ZF LIFETEC develops airbags for autonomous driving

Alfdorf, Germany- ZF LIFETEC, an automotive supplier has developed dual-contour airbags for passengers and is advancing similar technology for drivers in the next generation of automated vehicles. These airbags adjust their inflation size based on the specific seating position, enhancing protection in various scenarios.

Level 3 highly automated driving is becoming feasible in a wider range of vehicles and receiving approvals in more countries. Drivers are allowed to divert their attention from traffic once the system is engaged, provided they can promptly resume control if required. With Level 4 fully automated driving, this limitation could be lifted for sections of the route where the vehicle operates independently. Additionally, drivers will have the option to adjust their seat position and backrest angle slightly for greater comfort when the automated system assumes control of driving duties.

Mr.Harald Lutz, Head of Development at ZF LIFETEC, said, “Our aim is to ensure that occupants in comfort seating positions also enjoy at least the same safety standards they are accustomed to in automated driving.”

One airbag, two sizes

Crash tests have demonstrated that when a frontal collision happens with front occupants seated in a comfort position, typically with a backrest angle of around 40 degrees, the traditional combination of seatbelt and airbag may no longer provide optimum protection for the occupants.

In this position, the distance between the inflated airbag and the occupant is too great to effectively cushion and restrain the passenger. It's important to note that the reclined position, where the backrest and seat surface form a 90-degree angle, is considered the baseline (0 degrees), with the usual seating posture around 20 degrees. As we move towards automated driving, a solution is needed that ensures high safety standards for both seating positions. This is the concept behind the dual contour airbag.

During development, ZF Lifetec utilized insights gained from creating a dual-contour passenger airbag, slated for rollout this year. The new driver airbag also incorporates dual-stage functionality, adjusting based on whether the driver is in an upright or comfort seating position. This feature is managed by a control unit that activates a system of bag-cushion-tethers, which are released as required by an active release unit. 

Inflator for extra volume

ZF Lifetec has developed a two-stage gas generator for dual-contour driver airbags, enabling rapid inflation to accommodate larger airbag volumes. This technology allows for approximately 200 mm of depth adaptivity on the driver's side. On the passenger side, ZF Lifetec achieves a maximum inflation volume of up to 190 litres, which is unique on the market.

Adjusted filling pressure

The car's airbag control system is embedded within its electronics, enabling it to pinpoint the driver's seat position at the moment of impact and deploy the gas generator accordingly. Alongside seat tilt and weight sensors, the system may integrate interior cameras to enhance its precision in assessing the interior environment during a crash.

An additional enhancement can be made to the dual-contour airbag system, allowing it to adjust the inflation pressure based on the occupants' size, weight, and posture. For instance, if sensors or interior cameras detect a tall and heavy individual in the driver's seat, the system can dynamically open-air vents to vary the inflation pressure. This capability optimizes the airbag's effectiveness in providing restraint tailored to the specific characteristics of the occupant.