Averaging sensors technique for active vibration control applications

Fiber Bragg Gratings (FBG) sensors have a great potential in active vibration control of smart structures thanks to their small transversal size and the possibility to make an array of many sensors. The paper deals with the opportunity to reduce vibration in structures by using distributed sensors embedded in carbon fiber structures through the so called sensors-averaging technique. This method provides a properly weighted average of the outputs of a distributed array of sensors generating spatial filters on a broad range of undesired resonance modes without adversely affecting phase and amplitude. This approach combines the positive sides of decentralized control techniques as the control forces applied to the system are independent of one another, while, as for the centralized controls it has the possibility to exploit the information from all the sensors. The ability to easily manage this information allows to synthesize an efficient modal controller. Furthermore it enables to evaluate the stability of the control, the effects of spillover and the consequent effectiveness in reducing vibration. Theoretical aspects are supported by experimental applications on a large flexible system composed of a thin cantilever beam with 30 longitudinal FBG sensors and 6 piezoelectric actuators (PZT).