Adaptive control of F/A-18 Wind tunnel model Tail Buffeting
During high-angle-of-attack maneuvers of the F/A-18 aircraft, the unsteady
flow over the vertical tails that result from a breakdown of vortices
produced at the leading edge and intersection of the wing and fuselage.
This unsteady flow results in a severe buffet-induced vibrations of the
vertical tails. This leads to early and premature fatigue failure of the
vertical tail structure. Many solutions have been proposed to solve this
problem but with very limited results. Linear controllers operating at
the same frequency as the structural mode they are controlling (crossover
condition) have been very effective. However, these modal frequencies can
shift due to panel utter, corrosion, battle damage and other sources. As
this frequency shift increases the linear controller becomes less
effective thus reducing it's control authority. Thus, the linear
controller alone will not be able to completely control vibrations of the
vertical tail in normal flight operations. In this research, an adaptive
neural network is designed to augment the linear controller which will
help to control the vertical tail as the controlled frequency shifts.
This design of the active structural control system is based on the use of
the offset piezoceramic stack actuators (OPSA) and an acceleration
feedback control (AFC) technique. The design objective is to control the
worst buffet scenario that has been observed during high angle of attack
maneuvers while the tail is vibrating in the linear range.
Personnel
Patrick Roberts and Dr. Sathya Hanagud are the main researchers in this
project. Bong-Jun Yang, Anthony J. Calise, and James I. Craig are
collaborating to help neural-network adaptive control design.
Related links:
- Structural Dynamics and Smart Structures Lab at Georgia Tech
- Tail buffet alleviation research at the smart structure lab
- Links for experimental structural dynamics and smart materials ( hardware vendors collected in the smart structure lab)