Combination of decentralized sliding mode control and online wavelet analysis for control of equipment with isolation system

Abstract

Summary Critical equipment and machinery, especially the one in the technology facilities, hospitals, data centers, etc., are vulnerable to strong earthquakes, and most importantly, the failure of the critical equipment will result in countless economic loss, directly and indirectly. For decades, passive control devices in the form of isolation systems between the equipment and its supporting structure have been acknowledged as an effective measure to promote the earthquake resistibility on the basis of theoretical and experimental results. Alternative to passive isolation systems, researchers found that adding a semiactive device to the isolation system can increase damping and lessen the isolator displacement. In order to mitigate the acceleration of equipment, various control algorithms have been developed to reduce the response produced by the internal forces. However, little attention has been given to the balance between the response of equipment and the structural response. In this study, an innovative control algorithm is developed based on decentralized control architecture and wavelet analysis, and this control algorithm is proposed for semiactive isolation systems to protect acceleration‐sensitive equipment against strong earthquakes. Subsequently, a full‐scale specimen is constructed; moreover, a curved surface slider (CSS) system with a magneto‐rheological (MR) damper are placed between the equipment and the floor to suppress the vibration. The experiment is conducted with a feedback control system to validate the performance and efficiency of proposed control algorithm. In the last place, the discussion and some conclusion are also drawn in this paper.

Real-time hybrid simulation for a base-isolated building with the transmissibility-based semi-active controller

“…The MR damper is selected as a semi-active damping device. The performance and application of MR dampers in structures is studied by numerous researchers (Bass and Christenson, 2007;Chae et al, 2013bChae et al, , 2013cDyke et al, 1996;Sodeyama et al, 2004), including the recent studies where the MR dampers are applied to semi-actively controlled base isolation systems (Gu et al, 2020;Huang and Loh, 2019;Rodrı´guez et al, 2012). MR dampers normally have cylindrical shape with a piston which moves through the cylinder.…”

Structural sparsity in control design of active and semi‐active systems

“…Other research work has proposed designing strategies where the control action for each actuator is computed using only the information from the story where the actuator is located at and the one from adjacent stories. It involves conducting a control design process that is constrained to a predefined sparsity pattern 11‐14 . This imposed pattern is determined based on physical interpretations of the structure that is being controlled.…”

An instantaneous frequency analysis method of stay cables

“…25,26 Wavelet packet, VMD can multi-decompose the measured signal into the different frequencies to obtain the localized impulse signals. [27][28][29][30][31] HHT is a combination of EMD and Hilbert Transform (HT). Huang et al 32,33 introduced EMD, which is employed to decompose a nonstationary or nonlinear signal to intrinsic mode functions (IMFs), and the IF can be extracted by post-processing each IMF.…”

“…25,26 Wavelet packet, VMD can multi-decompose the measured signal into the different frequencies to obtain the localized impulse signals. 27–31 HHT is a combination of EMD and Hilbert Transform (HT). Huang et al.…”