In the past 20 years, newly produced automobiles have been equipped with occupant restraint systems, such as air bags, to reduce passenger injuries and fatalities in the event of a crash. An air bag is a passive restraint system—an automatic safety system that requires no action by the occupant. Government regulations, industrial participation, and social consciousness of safety have popularized the use of occupant restraints in vehicles worldwide. Using advanced technologies, additional restraints and enhanced functionalities are being implemented.
Automobiles entered the market more than 100 years ago. Since then, tremendous progress in reliability, usability, and safety of roadway vehicles has been made. However, the availability of passive safety systems was slow in coming, despite the initial conception in 1950s and experimental production in 1970s. It was not until the late 1980s that air bags became standard equipment, beginning in the United States. Over the last 20 years, the automotive safety industry has gone through considerable changes.In recent years, passive restraint systems have been one of the fastest-growing sectors within the automotive industry. One reason for this growth is the inclusion of additional restraint devices on vehicles. For example, the average number of air-bag modules has increased from one to two per vehicle in the early 1990s to four to six per vehicle for the latest models, with more expected to come. Another reason for this growth is an increase in the complexity and sophistication of the safety systems' functional requirements. For example, to minimize out-of-position occupant injuries, a smart air-bag system needs to be equipped with occupant-sensing capabilities.