A few weeks ago, Ford Motor Co. quietly announced that it was rolling out a new wrinkle to the powerful safety feature called stability control, adding even more lifesaving potential to a technology that has already been very successful.
The news, of course, made barely a ripple, which is absolutely consistent with technology’s humble history. Electronic stability control has always been low-profile, in part because its modus operandi seems like such an abstraction. And Ford’s new product is no exception.
“We haven’t added any hardware,” Chris Terry of Ford Motor Co. told Design News recently. “It’s merely the adoption of an algorithm that changes the function of stability control.”
Ford’s 2015 Focus will offer a stability control system that recognizes a spin-out before it happens.
(Source: Ford Motor Co.)
The algorithm could be important, though, because it takes stability control from the realm of being a reactive technology to one that is preemptive. Working with Continental Automotive, Ford developed software that examines three driving variables -- the speed of the car, along with the angle and turning rate of the steering wheel. From those variables, it can determine if the vehicle is about to yaw.
To understand why that’s important, consider how ordinary stability control works. It uses three main sensors -- a lateral accelerometer, gyroscopic yaw rate sensor, and steering angle sensor. By gathering information from those three, and by deriving a rough estimate of the coefficient of friction on the surface it’s traversing, the system “knows” which brakes to apply and when to apply them. If the car is in oversteer and yawing in a counterclockwise direction, for example, it will apply two of the car’s four brakes as a means of producing a clockwise force. Result: Yawing stops.
Over the past five years, the effect of stability control has been positively stunning. During its rise in the US, fatality numbers have dropped steadily. According to data published by the National Traffic Safety Highway Administration late last year, cars manufactured in years prior to 2005 had more than nine traffic deaths per 100,000, whereas cars built after 2009 have had between three and 5.9 deaths per 100,000. The dates are important because the period after 2009 is when stability control gradually took hold in vehicle fleets, eventually becoming law in the US in 2012.
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“Stability control is huge,” John Capp, director of global vehicle safety for GM, told The Wall Street Journal recently. “It’s head and shoulders above the seat belt, in terms of effectiveness.”
With the new Ford-Continental system, it could become even bigger. Up to now, stability control systems have taken between 80-500 milliseconds (msec) to react. But by doing the job preemptively, Ford says its cars will be able to react to the potential spin about 100-200 msec before the event happens. All told, that’s a difference in some cases of more than half a second, which could be enough time to halt the yawing before the vehicle has a chance to trip on a curb and roll over.
Safety numbers, of course, aren’t available for a feature so new. But Ford believes the technology is making another step forward, which is why it will offer the enhanced feature on the 2015 Ford Focus. “There’s no safety claim we can make yet,” Terry told us. “All we know is that it does what it’s intended to do, which is to react earlier than stability control systems have reacted in the past.”
Senior technical editor Chuck Murray has been writing about technology for 31 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and autos.