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TRW load-limiting retractor for seat belts helps keep pressures under control for different-sized users in a collision situation (i.e., the belt doesn’t apply the same amount of force for a small female and a robust male).
TRW electronic stability control (ESC) system is specifically developed for hybrid vehicles. It provides the means to provide other safety capabilities beyond helping control vehicle yaw.
With more than 60,000 employees in some 185 facilities in 26 countries, and with 90% of its business focused on safety, TRW Automotive (trwauto.com) clearly knows more than a little about trends and developments in the technology that can make vehicles safer to drive. And so we meet with Matt Roney, vp, Product Planning & Business Development; Andrew Whydell, senior manager, Product Planning; and Danny R. Milot, deputy technical director, Slip Control Systems, to learn what the state of the technology is in this area that is both important from the point of view of consumers who are making decisions about what to buy, as well as from a regulatory requirement, as “The National Highway Traffic Safety Administration has a legislative mandate under Title 49 of the United States Code, Chapter 301, Motor Vehicle Safety, to issue Federal Motor Vehicle Safety Standards (FMVSS) and Regulations to which manufacturers of motor vehicle and equipment items must conform and certify compliance” (nhtsa.gov/cars/rules/import/fmvss/index.html), and the list of FMVSS is extensive, to say the least.
In addition to which, there are several global variants of the New Car Assessment Program (NCAP), as well as ratings from organizations like the Insurance Institute for Highway Safety (IIHS) that look at car crashes under a variety of conditions, so again, this is a case where safety really matters.
And as for the importance to the consumers who are buying a vehicle, according to George Peterson, president of AutoPacific (autopacific.com), a leading automotive consumer research firm, safety is in the top five of elements related to purchase decisions. Based on its 68,000-respondent database of new car and truck buyers in the U.S., “Feeling Safe While Driving” is “very or extremely important” to 88%. In addition to which, Peterson points out that “Safety Features” ranks 9th and “Safety Ratings” 13th. Which puts safety ahead of things ranging from design to acceleration, quietness to cargo space. Peterson goes on to note that “Feeling Safe While Driving” is most important to Large Car (92%) and Luxury Car (91%) buyers.
In the U.S., the level of passive safety—as in seat belts and airbags—is fairly comprehensive, but, as Roney points out, “There’s still more innovation to be had in passive safety,” which is largely predicated on making those passive systems smarter and more adaptable. For example, whereas crash testing was once performed on 50th percentile dummy—essentially a 5-ft, 10-in. male weighing in at 168 lb.—nowadays, NCAP testing puts 5th percentile dummy (5-ft female weighing 110 lb.) into the mix. Consequently, an airbag that works just fine for the former is not going to be quite as effective for the latter. So what they’re looking to do is to deploy what Roney calls “smart features” in the airbags (such as having tethers on the inside of the bag that restricts the size of inflation should the person be more diminutive) as well having seat belt load limiters that help control the forward movement of the individual involved in an accident.
But a real way that safety can be enhanced, one that brings active safety into play along with the passive systems, is through the use of sensor technology that can actuate the airbags and the seatbelts more quickly. “In the past,” Roney says, “crash sensors would detect that a crash has happened and would deploy the technology; now it is about sensing that a crash will happen and things like pretensioning the safety belts, pre-arming the airbags, and building brake pressure can occur.” The collision will still happen, but the consequences can be mitigated.
If you consider the architecture of a vehicle, if there is a frontal collision, there is some real estate between the front of the car and the front seat occupants. In a side collision, there isn’t a whole lot of space between the outside sheet metal and the inside door trim. Whydell explains, “In a conventional car we have accelerometers in the B-pillars or doors. That’s backed up by a secondary sensor that is normally in the airbag control unit that’s located in the center tunnel,” a well-protected area within a vehicle. So if there is a side impact, the accelerometer is actuated but to make sure this isn’t a false alarm, the measured pulse goes through the vehicle to the sensor in the center tunnel. This can take on the order of 10 to 12 msec. Not long measured on a wrist watch, but a whole lot of time for someone sitting in the car.
So the next step is having side-facing radar that is used as the primary sensor. It “sees” an incoming vehicle, and then when the accelerometer “picks up the corresponding acceleration trace,” it can fire the airbag: “It doesn’t wait for the signal to travel to the sensor in the tunnel.”
While this might seem as though it would be a natural, there is the issue of cost. So Whydell says that one way to amortize the cost is by using the side-facing radar not only for accidents, but for a more common application: blind-spot detection. Depending on the location of the radar sensor and the size of the sweep, the radar system can be used for both everyday driving as well as for some-thing that people would prefer to avoid.
Similarly, there is the situation in the front of the car. An increasing number of vehicles—generally high-end vehicles—are being offered with automatic cruise control (ACC). ACC uses a radar system to help keep a set distance between a vehicle and a vehicle in front of it. The signals from the radar can be used to adjust the brakes and the throttle to maintain the set distance. According to Whydell, the first systems were launched by Mercedes based on long-range, 77-GHz radar systems. But these systems are typically engineered for Autobahn-type speeds, which aren’t the norm in places like the U.S., and consequently comparatively costly (e.g., a system engineered to handle speed of 120 mph is certainly different than one that deals with 90 mph).
So TRW has developed 24-GHz radar systems for ACC, which are in themselves less expensive, and which have less expensive associated control electronics. (“We want to develop advanced safety that’s affordable that can be driven into the mass market,” Roney says.)
Here’s where it gets interesting. Because ACC means that there is integration with the braking system and the engine, and because many cars now have electronic stability control (all model year 2012 cars sold in the U.S. must be equipped with ESC), there is the possi-bility of further integration of systems that would provide even greater levels of vehicle control for active safety: not only braking and throttle control, but even suspension and, assuming electronic steering, steering as well.
However, with the addition of things like ACC, there can be the need for more-robust braking systems. That is, Danny Milot points out that if there is a desire to go beyond simply slowing down a vehicle and to be able to provide full stop in a hurry—a.k.a., a panic braking situation—it can be necessary to have a more powerful braking system that would be able to instantaneously provide that capability (e.g., higher power motor, additional pumps, additional pressure transducers).
While some people are talking about safety developments being predicated on vehicles communicating with vehicles (V2V) or with the infrastructure (V2I), Whydell makes an interesting observation: “If someone decided tomorrow to fit this technology into all vehicles, and if cars turn over at a rate of 5% per years, then it will take a long time for the fleet to have that capability.” Which is why they’re focusing at TRW on developing the wherewithal to provide smart, affordable technology in individual vehicles.