSC) and Traction Control (TRAC) systems
Lincoln: AdvanceTrak
Maserati: Maserati Stability Program (MSP)
Mazda: Dynamic Stability Control
Mercedes: Electronic Stability Program (ESP)
Mercury: AdvanceTrak
MINI Cooper: Dynamic Stability Control
Mitsubishi: Active Skid and Traction Control
MULTIMODE
Nissan: Vehicle Dynamic Control (VDC)
Pontiac: StabiliTrak
Porsche: Porsche Stability Management (PSM)
Saab: Electronic Stability Program
Saturn: StabiliTrak
Subaru: Vehicle Dynamics Control Systems (VDCS)
Suzuki: Electronic Stability Program (ESP)
Volvo: Dynamic Stability and Traction Control (DSTC)
VW: Electronic Stability Program (ESP)