Despite the numerous advantages associated with the flexible manipulators, link vibrations stand in the way to reaping these benefits. This leads to time wastage waiting for vibrations to decay to safe operating levels and the possibility of mechanical failure due to vibration fatigue. This paper presents direct strain feedback vibration control by tuning the feedback gains using artificial neural networks on a 3D flexible manipulator. Online backpropagation was developed in MatLab Simulink and implemented in dSPACE environment for practical experiments. Results show significant reduction in the link vibration relative to the performance of fixed feedback gain.