• 한국정밀공학회지
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• 제17권7호
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• pp.196-202
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• 2000

In the precision point synthesis of mechanisms, it is usually required to solve a system of polynomial equations. With the aid of efficient algorithms such as elimination, it is possible to obtain all the solutions of the equations in the complex domain. But among these solutions only real values can be used fur real mechanisms, while imaginary ones are liable to be discarded. In this article, a method is presented, which leads the imaginary solutions to real domain permitting slight alteration of prescribed positions and eventually increases the number of feasible mechanisms satisfying the desired motion approximately. Two synthesis problems of planar 4-bar path generation and spatial 7-bar motion generation are given to verify the proposed method.

• 한국정밀공학회지
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• 제12권6호
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• pp.80-86
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• 1995

A method of eliminating the branch problem in driving crank center point plane for 3 position synthesis of 4 bar mechanism is introduced. By studying various transformation characteristics from the circle point plane into the center poi t plane, the curves in the center point plane transformed from the filemon line in circle point plane are analytically obtained, which will seperate the whole center point plane into many sub-areas for the selec- tion of the center point of the driving crank. And a simple method to identify which of the sub-areas will cause the branch problem is also presented. The method will allow the selection of the center point of driving crank without the branch problem.

• 한국정밀공학회지
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• 제16권10호
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• pp.126-131
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• 1999

Up until now, it is said that no satisfactory computer solutions have been found for synthesizing four-bar linkage based on the prescribed coupler link curve. In our study, an algorithm has been developed to improve the design synthesis of four-bar linkage automatically generating prescribed path by using B-spline interpolation. The suggested algorithm generates the desired coupler curve by using B-spline interpolation, and hence the generated curve approximates as closely as to the desired curve representing coupler link trajectory. Also, when comparing each generated polygon with the control polygon, rapid comparison by applying convex hull concept. finally, optimization process using ADS is incorporated into the algorithm based on the 5 precision point method to reduce the total optimization process time. As for examples, three different four-bar linkages were tested and the results showed the effectiveness of the algorithm.

• 한국정밀공학회지
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• 제15권3호
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• pp.88-98
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• 1998

In many automatization applications, a rigid body is required to go forward and backward repeatedly through a set of given position/orientations precisely while a crank is rotated. Such a motion can be generated by 6 bar mechanism adding a dyad to a 4 bar mechanism. If this is the case for 3 position synthesis of the 4 bar mechanism, the feasible solution area for designing the 4 bar mechanism will be limited over the general solution area. This paper proposes a procedure to synthesize 4 bar mechanism to be used to generate the required motion. It is found that the only input crank of the 4 bar mechanism should be limited to satisfy the condition. And the feasible design area for the circle point/ center point of the input crank is identified so that design of the undesired mechanism could be avoided. The method is tested and the results are shown.

• 한국생산제조학회지
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• 제18권6호
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• pp.576-584
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• 2009

Up to now, it has been said that no satisfactory computer solution has been found for synthesizing four-bar linkage based on the prescribed coupler link curve. In our study, an algorithm has been developed to improve the design synthesis of four bar linkage based on the 5 precision points method. The suggested algorithm generates the desired coupler curve by using NURBS, and then the generated curve approximates as closely as possible to the desired curve representing coupler link trajectory. Also, when comparing each generated curve by constructing the control polygon, rapid comparison is easily achieved by applying convex hull of the control polygon. Finally, an optimization process using ADS is incorporated into the algorithm based on the 5 precision point method to reduce the total optimization process time. As for examples, two four bar linkages were tested and the result well demonstrated the effectiveness of the algorithm.

• 대한기계학회논문집
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• 제17권6호
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• pp.1330-1341
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• 1993

본 연구에서는 회전대우(revolute joint)들로 이루어진 1자유도 평면기구들의 특성을 파악하고 그래이프이론(graph theory)을 이용하여 기구의 형태를 행렬로 표시 하여 체이터베이스에 저장하였다. 또한 기구의 특성중의 하나인 작업조건(function specification)에 따른 무오차점(precision point)의 최대 개수를 알아내는 프로그램 을 개발하여 이로써 얻은 정보를 또 다른 데이타베이스에 저장하였다. 이와같이 구축 된 데이터베이스들로부터 설계자의 요구에 적합한 기구를 선택하여 형태합성 문제를 해결하였다.

• 대한전자공학회논문지SD
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• 제48권10호
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• pp.72-81
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• 2011

본 논문에서는 IEEE754 표준의 단정도 및 배정도를 지원하는 새로운 부동소수점 변환기를 제안하고 설계하였다. 제안된 변환기는 부호 있는 정수(32비트/64비트)와 부동소수점(단정도/배정도) 간 변환, 부호 없는 정수(32비트/64비트)를 부동소수점(단정도/배정도)으로의 변환, 부동소수점 단정도와 배정도 간 변환뿐만 아니라 부호 있는 고정소수점(32비트 64비트)과 부동소수점(단정도 배정도) 간 변환을 지원한다. 모든 입력 형태를 하나의 형태로 만드는 새로운 내부 형태를 정의함으로써 출력 형태의 표현 범위에 따른 오버플로우 검사를 쉽게 하도록 하였다. 내부 형태는 IEEE754 2008 표준에서 정의된 부동소수점 배정도의 확장된 형태(extended format)와 유사하다. 이 표준에서는 부동소수점 배정도의 확장된 형태(extended format)의 최소 지수부 비트폭은 15비트라고 명시하지만 제안된 컨버터를 구현하는데 11비트만으로도 충분하다. 또한 덧셈기가 대신 +1 증가기를 사용하면서 라운딩 연산과 음수의 정확한 표현이 가능하도록 변환기의 라운딩 스테이지를 최적화하였다. 단일 클럭 사이클 데이터패스와 5단 파이프라인 데이터패스를 설계하였다. 변환기의 두 데이터패스에 대한 HDL 모델을 기술한 후에 Synopsys design compiler를 사용하여 TSMC 180nm 공정 라이브러리로 합성하였다. 합성 결과의 셀 면적은 12,886 게이트(2입력 NAND 게이트 기준)이고 최대 동작 주파수는 411MHz이다.

• 기계저널
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• 제16권2호
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• pp.77-83
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• 1976

A computer aided design of a Stephenson type of Chained six-link mechanism with synthesis equations of the precision positions technigue to generate a required point path is presented. Analysis of this mechanism is carried out by the matrix method. The torque on the input link required to operate the mechanism was obtained by considering inertia and gravity forces of the coupler link.

• International Journal of Advanced Culture Technology
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• 제8권3호
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• pp.260-268
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• 2020

Currently, it is usually a 3D scanner processing method as a laser method. However, the laser method has a disadvantage of slow scanning speed and poor precision. Although optical scanners are used as a method to compensate for these shortcomings, optical scanners are closely related to the distance and precision of the object, and have the disadvantage of being expensive. In this paper, 3D scanner using variable focus lens-based structured light module with improved measurement precision was designed to be high performance, low price, and usable in industrial fields. To this end, designed a telecentric optical system based on a variable focus lens and connected to the telecentric mechanism of the step motor and lens to adjust the focus of the variable lens. Designed a connection structure with optimized scalability of hardware circuits that configures a stepper motor to form a system with a built-in processor. In addition, by applying an algorithm that can simultaneously acquire high-resolution texture image and depth information and apply image synthesis technology and GPU-based high-speed structured light processing technology, it is also stable for changes to external light. We will designed and implemented for further improving high measurement precision.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.391-395
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• 1996

This paper presents a robust force tracking control of a small-sized SMA gripper with two fingers using shape memory alloy(SMA) actuators. The mathematical governing equation of the proposed system is derived by Hamilton's principle and Lagrangian equation and then, the control system model is integrated with the first-order actuator dynamics. Uncertain system parameters such as time constant of the actuators are also included in the control model. A robust two degree of freedom(TDF) controller using H$_{\infty}$ control theory, which has inherent robustness to model uncertainties and external disturbances, is adopted to achieve end-point force tracking control of the two-finger gripper. Force tracking control performances for desired trajectories represented by sinusoidal and step functions are evaluated by undertaking both simulation and experimental works.