Conventional Semi-active Control Research Articles

Performance investigation of variable damping shock absorber combined with conventional semi-active vibration control logics

The shock induced by a rocket lift-off and pyrotechnic device actuation for interstage separation can cause damage to the on-board instruments of a spacecraft when the acceleration generated by the input shock exceeds their allowable acceleration value. The shock can be attenuated by mounting a shock absorber. In this paper, we propose a variable damping shock attenuation strategy combined with conventional semi-active vibration control laws derived from a two elements model composed of variable damping and spring stiffness that would attenuate the shock such that the main instrumentʼs input acceleration does not exceed the allowable acceleration value. The analysis results indicate that the combination of shock and conventional semi-active control logic attenuates the shock level better than an optimal passive and conventional semi-active control system. The strategy is also effective for suppressing the consequent vibration induced by the shock event.

Enhancement of pointing performance by semi-active variable damping isolator with strategies for attenuating chattering effects

Semi-active control strategy is one of the most attractive approaches for space applications because of it provides better performance than passive systems and higher robustness than active systems. However, conventional semi-active approaches, such as skyhook and bang-bang control, cause the pointing accuracy of the on-board payload to degrade due to chattering effects created by the sudden variation of damping force when a semi-active isolation system is switched on or off. In this paper, we propose a semi-active strategy to minimize performance deterioration due to chattering effects. Numerical simulation result obtained using a simplified on-board payload model demonstrate that the proposed LQ semi-active control logic with variable damping achieves much better isolation performance than the conventional semi-active control laws under single and fly-wheel force excitation environments.

Control of a building complex with Magneto-Rheological Dampers and Tuned Mass Damper

Coupled building control is a viable method to protect tall buildings from seismic excitation. In this study, the semi-active control of a building complex is investigated for mitigating seismic responses. The building complex is formed of one main building and one podium structure connected through Magneto-Rheological (MR) Dampers and Tuned Mass Damper. The conventional semi-active control techniques require a primary controller as a reference to determine the desired control force, and modulate the input voltage of the MR damper by comparing the desired control force. The fuzzy logic directly determines the input voltage of an MR damper from the response of the MR damper. The control performance of the proposed fuzzy control technique for the MR damper is evaluated for the control problem of a seismically-excited building complex. In this paper, a building complex that include a 14-story main building and an 8-story podium structure is applied as a numerical example to demonstrate the effectiveness of semi-active control with Magneto-Rheological dampers and its comparison with the passive control with the Tuned Mass Damper and two uncoupled buildings and hybrid semi-active control including the Tuned Mass Damper and Magneto-Rheological dampers while they are subject to the earthquake excitation. The numerical results show that semi-active control and hybrid semi-active control can significantly mitigate the seismic responses of both buildings, such as displacement and shear force responses, and fuzzy control technique can effectively mitigate the seismic response of the building complex.

Semi-active fuzzy control of cable-stayed bridges using magneto-rheological dampers

A semi-active fuzzy control technique to enhance the seismic performance of cable-stayed bridges using magneto-rheological (MR) dampers is presented. Conventional semi-active control techniques require a primary controller as a reference to determine the desired control force, and modulate the input voltage of the MR damper by comparing the desired control force and the actual damper force in a secondary controller. The proposed method, however, adopts fuzzy logic instead of primary and secondary controllers. The fuzzy logic directly determines the input voltage of an MR damper from the response of the MR damper. Thus, it provides a simple design procedure and can be easily implemented on a physical structure. The control performance of the proposed fuzzy control technique for the MR damper was evaluated for the benchmark control problem of a seismically-excited cable-stayed bridge. The simulated results show that the proposed semi-active fuzzy control technique can effectively mitigate the seismic response of cable-stayed bridges and successfully enhance the robust performance of the MR damper system.

Fuzzy Control of Base-Isolation System Using Multi-Objective Genetic Algorithm

Abstract: In this study, a friction pendulum system (FPS) and a magnetorheological (MR) damper are employed as the isolator and supplemental damping device, respectively, of a smart base-isolation system. Neuro-fuzzy models are used to represent dynamic behavior of the MR damper and FPS. A fuzzy logic controller (FLC) is used to modulate the MR damper so as to minimize structural acceleration while maintaining acceptable base displacement levels. To this end, a multi-objective optimization scheme that uses a nondominated multi-objective genetic algorithm (NSGA-II) is used to optimize parameters of membership functions and find appropriate fuzzy rules. To demonstrate the effectiveness of the proposed multi-objective genetic algorithm for FLC, a numerical study of a smart base-isolation system is conducted using several historical earthquakes. It is shown that the proposed method can find optimal fuzzy rules and that the NSGA-II-optimized FLC outperforms not only a passive control strategy but also a human-designed FLC and a conventional semiactive control algorithm.

사장교의 지진응답제어를 위한 준능동 MR 감쇠기의 퍼지제어

사장교의 효과적 지진응답제어를 위하여 MR 감쇠기를 이용한 준능동 퍼지 제어기법을 제시하였다. 제시하는 방법은 MR 감쇠기의 응답정보만을 이용한 퍼지추론 과정을 통하여 준능동 제어를 수행하는 방법으로서, 능동제어이론에 기반한 기존 준능동 제어기법과 달리, 별도의 능동제어기를 설계할 필요가 없는 간단한 구조로서 구성될 수 있다. 제시한 제어기법의 제어성능을 평가하기 위해 사장교 벤치마크 문제에 적용하였으며 기존 준능동 제어기법들과의 성능비교를 통하여 그 효율성을 평가하였다. 제어성능을 비교한 결과, 제시하는 준능동 퍼지 제어기법은 주탑의 전단력 및 휨모멘트, 데크의 수평변위, 그리고 케이블 장력 등의 상충하는 지진응답들을 동시에 효과적으로 제어함으로써 지진응답제어에 매우 효율적인 제어전략이 될 수 있음을 보였다. This paper proposes semi-active fuzzy control technique of magneto-rheological dampers for seismic response control of cable-stayed bridges. Through the fuzzy inference process, the proposed technique performs the semi-active control with the responses of MR dampers only. Moreover, differently from the conventional semi-active control technique, this technique does not require additional active controller for the primary controller, which provides a simple design process. in order to validate the control performance of the proposed technique, the semi-active fuzzy control technique is applied to the benchmark control problem of cable-stayed bridge and its control performance is compared with those of conventional semi-active control techniques. The comparative results show that the proposed fuzzy control technique can be an effective control strategy by efficiently and simultaneously reducing the mutual conflicting responses such as the shear forces and moments at the base of the lowers, longitudinal displacement of the deck, and tensions in the stay cables.

Design of fuzzy logic controller for smart base isolation system using genetic algorithm

Several recent works investigate the performance of smart base isolation systems and show that they can reduce base drifts without accompanying increases in acceleration that are seen with conventional passive isolation systems. To date, many viable smart base isolation systems have been proposed. In this study, a novel friction pendulum system (FPS) and an MR damper are employed as the isolator and supplemental damping device, respectively, of the smart base isolation system. A fuzzy logic controller (FLC) is used to modulate the MR damper because the FLC has an inherent robustness and ability to handle non-linearities and uncertainties. A genetic algorithm (GA) is used for optimization of the FLC. The main purpose of employing a GA is to determine appropriate fuzzy control rules as well to adjust parameters of the membership functions. To this end, a GA with a local improvement mechanism is applied. This method is efficient in improving local portions of chromosomes. Neuro-fuzzy models are used to represent dynamic behavior of the MR damper and FPS. The effectiveness of the proposed method for optimal design of the FLC is judged based on computed responses to several historical earthquakes. It has been shown that the proposed method can find optimal fuzzy rules and the GA-optimized FLC outperforms not only a passive control strategy but also a human-designed FLC and a conventional semi-active control algorithm.

MR fluid damper with multiple annular flow gaps

Several recent works investigate the performance of smart base isolation systems and show that they can reduce base drifts without accompanying increases in acceleration that are seen with conventional passive isolation systems. To date, many viable smart base isolation systems have been proposed. In this study, a novel friction pendulum system (FPS) and an MR damper are employed as the isolator and supplemental damping device, respectively, of the smart base isolation system. A fuzzy logic controller (FLC) is used to modulate the MR damper because the FLC has an inherent robustness and ability to handle non-linearities and uncertainties. A genetic algorithm (GA) is used for optimization of the FLC. The main purpose of employing a GA is to determine appropriate fuzzy control rules as well to adjust parameters of the membership functions. To this end, a GA with a local improvement mechanism is applied. This method is efficient in improving local portions of chromosomes. Neuro-fuzzy models are used to represent dynamic behavior of the MR damper and FPS. The effectiveness of the proposed method for optimal design of the FLC is judged based on computed responses to several historical earthquakes. It has been shown that the proposed method can find optimal fuzzy rules and the GA-optimized FLC outperforms not only a passive control strategy but also a human-designed FLC and a conventional semi-active control algorithm.