SMART Airbags: Notes

Front driver and passenger airbags have been in use with single stage activation since 1986. Once an impact is detected, the airbags are triggered with one specific level of deployment force.

From 1999, BMW developed the SMART airbag which is designed to deploy in 2 stages.

There are 4 triggering thresholds which are dependent upon the severity of impact detected, the status of the seatbelts and whether the passenger seat is occupied.

Driver's side SMART Airbag (Rear view) 

Fig 1: Identifying Driver Side SMART Airbag System

Courtesy of BMW OF NORTH AMERICA, INC.

Passenger side SMART Airbag (Rear view) 

Fig 2: Identifying Passenger Side SMART Airbag System

Courtesy of BMW OF NORTH AMERICA, INC.

The two stage airbags are used for both the front driver and front passenger which allows for a softer cushioning effect when the bags are triggered at lighter impacts.

The 2-stage airbags also employ the "cold-gas" inflation method which differs from the previous single stage airbags. The gas generators contain an inert gas mixture which is released when the airbags are triggered.

Also, the cold gas inflation method was incorporated into the side airbags and the ITS assemblies.