• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.737-752
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• 1992

Analysis of elasto-dynamic deformation of flexible linkage mechanism is conducted using the finite element method. The equations of motion of the system are derived from the static structural problem in which dynamic inertia, gravitational and driving forces are treated as external loads. Linear spring model is included in the formulation of equation of motions to represent the effects of deformation of elastic bearings of revolute joints on the system behavior. A computer program is constructed and applied to analyze a specific crank-lever 4-bar mechanism. The algorithm of the program is as follows. First, the natural frequencies and the mode shapes of the system are calculated by solving the eigenproblem of the mechanism system which can be considered as a static structure by assuming the input shaft (crank shaft) to be fixed at any given configuration of mechanism. And finally, the elasto-dynamic deformation of the whole system is obtained using mode superposition method for the case of constant input speed. The effect of geometric stiffness on the mechamism is included in the program with the axial forces of links obtained through the quasi-static displacement analysis. It is found that the geometric stiffness exerts an important effect upon the elasto-dynamic behavior of the flexible linkage mechanism. Elastic deformation of bearing lowers the natural frequencies of the system, resulting smaller elastic displacement at the mid-point of the links and bigger elestic displacement at the ends of the links than rigid bearing. The above investigation of flexible linkage mechanism shows that the effects of the elastic deformation of bearing on the mechanism should be considered to design the mechanism which satisfies more preciously the purpose and the condition of design.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.361-367
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• 2014

Ultra-precision positioning plays a crucial role in emerging technologies such as electronics, bioengineering, optics, and various nanofabrication technologies. As a result, various nanopositioning methods have been presented. In particular, nanopositioning using a flexure mechanism and piezo-electric actuator is one of the most valuable methods because of its friction-free motion and subnanometer-scale motion resolution. In this study, a rotational nanoactuator based on a right-circular flexure mechanism and piezo-electric actuator was developed through a consideration of the kinematics and structural deformation. An experimental setup was constructed to verify the performance expectation. Consequently, it was demonstrated that the developed system had a maximum rotational angle of about 0.01 rad, as well as sufficient linearity with respect to the input voltage.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.381-387
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• 2012

The planetary exploration rover executes various missions after moving to the target point in an unknown environment in the shortest distance. Such missions include the researches for geological and climatic conditions as well as the existence of water or living creatures. If there is any obstacle on the way, it is detected by such sensors as ultrasonic sensor, infrared light sensor, stereo vision, and laser ranger finder. After the obtained data is transferred to the main controller of the rover, decisions can be made to either overcome or avoid the obstacle on the way based on the operating algorithm of the rover. All the planetary exploration rovers which have been developed until now receive the information of the height or width of the obstacle from such sensors before analyzing it in order to find out whether it is possible to overcome the obstacle or not. If it is decided to be better to overcome the obstacle in terms of the operating safety and the electric consumption of the rover, it is generally made to overcome it. Therefore, for the purpose of carrying out the planetary exploration task, it is necessary to design the proper suspension system of the rover which enables it to safely overcome any obstacle on the way on the surface in any unknown environment. This study focuses on the design of the new double 4-bar linkage type of suspension system applied to the Korea Aerospace Research Institute rover (a tentatively name) that is currently in the process of development by our institute in order to develop the planetary exploration rover which absolutely requires the capacity of overcoming any obstacle. Throughout this study, the negative moment which harms the capacity of the rover for overcoming an obstacle was induced through the dynamical modeling process for the rocker-bogie applied to the Mars exploration rover of the US and the improved version of rocker-bogie as well as the suggested double 4-bar linkage type of suspension system. Also, based on the height of the obstacle, a simulation was carried out for the negative moment of the suspension system before the excellence of the suspension system suggested through the comparison of responding characteristics was proved.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1285-1288
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• 1997

The basic technology of virtual reality can be described as the cognition of the condition change in virtual world by stimulating the visual, auditory, kinesthetic and tactile sensation. Among these, the kinesthetic and tactile sensation is one of the most important things to recognize the interaction. In this paper, it is addressed the haptic device which help the human feel the sense of the operator, and is designed in modular type to expand for five fingers later. the haptic device is driven by tendon and ultrasonic motors located in the wrist part. Each joint is actuated by coupled tendons and adopts more actrator by one than the number of the joints, called 'N+1 type'. The haptic device adopts metamorphic 4-bar linkage structure and the length of linkages, shape and the location of joint displacement sensor are optimized through the analysis.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.173-181
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• 2017

The obstacle deflector sweeps obstacles off the track or absorbs crash energy with an energy absorber to prevent derailment of a train and to minimize damage and casualties after an accident. In this study, an obstacle deflector and its operational mechanism were designed with a tension-type energy absorber and a 4-bar linkage system. Also, a test method was suggested and verified with FEA (Finite Element Analysis) and UTM (Universal Test Machine) for testing of the static load and energy absorbing ability according to EN 15227 regulations. Through this study, an obstacle deflector that meets the EN 15227 standard was designed and a test method was suggested to adjust the collapse load easily and to verify it experimentally according to the design and verification procedure of the obstacle deflector.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.42-47
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• 2021

A one-touch descending lifeline that can easily be installed and rapidly evacuated in the event of a fire accident in high-rise buildings was proposed to overcome difficulties of conventional descending lifeline such as complex installation methods and procedures. However, this lifeline exhibits limitations such as restrictions in installation location and large apparatus size. Therefore, this paper proposes a sliding-type descending lifeline, which has a similar operation to that of current one-touch descending lifeline and solves the aforementioned limitations. A double square link mechanism including a sliding four-bar linkage is proposed and the descending lifeline support is redesigned to unfold in two different planes, allowing 3D movement. Additionally, the shape of the support frame is designed to obtain two attachment surfaces that can be attached to a wall, irrespective of the angle between the window and the inner wall. FEA analysis using ABAQUS is performed to ensure that the robustness of the presented support complies with the Fire Control Act Enforcement Decree. Finally, the feasibility of the proposed sliding one-touch descending lifeline is verified through fabrication.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.217-220
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• 1996

In this paper, a fully geometrical method for the determination of the workspace of a 6-DOF parallel manipulator is presented using the concept of 4-bar linkage. The reachable and dexterous can be determined from the proposed algorithm. In order to evaluate the workspace, each leg is considered as an open chain, and two kinematic constraints are developed. The proposed method is verified by simulation.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.25-30
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• 2005

The 4-bar linkage is the simplest model for the simulation of a retractable landing gear. In general, a designer uses a commercial software to design a linkage, which requires tedious iterations to obtain a good solution. By applying synthesis methodology the iteration process can be reduced remarkably. However, most of solutions obtained using synthesis process may not be an optimized solution. In this study, the characteristics of the optimization solution domain has been analyzed so that an optimization process can be adapted easily to a synthesis process.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.515-520
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• 2020

The design and actual implementation of the four-bar parallel link was studied in the paper. The parallel four-section link is widely used as a basic kinematic mechanism for transmitting the rotation of one axis to the rotational motion of the other axis. However, the parallel 4 link has a problem that phase reversal occurs at the turning point during the movement. In order to prevent the link reversal, it is known that a double parallelogram-type link is formed by attaching an additional phase reversal suppression link with an offset. However, as a result of the actual fabrication experiment, the movement is not smooth at the transition point. In order to solve this problem, in this study, a link for smooth movement is added in addition to a link that provides an offset to prevent phase reversal, so that the phase reversal does not occur at a specific point when the driven shaft rotates along the drive shaft. The test result confirms the validity of our suggestion.

• Journal of Biosystems Engineering
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• v.7 no.2
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• pp.8-17
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• 1983

특수(特殊)한 기능(機能)을 수행(遂行)하기 위한 4링크 기구(機構)의 설계(設計)에서는 링크의 연간궤적(連稈軌跡)이 중요(重要)한 설계조건(設計條件)이 된다. 이앙기(移秧機)의 이식기구(移植機構)나 바인던의 방출(放出)암은 모두 4링크 기구(機構)를 이용(利用)하여 작업수행(作業遂行)에 필요(必要)한 연간궤적(連稈軌跡)을 얻고 있는 것이다. 필요(必要)한 연간궤적(連稈軌跡)을 얻기위한 4링크 기구(機構)의 합성(合成)은 도해적(圖解的), 해석적(解析的) 방법(方法)을 통(通)하여 많은 연구(硏究)가 이루어져 왔으며 최근(最近)에는 콤퓨터를 이용(利用)한 기구합성(機構合成)에 대(對)한 연구(硏究)가 활발하게 이루어지고 있다. 본(本) 연구(硏究)에서는 연간궤적상(連稈軌跡上)의 점(點)들을 이용(利用)하여 주어진 연간궤적(連稈軌跡)을 얻기 위한 4링크 기구(機構)의 합성(合成)에 대(對)한 새로운 방법(方法)을 개발(開發)하고 이 방법(方法)을 콤퓨터 프로그래밍하여 주어진 연간궤적(連稈軌跡)과 콤퓨터로 합성(合成)한 4링크 기구(機構)의 연간궤적(連稈軌跡)을 비교(比較)검토 하였다.