The road to Victorville: Oshkosh's TerraMax successfully completes site visit; qualifies for the NQE; learns how to behave in traffic

Diesel Progress North American Edition, Nov, 2007 by Dawn M. Geske, Mike Osenga

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Late June 2007

When we last looked in on Oshkosh Truck Corp.'s TerraMax autonomous vehicle in August Diesel Progress, the 425 hp, 29,580 GVWR vehicle had just taken its driver's test.

One of the steps leading up to this month's DARPA Urban Challenge was putting the truck through its paces under the watchful eyes and directions of DARPA (Defense Advanced Research Projects Agency) officials.

These "site visits" by DARPA are a critical step in choosing the 30 teams that would advance to the National Qualifying Event (NQE) held late last month. From the NQE, approximately 20 teams would advance to the DARPA Urban Challenge on Nov. 3.

So by the time you read this, the whole thing will be over. Watch for your December issue of Diesel Progress for reports from the Urban Challenge, as well as how Oshkosh's TerraMax fared.

In the days immediately following the June 26 site visit by DARPA at TerraMax's Oshkosh, Wis., home, the team was feeling confident that it had performed as expected.

"We thought the site visit went very well," said Chris Yakes, director, advanced products for Oshkosh Truck Corp. "Leading up to it, we were doing a lot of testing on our own--trying to come up with every conceivable scenario that DARPA might throw at us."

DARPA officials tested TerraMax's ability to stop in an emergency, plan a route, pass stationary vehicles, take its turn at a four-way intersection, and complete U-turns. TerraMax completed the four-hour test in two-and-a-half hours.

Mid-July

After a short pause immediately following the site visit and a demonstration trip to Peoria, III., for TerraMax team partner Caterpillar Inc. employees, TerraMax was back in testing and development mode.

Coming out of the second DARPA Grand Challenge (which was originally supposed to be the final challenge), Oshkosh said if it had to do it over again, it would have tested for many more hours. Given the chance to do it again, that is exactly what Team TerraMax is doing--testing, testing, testing.

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At the heart of the testing is the transition from DARPA's basic Traffic and Basic Navigation technical criteria to Advanced Navigation and Advanced Traffic.

Basic Navigation requires vehicles to be ready to run five minutes after receiving a Mission Data File (MDF) on a USB 2.0 flash drive. It also requires the front bumper of the vehicles to pass over each checkpoint in the MDF in the correct lane or spot and in the correct sequence. The vehicle is required to stay entirely in the travel lane at all times, except when performing legal traffic maneuvers (like a left turn) or avoiding obstacles.

Further, Basic Navigation requires adherence to minimum and maximum speed limits, the ability to avoid collisions or near-collisions and to stop with its front bumper within 1 m of the center of the stop line at an intersection.

It also calls for the Urban Challenge vehicles to keep 1 m between itself, all obstacles and vehicles all the time. When traveling, the Urban Challenge vehicles are required to keep one vehicle length for every 10 mph between other vehicles and at least one vehicle length when passing another vehicle and after passing.

Basic Navigation also requires the ability to perform a U-turn on a 9 m wide road within a 30 m road length.

Basic Traffic requires: respecting precedence order at all intersections and not proceeding out of turn; and correct stop-and-go queuing behavior in a line of stopped vehicles, while always keeping minimum spacing.

Advanced Navigation and Advanced Traffic add additional layers of complexity. Advanced Navigation requires TerraMax to negotiate an obstacle field safely and effectively, as well as to perform correct parking lot behavior and to be able to pull forward and reverse out of a specified parking spot.

More interestingly, Advanced Navigation requires the vehicle to figure out what to do when the roadway is blocked, using only its sensors and vision systems. Remember, there is no human control or telemetry allowed.

DARPA said road blockages will not be indicated on the Route Network Definition File (RNDF) and may be changed during the NQE and the Urban Challenge itself. DARPA said the vehicle should not attempt to leave the road surface, but find an alternative route network.

Other Advanced Navigation criteria include sparse waypoint road navigation by sensing berms or road edges or any other sensor-based techniques. The criteria also calls for the vehicle to be able to operate with degraded GPS capability due to foliage or buildings.

Advanced Traffic requires TerraMax to learn how to merge into traffic and further defines vehicle separation during merging. TerraMax also has to know how to execute a left turn across a lane with oncoming traffic, all the while maintaining the required vehicle separation with vehicles in its lane.

Emergency stop and defensive driving are also elements of Advanced Traffic. Vehicles must come to a safe stop without collision when the anticipated time to collision is four seconds or longer. It also must drive defensively and avoid head-on collisions (which is probably always a good idea).