Control of Equipment Isolation System using Wavelet-based Decentralized Sliding Mode Control

Critical non-structural equipment, including high-precision equipment in the technology facilities, life-saving equipment in the hospitals, data storage equipment in the communication, computer, and data centers, etc., is vulnerable to vibration, and on top of that, the failure of these vibration-sensitive equipment will cause severe economic loss. In recent years, a lot of research has been conducted towards evaluation of semi-active control strategy for earthquake protection of vibration-sensitive equipment. Various innovative control algorithms have been studied to compensate the inertial loading, and these new or improved control strategies, such as the control algorithms based on the linear-quadratic regulator (LQR) and the sliding mode control (SMC), are also developed as a key element in smart structure technology. However, except to the advantage of simplicity and variability, both LQR and SMC are (centralized) full-state feedback controller and the state vector needs to be presented through a state estimator or compensator if it is not measured during earthquake excitation. On the other hand, considering decentralized control strategy, the controller is only evaluated using the response in the vicinity of control devices, thus minimizing the wiring and sensor communication requirements. However, the very limited information obtained and used by decentralized control strategy also restrains the control capability from reducing the response where without installing sensors. The aim of this paper is to develop a decentralized control algorithm on the control of both structure and non-structural equipment simultaneously to overcome the limitations of decentralized control through combining the advantage of wavelet analysis. This wavelet-based decentralized control algorithm will be simulated based on a frame with an equipment isolation system and a magnetorheological (MR) dampers located on the top of first floor numerically. The performance and robustness of wavelet-based decentralized control algorithm as well as the response of primary structure are evaluated and discussed through simulation study to demonstrate the efficiency of proposed control algorithms.