(Georgia Institute of Technology, 2008-03)
Johnson, Eric N.; Wu, Allen D.; Neidhoefer, James C.; Kannan, Suresh K.; Turbe, Michael A.
Linear systems can be used to adequately model and control an aircraft in either ideal steady-level flight or in ideal
hovering flight. However, constructing a single unified system capable of adequately modeling or controlling an
airplane in steady-level flight and in hovering flight, as well as during the highly nonlinear transitions between the
two, requires the use of more complex systems, such as scheduled-linear, nonlinear, or stable adaptive systems. This
paper discusses the use of dynamic inversion with real-time neural network adaptation as a means to provide a single
adaptive controller capable of controlling a fixed-wing unmanned aircraft system in all three flight phases: steady-level
flight, hovering flight, and the transitions between them. Having a single controller that can achieve and
transition between steady-level and hovering flight allows utilization of the entire low-speed flight envelope, even
beyond stall conditions. This method is applied to the GTEdge, an eight-foot wingspan, fixed-wing unmanned
aircraft system that has been fully instrumented for autonomous flight. This paper presents data from actual flight-test
experiments in which the airplane transitions from high-speed, steady-level flight into a hovering condition and
then back again.
(Georgia Institute of Technology, 2006-08)
Johnson, Eric N.; Turbe, Michael A.; Wu, Allen D.; Kannan, Suresh K.; Neidhoefer, James C.
Fixed-wing unmanned aerial vehicles (UAVs) with the ability to hover have significant
potential for applications in urban or other constrained environments where the
combination of fast speed, endurance, and stable hovering flight can provide strategic
advantages. This paper discusses the use of dynamic inversion with neural network
adaptation to provide an adaptive controller capable of transitioning a fixed-wing UAV to
and from hovering flight in a nearly stationary position. This approach allows utilization of
the entire low speed flight envelope even beyond stall conditions. The method is applied to
the GTEdge, an 8.75 foot wing span fixed-wing aerobatic UAV which has been fully
instrumented for autonomous flight. Results from actual flight test experiments of the
system where the airplane transitions from high speed steady flight into a stationary hover
and then back are presented.