Defense Technology International - December 2007 - (Page 34)

VEHICLES ROBOTIC Carnegie Mellon SUV wins Urban Challenge. The team even put TerraMax through the paces at a commercial driver’s license course belonging to a Wisconsin technical college. “From there we went to K.I. Sawyer AFB, Mich., and spent eight weeks, thinking that would give us the road network we needed to really test in a similar environment to Urban Challenge,” Beck says. Based on the testing, Team Oshkosh tweaked TerraMax’s sensors and algorithms, emerging with a robot that Darpa says performed “perfectly” during the qualifying round. Considering this, plus the vehicle’s robustness and pre-race testing, Schmiedel was at a loss to explain the collision with the building. Yakes speculated that there might be a software bug. DAVID AXE/DEFENSE TECHNOLOGY INTERNATIONAL and Lidars are emitting” and can be detected miles away, Yakes says. There are drawbacks to optical sensors. Bad weather tends to blur images. But Lidars have their own liabilities— dust is a major problem—and besides, optical sensing has more potential for improvement in coming years than Lidar does, in Yakes’ assessment. Already, Oshkosh is eyeing infrared versions of the TerraMax sensor suite to broaden the vehicle’s vision spectrum. While its sensor suites represented TerraMax’s most important divergence from the design consensus at Urban Challenge, size was its most obvious departure. This was no accident. TerraMax was intended to reﬂect the dimensions of a typical U.S. military logistics truck. The hulking vehicle dwarfed the other racers and challenged Darpa’s and the robotics community’s assumptions about the competition. Despite paying lip service to military supply missions, Darpa based its course design on SUV dimensions and installed guardrails for spectator safety at widths too narrow for TerraMax. During the qualifying round in October, Darpa widened the lanes. What’s more, some of the standard maneuvering algorithms used by many teams assumed a smaller robot despite Darpa stating that the race was supposed to simulate a military mission. “Making all those algorithms work on a larger vehicle is more complicated than on a smaller vehicle,” Yakes says. Anticipating these di culties, Team Oshkosh built “dials” into its algorithms to allow it to alter some parameters on the ﬂy as late as the qualifying round. In order to ensure that the race’s largest entrant wouldn’t be further disadvantaged by its size, Team Oshkosh installed a nonstandard four-wheel steering system. This gave TerraMax 34 DEFENSE ADVANCED RESEARCH PROJECTS AGENCY turning performance superior to that of even some smaller contenders. But the steering system “is a little more complicated for algorithms,” Beck says. “Front-wheel steering only steers the front axle. Our [axle] moves around a bit as you kick in the steering. That adds complexity from a control standpoint.” TerraMax’s larger mass and higher center of gravity also complicated the control algorithms, he says. The complexity of TerraMax’s control software demanded early and rigorous testing. “We’ve been testing since day one, on and o the vehicle, in the real world and in a simulated environment,” Beck says. “In February, at the National Automotive Test Center in Nevada, we turned the sensors on for the ﬁrst time and tested the capabilities of the vehicle in steering, throttle control and braking. We spent a lot of time testing at Oshkosh. We had a course set up in a parking lot where we store military vehicles.” TerraMax relies for “vision” on primary optical sensors, which are attached to the bumper. Carnegie Mellon’s modiﬁed Chevy Tahoe ultimately took the $2-million ﬁrst prize. But despite losing, TerraMax is a more mature and robust system, boasting more practical sensors integrated into a more durable and militarily useful platform than its rivals. TerraMax’s performance at Urban Challenge validates the team’s sensor and platform choices, and gives Oshkosh a reason to continue development. The next step, team representative Katie Paulson says, is to line up military demonstrations that might attract the necessary funding to turn TerraMax into a production program. I To read Axe’s posts and see his photos from Urban Challenge, go to DTI’s homepage, AviationWeek.com/dti, and click on ‘Extras for this issue’ under ‘DTI Interactive.’ www.aviationweek.com/dti DEFENSE TECHNOLOGY INTERNATIONAL DECEMBER 2007 http://AviationWeek.com/dti http://www.aviationweek.com/dti

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Defense Technology International - December 2007 Contents Around the World Science Watch Tech Watch BrahMos: Ramjet Ship Killer r-e-s-p-e-c-t Deja Vu Trump Card Dubai Demos Agile Helos Joint Force Online Charge UGVs Creep, Crawl to Victory Sweet Ride Fast, Lethal Ship Defense Networking Stealth: Why Raptors Can't Talk The Net Cutting Edge First Person In Review Insight

Defense Technology International - December 2007

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