• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.4
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• pp.55-61
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• 2010

This paper is concerned with an experimental research to random vibration control caused by external loads specially in bridges which tend to be structurally flexible. Experimenting on a reduced structure modelled on Seohae Grand Bridge, we inflicted a reduced form of El-centro wave on the model structure to a proper proportion. On the center of its middle span, we placed a shear type MR damper which was to control its vibration and also acquire its structural responses such as displacement and acceleration at the same site. The experiments concerning controlling vibration were performed according to a variety of theories including un-control, passive on/off control, and Lyapunov stability theory. Its control performance was evaluated in terms of the peak absolute displacements, the peak absolute accelerations and the total power required to control the bridge which differ from each different experiment method. Among all the methods applied in this paper, case of Lyapunov control method turned out to be the most effective to reduces of displacement and acceleration. Also, this method could to decrease consuming of external power for vibration control. Finally, it was noteworthy that Lyapunov control method was specially effective in the vibration control employing a semi-active damper such MR damper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.85-94
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• 2011

This paper is concerned to constitute a semi-active realtime feedback vibration control system and evaluate it through experiments in order to control in realtime the vibration externally generated, specially on the bridges which is structurally flexible. For the experiment of vibration control, we built a model bridge structure of Seohae Grand Bridge in a 1/200 reduced form and inflicted El-centro wave on the model structure also in a reduced force considering the lab condition. The externally excited vibration was to be controled by placing a shear type MR damper vertically on the center of bridge span, and the response (displacement and acceleration) of structure was to be acquired by placing LVDT and Accelerometer at the same time. As for the experiment concerning controlling vibration, a realtime feedback vibration control experiments were performed under each different condition largely such as un-control, passive on/off control, Lyapunov stability theory control, and Clipped-optimal control. Its control performance under different condition was quantitatively evaluated in terms of the peak absolute displacements, the peak absolute accelerations and the power required for control on the center of span. The results of experiments proved that the Lyapunov control and clipped-iptimal control were effective to decrease the displacement and acceleration of the structure, and also to decrease the power consumption to a great extent. Finally, the semi-active realtime feedback vibration control system constituted in this research was proven to be an effective way to control and manage the vibration generated on bridge structure.

• Journal of Navigation and Port Research
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• v.47 no.4
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• pp.256-270
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• 2023

In this study, a sliding mode (SM) controller for dynamic positioning (DP) was specifically designed for a turret connection operation of a ship or an offshore structure in which an arbitrary point on the structure could be controlled as the motion center instead of the center of mass. The SM controller allows control of the arbitrary point and provides capability to manage uncertainties in the dynamics of ships and offshore structures, external forces caused by unknown changing marine environments, and transient performance of DP systems. The Jacobian matrix included in kinematic equations of the controlled object was modified to design the SM controller to control based on an arbitrary point of ships or offshore structures. To ensure robustness of the controller, the Lyapunov stability theory was applied in the design of the SM controller. In general, for robustness in DP control, gain scheduling based on a proportional-derivative (PD) control algorithm is employed. However, finding appropriate gains for gain scheduling complicates the application of DP systems. Therefore, in this study, the SM control algorithm was considered to mitigate the complexity of the DP controller for ships and offshore structures. To validate the proposed SM control algorithm, time-domain simulations were conducted and utilized to evaluate the performance of the control algorithm. The effectiveness of the proposed SM controller was assessed by comparing simulation results with results of a conventional PD control algorithm applied in DP control.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.760-765
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• 1992

In this paper, robust adaptive control algorithms which can be applied to unknown uncertain systems are suggested. Transform matrix for dividing states into "uncontrolled" states and "controlled" states and general searching procedure for the transform matrix which assign arbitrary n-1 eigen values for the uncontrolled subsystem of n-th order single-input single-output systems is also studied and utilized for the design of new-type controllers. We derived new-type control laws by using adaptive control theory and variable structure system and its stability is proved by using Lyapunov stability theory. From computer simulation results, we can see that the proposed adaptive control algorithm is robust and stable.s robust and stable.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.147-155
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• 2007

In this study, the performance of the modified sliding mode control proposed in the previous study is evaluated for seismic response control of nonlinear hysteretic structures. Modified sliding mode control(MSMC) utilizes the target derivative of Lyapunov function in order to calculate control force, and its performance was evaluated only lot linear structures in the previous study. However, considering that most structures subject to strong earthquake show nonlinear hysteretic behivior, the results from the previous study have limitations in practical application. The results from numerical analyses of single degree of freedom systems and base isolated system, which were described using Bouc-Wen model, indicate that the proposed MSMC algorithm shows better control performance than the existing sliding mode controller.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.603-610
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• 2000

In this paper, the direct and indirect adaptive controller are combined based on the Lyapunov synthesis approach. The Proposed controller is constructed from RBF Neural Network and weighting parameters are adjusted on-line according to some adaptation law. In this scheme, fuzzy IF-THEN rules are used to decide the combined weighting factor. In the results, proposed controller has the main advantages of both the direct adaptive controller and the indirect adaptive controller. The effectiveness of the proposed control scheme is demonstrated through simulation results of control for one-link rigid robotics manipulator.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.729-737
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• 2014

A study has been carried out that effectively controls the vibration of asymmetric cable-stayed bridges caused by earthquakes with MR dampers. In order to enhance the practical serviceability of MR dampers, an asymmetric cable-stayed bridge structure has been designed and produced, and a MR damper has been produced so as to have this bridge structure controlled appropriately. An experiment that controls vertical and horizontal vibrations has been carried out by exciting the asymmetric cable-stayed bridge in the horizontal direction with the El-centro seismic wave. The control performance of the MR damper has been evaluated under the five control conditions in the experiments of vibration control in each direction. As a result of the experiment, MR dampers were proved to control vibrations more effectively when either Lyapunov control algorithm or Clipped-optimal control algorithm was used to control vibrations of the asymmetric cable-stayed bridge caused by earthquakes. In addition, different controlling effects were found in vibration controls in vertical and horizontal directions due to the asymmetry of the structure and the horizontal excitation. With such controlling effects, semi-active MR dampers are evaluated to effectively control vibrations caused by earthquakes in flexible and asymmetric structures such as asymmetric cable-stayed bridges.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.744-747
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• 2010

This paper presents a novel adaptive control method for DC-DC converters applied in PV generator systems. We derive an state-space average model of the converter system and then propose a adaptive control methodology to enhance transient response performance for time-varying PV systems. A well-knwon Lyapunov theory is utilized for constructing our control algorithm. Numerical simulation demonstrates reliability of our control methodology and its superiority by comparison to a traditional control strategy.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.523-530
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• 2007

Crane systems are very important in industrial fields to carry heavy objects such that many investigations about control of the systems are actively conducted for enhancing its control performance. This paper presents an adaptive control approach using the model matching for a complex 3-DOF nonlinear crane system. First, the system model is linearized through feedback linearization method and then PD control is applied in the approximated model. This linear model is considered as nominal to derive corrective control law for a perturbed crane model using Lyapunov theory. This corrective control is primitively aimed to compensate real-time control deviation due to partially known perturbation. We additionally study stability analysis of the crane control system using Lyapunov perturbation theory. Evaluation of our control approach is numerically carried out through computer simulation and its superiority is demonstrated comparing with the classical control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.295-301
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• 2006

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS systems. In order to achieve the superior braking performance through the wheel-slip control, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance, stability enhancement, etc. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm. An adaptive law is formulated to estimate the longitudinal braking force in real-time. The wheel slip controller is designed using the Lyapunov stability theory and considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm is developed for the maximum braking force and searches the optimal target slip value based on the estimated braking force. The performance of the proposed wheel-slip control system is verified In simulations and demonstrates the effectiveness of the wheel slip control in various road conditions.