This study presents a numerical and an experimental study on an active vibration control system. The system includes a fully-clamped plate and two surface bonded piezoelectric actuators and a collocated velocity sensor at one of the actuator locations. One of the piezoelectric actuators is used for disturbance actuation and the other one is used for control actuation. A model based optimal velocity feedback controller is used as control algorithm. The disturbance and actuator models are obtained through experimental characterization of the plate under the effect of the disturbance source. A representative SIMULINK model is built in parallel to the development of the experimental setup in order to investigate performance of the controller for various control parameters. After the model based optimal controller is designed, performance of the optimal velocity feedback controller is validated with the experimental study by comparing the vibration suppression values at multiple modes of the structure. Results show that the developed control methodology effectively suppresses the vibration amplitudes at multiple modes of the structure and also vibration attenuation levels can be predicted accurately with the simulations for various controller design parameters. It is also demonstrated that using an optimal controller enhances the performance of the system as opposed to just using velocity feedback algorithm for the active vibration control of the smart plate.

Structural vibrations is a major cause for noise problems, discomfort and mechanical failures in aerospace, automotive and marine systems, which are mainly composed of plate-like structures. In order to reduce structural vibrations on these structures, active vibration control (AVC) is an effective approach. Adaptive filtering methodologies are preferred in AVC due to their ability to adjust themselves for varying dynamics of the structure during the operation. The filtered-X LMS (FXLMS) algorithm is a simple adaptive filtering algorithm widely implemented in active control applications. Proper implementation of FXLMS requires availability of a reference signal to mimic the disturbance and model of the dynamics between the control actuator and the error sensor, namely the secondary path. However, the controller output could interfere with the reference signal and the secondary path dynamics may change during the operation. This interference problem can be resolved by using an infinite impulse response (IIR) filter which considers feedback of the one or more previous control signals to the controller output and the changing secondary path dynamics can be updated using an online modeling technique. In this paper, IIR filtering based filtered-U LMS (FULMS) controller is combined with online secondary path modeling algorithm to suppress the vibrations of a plate-like structure. The results are validated through numerical and experimental studies. The results show that the FULMS with online secondary path modeling approach has more vibration rejection capabilities with higher convergence rate than the FXLMS counterpart.

In this paper, an analog velocity feedback controller is considered for active vibration suppression of a thin plate for attenuation of sound levels in the frequency range of 0–100 Hz. The active control methods can be applied to interior cavity noise reduction, as encountered for instance in automotive applications. For that purpose, a simplified experimental vibro-acoustic cabin model was built in our laboratory and developed methodologies are demonstrated on the set-up. The set-up includes a rectangular box (1 × 1 × 2 m) which is separated with a flexible thin plate (1 × 1 × 0.001 m) to obtain two enclosed cavities: the passenger compartment (PC) and the engine compartment (EC). The vibration control is applied only on the flexible plate since the walls enclosing the cavities are made of more rigid material (wood filled concrete). By employing piezoelectric patch as actuator and laser doppler vibrometer as vibration sensor, an analog proportional velocity feedback controller is designed and built experimentally for suppressing the low-frequency modes of the flexible plate. In order to attenuate only lower-frequency structural modes of the thin panel, pre-filters are also included in analog circuit. The vibration of thin plate and sound in the passenger compartment is measured for controller-inactive and active cases while disturbing the thin plate via shaker. By measuring vibration and sound response, closed and open loop experimental frequency responses are obtained and presented. The aim of this experimental study is to investigate performance of active vibration control applications on acoustic attenuation as the first step towards robust structural acoustic control.

No abstract

Tensegrity offers lightweight deployable structures for use in many engineering disciplines. Among all of the available tensegrity forms, D-Bar has a potential for combined applications of sensing, actuation, and structural support. In this paper, we enhance the minimal mass formulation of the D-Bar by including yielding of the compressive members as a design constraint in contrast to the previous assumption which considers buckling as the sole failure mechanism. In addition, we analyze the length and force gains of a D-bar system analytically by considering the minimal mass D-bar as the design constraint. Furthermore, we calculate the stiffness of the D-Bar and when appropriate use as design constraints as well. To enhance the minimal mass properties of the D-Bar, we combine T-bar and D-bar systems. The analysis shows that these structures are the basis for effective force transducers, force-controlled actuators, and efficient deployable compressive structures.