Nothing captured the eclectic and grassroots spirit of the event more than Point One Navigation's autonomous negotiation of Thunderhill Racetrack in reverse. It was an idea that Nathan, project leader of Cornell University's DARPA Urban Challenge team, had mulled for more than a year. Over dinner the night before, he decided almost on a whim to attempt the backward lap. He and his team stayed up much of the night tweaking the same code that underpinned Cornell's Urban Challenge entry 15 years ago to make a reverse lap possible.
"We have a very simple simulator to test it to make sure the car doesn't careen off a cliff or something, and it basically showed it worked," he said. "We took the code and modified it to drive in reverse. The math works. It's all physics-based. You just have to make sure the controls tell the car to go to the next point correctly."
Point One Navigation enables precise location mapping with proprietary technology. Using satellites and other ground-based infrastructure, it can identify the position of vehicles to within 10 centimeters of their actual location — about the width of a softball.
The company's Lexus CT 200h did its first lap in painstaking fashion, taking 18 minutes to complete the 2-mile course during a trial run. Point One reached 25 mph during a second run, completing it in five minutes. Three other teams — using everything from one-fifth scale cars to three-wheeled motorcycles — completed conventional, forward-facing autonomous trips during the weekend-long event.