Engineering 101

Sensors Evolve to Deploy Pre-Crash Airbags in the Blink of an Eye

By Ruth Seeley

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Deadliest for children, overall deaths from side-impact collisions have increased in the U.S. from 31% to 51% in the 20 years between 2007 and 2017. Faster travel speeds and the popularity of SUVs, light pickup trucks, and crossover vehicles are largely responsible. In Germany, side-impact collisions cause 700 deaths per year and result in nearly a third of all occupant fatalities on German roads.

A new pre-crash safety system prototype developed by ZF Friedrichshafen AG uses an external side airbag that deploys just milliseconds before a collision. It provides an additional lateral crumple zone, which can help save lives and reduce occupant injury severity by up to 40%. To make this possible, ZF has networked the airbags to the vehicle’s sensor systems and developed algorithms that can determine if a crash is imminent and decide whether or not to deploy the airbag.

ZF provides full spectrum integrated vehicle safety technology, from sensor systems, algorithms, and control units to active and passive actuators. The company focuses on the  “see. think. Act.” process to design integrated vehicle safety solutions. The side airbag system has the potential to significantly reduce occupant injury severity in cases of side impact collisions.

The biggest challenge in the development of this system was reliably recognizing an unavoidable collision and deploying the external side airbag before the collision takes place. The system has approximately 150 milliseconds to make the decision to deploy the airbag and fill it—roughly the amount of time it takes a person to blink.

The vehicle’s sensors first must identify a potential impact quickly and accurately. This is possible with connected cameras, radar and lidar. Algorithms within the system software decide whether or not a collision is unavoidable, and the deployment of the airbag is both possible and beneficial. If these decisions are all affirmative, the system ignites the inflators to fill the airbag. The airbag, which has a capacity of between 280 and 400 liters (five to eight times the volume of a driver airbag) depending on the vehicle, then expands upwards from the side sill to form an additional crumple zone in the door area between the A and C pillars.

In a side impact collision, the occupants on the side of the impact are at particular risk of serious injuries in the chest area if the passenger cabin is severely deformed. The ZF pre-crash safety system can reduce the penetration of the intruding vehicle by up to 30% percent, helping to significantly reduce the occupants’ risk of injury.

The predictive information about an unavoidable collision also helps to further improve the effectiveness of established standard safety technology. For example, the ACR8 Active Control Retractor can warn the occupants or help secure them in a safe position in the critical fractions of a second before the collision.

Source:  ZF

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