Airbag Technology Trends

From Passive to Active
Last Updated 12/19/2014

Automakers are constantly improving the effectiveness of airbags by placing them in new areas of a vehicle and coming up with innovations. An airbag is a protective cushion that rapidly inflates with gas to protect the occupants of a vehicle from injury in the event of a crash. We'll explain how airbag technology is advancing from being a passive safety feature to becoming part of active safety systems.   

Next Gen Airbags

“Riding on a cushion of air” may soon be more than a euphemism for a smooth riding car. Airbags that deploy below your vehicle may well become as important in preventing crashes as they currently are in preventing injuries in the wake of an accident. Such is the fast-changing world of airbags.

For years, driver-side airbags (along with seat belts) were the poster children for “passive” safety devices—or devices designed to protect people when an accident occurs. But engineers have continued to push the envelope with airbags. Since 2010 in particular, everything about passive airbag safety has changed: how they inflate, where they are located, and how many are in a given car.

Today, the focus on their application as an “active” safety device—or helping you avoid crashes in the first place—is stepping to the fore. 

Let’s sort it all out, beginning with the advances in airbags as passive safety devices.

Passive Safety

In 1999, frontal airbags were mandated in all US cars. How effective have they been? In frontal crashes, driver fatalities have been reduced by 29 percent, and fatalities among front-seat passengers age 13 and above have declined 32 percent, according to the National Highway Traffic Safety Administration (NHSTA). These are great numbers, but in the drive to bring highway deaths to zero, engineers have focused on improving airbags in the following areas: Deployment and Location.

Deployment.

If you’ve ever been in an accident in which airbags deployed, you know it’s not like face-planting in a Sealy Posturepedic mattress. It’s more akin to belly-flopping from the diving board. Painful at best, injurious at worst. Initially, airbags deployed at one speed; by the late 1990s automakers were switching to “de-powered” airbags to prevent injuries to passengers. No longer. Today, the key terms are dual-stage, multi-stage, variable output, and flexible-venting. Dual-stage and multi-stage airbags, as the names imply, have two or more levels of inflation, based on the severity of the impact. Variable option airbags use a range of data—from crash impact and driver size/weight—to determine how much force with which to deploy the bag. Flexible-venting airbags allow pressure to escape when a passenger makes contact with the bag, thus minimizing the impact.

Location

If one is good, more must better. Right? In the world of auto-safety, yes. In recent years, knee airbags, center airbags, pedestrian airbags, even head airbags have become commonplace additions to the more-traditional frontal airbags. 

  • Available since the late 1990s, knee airbags are getting more attention and becoming increasingly popular as a way to protect passengers’ knees, hips, and legs. The concern with these has always been the amount of space they take up in a car. In 2015, Ford is introducing a new knee airbag that deploys from the glove compartment, using considerably less space. 
  • Head airbags, or curtain airbags, are becoming increasingly popular. Initially, these deployed from the roof and were designed to provide protection against brain injury in side-impact and rollover crashes. Today, innovations include curtain airbags that deploy from the door upwards, and curtain airbags for rear-seat passengers.
  • Inflatable seat belts are also now available. Designed to protect the head, neck, and torso, this idea is gaining popularity with Ford in particular. Be aware, however, that makers of child safety seats do not currently recommend combining safety seats with inflatable seat belts.

Each of these are really upgrades of long-existing airbags. The real innovation has come in side-impact airbags and in pedestrian airbags designed to protect folks who may be hit by a car.

The issue with side-impact bags is car design. In front and rear collisions, much of the energy is absorbed by bumpers. This energy absorption greatly improves airbag performance. Side-impact collisions have only a thin door between passengers and the car that would hit them. In addition, to be effective, side-impact airbags have to deploy much faster to be beneficial. 

Volvo decided to solve this problem with the center airbag that deploys from the seatbacks. First appearing in 2009, this airbag is designed to provide driver-side protection in the event of side collision when no passenger is riding in the front seat. In the event a passenger is present, the airbag absorbs energy from a side-impact collision as well as maintains the space between driver and passenger, thus, protecting both. 

BMW is going with door-mounted bags as these allow a bigger bag, creating more protective space.

Which of the two styles is more effective remains to be seen.

Thinking “outside” the airbag box, Volvo invented pedestrian airbags. Currently in use only in Europe, these have yet to be widely adopted. Even Volvo is having second thoughts.

Ideally, the airbags deploy by sensor just prior to striking a pedestrian or bike rider. When engaged, the bag deploys from the rear of the hood, covering the windshield and preventing the person struck from flying through and harming himself or herself on the glass and surrounding metal.

However, Volvo last year stated it would not expand the pedestrian airbag to other models. Instead, the automaker sees the future of pedestrian and cyclist safety coming from sensors that detect a person outside the car and bring the vehicle to a stop before contact is made. 

As reported to Drive magazine in late 2013, Volvo is emphasizing “active” safety over “passive” safety. In short, they’re not interested in increasing the number of “balloons” on and in a car to protect people, but to technology that avoids the accident in the first place.

Active Safety

Does the switch to active safety mean the days of airbags are numbered? Not exactly. The most interesting airbag innovations continue to be their use on the outside of the car. And while their application is not strictly “active safety,” they’re coming close. 

Mercedes-Benz is leading the way with an airbag that literally puts the car on a cushion of air in the event of an imminent crash. In head-on collisions, the driver’s instinct is to hit his or her brakes hard. This causes a front-end dip that mitigates the front-bumper’s ability to absorb the crash’s energy. To off-set this, Mercedes would have bags deploy beneath the car. Two things occur. First, it greatly decelerates the car (thus potentially avoiding a collision) and it also elevates the car so that if the crash occurs, you hit bumper to bumper, taking full advantage of the car’s energy absorbing front-end. 

Safety manufacturer TRW wants to take external airbags to whole other level, literally surrounding a car with airbags. Think Mars Lander, which hit the surface of the Red Planet completely surrounded by inflated bags. 

The idea is that, using sensors, these airbags would deploy milliseconds prior to crash and wrap the occupants in a bundle of bags that deflects the impact’s energy. 

This latter idea is probably 5-10 years out, but it has interesting possibilities. 

That’s a Wrap

One can begin to envision a time when airbags are no longer necessary. When computers, not humans, are driving cars and accidents become a thing of the past (though, computers fail, too—so whether we’ll ever cede control to computers completely remains an open question).

That said, for the foreseeable future, airbags are here to stay as they evolve and adapt alongside the newest innovations in active safety. In fact, we look to be in a new age of airbag invention.

By Martin Davis