• 한국소음진동공학회논문집
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• 제13권9호
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• pp.663-670
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• 2003

As the micro-technologies in the high precision manufacturing processes are developed, the demand for micro actuating device is increasing. But, it is difficult to achieve high resolution and wide operating range simultaneously with the conventional actuating systems which are contacting and type of dual servo system. So, the contact-free surface actuators whose movers are suspended or levitated were proposed. These systems can be applied to high precision stages and alignment apparatuses. The suspended mover can be assumed to be rigid body, but the mover is a structure in this study, therefore the vibration caused during the operating process has a serious adverse effect on the performance and it is very important to identify the vibrational characteristics. In this paper, a contact-free surface actuator is modeled in finite element method and updated by using the experimental modal data. Finally, the static and dynamic characteristics of the finite element model are predicted and then discussed.

• 드라이브 ㆍ 컨트롤
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• 제9권3호
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• pp.16-22
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• 2012

Nowadays, electro hydrostatic actuator (EHA) has shown great advantages over the conventional hydraulic actuators with valve control system. This paper presents a position control for an EHA using a modified back stepping controller. The controller is designed by combining a backstepping technique and adaptation laws via special Lyapunov functions. The control signal consists of an adaptive control signal to compensate for the nonlinearities and a simple robust structure to deal with a bounded disturbance. Experiments are carried out to investigate the effectiveness of the proposed controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2411-2413
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• 2001

A SMA actuator fabricated in this paper generates the large force and it's structure is very simple. The SMA actuator was fabricated by small size with diameter of 9mm and length of 27mm and also it's actuations toward all the directions can be acquired because of three springs which was fabricated with diameter of 2.4mm and 28 turns. We showed into applicability to smart catheter by analysing accurately the dynamic characteristics such as heading angle, force, displacement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.97-99
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• 2009

In this paper, a new type of electromagnetic actuator, an electro magnetic force driving actuator (EMFA) is developed and analyzed, applicable to air circuit breaker (ACB). Transient analysis is performed in order to obtain the dynamic characteristics of the EMFA. The distribution of static magnetic flux is obtained using the finite element method (FEM). The coupled problems of electrics and mechanics governing equations are solved using the time difference method (TDM). Also according to interception rate of each contactor, investigation about load condition of contactor spring is conducted, applied it to three-link system. And comparison about dynamic characteristics of three-link simulation and experiment data are performed.

• 한국정밀공학회지
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• 제22권6호
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• pp.98-108
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• 2005

Conventional robot manipulators actuated by motors with the speed reducer such as the harmonic drive have weakness in the load capacity, since the speed reducer does not have enough strength. To improve this, a new type of robot actuator based on the four-bar-link mechanism driven by the ball screw was constructed. Also, a new type of revolute robot manipulator composed of the developed actuators was developed. But, modelling errors occur due to the off-set from the nominal model since the exact modeling of the complex inertia variation of the four-bar-link actuator is very difficult. To control the proposed robot along the prescribed trajectory, a sliding mode control algorithm was applied with compensation function for the modeling errors. To show performance of the proposed controller, a computer simulation was performed, and its results was presented.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.260-265
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• 1996

Active control of forced vibration response of a fixed-fixed beam implementing PZT sensor/actuator was conducted. Among various control scheme, PPF control was chosen due to its amenability and natural robustness. For a single frequency excitation, the PPF control provided reasonable controllability with the appropriate damping ratio of the compensator. Without increasing actuator voltage, best controllability can be obtained by the exact tuning between the natural frequency of the structure and the cut-off frequency of the compensator. Even the multi-frequency excitation, the PPF provided good vibration suppression for corresponding mode of interest, even though residual modes should be controlled with independent compensators for each mode.

• 항공우주시스템공학회지
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• 제15권6호
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• pp.1-9
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• 2021

In this study, a new design of an extension-type actuator (ExACT) is proposed based on a chevron structure with displacement amplification mechanisms by local heating. ExACT comprises diamond-shaped displacement amplification structures (DASs) containing axially oriented V-shaped chevron beams, a support bar that restricts lateral heat deformation, and a loading slot for thin-film heaters. On heating the thin film heater, the diamond-shaped DASs undergo thermal expansion. However, lateral expansion is restricted by the support bar, leading to displacement amplification in the axial direction. The performance parameters of ExACT such as temperature distribution and extended displacement is calculated using thermo-mechanical analysis methods with the finite element method (FEM) tool. Subsequently, the ExACTs are fabricated using a polymer-based 3D printer capable of reproducing complex structures, and the performance of ExACTs is evaluated under various temperature conditions. Finally, the performance evaluation results were compared with those of the FEM analysis.

• Smart Structures and Systems
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• 제14권6호
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• pp.1055-1079
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• 2014

Substructure shake table testing is a class of real-time hybrid simulation (RTHS). It combines shake table tests of substructures with real-time computational simulation of the remaining part of the structure to assess dynamic response of the entire structure. Unlike in the conventional hybrid simulation, substructure shake table testing imposes acceleration compatibilities at substructure boundaries. However, acceleration tracking of shake tables is extremely challenging, and it is not possible to produce perfect acceleration tracking without time delay. If responses of the experimental substructure have high correlation with ground accelerations, response errors are inevitably induced by the erroneous input acceleration. Feeding the erroneous responses into the RTHS procedure will deteriorate the simulation results. This study presents a set of techniques to enable reliable substructure shake table testing. The developed techniques include compensation techniques for errors induced by imperfect input acceleration of shake tables, model-based actuator delay compensation with state observer, and force correction to eliminate process and measurement noises. These techniques are experimentally investigated through RTHS using a uni-axial shake table and three-story steel frame structure at the Johns Hopkins University. The simulation results showed that substructure shake table testing with the developed compensation techniques provides an accurate and reliable means to simulate the dynamic responses of the entire structure under earthquake excitations.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2415-2420
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• 2002

In the present study, a new anchor design was proposed to minimize the initial deflection of micro multi-layer cantilever beam with step-up structure, which is a key component of thin film micro-mirror array. It is important to minimize the initial deflection, caused by residual stress, because it reduces the performance of the actuation. Theoretical and experimental studies were conducted to examine the cause of the initial bending deflection. It was found that the bending deflection at the anchor of the cantilever beam was the primary source of initial deflection. Various anchor designs were proposed and the initial deflections for each design were calculated by finite element analysis. The analysis results were compared with experiments. To reduce the initial deflection a secondary support was added to the conventional structure. The optimal shapes were obtained by simulation and experiment. It was found from the analysis that the ratio or horizontal and vertical dimensions of secondary support was the governing factor, which affected the initial deflection.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.210-215
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• 2007

In this paper, excitation systems using an active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.