A COMPARISON OF REACTION FORCE SUPPRESSION TO DISPLACEMENT SUPPRESSION FOR VIBRATION CONTROL IN A FLEXIBLE STRUCTURE

Vibrations in structures can lead to a number of problems, not the lea st of which can be fatigue failures from excessive long term cyclic st resses. Passive techniques for vibration control, though sometimes lim ited in their capabilities, have been the primary method used in the p ast to attenuate vibrations. Recently active techniques have been deve loped to provide vibration control performance beyond that provided by their passive counterparts. Most often, the focus of active control m ethods has been to suppress displacements, and little attention has be en given to their effect on structural loads. This paper presents an a nalytical and experimental study in which two optimal vibration contro l methods, displacement control and reaction force control, are compar ed in their effect on displacements and reaction forces in a flexible structure. It is shown that each control method is effective in meetin g its specific control objective, and that the two control approaches have greatly different effects on the reaction forces in the system. D epending on the disturbance frequency to be suppressed, the displaceme nt control method in some cases can drastically increase the reaction forces. (C) 1997 Academic Press Limited.