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Preparing for DARPA's urban road challenge

Later this year, Oshkosh Truck's TerraMax will be back in robotic racing action, attempting to master the obstacles of city streets.

On the chilly morning of October 9, 2005, spectators held their breath as a 16,000-pound robotic truck known as TerraMax started down the steep, narrow cliffs of Nevada's Beer Bottle Pass.

The day before, one of the oversized truck's competitors in a race of robotic vehicles sponsored by the Defense Advanced Research Projects Agency, Stanford University's unmanned Volkswagen SUV, had claimed victory in a 132-mile robotic desert race. So this was about pride.

After idling overnight in the desert partially because its support vehicle broke down and TerraMax couldn't proceed without it, Team OshKosh had blown its chance to win anything. It could no longer meet the time requirements. Still, onlookers were wide-eyed witnessing a massive military-grade robot creep down the twisting gravel roads--with sheer drop-offs on either side--that even human drivers would find harrowing.

It was history in the making.

"I don't know how in the world TerraMax made it down that. They were slow, but they got it done," said Doug Traster, team leader for 2005 entrant Indy Robotics and president of Indianapolis-based Precise Path Robotics.

As one of the biggest trucks in the DARPA Grand Challenge--a test of robotic engineering with a prize of $2 million--Oshkosh Truck's TerraMax garnered much attention. DARPA officials even decided to start it last in the competition, despite it qualifying for an early start, because they were concerned that if the massive truck were to get stuck, it would cause a bottleneck for the other robots.

Since 2004, DARPA's ultimate goal in designing the robotic competition has been to foster the development of autonomous vehicles for the military. TerraMax, born of the advanced products group at military vehicle supplier Oshkosh, was the only Army-grade truck in the race.

"Of course, size moved against us (in the 2005 race), but larger trucks (will) likely be where the military deploys this technology. In logistic scenarios, it's these bigger trucks that do that work," said Chris Yakes, director of advanced products at Oshkosh and team leader of TerraMax since its first race in 2004.

Next up...city streets

In 2007, TerraMax will be back in action for DARPA's Urban Challenge, the agency's third contest of autonomous vehicles. This time, teams must master the obstacles of city streets. DARPA will again award more than $2 million in prizes to the finalists, and it's already granted $1 million to TerraMax for development in this upcoming challenge.

TerraMax is among the more watched teams because it was one of only five robots to finish 2005's contest, even though it didn't complete the course in time. Others to watch include 2005 winner Stanford, 2005 finalist Carnegie Mellon University and newcomers like MIT. Other standouts like North Carolina State, which will race an unmanned Lotus Elise, are bucking the trend of bigger trucks like OshKosh's.

Still, event watchers say the 2007 race will likely produce a weak showing like DARPA's first Grand Challenge in 2004. That year, only CMU's robotic tank "Sandstorm" made it as far as 7.4 miles before spinning its wheels in the desert. The race was the first of its kind--with a wide-open, conceptual basis--and teams didn't have a practical idea of how to program or design their bots to win, event insiders say. That changed in 2005 when five vehicles finished the course.

Similarly, the 2007 Urban Challenge will raise the bar. Unlike the largely open space of the desert race, 2007 competitors will "drive" astride or head-on with other robots on the streets, possibly including human drivers or DARPA remote-controlled vehicles. The robots must navigate oncoming and cross traffic, light signal changes, and merge with other traffic. They must even master events like stop queuing, in which the robots figure out which vehicles pulled up to a four-way stop first and whose turn it is to proceed.

Before the race, contestants will download mission data files, which specify checkpoints on a map to complete a given mission. (Every contestant will likely get different checkpoints.) The object is to execute the mission files within the set time--60 miles in six hours or better.

"My guess is the first year, nobody will do it. The second year several people will do it easily," said Traster, whose team is not competing this year. Indy Robotics didn't qualify in the 2005 race.

Yakes' team has built an entirely new robot for the 2007 race (also called TerraMax). It's a military-grade vehicle, but smaller than 2005's six-wheeled truck. Now it's a 4-by-4, modified with rear-steering capabilities and a shorter wheel base for "better dynamic capability in an urban environment," according to the team. The team also used similar sensor technology but developed new autonomous software.

With two years between races, the team said it now has the luxury of more time to fashion its new, improved TerraMax, without taking any shortcuts. "We've learned that the robustness of the design is critical, whether software or hardware," said. That means building an autonomous vehicle that can withstand the wear and tear of 20 years in the military--the specified objective for these vehicles.

In that vein, Oshkosh is working on the project as a means of business. "We're focused on it from a soldier-safety standpoint, improving the safety of soldiers and Marines," said John Beck, senior auto project engineer at Team Oshkosh. "Winning a race is secondary."

"It's an interesting challenge, to be able to accomplish it will be a major milestone in this technology," Beck said.

The vehicle is still undergoing changes but Team Oshkosh plans to begin testing it in the Nevada desert in the coming weeks and will continue running it until the race on November 3. (DARPA has yet to specify the location of the race, saying only that it will be somewhere in the Southwest.)

Of course, most of the challenge competitors require a team effort, and TerraMax is no exception. TerraMax has a core team of several dozen people working on the project at OshKosh Truck, but that team can grow larger on any given task. As team lead, Oshkosh handles hardware and software, including systems integration, drive-by wire technology, modeling and simulation and overall design.

The University of Parma, Italy, supplies the team with its vision system, and Teledyne Scientific equips the vehicle with its sensor guidance system. A team from Auburn University handles integration of TerraMax's global positioning system and IBEO Automobile Sensor supplies a customized Lidar system, which detects surrounding range and distance to other objects.

If TerraMax's history is an indication, the team could have a real chance in 2007.

In the qualification trials for the 2005 race, Traster remembers how the giant truck charged toward a narrow gate everyone doubted it could pass. TerraMax stopped a few inches short of the gate, and sat there for 5 or 10 seconds before backing up to correct itself.

"That little bugger must have backed up 20 times until it went through this little gate with 6 inches on either side. That was amazing," he said.