DESIGN OF A FOUR-ROTOR AUTONOMOUS HELICOPTER FOR VEHICLE-BASED PHASED ANTENNA ARRAYS
Autonomous flying vehicles (AFVs) have applications ranging from police surveillance to military synthetic aperture radar mapping. In many such applications, AFVs must transmit large quantities of data to a distant base station. Since this can be difficult without the ability to place large, high-gain antennas on small vehicles, we propose the idea of flying the vehicles in formation while transmitting and forming a phased-array antenna with one element on each vehicle. To determine the feasibility of this concept, we studied the constraints imposed both by antenna theory and by present AFV technology. While position errors in the array can cause a great reduction in antenna gain, good position sensing can allow phase compensation to recover most of the ideal case antenna gain even with significant position error. Two electrical team members and one mechanical member worked together to produce a four-rotor helicopter-type AFV which was tested as well as modeled in simulation. The physical vehicle demonstrated autonomous hover and bench tests indicated that it should have 0.8 g excess thrust beyond hover and 10 minute battery endurance. Simulation of a formation of several of these AFVs showed very promising improvements in predicted AFV communication range (in one example, 9.6 dB gain for an array of ten in 10 MPH wind, for a range improvement of a factor of 3, representing 100 kilometer range with a total array power of only 1.5 Watts). Future work may include an actual physical test of formation flight of several AFVs, possibly even with a phased array antenna system, or at least with an antenna simulation based on real position data. This latter simulation was already performed on data from formation flight simulations, provided by Honeywell, of their Organic Aerial Vehicles (OAVs), showing promising antenna array gain results.
U.S. Air Force Grant F49620-02-0388 National Science Foundation Graduate Research Fellowship 2001
Unmanned Aerial Vehicle; Synthetic Aperture Radar; Phased Array Antenna; Autonomous Helicopter; Distributed Control; Cooperative Systems
dissertation or thesis