An active–passive absorber by using hierarchical fuzzy methodology for vibration control

It has been shown that piezoelectric materials are highly promising as passive electromechanical vibration absorbers when shunted with electrical networks. However, these passive devices have limitations that restrict their practical applications. The main goal of this study is to develop an innovative approach for achieving a high performance adaptive piezoelectric absorber—an active–passive hybrid configuration. This investigation addresses the first application of the concept of hierarchy for controlling fuzzy systems in such an active–passive absorber. It attempts to demonstrate the general methodology by decomposing a large-scale system into smaller subsystems in a parallel structure so that the method developed here can be applied for studying complex systems. The design of the lower-level controllers takes into account each subsystem ignoring the interactions among them, while a higher-level controller handles subsystem interactions. One of the main advantages of using a hierarchical fuzzy system is to minimize the size of the rule base by eliminating “the curse of dimensionality”. Therefore, the computational complexity in the process can be reduced as a consequence of the rule-base size reduction. Although the performance of the optimal passive absorber is already much better than the original system (no absorber), the intelligent active–passive absorber can still significantly outperform the passive system.