HAMBURG (dpa) – Since its introduction 20 years ago, the airbag has undoubtedly played a major part in enhancing vehicle safety. Yet the absorbent bags fitted to car steering wheels, seats and door interiors are not to be compared with soft cushions.
Under certain circumstances what is designed to save lives can represent a deadly hazard. The National Highway Traffic Safety Administration in the United States estimates that of the 1,000 car occupants saved by airbags, 57 would have been still alive if the devices had not be fitted to the vehicles they were travelling in.
Experts from insurance companies and motoring clubs are agreed that the rapid, explosive deployment of the airbag poses the biggest risk.
More than 100 litres of air are thrust into the bag within fractions of a second, sending it bursting through the dashboard.
Occupants wearing their safety belts properly and positioned on their seats correctly have nothing to fear but woe betide anyone who is “out of position”. They risk – as an examination of accidents in the U.S. has shown – serious injury ranging from a broken arm to a cracked skull.
Particularly hazardous are rear-facing seat restraints for children and in some countries legislation stipulates that they should not be installed uneless the airbag is switched off. According to German carmakers Audi and Mercedes, two-stage detonators fitted to many cars ensure that the bags deploy less violently.
The industry realizes that passengers need to be better protected from the side-effects of airbag inflation and experts are working on a number of fronts to solve the problem. Spurred on by tougher legislation due to come into force in the U.S. in 2004 the engineers are trying to devise smart airbags, with sensors which detect the severity of a collision and react accordingly.
At systems developer Siemens VDO Automotive in Regensburg, experts are working on a release mechanism fitted with a 3D camera and weight sensors. An occupant’s seat would recognize the person’s position and measure his or her distance from the airbag. Ideally the system would deploy with maximum force in the case of large or heavy passengers but more slowly and gently in the case of a small, lightweight child.
Siemens VDO plans to calibrate the response of airbags according to the occupant’s distance from the absorbent bag. If the passenger in the correct position no special reaction is needed but should the camera register an anomaly or passenger “out of position” deployment would be delayed so that the airbag poses no danger when inflating – even at the risk of lessening the cushioning effect.
Some production cars are already fitted with intelligent airbag solutions that go some way to ameliorating the dangers. In the Ford Mondeo the airbag can recognize the position of the seat in relation to the steering wheel and inflate accordingly and Jaguar spokesman Paul Schinhofen said the Jaguar XK8 uses infrared sensors to locate determine the coordinates of the front seat passenger before deployment.
The fact remains though that such sophisticated systems have not generally advanced beyond the experimental and test phase.
Of course experts are agreed that by 2003 the carmakers must come up with a solution that complies with the new U.S. legislation. Individually adjustable, sequential airbags are unlikely to be generally available that soon and Siemens VDO researchers believe an interim solution will be airbags which switch themselves off if a passenger is in the “wrong” position in the car.
Sensors for these must be 150 percent reliable since the difference between a saved life and a wasted one sometimes amounts to just a few centimetres.
