<Li> Pedestrian airbag module </Li> <P> During a crash event, the vehicle's crash sensor (s) provide crucial information to the airbag electronic controller unit (ECU), including collision type, angle and severity of impact . Using this information, the airbag electronic controller unit's crash algorithm determines if the crash event meets the criteria for deployment and triggers various firing circuits to deploy one or more airbag modules within the vehicle . Working as a supplemental restraint system to the vehicle's seat - belt systems, airbag module deployments are triggered through a pyrotechnic process that is designed to be used once . Newer side - impact airbag modules consist of compressed air cylinders that are triggered in the event of a side on vehicle impact . </P> <P> The first commercial designs were introduced in passenger automobiles during the 1970s with limited success . Broad commercial adoption of airbags occurred in many markets during the late 1980s and early 1990s with a driver airbag, and a front passenger airbag as well on some cars; and many modern vehicles now include six or more units . </P> <P> Over time, various manufacturers have used different terms for airbags . In the 1970s, General Motors marketed its first airbag modules under the unwieldy name "Air Cushion Restraint System (ACRS)". Common terms in North America refer to a nominal role as a supplement to "active" restraints, i.e. seat belts . Because no action by a vehicle occupant is required to activate or use the airbag, it is considered a "passive" device . This is in contrast to seat belts, which are considered "active" devices because the vehicle occupant must act to enable them . </P>

When was the first airbag put in a car