On active vibration isolation of floating raft system

A novel analytical active-passive model of floating rafts, a type of special isolation structures which present high-level vibration isolation and are widely used in large ships and submarines particularly, is developed for the first time. Then the mobility matrices of the subsystems are derived, thereby a general mathematical description of this combined active-passive model is realized. Based on the model, the concepts and relationships of machine control, raft control and full control are extensively discussed. The solution of the power flow transmitted into the foundation is obtained, and power transmission characteristics of the system are investigated under different control types when minimization of total power flow strategy is applied. Through numerical simulations, the control efficiencies of the different control types (machine control, raft control and full control) are compared, illustrating the efficiency of the presented model, obtaining some valuable results, and presenting some general design principles of the active floating raft isolation systems. © 2004 Elsevier Ltd. All rights reserved.