• Journal of Advanced Marine Engineering and Technology
• /
• 제34권2호
• /
• pp.267-274
• /
• 2010

중력보상기의 구조에 대해 연구하였고, 이를 적용하여 로봇 관절의 성능을 개선하기 위하여 새롭게 개발한 6축의 로봇 매니퓰레이터에 대해 설명한다. 로봇의 기구학 해석을 하였다. 또한, 다양한 스프링으로 구성된 중력보상기를 적용한 로봇 관절구동기의 성능에 대하여 시뮬레이션 하였다. 시뮬레이션 결과에 따르면, 중력보상기를 적용한 로봇 매니퓰레이터의 관절에 가해지는 외부부하는 중력보상기에 사용되는 스프링의 강도에 비례하여 줄어드는 것이 검증되었다.

• 한국자기학회지
• /
• 제20권1호
• /
• pp.24-27
• /
• 2010

솔레노이드 전자기 엔진 밸브 액츄에이터는 현재의 내연 연소 엔진의 가변 밸브 타이밍에 가장 적합하고 진보된 장치이다. 하지만 솔레노이드 전자기 액츄에이터는 전력소모가 크다는 단점을 가지고 있다. 따라서 전력소모가 작은 가변 밸브 타이밍을 구현하기 위해 영구자석을 활용한 새로운 전자기 엔진 밸브 액츄에이터를 제안한다. 이 연구에서는 엔진 밸브의 과도운동 시간의 최소화를 통해 엔진의 속도를 극대화하기 위하여 새롭게 제안한 액츄에이터의 형상을 최적 설계하였다. 최적화를 위해 유전자 알고리즘을 사용하고 Matlab과 Maxwell을 활용하여 전역 최적화 시뮬레이션을 수행하였다.

• 한국정밀공학회지
• /
• 제21권1호
• /
• pp.109-115
• /
• 2004

Polishing process has been applied to get extremely fine surfaces, e.g., mirror surfaces such as optical mirrors, lens, molds and etc. Nowadays not only fine surface quality but also submicron order of dimensional accuracy is required for many applications. To meet the requirements polishing process should be provided with an active control of polishing pressure especially for automation of polishing process. In this paper a study on development of an active polishing pressure control system has been presented. A new type of tool assembly has been developed to facilitate the control. The tool is attached to an axis of a polishing machine with a coil spring and control of the polishing pressure is done by the position control of the axis, which needs no additional actuator. The polishing pressure is successfully measured by the measurement of the spring deformation. Control specifications were quantitatively considered by weighting functions and a controller was designed by using loop-shaping technique based on the no synthesis. Some experiments have been executed on a polishing machine with a PC-NC controller. It is shown that the results were coincident well with the theoretical analyses and satisfied the design specifications.

• Structural Engineering and Mechanics
• /
• 제34권4호
• /
• pp.449-474
• /
• 2010

A smart hollow cylinder consisting of a host functionally graded elastic core layer and two surface homogeneous piezoelectric layers is presented in this paper. The bonding between the layers can be perfect or imperfect, depending on the parameters taken in the general linear spring-layer interface model. The effect of such weak interfaces on free vibration and steady-state response is then investigated. Piezoelectric layers at inner and outer surfaces are polarized axially or radially and act as a sensor and an actuator respectively. For a simply supported condition, the state equations with non-constant coefficients are obtained directly from the formulations of elasticity/piezoelasticity. An approximate laminated model is then introduced for the sake of solving the state equations conveniently. It is further assumed that the hollow cylinder is embedded in an elastic medium and is simultaneously filled with compressible fluid. The interaction between the structure and its surrounding media is taken into account. Numerical examples are finally given with discussions on the effect of some related parameters.

• 한국정밀공학회지
• /
• 제30권1호
• /
• pp.47-52
• /
• 2013

In order to operate a search and rescue robot in hazardous area, the robot requires high mobility and adaptable locomotion for moving in unpredictable environments. In this paper, we propose the deformable soft wheel robot that can produce three kinds of driving modes; caterpillar driving mode, normal wheel driving mode, legged-wheel driving mode. The robot changes its driving mode as it faces the various obstacles such as a small gap, stairs etc. Soft film and composite materials are used for fabrication of deformable wheel structure and Shape Memory Alloy (SMA) coil spring actuators are attached on the structure as an artificial muscle. Film lamination and an composite manufacturing process is introduced and the robot design is required to be modified and compromised to applying the manufacturing process. The prototype is developed and tested for verifying feasibility of the deformable wheel locomotion.

• 한국항공우주학회지
• /
• 제47권9호
• /
• pp.607-616
• /
• 2019

항공우주비행체 정적구조시험을 위한 과하중 방지를 위해 사용되는 하중제한밸브(LLV)의 파일럿 스테이지의 주요 구성품들에 대한 자유물체도 분석을 수행하였다. 이 분석을 통하여 유압작동기의 동일한 힘에서 일관성있게 포펫 개방되도록 하기 위해서는 파일럿스테이지에 있는 두 포펫의 직경비($(D_2)^{ten}/D_2)^{comp}$)가 작동기의 피스톤 면적비($A_{comp}/A_{ten}$)와 동일해야만 한다는 것을 보였다. 실험실에서 외산으로 수입하여 사용하고 있는 4개의 서로 다른 하중제한밸브의 포펫들 형상을 측정하고 대응되는 4개의 다른 용량을 갖는 유압작동기들의 피스톤 면적비들로부터 위의 분석결과가 타당함을 확인하였다. 두 개의 다른 파일럿스테이지로 수행한 "조절자 분해능시험들"의 결과들로부터 조절자 각 회전에서 얻은 Fi(포펫개방 순간의 작동기 힘)의 최대 표준편차는 각 평균값으로부터 0.3KN이고 표준편차를 각 평균값으로 나눈 무차원값으로 분석하면 최대편차는 3.7%이다. 이 결과로 부터 동일 포펫 직경비를 갖는 두 개의 파일럿스테이지들의 포펫은 각 조절자 회전에 대해 Fi/(평균 Fi) 값이 +/- 3.7% 범위에서 일관성 있게 개방되고 있음을 확인하였다. 위의 편차는 포펫 O-링의 마찰력으로부터 유발되는 것임을 보였다. 부가적으로 파일럿스테이지의 다른 주요부품인 포펫 스프링과 조절자의 주요설계인자들도 식별하였고 이들의 결정과정도 본 연구에서 보였다.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
• /
• pp.253-256
• /
• 2005

Nonlinear aeroelastic analyses of composite wing with flap are performed considering free-play and dynamic stiffness of actuator. Doublet-Hybrid method is used for the calculation of subsonic unsteady aerodynamic forces. Free-play is modeled as an asymmetric bilinear spring and is linearized by using the describing function method. The linear and nonlinear flutter analyses show that the flutter characteristics are significantly dependent on the free-play and dynamic stiffness. From the nonlinear flutter analysis, various types of limit cycle oscillations are observed in a range of air speeds below or above the linear divergent flutter boundary.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.777-781
• /
• 2004

This paper presents a force/displacement sensing system to measure penetration depths and machining forces during pattering operation. This sensing system consists of a leaf spring mechanism and a capacitive sensor, which is mounted on a PZT driven in-feed motion stage with 1nm resolution. The sample is moved by a xy scanning motion stage with 5nm resolution. The constructed system was applied to nano indentation experiments, and the load-displacement curves of silicon(111) and aluminum were obtained. Then, the indentation samples were measured by AFM. Experimental results demonstrated that the developed system has the ability of preforming force/depth sensing indentations

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.680-683
• /
• 2002

In this paper, it has been investigated that the design and simulation of vacuum pump driven by linear motor. Vacuum pump consists of unified plunger and piston part, coils, inlet valve and outlet valve. Operating principal of vacuum pump show that air is to flow to go inside through the inlet valve when the magnetic force (16N) is exerted, whereas, air is to flow to go outside through outlet valve when spring farce (14.8N) is exerted. The results of simulation. it was turned out that reached vacuum pressure was about -0.55 bar at 150 seconds, magnetic force was loaded with 16 Newton, displacement of actuator was about 8mm.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.1109-1112
• /
• 2004

This paper presents a high sensitive force sensing module to measure machining forces for a tip-based nanopatterning instrument. The force sensing module utilizing a leaf spring mechanism and a capacitive displacement sensor has been designed to provide a measuring range from 80$\mu$N to 8N. This force sensing module is mounted on a PZT driven in-feed motion stage with 1 nm resolution. The sample can be moved by a X-Y scanning motion stage with 5 nm resolution. In the patterning experiments, the machining forces were controlled and monitored by the force sensing module. Then, the patterned sample was measured by AFM. Experimental results demonstrated that the developed force sensing module can be used as an effective sensing device in the nanopatterning operation.