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Occupant protection gets ahead of the collision

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Tags: Safety, Software
ZF develops predictive safety with BMW for enhanced occupant protection in automated passenger cars: safety systems can be designed to reliably deploy before a crash and help provide greater protection for occupants.
Achim Neuwirth, July 05, 2021
Achim Neuwirth has been writing for ZF since 2011. He has specialized in writing texts about all kinds of car-related topics: from vehicles to the technology behind them, to driving and traffic.
If a car crashes, it can prepare itself for the impact in many ways while still falling. In this way, it can survive impacts more effectively. ZF and BMW want to teach cars similar capabilities: Predictive safety will help make accidents potentially less serious for people.

Assisted and automated driving only works if the car is aware of its surroundings. The same sensor technology also helps enable it to adapt to impending crashes "with an eye to the future”. Examples include seat belts that are pretensioned or seats that recline when a crash seems unavoidable. In principle, this can be compared to muscles that tense as a precaution, to stay in the cat's image. "But now, together with BMW, we are expanding the protection potential in dangerous situations much further," says Dr. Bernhard Grotz, Project Manager Predictive Safety, in ZF’s Advanced Systems Development department.
"Together with BMW, we are expanding the protection potential in dangerous situations much further."
Dr. Bernhard Grotz, Project Manager Predictive Safety, in ZF’s Advanced Systems Development department.

ZF allows airbag systems to see

ZF allows airbag systems to see
The teams' common goal: Airbags and seatbelt pretensioners are to be triggered, if necessary, even before a collision - and be precisely coordinated with how severe it will be. "The time advantage we gain can help make the decisive difference in mitigating the consequences of an accident," says Dr. Philipp Straßburger, System Architect, Predictive Safety in ZF’s Advanced Systems Development department. This is confirmed by initial simulations with a corresponding pre-crash system (prototype): The injury severity in a frontal collision with a speed reduction of around 25 km/h, for example, can be reduced by up to 50 percent.

Safety system learns from accidents of others

Safety system learns from accidents of others
Elementary to this is a new software platform for predictive safety. After all, airbags can't just be triggered "on spec”. The electronics must be able to decide with maximum reliability that an unavoidable crash is imminent. "To achieve this, we first had the system learn digitally from various 'real' world accident events," says systems engineer Lena Amann.
ZF accessed one of the world's most important data collections: the German In-Depth Accident Study (GIDAS). From this, the engineers filtered out frontal collisions involving passenger cars and light commercial vehicles in Germany since 2008 - specifically those in which occupants were injured. They then narrowed these down further to first collisions in which the cars did not skid. This left 5,798 crashes between vehicles (car-to-car) and 596 with static objects (walls, trees, stationary vehicles).
ZF engineers used the data from 6,396 accidents to assess dangerous situations to the system.

Prediction must be accurate and fast

Prediction must be accurate and fast
ZF then taught the function to assess dangerous situations precisely and quickly. If, for example, two vehicles are heading toward each other, the decision algorithm has to weigh the following, among other things: How likely is it that an accident or collision will occur? What will be the positions of the vehicles before and during the collision? How long will it take for the crash to occur and at what speeds will the vehicles collide? There is hardly any time to think about this: it must be clear in very few milliseconds whether an electronic ignition command is sent to the airbags.

Advanced protection creates more freedom

Advanced protection creates more freedom
Cats are naturally programmed to anticipate the unavoidable. While still in the air, they reflexively bring themselves into a safer position and with their limbs stretched away. As described, the automotive pre-crash function is similar at preparing to potentially cushion the risk of injury to passengers.
It can also be adapted to the safety concept of virtually any self-enclosed passenger vehicle. In the future, this would make advanced electromechanical restraint systems possible: for example, seat belt pretensioners and airbag gas generators that use much less or even no pyrotechnics. Restraint systems that, as in the past, only trigger after a crash could do so in a more precisely timed manner and be better adapted to the specific hazardous situation. And predictive safety is even laying the foundation for the greater freedom of movement that occupants in autonomous cars would like to see. To this end, it is combined with interior monitoring systems (ImS) that detect where and how people are currently sitting.
The predictive solution thus also has its place in the upcoming ZF modular software system for integrated safety. This will link further active and passive system solutions in order to bring us closer to the goal of zero accidents and traffic fatalities. After all, only cats can count on nine lives.

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