• 한국정밀공학회지
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• 제22권10호
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• pp.195-201
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• 2005

A laterally driven electromagnetic microactuator (LaDEM) is presented, and a micro-optical switch is designed and fabricated as a possible application. LaDEM provides parallel actuation of the microactuator to the silicon substrate surface (in-plane mode) by the Lorentz force. Poly-silicon-on-insulator (Poly-SOI) wafers and a reactive ion etching (RIE) process were used to fabricate high-aspect-ratio vertical microstructures, which allowed the equipment of a vertical micro mirror. A fabricated arch-shaped leaf spring has a thickness of $1.8{\mu}m$, width of $16{\mu}m$, and length of $800{\mu}m$. The resistance of the fabricated structure fer the optical switch was approximately 5$\Omega$. The deflection of the leaf springs increases linearly up to about 400 mA and then it demonstrates a buckling behavior around the current value. Owing to this nonlinear phenomenon, a large displacement of $60{\mu}m$ could be measured at 566 mA. The displacement-load relation and some dynamic characteristics are analyzed using the finite element simulations.

• 대한기계학회논문집A
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• 제30권6호
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• pp.622-630
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• 2006

This paper is about the magnetic suspension stage based on the Switched Reluctance propulsion principle. Because the previous studies on contact-free stage adopted the Lorentz force for main force generation mechanism they have suffered from thermal problem deteriorating the precision. Thus, the magnetic suspension stage adopting SR principle which can achieve high force density is proposed. The main operating principle and structure for achieving high resolution and long travel range are represented. The magnetic force analysis of each actuator, providing back data for dynamic modeling and controller design are carried out. By conducting basic experiments, the feasibility of the proposed system is shown. In addition the problems which should be improved and their solutions are represented.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.11-19
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• 2008

This paper proposes small VCM(voice coil motor) type, auto-focusing and zoom actuators for mobile information devices. In order to meet the large output displacement within small height restriction, the proposed auto-focusing actuator adopts curved suspensions, which are similar to a leaf-spring type suspension of optical disk drives. The sensitivity of design parameters on output displacement and dynamic performance is implemented using ANSYS (3D FEM tool) to determine the optimal geometry and stiffness of the curved suspensions. This paper also investigates a new zoom actuator without a suspension supporting a bobbin. The zoom actuator uses a moving rail and a stoper mechanism by generating rotational force at lens holder. Magnetic flux density of the zoom actuator are calculated by both the FEM and permeance method. Experiments using prototypes of the proposed focusing and zoom models show that both actuators meet the required displacement and performance.

• 대한기계학회논문집A
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• 제26권3호
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• pp.452-460
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• 2002

The precision stage using a novel contact-free planar actuator based on magnetic farces, magnetized force and Lorentz farce, is suggested. In the promising magnetic structure, the mover is driven directly without any transmission mechanism, and doesn't need any auxiliary driver for its posture calibration. Then it is estimated that the proposed operating principle is very suitable for work requiring high accuracy and cleanness, or general-purpose nano-stage. In this paper, we discuss a driving principle of the planar system including the magnetic force generation mechanism, a framework for the force model, governing characteristics of the levitated plate, and a planar motion control of the constructed prototype. And experimental results are given to verify the derived theoretical model and a feasibility of the system.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1119-1127
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• 2010

본 논문에서는 작동 평면상의 네 위치에서 사중안정점을 가지는 신개념 전자기형 마이크로 액추에이터의 구조체와 전자기 로렌츠력을 이용하는 구동 방식을 제시하고, 이의 타당성을 비선형 구조해석 및 전기-열해석을 통하여 검증하였다. 사중안정성 액추에이터의 구현을 위해서 관련 분야에서 널리 연구되고 있는 쌍안정성 액추에 이터의 개념을 확장 응용하였다. 비선형 유한요소해석을 이용하여 사중안정성 미소 구조체의 정적 해석과 과도동 적 해석을 수행함으로써 액추에이터 구조체의 다중안정성 유무를 파악하고 이 결과를 분석하여 구조체 설계에 반영하였다. 사중안정성 미소 구조체를 도체화하여 자기장 내에서 구조체에 전류를 통할 때에 발생하는 로렌츠력으로 평면상의 네 안정점으로 구조체를 구동할 수 있도록 고안하고, 그 때 필요한 구동전류의 크기 및 전자기 구동에 의한 주울열에 의한 온도분포를 계산하여 전반적인 타당성을 검토하였다. 본 논문은 지금까지의 관심 대상인 쌍안정성의 이용이 아니라 더욱 확장된 다중안정성을 가진 미소 액추에이터의 구조체와 전자기 구동방법을 제안하여 향후에 다중안정성을 필요로 하는 마이크로 시스템에 활용될 수 있도록 하는데 그 의미가 있다.

• Smart Structures and Systems
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• 제9권5호
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• pp.427-439
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• 2012

The present paper deals with the analytical solution of a functionally graded piezoelectric (FGP) cylinder in the magnetic field under mechanical, thermal and electrical loads. All mechanical, thermal and electrical properties except Poisson ratio can be varied continuously and gradually along the thickness direction of the cylinder based on a power function. The cylinder is assumed to be axisymmetric. Steady state heat transfer equation is solved by considering the appropriate boundary conditions. Using Maxwell electro dynamic equation and assumed magnetic field along the axis of the cylinder, Lorentz's force due to magnetic field is evaluated for non homogenous state. This force can be employed as a body force in the equilibrium equation. Equilibrium and Maxwell equations are two fundamental equations for analysis of the problem. Comprehensive solution of Maxwell equation is considered in the present paper for general states of non homogeneity. Solution of governing equations may be obtained using solution of the characteristic equation of the system. Achieved results indicate that with increasing the non homogenous index, different mechanical and electrical components present different behaviors along the thickness direction. FGP can control the distribution of the mechanical and electrical components in various structures with good precision. For intelligent properties of functionally graded piezoelectric materials, these materials can be used as an actuator, sensor or a component of piezo motor in electromechanical systems.

• 대한기계학회논문집A
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• 제34권10호
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• pp.1385-1391
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• 2010

본 논문에서는 폰 카메라 응용을 위해 H 형 비틀림 스프링으로 지지된 한 쌍의 사다리꼴 셔터 블레이드를 이용하는 초소형, 저전력, 고속 전자기력 Flapping 셔터를 제안한다. 기존의 정전기력 Rolling 셔터와 Flapping 셔터는 폰 카메라 응용을 위해 큰 입력 전압이 필요하며, 기존의 전자기력 Rotating 셔터는 큰 부피로 인해 폰 카메라에 사용하기 어렵다. 본 논문에서 제안하는 전자기력 Flapping 셔터는 폰 카메라에 사용 가능한 작은 크기로 회전 구동을 위해 저강성 H 형 비틀림 스프링과 저관성 사다리꼴 블레이드로 설계하여 제작된다. 실험에서 전자기력 Flapping 셔터는 입력전류 60 mA 에서 자기장 0.15 T 와 0.30 T 에 대하여 각각 최대 오버슈트 회전각 $80.2{\pm}3.5^{\circ}$와 $90.0{\pm}1.0^{\circ}$와, 정상 상태 회전각 $48.8{\pm}1.4^{\circ}$와 $64.4{\pm}1.0^{\circ}$ 성능을 보인다. 응답 시간 성능에서는 셔터 개방의 경우, 1.0 ms/20.0 ms 의 상승/정착 시간을 보이며, 셔터 폐쇄의 경우는 1.7 ms/10.3 ms 의 하강/정착 시간을 보인다. 본 논문에서는 폰 카메라용 셔터 응용을 위해 제안하는 전자기력 Flapping 셔터의 초소형(${\sim}8{\times}8{\times}2\;mm^3$), 저전력(${\leq}60\;mA$), 고속(~1/370 s) 성능을 실험적으로 검증하였다.