• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.265-271
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• 2005

Randomness exists in engineering. Tolerance, assemble-error, environment temperature and wear make the parameters of a mechanical system uncertain. So the behavior or response of the mechanical system is uncertain. In this paper, the uncertain parameters are treated as random variables. So if the probability distribution of a random parameter is known, the simulation of mechanical multibody dynamics can be made by Monte-Carlo method. Thus multibody dynamics simulation results can be obtained in statistics. A new concept called functional reliability is put forward in this paper, which can be defined as the probability of the dynamic parameters(such as position, orientation, velocity, acceleration etc.) of the key parts of a mechanical multibody system belong to their tolerance values. A flexible mechanical arm with random parameters is studied in this paper. The length, width, thickness and density of the flexible arm are treated as random variables and Gaussian distribution is used with given mean and variance. Computer code is developed based on the dynamic model and Monte-Carlo method to simulate the dynamic behavior of the flexible arm. At the same time the end effector's locating reliability is calculated with circular tolerance area. The theory and method presented in this paper are applicable on the dynamics modeling of general multibody systems.

• Journal of Biosystems Engineering
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• 제30권3호
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• pp.179-184
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• 2005

The purpose of this study was the development of teat-cup attachment module for robot milking system. The teat-cups attachment module was controlled on the two dimensional space independently, Each teat cup of an end effector was independently controlled via two axis control based on the position information data obtained from the image processing system. This system was developed install of all 4 teat cups at the same time after adjusting positions of each teat sequentially. The individual motion system was operated using two servo motors for the high speed of teat position adjustment. The errors fur the individual motion system of teat cups were maximum 1.0mm, minimum 0.0mm, and average 0.6mm. The operating time for adjusting the teat cups position required about 1.0 second. It is envisaged that teat cups attachment module can be applicate to milking robot being developed in consideration of the experiment results for the teat cups operation accuracy and the actuation speed of servo motors.

• 대한물리의학회지
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• 제15권4호
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• pp.101-109
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• 2020

PURPOSE: This study investigates the therapeutic effect of a prototype of a hand rehabilitation device based on magnetic forces. METHODS: Using an electromagnet and permanent magnets, we developed an end effector type device that induces various movements of the finger in accordance with the magnetic field direction. A total of 26 subacute stroke patients were enrolled and assigned to two groups in this randomized controlled trial. The intervention group received 30 minutes hand rehabilitation therapy per day for 4 weeks, using the device developed by us. Conventional physical therapies were conducted equally twice a day, 30 minutes per session, during the same period in both groups. RESULTS: After 4 weeks, rate of the Wolf Motor Function Test as a primary outcome measure showed significant improvement in the intervention group as compared to control group(p = .036). Scores of the Manual Function Test and Fugl-Meyer Assessment of upper limb were also significantly increased in the intervention group as compared to control group(p = .038 and p = .042, respectively). Moreover, the Korean version of Modified Barthel Index tended to improve after subjecting to physical therapy in both groups. CONCLUSION: Our results indicate that the novel hand rehabilitation device developed using a magnetic force, improves the hand motor functions and activities of daily life in subacute stroke patients.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.171-176
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• 2005

This paper presents a novel Intelligent-Welding-Carriage (IWC) for automation of curved block in shipbuilding. The curved block is usually used in both front and back side of the ship. In curved block root gap is big, 1-7 (mm) and inclination, 0-30 (deg). Since available conventional carriage type is limited to use below root gap of 3 (mm), only manual welding is employed in curved block. To adopt an IWC in curved block, it requires control of the welding conditions, i.e., voltage. current, weaving speed, dwell time and travel speed, with respect to root gap and inclination to achieve good welding qualify. In this paper, an IWC is developed for automization of welding operation to accommodate gap and inclination. Kinematics model and dynamics using Lagrangian formulation of the manipulator is introduced. IWC utilizes a database to perform accurate welding. The database is programmed based on numerous experimental test results with respect to gap, inclination, material, travel speed, weaving condition, voltage, and current. Finally, experimental result using PID control is addressed for verifying the trajectory tracking accuracy of end-effector.

• 한국공작기계학회논문집
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• 제14권4호
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• pp.81-88
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• 2005

This paper attempts to derive the dynamic model of handling tasks in finger robot which grasps stable and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, the roblems of controlling both the forces of pressing object and the rotation angle of the object under the geometric constraints are discussed. The effect of geometric constraints of area-contacts between the link's end-effector and the object is analyzed and the model based on the differential-algebraic equations is presented. In this paper, the control method for dynamic stable grasping and enhancing dexterity in manipulating things is proposed. It is illustrated by computer simulation and the experiment that the control system gives the performance improvement in the dynamic stable grasping and nimble manipulating of the dual fingers robot with soft tips.

• 대한건축학회논문집:구조계
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• 제34권4호
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• pp.65-74
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• 2018

The primary objective of this study is to develop a conceptual design of automated pothole patching machine that improves the conventional work in safety, quality, and productivity. For this, the following research works are conducted sequentially; 1)literature review, 2)selection of element technology for conceptual design, 3)deduction of work process and conceptual design, 4)life cycle cost analysis of the conceptual design. As a result, X-Y table telescopic manipulator, pothole patching end effector, realtime pothole recognizer, 3D pothole volume profiler, automated pothole patching machine controller are selected as core technologies. Furthermore, a conceptual design and working process of an automated pothole patching machine are developed based on the core technologies. According to the life cycle cost analysis result, the cost of the automated method was 38.3% less than that of the conventional method, and the economic efficiency was also superior(ROR 77.1%, Break-even Point 23.8month). It is expected that the application range and impact on the construction industry will be enormous due to the increasing trend of road maintenance market.

• 로봇학회논문지
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• 제18권4호
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• pp.359-366
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• 2023

In order to fully utilize the functions of the hand which is the end effector of the upper limb, other parts of the upper limb have to perform their own roles. Among them, the pronation and supination of the forearm, which allows the hand to rotate along the longitudinal direction of the forearm, play an important role in activities of daily living. In this paper, a soft wearable robot that assists the pronation and supination of the forearm for individuals with weakened or lost upper limb function is proposed. The wearable robot consists of an anchoring part with polymer (wrist strap, elbow strap), a tendon with a belt and wire, and an actuation module. It was developed based on the requirements with respect to friction of anchoring part, forearm compression, and friction of the tendon. It was confirmed that these requirements were satisfied through literature review and experiments. Since all components exist within the forearm when worn, it is expected to be easy to combine with the already developed soft wearable robots for the hand, wrist, elbow, and shoulder.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.229-232
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• 2005

In this paper, an image-based "approach-align -grasp" visual servo control design is proposed for the problem of object grasping, which is based on the binocular stand-alone system. The basic idea consists of considering a vision system as a specific sensor dedicated a task and included in a control servo loop, and we perform automatic grasping follows the classical approach of splitting the task into preparation and execution stages. During the execution stage, once the image-based control modeling is established, the control task can be performed automatically. The proposed visual servoing control scheme ensures the convergence of the image-features to desired trajectories by using the Jacobian matrix, which is proved by the Lyapunov stability theory. And we also stress the importance of projective invariant object/gripper alignment. The alignment between two solids in 3-D projective space can be represented with view-invariant, more precisely; it can be easily mapped into an image set-point without any knowledge about the camera parameters. The main feature of this method is that the accuracy associated with the task to be performed is not affected by discrepancies between the Euclidean setups at preparation and at task execution stages. Then according to the projective alignment, the set point can be computed. The robot gripper will move to the desired position with the image-based control law. In this paper we adopt a constant Jacobian online. Such method describe herein integrate vision system, robotics and automatic control to achieve its goal, it overcomes disadvantages of discrepancies between the different Euclidean setups and proposes control law in binocular-stand vision case. The experimental simulation shows that such image-based approach is effective in performing the precise alignment between the robot end-effector and the object.

• 생물환경조절학회지
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• 제12권2호
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• pp.57-62
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• 2003

본 연구는 오이 수확기 개발을 위해 매니퓰레이터를 설계 제작하였다. 실험에 사용한 3축 매니퓰레이터는 견고성, 내구성, 모멘트를 줄이기 위해 모터 및 감속기의 하중이 실리지 않는 곳에 장착하였다. 주요 연구 결과를 요약하면 다음과 같다. 3차원 공간상의 좌표에 대하여 매니퓰레이터의 10회 반복 측정한 오차의 평균은 Z축에 관계없이 0.1 mm내외로 정확하게 작동하는 것으로 나타났다. 실내 실험에서 25개의 오이에 대한 실험 결과 22개의 절단하여 92%의 성공률을 보였으나, 원인은 오이가 기형과이며, 수확한 후 시간이 경과하여 오이 과병의 물성이 변한 것으로 판단된다. 실내 실험에서 오이 과병을 절단하지 못한 경우에도 매니퓰레이터는 오이 과병에 0.1 mm 내외로 엔드이펙터을 접근시켰다. 50개의 오이에 대하여 현장 실험을 한 결과 42개, 84%의 절단율을 보였다. 16%의 오차가 발생한 것은 수확적기가 지나서 오이의 과병이 짧고 뭉툭해서 나타난 것으로 판단된다.

• 한국생산제조학회지
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• 제22권2호
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• pp.318-323
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• 2013

For fast and accurate motion of 6-axis articulated robot, more noble motion control strategy is needed. In general, the movement strategy of industrial robots can be divided into two kinds, PTP (Point to Point) and CP (Continuous Path). Recently, industrial robots which should be co-worked with machine tools are increasingly needed for performing various jobs, as well as simple handling or welding. Therefore, in order to cope with high-speed handling of the cooperation of industrial robots with machine tools or other devices, CP should be implemented so as to reduce vibration and noise, as well as decreasing operation time. This paper will realize CP motion (especially joint-linear) blending in 3-dimensional space for a 6-axis articulated (lab-manufactured) robot (called as "RS2") by using LabVIEW$^{(R)}$ (6) programming, based on a parametric interpolation. Another small contribution of this paper is the proposal of motion blending simulation technique based on Recurdyn$^{(R)}$ V7 and Solidworks$^{(R)}$, in order to figure out whether the joint-linear blending motion can generate the stable motion of robot in the sense of velocity magnitude at the end-effector of robot or not. In order to evaluate the performance of joint-linear motion blending, simple PTP (i.e., linear-linear) is also physically implemented on RS2. The implementation results of joint-linear motion blending and PTP are compared in terms of vibration magnitude and travel time by using the vibration testing equipment of Medallion of Zonic$^{(R)}$. It can be confirmed verified that the vibration peak of joint-linear motion blending has been reduced to 1/10, compared to that of PTP.