Fiber-Optic Gyros Help Robotic Vehicles Race Across Desert

Created in response to a Congressional and Department of Defense mandate, the Defense Advanced Research Projects Agency (DARPA) Grand Challenge is a field test proposed to expedite research and development of autonomous ground vehicles to assist on the battlefield.

The objective is to successfully race two driverless Hummers against other teams across 175 miles of Mojave Desert terrain in 10 hours or less.

Out of an initial field of 118 teams from around the U.S. and Canada, two teams (dubbed Red Team and Red Team Too) from Carnegie Mellon's Robotics Institute have autonomous vehicles (see Figure 1) among the 40 semi-finalists competing in the DARPA Grand Challenge national qualifying event in September 2005. From there, only 20 teams go on to compete for the grand prize on race day, October 8, 2005.

Figure 1. Fiber-Optic Gyros Help Stabilize Navigation Systems on the Sandstorm and H1ghlander autonomous vehicles.

One of the vehicles, a radically modified 1986 Humvee called Sandstorm, is the returning Grand Challenge recordholder. Upgrades for the 2005 season include a new engine and drive-by-wire, fast computing, and a million lines of solid software. Sensors include lasers, radar, and single-camera road following. The second vehicle, H1ghlander, is a 1999 H1 Hummer that incorporates new technology, viewing terrain with seven laser scanners, three cameras, and two radar sensors. Several of these are pointed and stabilized by a three-axis gimbal using fiber-optic gyros (FOGs).

Both Carnegie Mellon vehicles use DSP-3000 FOGs (see Figure 2) on a stabilized sensor platform to sense pitch, roll, and yaw angular rates relative to the vehicle's position. Data from the FOGs is used to stabilize the vehicle's navigation and guidance system regardless of uneven terrain and vehicle motion.

Figure 2. The Fiber-Optic Gyros have a patented, all-fiber design incorporating digital signal processing.

These FOGs have a patented all-fiber design (fabricated from proprietary E.Core polarization-maintaining fiber) and Digital Signal Processing (DSP). DSP electronics improve performance in such critical areas as scale factor and bias versus temperature, scale factor linearity, turn-on to turn-on repeatability, and maximum input rate. The DSP design also virtually eliminates temperature-sensitive drift and rotation errors. The FOGs can be used in diverse commercial and defenserelated applications.

Learn more about Carnegie Mellon Robotics Institute's (Pittsburgh, PA) Sandstorm and H1ghlander autonomous vehicles online at http://info.ims.ca/5215-334. For more information on KVH Industries, Inc.'s (Middletown, RI) DSP-3000 fiber-optic gyros and related patents, contact Chris Watson, corporate communications manager, at (401) 847- 3327 or cwatson@kvh.com, and visit http://info.ims.ca/5215-335.