Hakan Yazici

Fuzzy Logic Control of a Non-linear Structural System against Earthquake Induced Vibration

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 (Mw = 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.

Active Vibration Control of Container Cranes against Earthquake by the Use of Delay-Dependent H∞ Controller under Consideration of Actuator Saturation

This paper studies the design of a state-feedback delay-dependent H∞ controller for vibration attenuation problem of a seismic-excited container crane subject to having time-varying actuator delay, L2 type disturbances and actuator saturation. First, a sufficient delay-dependent stability criterion is developed by choosing a Lyapunov-Krasovskii functional candidate based on matrix inequalities for a stabilizing H∞ synthesis. To convexify the Bilinear Matrix Inequality (BMI) based optimization problem involved in the delay dependent conditions; a cone complementary linearization method is adopted to find a sub-optimal solution. The proposed method also utilizes convex description of nonlinear saturation phenomenon by means of convex hull of some linear feedback which leads to a few additional ellipsoidal conditions in terms of Linear Matrix Inequalities (LMIs). By use of the proposed method, a suboptimal controller with maximum allowable delay bound and minimum allowable disturbance attenuation level can be easily obtained by a convex optimization technique. In order to show effectiveness of the proposed approach, a five Degrees-of-Freedom (DOF) container crane structure is modeled using a spring-mass-damper subsystem. The system is then simulated against the real ground motions of Kobe and Northridge earthquakes. Finally, the time history of the crane parts displacements, accelerations, control forces and frequency responses of the both uncontrolled and controlled cases are presented. Additionally, the performance of the proposed controller is also compared with a nominal state-feedback H∞ controller performance. Simulation results show that, in spite of the actuator saturation, the designed controller is all effective in reducing vibration amplitudes of crane parts and guarantees stability at maximum actuator delay.

Observer Based Optimal Vibration Control of a Full Aircraft System Having Active Landing Gears and Biodynamic Pilot Model

This paper deals with the design of an observed based optimal state feedback controller having pole location constraints for an active vibration mitigation problem of an aircraft system. An eleven-degree-of-freedom detailed full aircraft mathematical model having active landing gears and a seated pilot body is developed to control and analyze aircraft vibrations caused by runway excitation, when the aircraft is taxiing. Ground induced vibration can contribute to the reduction of pilot’s capability to control the aircraft and cause the safety problem before take-off and after landing. Since the state variables of the pilot body are not available for measurement in practice, an observed based optimal controller is designed via Linear Matrix Inequalities (LMIs) approach. In addition, classical LQR controller is designed to investigate effectiveness of the proposed controller. The system is then simulated against the bump and random runway excitation. The simulation results demonstrate that the proposed controller provides significant improvements in reducing vibration amplitudes of aircraft fuselage and pilot’s head and maintains the safety requirements in terms of suspension stroke and tire deflection.

L2 gain state derivative feedback control of uncertain vehicle suspension systems

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.

Active Trailer Braking system design with Linear Matrix Inequalities based multi-objective robust LQR controller for vehicle-trailer systems

An Active Trailer Braking system is designed for the mitigation of trailer sway. Motion of the vehicle-trailer system on the horizontal plane with three degrees of freedom is modeled. Variations on the dynamic behaviors are studied due to the changes in longitudinal velocity. Then, performance objectives of controller is specified in terms of robust stability and lower bound of damping ratio for a prescribed longitudinal velocity range. Linear Matrix Inequalities based robust multi-objective LQR controller is designed with constraints on closed-loop pole locations and guarantee of robust stability. Finally, superiority of the designed controller is shown by using some numerical comparison with a classical Algebraic Riccati Equation based LQR design reported in the literature.

Disturbance attenuation of asymmetric structure by LMI based optimal state feedback controller with saturated actuators

This paper is concerned with the design of linear matrix inequalities (LMIs) based optimal state-feedback controller design for seismically excited asymmetric structures (AS) having stiffness irregularities. The system is modelled in terms of mass, natural frequencies, damping ratio and eccentricities to easily obtain torsionally flexible (TF) model. A one storey, two-way asymmetric structural system is used to illustrate the effectiveness of the approach through simulations. The modelled system has bi-lateral and rotational degrees of freedom. Frequency responses show the effectiveness of proposed controller by means of a decrease in the peak values of translation at each resonance frequency. Moreover, the time domain simulation results, acquired by using real time-history data of San Francisco and El Centro Earthquakes also show that proposed controller is very effective in reducing vibration amplitudes of each direction by applicable control signals and guaranteeing the stability of the closed loop system.

Delay-Dependent H∞ Controller Design for Seismic-Excited Structures with Actuator Delay under Consideration of Actuator Saturation

Abstract This paper studies the design of a state-feedback delay-dependent H ∞ controller for vibration attenuation problem of a seismic-excited structural system having time-varying actuator delay, L 2 disturbances and actuator saturation. First, sufficient delay-dependent stability criteria are derived by choosing a Lyapunov-Krasovskii functional candidate based on matrix inequalities for a stabilizing H ∞ synthesis. To overcome the bilinear matrix inequality problems involved in the delay dependent conditions; a cone complementary linearization method is used to find a feasible solution set. The proposed method utilizes convex description of nonlinear saturation phenomenon by means of convex hull of some linear feedback which leads to a few additional ellipsoidal conditions in terms of linear matrix inequalities (LMIs). By use of the proposed method, a suboptimal controller with maximum allowable delay bound and minimum allowable disturbance attenuation level can be easily obtained by a convex optimization technique. The effectiveness of the proposed controller is illustrated through simulations of the responses of a-four-degree-of-freedom structural system under seismic excitations. Simulation results show that, in spite of the actuator saturation, the designed controller is all effective in reducing vibration amplitudes of storeys and guarantees stability at maximum actuator delay.

LMI-based design of an I-PD+PD type LPV state feedback controller for a gantry crane

In this paper, an alternative gain-scheduled PID tuning procedure is proposed for gantry crane control systems. In order to avoid excessive overshoot and aggressive control action due to the proportional kick and/or derivative kick effects, an I-PD+PD type control law is considered. The scheduling parameter is considered the cable length due to the payload lifting and lowering movements. A linear parameter-varying (LPV) gantry crane model is constructed to enable gain-scheduled controller design with a linear matrix inequalities (LMIs) framework. Based on the LPV model, a convex optimization problem is formulized to minimize L2 gain under regional pole location constraints. Then, a fixed gain L2 gain state feedback I-PD+PD type controller and a conventional pole placement state feedback I-PD+PD controller are designed to investigate the efficiency of the proposed controller. A pole placement controller is tuned to minimize the very common ITAE (integral of time multiplied by absolute error) performance index. Simulation results show that the proposed controller has superior tracking performance under time-varying cable length, when compared with nominal fixed gain controllers.

Active control of a non-linear landing gear system having oleo pneumatic shock absorber using robust linear quadratic regulator approach

This paper deals with the active control of a non-linear active landing gear system equipped with oleo pneumatic shock absorber. Runway induced vibration can cause reduction of pilot’s capability of control the aircraft and results the safety problem before take-off and after landing. Moreover, passenger–crew comfort is adversely affected by vertical vibrations of the fuselage. The active landing gears equipped with oleo pneumatic shock absorber are highly non-linear systems. In this study, uncertain polytopic state space representation is developed by modelling the pneumatic shock absorber dynamics as a mechanical system with non-linear stiffness and damping properties. Then, linear matrix inequalities-based robust linear quadratic regulator controller having pole location constraints is designed, since the classical linear quadratic regulator control design is dealing with linearized state space models without considering the non-linearities and uncertainties. Thereafter, numerical simulation studies are carried out to analyse aircraft response during taxiing. Bump- and random-type runway irregularities are used with various runway class and wide range of longitudinal speed. Simulation results revealed that neglecting the non-linear dynamics associated with oleo pneumatic shock absorber results significant performance degradation. Consequently, it is demonstrated that proposed robust linear quadratic regulator controller has a superior performance in terms of passenger–crew comfort and operational safety when compared to classical linear quadratic regulator.

Output derivative feedback vibration control of an integrated vehicle suspension system

In this article, we present a novel approach to design an L2 gain output derivative feedback controller for active vibration control of a vehicle suspension system. In vibration control problems, state derivative signals such as acceleration and velocity are easier to obtain rather than the state variables such as position and velocity, since the accelerometers are simpler, cheaper and more reliable than position sensors. First, an L2 gain output derivative feedback controller is proposed by taking into account that measuring state derivative signals belong to driver body and electro-hydraulic actuator is not applicable in practice. Then, an L2 gain state derivative feedback controller and an L2 gain static output feedback controller are designed to investigate efficacy of the proposed controller. Performance of the controllers is tested against bump- and random-type road irregularities. A 4-degree-of-freedom integrated vehicle suspension model that includes a quarter vehicle suspension, a seat suspension, a driver body and an electro-hydraulic actuator is used throughout the numerical simulation studies. Simulation results show that proposed L2 gain output derivative feedback controller provides compatible performance improvement in the state derivative feedback control and static output feedback control with more viable feedback strategy.