Reaction force compensation with frequency identifier in shaking table systems

This paper presents a practical control methodology of shaking tables for earthquake simulators. Reaction force generated by a specimen on the shaking table generally deteriorates the motion performance of the table, resulting in the lower control accuracy of seismic tests. Especially, in cases of excitation tests for structures (power facilities, large vehicles, etc.) including motors with periodic rotation, the reaction force as a disturbance is excited with a specific frequency during their actual operations. In addition, the variation of the rotational frequency in the motor causes the variation of frequency in the disturbance. In order to compensate for such variable disturbances, therefore, an adaptive feedback compensator should be a promissing approach to improve the disturbance suppression capability, by applying an adaptive notch filter to identify the frequency in on line manner. The proposed control approach has been verified by experiments using a prototype of shaking table system.