Seok-Jun Moon

Experimental Study on Stability of Robust Saturation Controller

In our previous research, we proposed a robust saturation controller which involves both control input saturation and structured real parameter uncertainties. This controller can analytically prescribed the upper and lower bounds of parameter uncertainties, and guarantee the closed-loop robust stability of the system in the presence of actuator`s saturation. And the availability and the effectiveness of the proposed robust saturation controller were verified through numerical simulations. In this paper, we verify the robust stability of this controller through experimental tests. Expecially, we show unstable cases of other controllers in comparison with this controller. Experimental tests are carried out in the laboratory using a two-story test structure with a hydraulic-type active mass damper.

Experimental Verification on the Availability of Robust Saturation Controller for the Active Vibration Control of Building using AMD

In active vibration control of building, controller design considering both control input saturation of controller and parameter uncertainties of building is needed. In our previous research, we proposed a robust saturation controller which guarantees robust stability and control performance of the uncertain linear time-invariant system in the presence of control input saturation. In this paper, the availability of the robust saturation controller for the building with an active mass damper (AMD) system is verified through experimental tests. Experimental tests are carried oui using a two-story building model with a hydraulic-type AMD.

Design of Control Algorithm for Mass Driving Anti-Rolling System Considering Control Input Constraint

Reduction of a ship`s rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargos as well as improving the comfort of the ride. A mass driving anti-rolling system (MO-ARS) might be one candidate of several systems against the ship`s rolling. As the movable range of the mass on the ship is finite, the control system must include restriction on the mass position to protect the device and the ship. This restriction usually causes windup phenomenon and control performance is deteriorated seriously. Two control algorithms, anti-windup control and saturated sliding mode control, are studied in this paper. Control performance and robustness problem are checked out by numerical simulationsuee17u200d㔀܀㘱㐮㠴㬏S潣楡氠浥摩捩湥

A Study on the Experimental Dynamic Identification of Cylindrical Oil Dampers in the Wide Frequency Range

ABSTRACT System identification for cylindrical oil dampers is carried out based on a series of dynamic experimental tests and theoretical approach for the analysis of the experimental data. Experimental tests are conducted using a specific hydraulic actuator in the wide frequency range from 10 Hz to 90Hz. From this study, it is confirmed that control force of the damper is composed of inertia, damping and restoring components. In general, both restoring and damping components are significant and comparable. However, the portion of the inertia components becomes more significant than to be negligible in the high frequency range. * 1. 서 론 오리피스를 이용한 유체 댐퍼(orificed oil damper)는 피스톤, 실린더 및 오리피스로서 구성되어 있다. 외부에서 진동과 같은 외부하중이 입력될 때 피스톤에 의해 상대 운동이 발생하고, 실린더 내부의 한 유실(chamber)에 있는 유체에 압력에너지로 전달되어짐에 따라 피스톤 반대방향에 위치하는 다른 유실로 연결되어진 좁은 틈새(오리피스)를 통하여 유체가 빠져나가면서 점성 저항에 의한 에너지로 소산됨으로써 감쇠력이 발생하는 원리를 가지고 있다. 자동차, 선박, 교량 등 수송기계시스템, 건축․토목구조물 및 산업설비의 다양한 형태의 진동 및 충격†교신저자; 정회원, 한국기계연구원E-mail : sjmoon@kimm.re.krTel : (042)868-7428, Fax : (042)868-7418* 정회원, 한국기계연구원** (주)세영인더스트리을 저감하기 위해 널리 사용되고 있다. 또한 선박 및 육상 수송 장비(예를 들면, 자동차, 전차 등)의 운전 중 엔진 및 프로펠러 추진축계에서 발생하는 비틀림 진동에 의해서 각 요소에 부가되는 과도한 진동의 저감 목적으로 비틀림 댐퍼를 사용한다. 대부분의 비틀림 댐퍼의 경우에도 오리피스내의 유체흐름에 의해서 발생하는 저항력이 감쇠력으로 작용한다. 추진축계의 진동은 일반적인 구조물이나 기계시스템의 진동과 달리 상대적으로 고주파수 영역에서 발생하고 있다. 유체 댐퍼와 관련된 연구동향을 살펴보면, 진동방지용 에너지 흡수장치인 점성 유체 댐퍼의 동적거동특성을 파악하기 위하여 분수도함수를 이용한 수치모델로 해석을 수행하고, 실험을 통하여 수치모델에 필요한 변수들을 결정한 연구가 있다

Active Vibration Control of Structure Using LMI Optimization Design of Robust Saturation Controller

In our previous paper, we developed a robust saturation controller for the linear time-invariant (LTI) system involving both actuator`s saturation and structured real parameter uncertainties. This controller can only guarantee the closed-loop robust stability of the system in the presence of actuator`s saturation. But we cannot analytically make any comment on control performance of this controller. In this paper, we suggest a method to use linear matrix inequality (LMI) optimization problem which can analytically explain control performance of this robust saturation controller only in nominal system. The availability of design method using LMI optimization problem for this robust saturation controller is verified through a numerical example for the building with an active mass damper (AMD) system.

Stability of Saturation Controllers for the Active Vibration Control of Linear Structures

Control input`s saturation of active control devices for large structures under large external disturbances are often occurred. It is more difficult to obtain the exact values of mass and stiffness as structures are higher. The modelling errors between mathematical models and real structures must be also included as parameter uncertainties. Therefore, in active vibration control of civil engineering structures like buildings and bridges, the robust saturation controller design method considering both control input`s saturation and parameter uncertainties of system is needed. In this paper, stabilities of linear optimal controller LQR, modified bang-bang controller, saturated sliding mode controller, and robust saturation controller among various controllers which have been studied and applied to active vibration control of buildings are investigated. Especially, unstable phenomena of the LQR, the modified bang-bang controller and the saturated sliding mode controller when the control input is saturated or parameter uncertainties exist are presented to show the necessity of the robust saturation controller. The robust stability of the robust saturation controller are shown through a numerical example of a 2DOF linear vibrating system and an experimental test of the two-story structure with an active mass damper (AMD).

Active Control of Structural Vibration Using Linear Oscillating Actuator (LOA)

In this paper, an iron core type LOA is designed and analyzed electro-magnetically for the application to the active control of structural vibration as an active mass driver. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass of LOA giving anti-phase inertia force to the structure. As a result, LOA is confirmed to be applied to the active control of the structural vibration as an servo actuator by controlling the position of armature accurately.