Rollover is a very unique event in the fact that it can take up to 6 seconds for the crash to complete compared to a frontal or side impact collision that is over in milli-seconds. The rollover crash also comes in many forms such as a curb trip, slipping off the side of the road, uneven pavement and sharp avoidance maneuvers on regular raods. Each one of these depending on the vehicle speed can very different types of rollovers. Rollovers are rated in terms of how many quarter turns the vehicle turns during the event before coming to rest and over what time duartion.
The rollover sensor must be able to detect all of the rollover type accidents and deploy the rollover airbag at the right time and keep it inflated through the entire event. The sensor works by detecting the roll angle of the center of the vehicle and making calculations to deploy or not. The rollover airbag is designed to stay inflated to provide head impact protection and occupant ejection protection through the entire event up to 6 seconds. Federal laws define the anti-ejection criteria by using a head form test on a deployed airbag and measuring the ability of the airbag to contain the head form excessive movement beyond the window area.