DARPA Urban Challenge: Axion Racing Interview
Westlake Village (CA) – With the DARPA Urban Challenge just over two months away, we are starting a series of in-depth and very technical interviews of the 36 semi-finalists. Today we interviewed Bill Kehaly, the team leader of Axion Racing based in Westlake Village California. You can call Axion a veteran of the DARPA races because the team has competed in the previous two desert-based Grand Challenge races in 2004 and 2005. Kehaly says stereo vision, a PlayStation 3 and an armored Jeep are his main advantages in the upcoming urban race.
Axion Racing's "Spirit" Jeep
Axion’s “Spirit” car will be using stereo vision as its guidance. Many of the other teams have focused on either RADAR or spinning Velodyne LADAR laser units for guidance. Using “bumblebee” stereo cameras, Spirit can detect objects better with less false positives that can come from lasers or radar. The cameras are housed inside of an enclosure called the Axion Remote Sensing Enclosure (yes it’s ARSE) which has windshield wipers to clear away dust and water.
“Our computers merely disregard the image noise created by the wipers. Once you recognize how a windshield swipe looks like, it’s no big deal,” said Kehaly.
Another advantage of using stereo vision is less potential interference with other competitor’s cars. Since the race will be held in one day, there is a possibility that several teams could be on the same course at the same time with all of them beaming laser and radar signals everywhere. Kehaly told us this presents some interesting challenges like false positives on the sensors because the cars won’t know if it’s their own laser beam coming back or another car’s laser.
“Four to five Velodyne lasers sending out light beams in all directions… that might make for an interesting day.”
Along with the stereo cameras, Spirit uses a laser range finder, FLIR infrared camera and two NAVCOM Starfire GPS units. An inertial navigation system has been added to correct for GPS errors and signal losses. Most of the computer power consisting of Dell computers and even a PlayStation 3 are fitted inside a modified server rack in the back of the car. The PS3 runs Yellow Dog Linux and examines information from the road finding camera system. Kehaly is thinking about adding more consoles.
“To the chagrin of our team, I’m looking at replacing all the Dell servers with a cluster of PS3s.”
A reinforced car body is another area where Kehaly thinks he can literally beat other teams. For the Grand Challenge, his team installed protective metal plates into the car just in case it drove into a ditch or off a cliff. They’ve kept the armor on so that Spirit can survive hitting a wall or even another competitor’s car. Now Kehaly stresses that he isn’t actually actively steering Spirit towards his competitors, but he adds, “If that Lotus makes a mistake around me, I’ll crush it. I can take on anybody, except the Oshkosh truck.”
While many people think the technology gained from the Urban Challenge will be used to make high-speed urban delivery vehicles, Kehaly has a different view. He says robotic trucks could replace the dozens or even hundreds of vehicles, along with their human drivers, used in a typical military base. These trucks typically have one of two drivers each delivering supplies like food and mail to other buildings inside of the base.
Anyone who has been on a military base knows that a vast majority of personnel aren’t the ones who pull the triggers, but are delivery people, cooks, typists and lawyers. The freed up personnel could then be moved to combat positions or more important tasks. Robotic delivery vehicles could also mean less human targets for enemy soldiers and artillery teams operating near United States military bases in hostile countries like Afghanistan or Iraq.
“A robot truck could deliver the mail to a building and then you just need one or two people to offload the stuff. Then it goes on to the next building,” Kehaly told us.
Kehaly backs up his beliefs by pointing out the Urban Challenge rules which seem to obsess about safety. All vehicles must obey California traffic laws and must completely stop at stop signs and signals. The cars must also yield to people and other cars. These rules would seem to suit sedate and slow driving on a military base, rather than the hectic “accelerate like crazy” driving you would see in the streets of Iraq.
In many ways preparing for the Urban Challenge has been much easier than previous two Grand Challenge races which were run in the desert. Kehaly told us that in the Grand Challenge he had to run an air conditioning at full blast just to keep all electronics from overheating. The air conditioning was also used to keep human drivers awake during brutal practice runs.
“For the Grand Challenge, we tested in the Badlands where it was 140 degrees in the car. I have a saying that both the computers and programmers stop working at a 108.”
The city environment should be a bit cooler and Kehaly’s team has switched one of the two marine batteries on board to help run the auxiliary and computer systems, rather than the air conditioning unit in the previous races.
Axion Racing also had to deal with fine dust in the Grand Challenge races, something that is a “non-issue” now. “Back then we had this fine dust that would cover everything, you can’t really remove it easily and it would take a power wash to get the stuff off,” Kehaly told us. The dust would get into computers and cause hard drives to fail. It also would chew up and fray wire connections. Kehaly’s team had to deal with random failures by building redundant systems.
“Now that it’s city work, all of this is a non-issue. All of the testing so far has been done on the streets. We don’t have to worry about rattlesnakes and if a vehicle breaks down I just call Triple A.”