Stanford demonstrated the first non-military GPS guided autonomous aircraft (or UAV) circa 1996. Commercial, non-military GPS-guided UAVs (or drones) have become commonplace for use by commercial companies and/or hobbyists.
In this research, the objective was to prove that GPS alone was sufficient to control an unmanned vehicle from takeoff to precision landing. To achieve control, the ability to sense position and orientation accurately and robustly was necessary.
The gasoline powered model aircraft shown below has a twelve foot wingspan and was instrumented with 4 L1-only GPS antennas. One antenna was installed on each wing tip and one at the nose and tail.
After resolving cycle ambiguities, L1 carrier phase difference measurements between a base station antenna (fixed on the ground) and the aircraft nose antenna were used to determine aircraft position relative to the ground antenna at 10 Hz update rate. Carrier phase differences among the aircraft mounted antennas were used to determine the aircraft attitude at 10 Hz update rate.
Based on the GPS measurements, the aircraft demonstrated the ability to repetitively take off, fly a predetermined trajectory and perform a precision landing.
This research showed that GPS could be used to determine 6 degrees of freedom on a dynamic platform and could perform with sufficient robustness and update rate to control an air vehicle.
Today, GNSS is ubiquitous for providing guidance to UAV’s, but is not typically used in inner loop control.
Stanford originally received funding for these projects from the U.S. Department of Transportation (DOT) and the Federal Aviation Administration (FAA).
View the Wikipedia article on Unmanned Aerial Verhicles for more details.