MANILA, Philippines - Seven sensors, advanced technology and an airbag that deploys at lightning speed outside the windshield. These are the main elements of Pedestrian Airbag Technology, the system that makes Volvo—with its all-new V40—the first carmaker with a pedestrian airbag.
In China, 25 percent of traffic fatalities are pedestrians. In Europe the figure is 14 percent and in the USA, 12 percent. Far larger numbers of pedestrians are injured. The most serious head injuries involving pedestrians and cars are caused by the hard structure under the hood, the windshield’s lower edge, and the A-pillars.
These were some of the considerations when Volvo started the development of its Pedestrian Airbag Technology. The system was a world breakthrough when the new Volvo V40 was launched in Geneva earlier this year.
“We are proud to be able to offer a car with an airbag for pedestrians. The purpose of the airbag is to help protect pedestrians in certain situations when they impact the bonnet and the area around the windscreen wiper recess and A-pillar, where there may be a risk of serious head injuries,†says Thomas Broberg, Senior Technical Advisor Safety, Volvo Car Corporation.
Seven sensors embedded in the front of the car transmit signals to a control unit. When the car comes into contact with an object, the signals change. The control unit evaluates the signals and if it registers what it interprets as a human leg the pedestrian airbag is deployed.
The hood hinges are each equipped with pyrotechnical release mechanisms which, when the system is activated, pull out a pin and release the rear of the hood. At the same time, the airbag is activated and starts filling with gas. During the inflation sequence the airbag raises the hood by 10 cm. and stays in the raised position.
The added gap between the hood and the hard components in the engine compartment gives space for the bonnet to deform, creating an absorbing effect when it is hit by a pedestrian.
In its inflated position, the airbag covers the entire windshield wiper recess, about one-third of the windscreen and the lower part of the A-pillars. The entire sequence from activation of the system to full inflation takes a few hundredths of a second.
The system is active at speeds between 20 and 50 kph—75 percent of all accidents involving pedestrians take place at up to 40 kph.
“We developed the technology using computer simulations and human-like leg and head forms. The tests were carried out in a wide variety of configurations,†relates Broberg.
Two years ago, Volvo launched Pedestrian Detection with full auto brake. The system can avoid a collision with a pedestrian at speeds of up to 35 kph if the driver does not respond in time. At higher speeds the focus is on reducing the car’s speed as much as possible before the collision.