Dynamic Compensators for Floor Vibration Control

Abstract

In recent years, active control of flexible structures has been studied extensively. The motivation for continual studies with this approach is that the vibration performance of flexible structures can be improved significantly via control. For example, the performance of civil engineering floor structures, which the present research work is based on, is increasingly being governed by meeting permissible vibration serviceability limits depending upon their respective usages, and this can usually be enhanced via active control. This then offers designers increased flexibility to realise more lightweight, longer span and open-plan floor layouts that are in tune with the advancements in material and design technologies as well as meeting the challenges for reduced carbon footprint of new constructions. The work presented here focuses on active control of human-induced vibrations in floor structures using dynamic compensators. These are formulated from reduced order plant models and vary in complexity depending on the number of plant modes of vibration used for their respective designs. It is demonstrated that there are increased options offered by higher dynamic compensator orders with respect to realising various vibration mitigation performance objectives: for example, the isolation and targeting of specific vibration modes. These compensators are found to possess desirable stability margins and are much less sensitive to disturbances at lower frequencies in comparison with direct velocity feedback (DVF). A study of the robustness of the dynamic compensators designed here to changes in structural properties, for example, that would arise under human-structure interaction is also presented. It is found that the performance of dynamic compensator performance can be sensitive to changes in structural dynamic properties as compared with a direct velocity feedback scheme, as seen in the closed-loop stability properties, which is not so obvious from a study of the disturbance rejection properties.