Smarter Vehicles, Safer Roads
North Carolina has the tenth highest rate of traffic fatalities in the United States, according to the National Highway Traffic Safety Administration. More than 1,400 people died on state roads in 2008, the most recent year for which figures are available. That's roughly the same number who died in wrecks 15 years earlier, even though traffic fatalities had dropped 8 percent nationwide. NC State researchers are trying to improve those grim statistics, studying ways to help drivers stay in their lanes and avoid crashes or cushion the impact if a collision does occur.
The DARPA Grand Challenge, a Department of Defense competition to build driverless vehicles, got Dr. Wesley Snyder thinking a few years back about ways to build cars that use human-like vision. The professor in the Department of Electrical and Computer Engineering (ECE) didn't participate in the contest, but he used his expertise in robotics to take a step toward the goal of a "seeing" car by designing a system to keep a vehicle in its lane of traffic. Such a system could be crucial if a driver has a heart attack, seizure, or other medical condition that would cause a loss of control.
NC State researchers are studying ways to help drivers stay in their lanes and avoid crashes or cushion the impact if a collision does occur.
Snyder developed algorithms to mimic some of the biology believed to be behind the way people see. His research team then placed a video camera on the hood of a toy jeep and hooked it up to a laptop computer on the back of the jeep. The camera sends images of the road ahead to the computer, where the algorithms recognize lane markers, stop signs, tail lights of other vehicles, and traffic lights. The curvature of the road helps the computer infer the jeep's speed and distance from other objects as the vehicle moves. Snyder is now working on boosting computing power because the laptop can process only two images each second, limiting the jeep to a snail's pace. "We've got part of it solved, but we still have more work to do," he says. "Driving in tight traffic at high speeds is a very tough problem."
Dr. Mo-Yuen Chow, Snyder's ECE colleague, is taking a different tack to try to solve that problem. Using the concept of "intelligent space," or the control of distributed networks, he is working on a system to turn future vehicles into the equivalent of planes being tracked by air-traffic control. State transportation departments already have control centers to monitor traffic in metro areas, and Chow says global-positioning system (GPS) devices could one day beam information collected from various vehicle sensors to the control centers and receive real-time warnings not only about traffic congestion ahead, but also when the driver needs to take quick action to avoid a collision.
Using biological names to describe his work, Chow compares the overall project to an immune system for vehicles and says the first step is to create a "gene library" of situations a driver might face. Factors like vehicle speed, weather conditions, the curve of the road, and traffic combine in different ways to produce a range of outcomes, he says, much like genes do in humans. Eventually, human factors like driver age and fatigue will be in the gene library, too. As vehicle information is fed into traffic control centers from numerous GPS devices, a program will run through the database to assess the risk that two or more vehicles are headed for a collision and will alert them as needed to take corrective action. "This isn't like air traffic, where you have miles between planes," Chow says. "We need to process data in real time for split-second decisions."
For instances where a collision is unavoidable, Dr. Afsaneh Rabiei has patented a metallic foam that, when used behind bumpers and in other automotive body parts, could transform crashes into the vehicular equivalent of pillow fights. The associate professor in the Department of Mechanical and Aerospace Engineering was convinced she could devise a stronger metal foam than those made by simply injecting air bubbles into molten metal. "There's no control over the internal structure and properties of those foams," she says. "The lack of structural uniformity causes the cells to buckle and fail prematurely."
Rabiei eventually hit upon the idea of mixing hollow steel spheres into molten steel or aluminum. The resulting composite material, which looks like a silvery sponge, can absorb seven to eight times the energy of other metal foams and 70 to 80 times that of solid steel or aluminum. "The foam sacrifices itself, so passengers don't have to take a hit in an accident," she says. Tests have shown that bumpers with Rabiei's metal foam would make a 28-mile-per-hour collision feel like a bump at 5 miles per hour to a vehicle's occupants.
"The metal foam sacrifices itself so passengers don't have to take a hit in an accident."
Through her research, she customized the steel spheres, similar to tiny ball bearings, so the diameter and wall thickness provided the optimal strength. The spheres bond together well in the metallic matrix so they can be compressed up to 80 percent — as might occur in a wreck — without cracking or bulging. "Our mission here is to save lives," she says. "If my metal foam lets someone walk away from a crash, then I've done my job."