Active Vibration Isolation in a “Smart Spring” Mount using a Repetitive Control Approach

In a variety of different engineering systems there is a requirement to isolate sensitive equipment from foundation vibration or alternatively, isolate the foundation from machinery vibration. Passive solutions to this problem provide some isolation but performance is significantly degraded in the presence of structural compliance. A recently proposed hybrid active/passive solution known as the “Smart Spring” mounting system specifically addresses this problem of compliance. In earlier work on this system the required local controller was based on LQG design on the assumption that the vibration sources are random. The work reported here investigates the application of a repetitive control approach to deal with periodic vibration sources. The industrial potential of the approach has been shown using an experimental facility where isolation results in the region of 50dB have been achieved.