Vibration mitigation using adaptive control strategies for unknown system dynamics

Abstract

Vibration problems have raised debasement of quality in human life. Among them, micro-vibration problems in precision industry affect the quality of products and vibration problems in building structure due to the dynamic loads such as strong wind loads and earthquakes cause the safety and serviceability issues. Firstly to address the micro-vibration problems, a hybrid mount system with air springs and piezo-stack actuator that can deliver excellent performance in the micro-vibration control of precision instruments is proposed. Air springs are one of the most popular products for vibration isolation and deliver good performance in general. Piezo-stack actuators are capable of controlling micro- and nano-level displacement with a fast response. In order to fully utilize the isolation and leveling performances of an air spring as a passive part, it is connected in series with a piezo-stack actuator serving as an active part. As control logic for the hybrid mount, the filtered-X LMS algorithm is applied. A hybrid mount system with four hybrid mounts is configured in order to ensure the performance of the hybrid mount and its performance is verified through a series of experimental tests. With the micro-vibration problem in the precision instruments, structural control problem is dealt with. In this study, an active control methodology for structural control, time delay control (TDC) is proposed. It is a kind of adaptive control and cancels the uncertainties of unknown system dynamics and disturbances using direct estimation from time delay information, thus it can be applicable to not only linear time-invariant system but also nonlinear or time-varying systems. The structure and stability of the control system are discussed for the n-degree-of-freedom building structure. At the end, the control performance of the building control system is evaluated through series of numerical simulations and experimental tests.