Traffic-induced microvibration mitigation of high tech equipment inside a building using passive/active platform

Abstract

This chapter investigates the possibility of using a passively or actively controlled platform to isolate a batch of high tech equipment from micro vibration of the floor of a building subject to nearby traffic-induced ground motion. The governing equations of motion of the coupled platform-actuator-building system with actively controlled platform are derived in terms of the absolute coordinate to facilitate the feedback control. The performance evaluation of the platform is based on the BBN Vibration Criteria with the absolute velocity being targeted. A hybrid control system composed of passive mounts and active hydraulic actuators with a sub-optimal control algorithm is designed to actively control the platform. Hydraulic actuator dynamics are also considered in the modeling of the control system to avoid possible instability of the platform. The performance of actively controlled platform is assessed through comparisons with the cases of the building without control, the building with passively controlled platform. Simulation results of the study indicate that passively controlled platform can be effective in reducing micro vibration of high tech equipment if the parameters are properly selected. The actively controlled platform can, however, achieve high control performance within a wide range of isolator frequency and damping ratios. It is superior to the passively controlled platform in terms of its high performance and robustness.