• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.822-829
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• 2006

This paper presents a robust and superior control performance of a quarter-vehicle electrorheological (ER) suspension system. In order to achieve this goal, a moving sliding mode control algorithm is adopted, and its moving strategy is tuned by fuzzy logic. As a first step, ER damper is designed and manufactured for a passenger vehicle suspension system, and its field-dependent damping force is experimentally evaluated. After formulating the governing equation of motion for the quarter-vehicle ER suspension system, a stable sliding surface and moving algorithm based on fuzzy logic are formulated. The fuzzy moving sliding mode controller is then constructed and experimentally implemented. Control performances of the ER suspension system are evaluated in both time and frequency domains.

• Earthquakes and Structures
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• v.23 no.4
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• pp.329-338
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• 2022

This work addresses the optimization controller design problem combining the AI evolution bat (EB) optimization algorithm with a fuzzy controller in the practical application of a reinforced concrete frame structure. This article explores the use of an intelligent EB strategy to reduce the dynamic response of Lead Rubber Bearing (LRB) composite reinforced concrete frame structures. Recently developed control units for plant structures, such as hybrid systems and semi-active systems, have inherently non-linear properties. Therefore, it is necessary to develop non-linear control methods. Based on the relaxation method, the nonlinear structural system can be stabilized by properly adjusting the parameters. Therefore, the behavior of a closed-loop system can be accurately predicted by determining the behavior of a closed-loop system. The performance and durability of the proposed control method are demonstrated by numerical simulations. The simulation results show that the proposed method is a viable and feasible control strategy for seismically tuned composite reinforced concrete frame structures.

• Smart Structures and Systems
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• v.25 no.3
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• pp.323-335
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• 2020

Magnetorheological elastomer (MRE), a smart material, is an innovative material for base isolation system. It has magnetorheological (MR) effect that can control the stiffness in real-time. In this paper, a new hybrid base isolation system combining two electromagnetic closed circuits and the roller bearing is proposed. In the proposed system, the roller part can support the vertical load. Thus, the MRE part is free from the vertical load and can exhibit the maximum MR effect. The MRE magnetic loop is constructed in the free space of the roller bearing and forms a strong magnetic field. To demonstrate the performance of the proposed hybrid base isolation system, dynamic characteristic tests and performance evaluation were carried out. Dynamic characteristic tests were performed under the extensive range of strain of the MRE and the change of the applied current. Performance evaluation was carried out using the hybrid simulation under five earthquakes (i.e., El Centro, Kobe, Hachinohe, Northridge, and Loma Prieta). Especially, semi-active fuzzy control algorithm was applied and compared with passive type. From the performance evaluation, the comparison shows that the new hybrid base isolation system using fuzzy control algorithm is superior to passive type in reducing the acceleration and displacement responses of a target structure.

• International Journal of Automotive Technology
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• v.7 no.4
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• pp.469-475
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• 2006

In this paper, an optimal suspension system with preview of the road input is synthesized for a half tracked vehicle. The main goal of this research is to improve the ride comfort characteristics of a fast moving tracked vehicle in order to maintain the driver's driving capability. Several different kinds of preview control algorithms are evaluated with active or semi-active suspension systems. The road information estimated from the motion of the 1st road-wheel is adequate to make the best use of the preview control algorithm for tracked vehicles. The ride-comfort characteristics of the tracked vehicle are more dependent on pitching angular acceleration than heaving acceleration. The pitching motion is reduced by the suspension system with hard outer suspensions and soft inner suspensions. Simulation results show that the performance of sky-hook algorithms for ride comfort nearly follow that of full state feedback algorithms.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.13-21
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• 2001

Electrorheological(ER) fluid is a kind of smart material with variable shear stress and dynamic viscosity under various electric field intensity. Electric field can control the damping characteristics of ER damper. The objective of this study is the analysis of the performance of ER damper and its application to shock absorber. Idealized nonlinear Bingham plastic shear flow model is used to predict the velocity profile between electrodes. Cylindrical dashpot ER damper with moving electrode is constructed and tested under various electric fields. The analytic and experimental results for damping force are compared and discussed. Drop test system using ER damper is prepared to identify transient vibration characteristics. The rebound is eased as the applied electric field increases. When semi-active control algorithm is applied, rebound phenomenon disappears and vibration energy level decays faster than the case of zero electric field.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.87-92
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• 2001

Automotive suspension system is a mechanism for isolation of the vibration coming from the road inputs. Recently, the electronically controlled suspension systems which may improve ride and handling performance have been developed. Here, the continuously controlled semi-active suspension system is focused. As a mechanism to control damping forces continuously, a solenoid valve is used. The modeling for the solenoid valve is introduced briefly, a vehicle dynamics modeling is constructed, and then combined system model is completed. To design the efficient control algorithm for the semiactive suspension system the knowledge based fuzzy logic is applied and the technique how to apply the sky-hook theory to the fuzzy logic is developed. Finally, to confirm the improvement of performance the computer simulation is carried out.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.501-504
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• 1995

A Simultaneous optimal design of structural and control system of a semi-active suspension is applied on a helf-car model in this paper. Suspension stiffnesses and dampings are selected as structural design parameters and damping forces of variable dampers as controller parameters. Sence this optimization problem is of large discontinuous space, conventional exhaustive methods are not enough. So we here try out an approach using Genetic Algorithm for our problem. Through numerical simulation work, the performance of the simultaneously optimized system was tested and showed meaningful improvement over the partially optimized ones.

• Smart Structures and Systems
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• v.18 no.6
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• pp.1251-1267
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• 2016

In this paper, Simple Adaptive Control (SAC) is used to enhance the seismic response of nonlinear tall buildings based on acceleration feedback. Semi-active MR dampers are employed as control actuator due to their reliability and well-known dynamic models. Acceleration feedback is used because of availability, cost-efficiency and reliable measurements of acceleration sensors. However, using acceleration feedback in the control loop causes the structure not to apparently meet some requirements of the SAC algorithm. In addition to defining an appropriate SAC reference model and using inherently stable MR dampers, a modification in the original structure of the SAC is proposed in order to improve its adaptability to the situation in which the plant does not satisfy the algorithm's stability requirements. To investigate the performance of the developed control system, a numerical study is conducted on the benchmark 20-story nonlinear building and the responses of the SAC-controlled structure are compared to an $H_2/LQG$ clipped-optimal controller under the effect of different seismic excitations. As indicated by the results, SAC controller effectively reduces the story drifts and hence the seismically-induced damage throughout the structural members despite its simplicity, independence of structural parameters and while using fewer number of dampers in contrast with the $H_2/LQG$ clipped-optimal controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2274-2282
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• 2000

An MR(Magneto-Rheological) fluid damper is designed and applied to the semi-active suspension system of a 1/4 car model. The damping constant of the MR damper changes according to input current and the time delay of the damper is included in the system dynamics. The passive method, LQ control and Frequency shaped LQ control are compared in experiments. The advantage of the proposed frequency shaped LQ control is that the ride comfort improves in frequency range from 4 to 8Hz where human body is most sensitive and the driving safety improves around the resonance frequency of unsprung mass, 11Hz. The experiments using a 1/4 car model show the effectiveness of the algorithm.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.47-56
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• 1997

This paper presents the vibration control of an engine mount featuring an ER(electro-rheological) fluid. The Bingham properties of the ER fluid to be employed to the ER engine mount are experimentally obtained through Coeutte type viscometer. The ER engine mount is devised ant its governing equation is derived. After evaluating the performance of the ER engine mount on the basis of the mathematical model, the novel type of the ER engine mount is then designed and manufactured. The electric field-dependent transmissibility of the ER engine mount is evaluated by changing the particle concentration and the electrode gap size. To investigate the control performance of the ER engine mount, neuro-control algorithm is adopted. It is shown that the proposed ER engine mount has prominent capabilities of controlling the damping force by tuning the electric fields and excellent vibration isolation performance.