Autonomous Racing: Bob, Meet Alice
PASADENA, Calif. - We Went! We Raced! We Ate Barbed Wire! So stated the unabashedly honest headline on the "Team Caltech" website last year. It was lamenting how the California Institute of Technology's autonomous truck, nicknamed Bob, fared in last March's DARPA Grand Challenge desert road race.
The 142-mile race from L.A. to Las Vegas called for a vehicle that could operate with complete autonomy (no driver or remote control) and finish a course that included dirt trails and open desert in 10 hours or less. Bob completed about 1.3 miles of the course; its demise was getting tangled in barbed wire. The farthest any entry made it was 7.4 miles.
Enter Alice. It's the new driverless vehicle being built by Team Caltech 2005--a group of undergrads (more than 50 in the last nine months), graduate students, and faculty advisers--that will compete in this year's race on October 8. "We are light years ahead with Alice with respect to where we were last year at the same point with Bob," says project manager Richard Murray, a professor of control and dynamical systems. That may explain why Alice sports the license plate, "I 8 Bob."
The DARPA Grand Challenge race (DARPA stands for the Defense Advanced Research Projects Agency) is intended to hasten the research and development of autonomous ground vehicles that could ultimately be used to ferry supplies to the front lines or transport wounded soldiers. "The technology is also likely to have ramifications for future automobile technology, especially for helping disabled drivers," says Joel Burdick, a technical adviser and a professor of mechanical engineering and bioengineering. "And it will likely have an impact on future autonomous space exploration as well."
The race is open to individuals and organizations, and has a $2 million first prize. This year's desert racecourse will be similar to last year's, but participants won't know the exact route until two hours before the race.
Bob, the 1996 Chevrolet Tahoe four-wheel-drive SUV used last year, has been replaced by a Ford E-350 van that has been customized for off-road travel by a company called Sportsmobile, based in Fresno, that specializes in building 4X4 vehicles. It is powered by a six-liter diesel engine that allows for long periods of idling at low fuel consumption. Special hardware has been mounted on the bumper and roof to hold the various sensors that serve as the vehicle's eyes during autonomous driving. Inside, the students have transformed Alice into a complete software lab that includes its brain--seven Dell servers sitting in temperature controlled and shock-resistant housing--and four seats with racing harnesses that, during testing, keep the students safe while strapping them down enough to let them type on a computer keyboard during rough off-roading.
Although they won't know officially until June, presumably Alice passed an important test on May 11, when DARPA officials made a site visit to see how the truck was progressing. (The visits are intended to whittle down the 100-plus entries to a final 40 teams that will actually race.) "This was due, no doubt, to what was approximately 100 hours of additional work the students put into Alice in the week prior," says Burdick, who notes the students can receive academic credit for two classes by working on Alice.
The visit took place in the parking lot at Santa Anita racetrack. Alice completed two runs of the course in approximately 45 seconds, avoiding all obstacles, but crunched a trashcan in its third run and made an unnecessary safety stop when it "thought" it spied an obstacle. On run four, it re-ran the first part of the course (including the obstacles from the third run) at 15 mph, then demonstrated higher driving speeds while navigating through a cluttered field of trashcans.
"We've learned some valuable lessons and have some advantages this year," says Murray. "For one thing, last year's race took place during finals week; this year they'll be over. We've learned some tricks--for example, Alice is completely street legal, so we don't have to haul it on a trailer everywhere we go, like we did with Bob. And we now have the advantage of knowing what the actual racecourse will be like, so we'll be doing a lot of testing in the desert over the summer."
While no one is going out on a limb to say Caltech will win the race ("There's a lot of good competition," says Murray), Burdick, for one, predicts that someone will complete this year's course. That is, he says, "a remarkable evolution of the technology and a testament to the hard work of all the teams."
To win the race in less than 10 hours, as the rules state, Alice will need to average a speed of 20 mph. "But we believe we will have to be able to drive at speeds of up to 50 mph for portions of the course in order to maintain that average, since some sections will be slow going," notes Murray. This, in a driverless, fully autonomous vehicle.