A Study On Semi-active Multi-modal Vibration Damping Based On State-observer

The piezoelectric materials as a new type of smart materials have many outstanding advantages, especially in vibration control, because of their excellent mechanical-electrical coupling characteristics. Application of active vibration control systems based on piezoelectric elements in real-world structures has been limited by their requirement for complicated systems and sensibility to variation parameters. In order to overcome these drawbacks, a new method of semi-active vibration control based on a technique of a nonlinear synchronized switch damping (SSD) has been developed recently. This method is effective in single-mode control, but this method leads to over-frequent switching in multi-mode control, which reduces control performance because of energy loss during voltage inversion. To improve the control performance in multi-mode control, the main modal displacements or modal velocities are important information for switch control. This paper presented three different semi-active methods including SSDS/SSDI/SSDV/SSDNC techniques and their principle of operation。However, it is difficult to measure modal displacements or modal velocities directly in an MDOF system. In this paper modal displacements or modal velocities is estimated based on a state observer, and the establishment of Beam model and its state observer are developed in detail. The switch control signal could be obtained by a kind of algorithm, then we can use the control signal to control a special modal. An experimental platform for semi-active vibration control of a cantilever composite beam was established. The experiment was implemented under two kinds of excitation condition and good control performance was achieved. It semi-active vibration control method not only overcomes the drawback in traditional semi-active control that the control strategy is very complicated, but also can be extended to any active and semi-active system easily.