Navigating through traffic is difficult enough for even the best of drivers, but imagine having to do it without your hands on the wheel and your eyes on the road. That's what teams will be doing in this year's Defense Advanced Research Projects Agency (DARPA) Grand Challenge competition. The third annual competition, unlike its predecessors that took place in the desert, will take place on a 60-mile urban course November 3.

The DARPA Urban Challenge is an autonomous vehicle research and development program with the goal of developing technology that will keep war fighters off the battlefield and out of harm's way. It features autonomous ground vehicles maneuvering in a mock city environment, executing simulated military supply missions while merging into moving traffic, navigating traffic circles, negotiating busy intersections, making U-turns, passing slower vehicles, and avoiding obstacles.

The exact location of the event will be announced before the National Qualification Event scheduled for October 2007. DARPA is offering $2 million for the fastest qualifying vehicle, and $1 million and $500,000 for second and third place.

Colorado's entry this year is relying on rotary actuators to help it complete the course. Team Mojavaton is a 10-member team based in Grand Junction, Colo. The team plans to use the same vehicle as last year — a Nissan Xterra. It drove for 23 miles before the throttle stepper motor failed and the computer could not activate the throttle during last year's competition.

In order to view all angles at each intersection, the team needed a rotary actuator that could swivel and point specific sensors in whatever direction is of interest to the computer.

The team chose to use the Oriental Motor DG130R-ASBA hollow shaft rotary actuator and the ASD24A-AP driver. This combination provided both the speed and precision to rotate the sensors into location, as well as the power necessary to hold them steady so that data could be picked up accurately.

The on-board computer that will be used to run the entire vehicle, as well as all its sensors, is an industrial rack mount system designed and manufactured by General Technics in Ronkonkoma, N.Y. It features an Intel dual-core microprocessor that provides more than enough computing power to handle all sensors and all drive-by-wire devices.

The DG actuators feature a large-diameter, hollow output table, which allows direct installation of the load. The actuator offers high rigidity, and provides repetitive positioning accuracy of ±0.004°, shorter positioning time with permissible speeds to 200 rpm, and simple home hunting to the user. The units are RoHS compliant and offer a small frame size of 5.12 in2.

Road testing has already begun. The sensor suite is a proprietary device, which contains a variety of sensors able to be pointed in any desired direction. The Oriental Motor actuator and sensor system can investigate an intersection in under 4 sec and can make a correct determination of whether it is safe to proceed into the intersection.

For more information, visit darpa.mil/grandchallenge.