Along with performance, fuel economy, looks, and of course cost, safety is one of the main factors buyers weigh when making a vehicle purchasing decision. Automakers and safety system suppliers are acutely aware of this, as they constantly spend R&D resources to make vehicles safer—through both active systems such as forward collision avoidance and passive systems such as airbags.
Also driving safety technology development are ever-changing regulations. For example, the new U.S. New Car Assessment Program (NCAP) that will be used starting in model year 2011 is driving some content changes, according to Jeff Aird, Director of Customer Account Engineering at TRW Occupant Safety Systems.
“The new NCAP rating is going to require more sophisticated systems to maintain a high star rating,” Aird said. “Today, almost everybody is able to achieve 5-star ratings; if we did nothing with the new requirements and criteria, that’s going to set everybody back on average about two stars.”
These sophisticated passive systems will see the addition of more “active” features, according to Aird, such as bi-volume airbags for which "you can actually change the volume of the bag during or just prior to the crash event. Another thing is changing the venting on the airbags. The other area is on seatbelts with the force limiters or load limiters; we may have to introduce multiple levels of load limiting that react to the crash event,” he said.
Such technologies, under development at TRW and undoubtedly at other safety system suppliers, will continue to improve occupant safety in upcoming vehicles.
“Today’s electronic architecture is highly distributed, and complexity is ever increasing with up to 70 ECUs in some vehicles,” said Martin Thoone, Vice President of Engineering, Global Electronics, at TRW. “The industry needs to find smarter ways to further integrate active and passive systems and add value to vehicle manufacturers as the rate of electronics growth continues to accelerate.”
Integration is a core part of TRW’s strategy, Thoone noted, as its engineers work to develop products that help to reduce complexity, weight, packaging, and ultimately cost.
An example of this trend is a new airbag control unit (ACU) from TRW that integrates inertial sensors. “A typical airbag ECU already has accelerometers and rollover sensors,” explained Sharath Reddy, Director of Passive Safety Electronics at TRW. “By adding the yaw rate sensing into the airbag ECU, we’re able to improve the side impact and rollover performance by using the new sensor information.”
“This yaw rate sensor is used for active safety, for stability control, and was a separate module, separate housing, and extra cables,” Thoone added. “So that’s a general trend that we see—active and passive safety coming together.”
This integration not only offers a performance improvement, Reddy said, but also a “significant” cost reduction for the OEM by eliminating an electronic control unit. According to Reddy, typical cost savings would be around $5 to $10. But that figure “might go even higher if you take the cables, the connectors, the housing, and all that stuff into account,” Thoone noted.
The ACU will start production with two major vehicle manufacturers in 2012.
Sensor integration is just a first step, said Thoone. TRW is developing what it calls an initial Safety Domain ECU (i-SDE) concept, which allows for the integration of additional electronic control functions for active and passive safety.
“What we see is that chassis dynamics or vehicle dynamics functions [will also] integrate in the unit,” Thoone said. “In premium cars you have already a special chassis controller, and basically you can get that module out if you integrate the software and sensors in the airbag ECU. So that’s the next step of integration.”
TRW is currently in the concept phase with several OEMs and expects concept validation to be fixed in 2010. Production application could come in the 2013 or 2014 time frame, said Thoone.
In addition, combining data provided through various “environmental sensors” such as radars and cameras can result in the implementation of more effective “pre-safe functions,” Thoone added. For example, fusing input from radar sensors with pressure satellites or remote acceleration sensors located at the sides of a vehicle could enhance the performance (time to fire) of airbags.
“So we see a lot of integration coming in the complete safety area, active and passive safety,” Thoone concluded.