• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.342-347
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• 2003

In this paper, an active vibration control of a translating tensioned string with the use of an electro-hydraulic servo mechanism at the right boundary is investigated. The dynamics of the moving strip is modeled as a string with tension by using Hamilton’s principle for the systems with changing mass. The control objective is to suppress the transverse vibrations of the strip via boundary control. A right boundary control law in the form of current input to the servo valve based upon the Lyapunov’s second method is derived. It is revealed that a time-varying boundary force and a suitable passive damping at the right boundary can successfully suppress the transverse vibrations. The exponential stability of the closed loop system is proved. The effectiveness of the control laws proposed is demonstrated via simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.153-158
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• 2004

In this paper, we proposed a two-stage control of the container crane. The first stage control is time-optimal control for the purpose of fast trolley traveling. With suitable trolley velocity patterns, the sway which is generated during trolley moving is minimized. At the second stage control feedback control law is investigated for the quick suppression of residual vibration after the trolley motion. For more practical system, the container crane system is modeled as a partial differential equation (PDE) system with flexible cable. The dynamics of the cable is derived as a moving system with tension caused by payload using Hamilton's principle for the systems. A control law based upon the Lyapunov's method is derived. It is revealed that a time-varying control force and a suitable passive damping at the actuator can successfully suppress the transverse vibrations.

• 반도체디스플레이기술학회지
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• 제6권4호
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• pp.17-22
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• 2007

Vibration isolation equipments are mostly required in precise measurement and manufacturing system. Among all the vibration isolation equipments, air-spring is the most widely used equipment because of low resonant frequency and high damping ratio. In this study, we used Takagi-Sugeno fuzzy method to design an active vibration isolation system using air-spring, and compared the fuzzy method with passive control method and PID control method. Due to the non-linearity characteristics of air-spring, fuzzy controller was verified to be the most effective both in simulation and experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.597-602
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• 2006

In this paper, a proper support tuning method is established by identifying the dynamic characteristics of the machine, the floor. and the inertia force. Also, the limitation of a passive isolation is presented. To simplify the dynamic analysis and to establish a proper design method for supporting system, each of the machine and the floor is modeled as a single degree of freedom spring-mass-damper system under careful investigation of the dynamic characteristics of each system and appropriate assumptions. Then, the dynamic behavior of a 2DOF system and the effect of the mass and the damping are investigated. Also, the characteristics of motion profiles are investigated. In addition, a quasi-static analysis on the transmitted force through support is performed and related tests are performed.

• 한국군사과학기술학회지
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• 제6권4호
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• pp.9-21
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• 2003

This paper describes the practical implementation of a semiactive hydropneumatic suspension system to provide the high off-road performance of military tracked vehicles. Real gas behavior of a spring system, frictional forces of joints, and the dynamics of a continuously variable damper are considered. The control system is consisted of two control loops, an outer loop calculates a target spool position which can deliver the required damping force and an inner loop tracks the required spool position. Dynamic tests of the one axis model show that the semiactive suspension system considerably reduces the acceleration as well as velocity and displacement of the sprung mass than the passive one.

• 한국정밀공학회지
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• 제9권1호
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• pp.53-65
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• 1992

For improving the performance of maglev systems with a combined lift and guidance, it is suggested that the multivariable control systems and a secondary suspension should be added. The former is required to reject both track irregularities in vertical disturbances and wind gusts in lateral disturbances, and the latter to guarantee passengers against an unsatisfied criteria in ride quality. In this paper, bond graph model for the study of nonlinear dynamics of maglev systems with a combined lift and guidance is presented briefly. And, the secondary suspension is analyzed to understand the role of stiffness and damping factors in passive devices. Finally, LQG/LTR mulitivariable control systems are designed for the overall maglev systems with and without secondary suspension, and then the system performances in these two cases are evaluated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.769-772
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• 1995

Most turbo machines, which operate at high speeds, such as gas turbines, jet engines, pumps, and compressors are prone to perrturbing vibrations. The best vibration control method for rotors is to eliminate destabilizing factors. Careful balancing application of "more stable" oil-lubricated bearing, such as tilting pad bearings or use of anti-swirl devices in seals, are examplse of passive vibration control methods. the use of magnetic bearing is an active control method. An obvious advantage of active control is that it provides damping (or modifies system stiffness or other parameters) only when there is a need for that, i.e., in emergency states, while not affecting the rotor normal operational conditions. Moreover, active control methods provide exact position control through on-line control. In this study, a magnetic actuator, digital contrliier using DSP, and bipolar operational power supply/amplifiers were developed to show the effectiveness of reducing robot vibration. Also the curve fitting procedure to obtain the transfer function of frequency dependent component was developed. Results presented in this dissertation will provide a well-defined technical parameters in designing magnetic damper system.er system.

• 한국소음진동공학회논문집
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• 제24권9호
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• pp.687-694
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• 2014

The mount suppliers are providing limited information on the dynamic characteristics of the mounts to some designers and some manufacturers of the high-precision machines. In this technical study, the experimental review was carried out about dynamic characteristics of five kinds of commercial passive mounts sold in the market. The dynamic characteristics, natural frequency and damping ratio, extracted from experimental tests were compared to the materials supplied by mount makers. In order to predict the performance of the high-precision machines with mounts, exact values of the dynamic characteristics of mounts should be used in the stage of numerical analysis.

• Coupled systems mechanics
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• 제6권2호
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• pp.175-187
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• 2017

This paper deals with a uniform cantilever Euler-Bernoulli beam subjected to follower and transversal force at its free end as a model for a pipe conveying fluid under electromagnetic damper force. The electromagnetic damper is composed of a permanent-magnet DC motor, a ball screw and a nut. The main objective of the current work is to reduce the pipe vibration resulting from the fluid velocity and allow it to transform into electric energy. To pursue this goal, the stability and vibration of the beam model was studied using Ritz and Newmark methods. It was observed that increasing the fluid velocity results in a decrease in the motion of the free end of the pipe. The results of simulation showed that the designed semiactive electromagnetic damper controlled by on-off damping control strategy decreased the vibration amplitude of the pipe about 5.9% and regenerated energy nearly 1.9 (mJ/s). It was also revealed that the designed semi-active electromagnetic damper has better performance and more energy regeneration than the passive electromagnetic damper.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.469-476
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• 2005

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. A fuzzy logic controller (FLC) is used to modulate the MR damper. 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. Neuro-fuzzy models are used to represent dynamic behavior of the MR damper and FPS. 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 appropriate 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.