3d Formation Flight Using Diierential Carrier-phase Gps Sensors

This paper describes research on 3D formation ight using carrier-di erential GPS sensors. Although absolute position at the centimeter level is generally not possible in real-time, relative position between vehicles within the formation can be obtained at these levels of accuracy using carrier phase di erencing. However, several challenges exist before these measurements can be used in the formation state estimation, including solving for the integer biases. A method to generate a formation maneuver to rapidly solve for these biases is presented. In order to better understand the problems associated with 3D formation ight, a new testbed has been developed. This testbed currently consists of two lighter-thanair vehicles (blimps) that operate in an indoor GPS laboratory. Operating indoors has several advantages, but also presents some signi cant challenges. A description of both the indoor environment, and the GPS receiver developed for this application is given. Finally, experimental results are presented for a single blimp performing a large scale autonomous ight and landing. Data is also presented for the two vehicle formation undergoing several maneuvers. Presented at the Institute of Navigation GPS Meeting, Nashville, TN, September 18, 1998.