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In this paper, the problem of active vibration control of multi-degree-of-freedom structures is considered. Fuzzy logic and PID controllers are designed to suppress structural vibrations against earthquakes under the non-linear soil-structure interaction. The advantage of the fuzzy logic approach is the ability to handle the non-linear behavior of the system. Non-linear behavior of the soil is modeled in the dynamics of the structural system with non-linear hysteric restoring forces. The simulated system has fifteen degrees of freedom, which is modeled using spring-mass-damper subsystems. A structural system was simulated against the ground motion of the destructive Kocaeli earthquake (M w = 7.4) in Turkey on 17 August 1999. At the end of the study the time history of the storey displacements and accelerations, the control voltages and forces, and the frequency responses of both the uncontrolled and the controlled structures are presented. The performance of designed fuzzy logic control is checked using the changing mass parameters of each storey and the results are discussed. These results show that the proposed fuzzy logic controller has great potential in active structural control.

This paper is concerned with the design of a robust L2 gain state derivative feedback controller for an active suspension system. An uncertain quarter vehicle model is used to analyze vehicle suspension performance. Parametric uncertainty is assumed to exist in sprung mass, tire stiffness and suspension damping coefficients. Polytopic type state space representation is used to enable robust controller design via a linear matrix inequalities (LMIs) framework. Then nominal and robust L2 gain state derivative feedback controllers having bounded controller gains and robust L2 gain state feedback controllers are tested against ISO2631 random road disturbances with different road grades and vehicle horizontal velocities. Simulation results show that the proposed robust L2 gain state derivative feedback controller is very effective in improving ride comfort without deterioration on road holding ability.

Self-tuning fuzzy logic controllers (STFLC) for the active control of Marmara Kocaeli earthquake excited building structures are studied in this paper. Vibration control using intelligent controllers, such as fuzzy logic has attracted the attention of structural control engineers during the last few years, because fuzzy logic can handle nonlinearities, uncertainties, and heuristic knowledge effectively and easily. The improved seismic control performance can be achieved by converting a simply designed static gain into a real time variable dynamic gain through a selftuning mechanism. Self-tuning fuzzy logic controller is designed to reduce the story-drift of each floor.The simulated system has a nine-degree-of-freedom, which is modeled using nonlinear behavior of the base-structure interaction. Modeled system was simulated against the ground motion of the Marmara Kocaeli earthquake (M w = 7.4) in Turkey on 17 August, 1999. At the end of the study, the time history of the story displacements, accelerations, ATMD displacements, control voltage, and frequency responses of the both uncontrolled and controlled cases are presented. The robustness of the controller has been checked through the uncertainty in stiffness of the structure. Performance of the designed STFLC has been demonstrated for the different disturbance using ground motion of the Kobe earthquake. Simulations of an earthquake excited nine story structure are performed to prove the validity of proposed control strategy.

In this study, the design problem of a Model Predictive Controller (MPC) for attenuation of vertical motions of a passenger ship which is subject to irregular wave excitations is investigated. The proposed design considers actuator amplitude and rate saturation phenomenon. The motion control system of the ship utilises a pair of active stabilizing fins mounted to the head and tail. First, irregular long crested head waves are implemented by a well-established randomization theory in order to find heave force and pitch moment at F n = 0.40 and F n = 0.50 in the time domain. Then, a two-degree-of-freedom mathematical model, in which pitch and heave motions are coupled with the approximation of convolution integrals is solved to obtain the uncontrolled motions and accelerations of the ship. Finally, considering the physical amplitude and rate limitations of the active fin mechanism, an MPC design is proposed to obtain a practically applicable state-feedback control law for attenuating vertical motion of a passenger ship. The performance of the MPC is also compared with an elipsoid based H ∞ controller. An extensive amount of simulation studies are presented at the end to illustrate the effectiveness of the proposed approach.