This paper presents the optimal design of a passive autoparametric cantilever beam vibration absorber for a linear mass-spring-damper system subject to harmonic external force. The design of the autoparametric vibration absorber is obtained by using an approximation of the nonlinear frequency response function, computed via the multiple scales method. Based on the solution given by the perturbation method mentioned above, a static optimization problem is formulated in order to determine the optimum parameters (mass and length) of the nonlinear absorber which minimizes the steady state amplitude of the primary mass under resonant conditions; then, a PZT actuator is cemented to the base of the beam, so the nonlinear absorber is made active, thus enabling the possibility of controlling the effective stiffness associated with the passive absorber and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty. Finally, some simulations and experimental results are included to validate and illustrate the dynamic performance of the overall system.

This article describes semi-active modern control schemes for a quarter-vehicle suspension with a magnetorheological damper (MRD) to attenuate vibrations and simultaneously improve the passenger comfort and the vehicle road-holding. The first solution is a multiple positive position feedback (MPPF) control scheme to attenuate the vibration amplitude at the two modal frequencies. The second solution is based on elementary passivity considerations on the exact regulation error dynamics passive output. The passive output feedback is used to improve the control aims. Finally, the third solution deals with a disturbance rejection control (DRC) based on an extended state observer. The three proposed control schemes consider an inverse polynomial model of a commercial MRD for numerical implementation and are evaluated by comfort and road-holding performance indexes proposed in the literature. Furthermore, the effects of variation in the sprung mass (emulating different number of passengers) on the controllers’ performance is analysed. The numerical results show in both scenarios (constant and variable sprung mass) that passivity based control (PBC) and DRC improve the performance indexes compared with the classical sky-hook control and the open-loop systems with a different constant current input for the MRD. Obtained results for damping force and power consumption are within the operation range of the considered commercial MRD showing the viability for experimental implementation of the proposed control schemes.

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This article considers the dynamic analysis and semiactive vibration control on a building-like structure, excited on its base through an external force generated by an electromechanical shaker providing harmonic and seismic motion at the base of the overall structure. The mathematical model of the overall system is obtained using Euler-Lagrange methods, which is validated by means of experimental modal analysis techniques. In fact, the external force excites the first three (lateral) vibration modes of the building-like structure. Therefore, to suppress and/or attenuate the undesirable vibrations on the structure, it is proposed a semiactive vibration control scheme considering a Magneto-Rheological damper directly coupled between the base and the first floor. The hysteretic behavior of the Magneto-Rheological damper is modeled by means of the polynomial approach proposed by Choi-Lee-Park. Finally, a Multi Positive Position Feedback controller combined with Sliding-Mode Control techniques is synthesized, using as output the position provided by an accelerometer collocated on the first floor. Some experimental results are presented to show the dynamic performance of the overall building-like structure.

This work describes the problem of the unbalance response compensation in a rotor-bearing system using two control techniques based on measurements of the radial displacements or accelerations directly in a Magnetorheological (MR) bearing suspension. The rotor-bearing system is modeled using Finite Element Methods (FEM) for a Jeffcott-like rotor with one planar disk, two nonorthotropic supports, one traditional journal bearing and other similar but supported on an arrangement with two MR dampers. The mathematical model consists of two finite elements, with a total of 6 degrees of freedom for each horizontal and vertical direction. For the rotating speed regulation a PID control, is applied in order to track a proper speed profile to pass over the first critical speeds (runup or coast down). Control schemes to compensate the unbalance in the rotor are: a Positive Position Feedback (PPF) control, which requires only the measurement of one radial displacement in the MR suspension, and another scheme based on the measurement of the radial acceleration, known as Positive Acceleration Feedback (PAF). Both control schemes require only one sensor (proximitor or accelerometer) for each control input and they demand small control efforts. For the control design and physical implementations, we use the socalled Choi-Lee-Park polynomial model for both MR dampers, which can adequately describe the highly nonlinear and hysteresis behaviors for this type of actuators. Finally, by means of some numerical simulations are illustrated the dynamic and robust performance of the overall control system.