Passive Safety is the general name given to occupant protection systems that don’t require any action by the occupant once the accident occurs in order for them to work. These safety devices use crash sensors that determine if the collision is severe enough to cause significant injuries and therefore deploys the appropriate occupant protection device. Examples of this include electronic crash sensors; seat belts; frontal, side, rollover and knee air bags; and seat belt pretentioners.
The key to passive safety besides the products is the test dummy that confirms the safety value of a given technology in standard and regulatory tests. Dummies come in all sorts of shapes and sizes and are sometimes specialized to capture a specific crash or injury type like side impact. Crash dummies use sophisticated measuring devices along with simulated skeletal, muscle and skin properties to simulate the damage a human would sustain in a crash. While extremely technical, they still can only simulate certain body conditions and are continually being researched and improved to allow even more accurate predictions of injury in more situations.