Multi-modal Vibration Control Research Articles

Multi-Modal Vibration Control Using Adaptive Positive Position Feedback

An adaptive controller, Adaptive Positive Position Feedback (APPF) is proposed for the multi-modal vibration control of frequency varying structures. Spillover phenomena and real-time system identification have been obviously difficult obstacles for the multi-modal adaptive vibration control. To overcome these problems, a fast and powerful algorithm is proposed to identify the frequencies of time-varying structures. Variable PPF controllers are adjusted with estimated natural frequencies at every time step. A composite plate with a bonded piezoelectric sensor and an actuator was prepared as an experimental model, and the natural frequencies of the model are changed by attaching masses. The experimental results show that natural frequencies are estimated quite accurately and that the vibration of controlled modes is significantly reduced. No significant performance reduction has been observed with respect to approximately 10% frequency changes of the corresponding modes. On the contrary, the performance of the conventional LQG controller is significantly degraded due to frequency variations.

MULTI-MODAL VIBRATION CONTROL OF SMART COMPOSITE PLATES

In this paper, multi-modal vibration control of smart composite plates has been studied. Piezoelectric films and ceramics have been used as sensors and actuators in surface bonded forms. For modeling and analysis of smart composite plates, an efficient finite element method based on the layerwise plate theory has been used. The effect of thickness changes due to bonded piezoelectric materials and variable in-plane displacement fields on the dynamic, actuating and sensing characteristics have been considered in the finite element formulation. This study includes an optimization method based on genetic algorithms to select appropriate locations of piezoelectric sensors and actuators of a smart composite plate for maximization of control performance. The cost function used in the optimization is based on degrees of controllability, observability, and spillover prevention. Experimental multi-modal vibration control has been also performed. A smart composite plate is prepared according to the optimization results for the experimental works. Coupled positive position feedback algorithms have been implemented in digital signal processing (DSP) system. The control results show that vibration level of the controlled modes has been significantly reduced with negligible effect on the residual modes.

Multi-Modal Vibration Control of Laminated Composite Plates Using Piezoceramic Sensors/Actuators

Multi-modal vibration control of the cantilevered laminated composite plates using collocated piezoceramic sensors/actuators is analyzed theoretically and verified experimentally for various fiber orientations. Impact on the stiffness and the damping properties by varying the stacking sequence of [04/02/902j, for the laminated composite plate is studied. The finite element method is used for the dynamic analysis of the plates with and without the piezoceramics. Natural frequencies and modal damping of the first bending and the first torsional modes are predicted theoretically by taking into account damping and stiffness of the adhesive layer and the piezoceramics in the modeling. Active modal damping of the first bending and the first torsional modes are measured experimentally. It is demonstrated that the active control is more effective for the structure with higher stiffness when the feedback gain is large, whereas it follows trends of the passive control by tailoring when the gain is small.

Intelligent Material and Fluid Systems. Vibration Sensing and Control of a Flexible Beam Using Piezoelectric Films.

Multimodal vibration control of a cantilever beam using bonded piezoelectric film sensors and actuators is studied both theoretically and experimentally. Equations of motion of the Bernoulli-Euler beam with collocated bonded piezoelectric sensors / actuators are derived. Then, direct velocity feedback control is employed as the vibration control law, and applying Lyapunov's direct method, it is shown that this control law is stable for arbitrary vibration mode. Transient responses of the beam, with control and without control, are studied for the cases in which an impact force is applied to the tip of the beam. Numerical results and experimental results show good agreement, which shows the validity of the proposed control scheme. It is also shown that first three bending modes are efficiently controlled, and that in order to achieve more broadband vibration control, it is necessary to consider the dynamics such as extensional vibrations of the beam which is not considered in the present study.