This paper presents research into an adaptive nonlinear neural network cont
rol algorithm that can be used with smart structure actuators and sensors t
o control the shape and suppress the vibrations of flexible beams. The algo
rithm presented couples an explicitly model-based adaptive component, which
employs time-varying estimates of the beam material properties, with an ad
aptive neural network, learning in real-time, which is used to estimate the
additional actuator moments needed to offset the effects of periodic exter
nal disturbances. Experimental results are given for a thin beam, with bond
ed piezoceramic sensors and actuators, demonstrating the ability of the alg
orithm to track desired bending profiles and reject the vibrations caused b
y external disturbances, as well as to maintain this performance despite ch
anges in the material properties of the structure or in the properties of t
he external disturbance.