The Evolution of Front Airbags

Improving Benefits and Reducing Risks


  • The Evolution of Front Airbags

    The Evolution of Front Airbags

    What kind of airbags does your car have? The only way to know is to check your owner's manual. | March 18, 2010

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Frontal-impact airbags are something we take for granted in today's automobiles. But today's front airbags differ radically from the airbags of 1996, the year they became a federally required safety feature. What's more, depending on the age and the brand of vehicle you're driving, you could have one of several types of front airbags -- all of which have different benefits and risks. And as we've all heard, some can be a serious danger to your child should he or she be sitting in the front seat during a collision.

But airbag technology is getting a lot more advanced. Starting in the 2006 model year, all passenger cars and light-duty trucks must be equipped with sensors that identify children and very small adults and deploy the airbag with less force or not at all. This doesn't mean it's OK for kids to ride up front, but it does mean fewer risks for adults of short stature. Some automakers are taking things a step further by designing airbag systems that not only change the force that the airbag deploys, but also the size and shape of the airbag. These technology advances are all part of an effort to improve airbag safety and benefits.

Kids At Risk
While safety experts and automakers agree that the safest place for any child age 12 or under is the backseat, they recognize that some drivers do allow children to sit in the front seat and set out to study the potential injury to a child or small adult when a front-impact airbag deploys. After studying different types of airbag deployments, researchers concluded that airbags in older vehicles pose the greatest risk. A recent study in the Archives of Pediatric and Adolescent Medicine found that children had a 14.9 percent chance of serious injury from airbag deployment in a 1997 model year vehicle or older, versus a 9.9 percent risk in a vehicle from the 1998 to 2001 model years. Later-model vehicles were not studied.

The older vehicles came equipped with first-generation airbags, which could harm and even kill children and very small adults, especially those not wearing seatbelts, due to the extreme force with which the airbags deployed. In 1997, 53 people were killed when the airbag deployed in a collision, with 31 of those deaths children, according to the National Highway Traffic Safety Administration (NHTSA).

Many automakers had fought the federal requirement, precisely because of a fear of airbag injuries. After seeing the number of fatalities, federal regulators changed the airbag requirements to allow a "depowered" airbag, which gave automakers the opportunity to reduce the deployment force, thereby improving airbag safety, while still providing additional protection beyond the seatbelt in a crash.

Interestingly, children older than age 12 may also be at risk of injury when a depowered front airbag deploys, regardless of their height or weight. A June 2005 study conducted by medical researchers at Oregon Health & Science University concluded that young teens age 13 and 14 were also at risk due to their lack of bone density and muscle mass. Critical changes in body composition occur during puberty, and as a result the study found that older teens age 15 to 18 could benefit from an airbag deploying in a collision.

Advanced Airbags
As airbag technology progressed, automakers began to develop methods to reduce the deployment power of airbags based on the size of the occupant. By the early 2000s, some automakers introduced these new airbags, calling them "advanced," "smart," "dual-stage" or "multi-stage."

These airbags were created primarily to reduce the risk of airbag-related injury or death to children and small adults by either deploying with less force or not at all, depending on the situation. Sensors, usually located in the seat and seatbelts, sent signals to the vehicle's computer providing information such as the weight and seating position of the occupant and if he or she was wearing a seatbelt. In the event of a collision, the computer then made a split-second decision on whether to deploy the airbag at full force, reduced force or not at all.

Unfortunately, in the earliest versions of advanced airbags, the systems didn't always "sense" the occupant accurately, effectively fooling the computer. Some owners of Hyundai, Jaguar, Jeep, Lexus, Nissan and Toyota vehicles complained to NHTSA, that their vehicle's front-passenger "airbag off" warning light came on whenever a small adult was in the seat, or would intermittently turn off depending on the person's sitting position.

Other owners noted systems were so sensitive that the airbag sensors would deactivate the airbag if a seat cover was installed or a towel tossed over the seat. In addition, hard braking or swerving could throw the front passenger off balance and cause the airbag sensors chose to deactivate the airbag moments before an accident.

Fortunately, there were only a few reports of these issues and, in the years since automakers have continued to improve these advanced systems. Currently, NHTSA does not have a single investigation pending for any airbag-related issue.

NHTSA Weighs In
With all the changes in airbag technology, NHTSA began to look closely at the best way to regulate airbags to provide the greatest benefits to vehicle occupants, while at the same time reducing the risk of injury from the airbag itself. It created a rule requiring automakers to install advanced front airbag systems for the driver and front passenger. Each system must include sensors to detect the size of the occupant, the seat position, seatbelt use and the severity of the crash.

Some automakers take the technology one step further. Mercedes-Benz and BMW, for example, have sensors that can identify a child car seat on the front-passenger seat and suppress the airbag in a crash. Jaguar's Adaptive Restraint Technology System (ARTS) uses ultrasonic sensors to identify when occupants are out of the typical seating position and either reduce the force or suppress the airbag altogether.

Advanced airbags began being phased-in in 2003 and are required in all light-duty vehicles by the 2006 model year. About 20 percent of 2004 model year and about 65 percent of 2005 model year vehicles have these airbags. Federal testing requires these airbags to be safe for an average-sized male and a small woman (5 feet tall and 100 pounds) wearing seatbelts in collisions of up to 30 mph. The airbags must also be safe for a small woman who is not wearing a seatbelt in a crash of up to 25 mph.

Child dummies are also involved in airbag safety testing. These dummies are tested in car seats as well as unrestrained in various positions (sitting, kneeling and lying down) to ensure real children will not be injured by the airbag itself.

Reduced Force, Reduced Size
For the 2006 model year, some automakers have upped the ante in airbag technology, going beyond the federal requirements for airbag safety. Both General Motors and Ford have introduced new designs for their front airbags that not only deploy with less force but in a smaller size, depending on the size and location of the occupant.

In real world situations, sensors determine the size, shape and force that the airbag should deploy, or if the airbag should be suppressed completely, within milliseconds. Both automakers are offering these next-generation airbags on select 2006 models and will be adding it to additional models in the future.

"This new technology is a paradigm shift because previously airbags have been a 'one-size-fits-all' approach," explains Stephane Vitet, occupant restraints performance engineer at GM.

General Motors' "dual depth" system uses sensors to look at the force of the collision in real time, as well as the weight of the occupant and the position of the seat. The vehicle's computer then determines the appropriate size and force of airbag deployment. "This is especially important on the passenger side because [unlike the driver] the occupant can sit anywhere and in any position he wants," explains Vitet. Dual-depth frontal airbags are currently available on the 2006 Buick Lucerne and Cadillac DTS.

GM uses several dummies to test the system to ensure the airbags themselves pose no risk of serious injury. In the driver seat, engineers place a small female dummy leaning on the steering wheel — the position she would be in if she were not wearing her seatbelt in a frontal crash. In the passenger seat, they use a dummy representing the average-sized 10-year-old in several unrestrained positions.

Ford's dual-depth system, available on the 2006 Ford Explorer and Mercury Mountaineer, uses weight sensors that place passengers in five different weight classes, varying the size and force of the airbag accordingly. On the driver side, the system uses the seating position to change the airbag deployment and collapsible steering column, depending on the person's size. "For a smaller occupant, we make the airbag size smaller by routing some of the gas that would go into the airbag during a larger deployment into the instrument panel," explains Mike Leigh, safety research engineer at Ford. "This way the bag is smaller and softer and more appropriate for a small-statured occupant."

Lest you think all the advances are on the domestic side, Lexus has equipped the 2006 Lexus IS with a new twin-chamber airbag in the front-passenger position. The SRS Twin-Chamber Airbag deploys in a way that creates a depression in the airbag's center, dispersing the energy throughout the occupant's upper body. This is an advantage over a single-chamber airbag, which often places the force on a specific area of the body, increasing the risk of injury.

Looking To The Future
While it's likely that more automakers will adopt technology similar to GM and Ford's dual-depth airbags, even more advanced airbag technology is on the horizon. Soon, these ultra-intelligent systems should be able to identify even greater detail, such as if the front passenger is riding with his feet on the dashboard or is leaning over to pick something up off the floor at the moment of a collision.

Regardless of how advanced airbags become, one thing is likely to remain the same: the recommendation that children under 13 ride in the backseat. After all, technology can only work within, not eliminate, the laws of physics.

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