Alice on Trial, Redux

Oct 25, 2007
Alice on Trial, Redux
Image credit: Caltech

When Alice revs her engine at the start of the Defense Advanced Research Projects Agency (DARPA) Urban Challenge qualifying rounds on October 27, multitudes of cameras will be pointing at her. But she'll only care about the eight cameras that will be facing away.

Alice is the tricked-out Ford E-350 van that has been revamped to autonomously navigate the vagaries of an urban setting. To do so, she sports eight cameras that feed information to computers at rates of hundreds of megabits per second. Six of those cameras face forward, one faces the rear, and one is mounted on a pan-tilt unit programmed to turn and look to the left and to the right.

Team Caltech leader Richard Murray, Everhart Professor of Control and Dynamical Systems, says there's good reason the team chose a setup in which several cameras and lasers feed visual information into decentralized computers. With multiple computers telling Alice about surrounding obstacles, "it's like having multiple parts of your brain telling you what to do," he says. The computers are arranged in a hierarchy, with "lower level" computers doing computations based on the information they receive and passing on results to higher levels, where the ultimate decision is made. This way, there's less chance of driving into an obstacle and more chance of staying on the path the cameras detect. Team Caltech also chose this setup because it could easily accommodate new sensors.

The Urban Challenge presents far greater complexities than the two previous Grand Challenges, which took place in the desert of Barstow, California. "In the desert challenge, you simply had to drive on flat spots," Murray says. The teams have road information from aerial photos and maps of this year's challenge site, a mock city at the George Air Force Base in Victorville, California. But, says Murray, "that's not the hard part. It's dealing with what's not on the map. We don't know where there will be obstacles or where other vehicles will be."

Team Caltech's attempts at winning the first two DARPA challenges were met with defeat. In 2004, Alice's predecessor Bob drove 1.3 miles before losing a fight with a barbed-wire fence. In communications theory, Alice and Bob stand for sender and receiver, so the next year, Bob gave way to Alice, who ended an eight-mile run at a concrete barrier. Now, Alice, redux, is one of 35 vehicles entering the qualifying round for this year's Urban Challenge. Murray is confident Team Caltech will advance to the final round, on November 3.

What makes the new challenge so difficult is not news to any driver--the rules come from the California driver's handbook. Any collision or damage wreaked gets the team automatically disqualified. Broken rules like turning without signaling or crossing a solid traffic line incur a time penalty. Each team will vie with up to 34 other vehicles that may qualify for the race, and DARPA may make things even trickier by including human-driven vehicles.

It would be impossible to imagine and prepare for every error that pops up, says Murray. Instead, he says, the team took the approach of following a sequence of actions to try to solve any dilemma. For example, if there were dirt on one sensor the computers might mistake it for a real obstacle. Then Alice might try backing up to check if the obstacle remained. The Jet Propulsion Laboratory (JPL) uses some of these approaches in building its autonomous rovers to explore other planets' surfaces. "Part of the approach we take is to build on what JPL has been doing for years," Murray says.

The Caltech team consists of almost 80 undergraduate and graduate students, postdocs, and faculty, many of whom participated in the previous Grand Challenge. Specialists from JPL and Northrop Grumman added their expertise. In the final event, the team whose vehicle reaches the finish line first in less than six hours wins $2 million, second place garners $1 million, and third, $500,000.

Source: Caltech

Explore further: Gesture-controlled, autonomous vehicles may be valuable helpers in logistics and trans-shipment centers

add to favorites email to friend print save as pdf

Related Stories

Cockatoos know what is going on behind barriers

Jul 29, 2013

How do you know that the cookies are still there although they have been placed out of your sight into the drawer? How do you know when and where a car that has driven into a tunnel will reappear? The ability ...

A new glow for electron microscopy

Oct 22, 2012

The glowing green molecule known as green fluorescent protein (GFP) has revolutionized molecular biology. When GFP is attached to a particular protein inside a cell, scientists can easily identify and locate ...

Recommended for you

Lawsuits challenge US drone, model aircraft rules

7 hours ago

Model aircraft hobbyists, research universities and commercial drone interests filed lawsuits Friday challenging a government directive that they say imposes tough new limits on the use of model aircraft ...

For secure software: X-rays instead of passport control

Aug 21, 2014

Trust is good, control is better. This also applies to the security of computer programs. Instead of trusting "identification documents" in the form of certificates, JOANA, the new software analysis tool, examines the source ...

Razor-sharp TV pictures

Aug 21, 2014

The future of movie, sports and concert broadcasting lies in 4K definition, which will bring cinema quality TV viewing into people's homes. 4K Ultra HD has four times as many pixels as today's Full HD. And ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

nilbud
not rated yet Oct 26, 2007
I bet Lee Majors could stop them.
http://www.cliveb...obe2.htm