• International Journal of Internet, Broadcasting and Communication
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• 제13권4호
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• pp.90-96
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• 2021

The logistics market is continuously growing due to the development of technology and the growth of the online market. In addition, the social atmosphere that emphasizes non-face-to-face due to the pandemic situation is accelerating the growth of logistics. Delivery of goods ordered online requires delivery process through courier worker. In order for the courier worker to ship the product, the work of loading the product on the truck must be preceded. The accident caused by such delivery and loading work is increasing and it is emerging as a social problem. This study proposes a robot-based automated loading system to efficiently handle the increasing volume of courier service and to construct a more efficient and safe working environment by replacing the physical labor that was overloaded to courier workers. The proposed system replaces the loading of the courier worker and proposes the optimal loading function through the automation system.

• 로봇학회논문지
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• 제17권3호
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• pp.359-364
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• 2022

This study presents a nonlinear model predictive control (NMPC)-based obstacle avoidance and whole-body motion planning method for the mobile manipulators. For the whole-body motion control, the mobile manipulator with an omnidirectional mobile base was modeled as a nine degrees-of-freedom (DoFs) serial open chain with the PPR (base) plus 6R (arm) joints, and a swept sphere volume (SSV) was applied to define a convex hull for collision avoidance. The proposed receding horizon control scheme can generate a trajectory to track the end-effector pose while avoiding the self-collision and obstacle in the task space. The proposed method could be calculated using an interior-point (IP) method solver with 100[ms] sampling time and ten samples of horizon size, and the validation of the method was conducted in the environment of Pybullet simulation.

• 로봇학회논문지
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• 제17권1호
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• pp.58-67
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• 2022

In this paper, we propose an approach resolving inaccuracy of the low-cost redundant manipulator workspace with low encoder and low stiffness. When the manipulators are manufactured with low-cost encoders and low-cost links, the robots can run into workspace inaccuracy issues. Furthermore, trajectory generation based on conventional forward/inverse kinematics without taking into account inaccuracy issues will introduce the risk of end-effector fluctuations. Hence, we propose an optimization for the trajectory generation method based on the DDPG (Deep Deterministic Policy Gradient) algorithm for the low-cost redundant manipulators reaching the target position in Euclidean space. We designed the DDPG algorithm minimizing the distance along with the jacobian condition number. The training environment is selected with an error rate of randomly generated joint spaces in a simulator that implemented real-world physics, the test environment is a real robotic experiment and demonstrated our approach.

• 한국산업융합학회 논문집
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• 제26권1호
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• pp.15-26
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• 2023

In this study, an end-effector robot which is a two-axis delta robot type for upper-limb rehabilitation is designed. It is not only rehabilitation functions that has designed robot but also mechanical and electrical safety devices were constructed to ensure patient safety. By constructing the two-axis delta robot is combined with an LM guide, the operating range and rigidity required for rehabilitation were secured. The electrical safety system which is required for the medical robot was designed, and a safety strategy was established to ensure patient safety and it is applied in the integrated safety circuit. The safety is considered in whole design process from the robot's mechanical design to the electric control unit.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.638-647
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• 1996

Robot manipulators for harvesting fruits must be controlled to track the desired path of end-effector to avoid obstacles under the consideration of collision free area and safety path. This paper presents a robot path control algorithm to secure a collision free area with the recognition of work environments. The flexible space, which does not damage fruits or branches of tree due to their flexibility and physical properties , extends the workspace. Now the task is to control robot path in the extended workspace with the consideration of collision avoidance and velocity limitation at the time of collision concurrently. The feasibility and effectiveness of the new algorithm for redundant manipulators were tested through simulations of a redundant manipulator for different joint velocities.

• 한국정밀공학회지
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• 제10권4호
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• pp.200-205
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• 1993

In many applications, the typical parallel-jaw end-effector of a robot arm has been remarkably satisfactory. But, it is not adequate for the applications such as complicated manipulation. In the study, a finger with 4 joints (so, having redundancy) was consturcted to investigate the characteristics of an articulated hand. Each joint was driven by one actuator, and the motor torque was transmited to each joint through a tendon-pulley system. In the context, major considerations for hardware design and the method to solve the inverse kinematics of a redundant manipulator were presented. Finally, the basic capabilities of an articulated hand were presented through experiments.

• 한국정밀공학회지
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• 제10권4호
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• pp.54-63
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• 1993

This paper presents the dynamic modeling and control methodology to arrest structural deflections of industrial robotic manipulators featuring elastic members retrofitted with surface bonded pizoelectric actuators and sensors. The cynamic modeling is accomplished by employing a variational theorem, prior to developing a finite element formulation. This finite element formulation accounts for both original robot member elements and also bonded piezoelectric material elements. The governing equation of motion is then modified by condensing the electric potential vectors and subsequently two different negative velocity feedback controllers are established; a constant-gain feedback controller and a constant- amplitude feedback controller. By adopting a Model P50 articulating industrial robot manufactured by Gerneral Electric Company, conputer simulations are underlaken in order to demonstrate superior performance characteristics to be accrued from this proposed methodology such as smaller deflections at the end-effector.

• International Journal of Computer Science & Network Security
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• 제24권1호
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• pp.17-22
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• 2024

The objective of this work is to design a low cost yet fully functional 4-DOF articulate manipulator for educational applications. The design is based on general purpose, programmable smart servo motors namely the Dynamixel Ax-12. The mechanism for motion was developed by formulating the equations of kinematics and subsequent solutions for joint space variables. The trajectory of end-effector in joint variable space was determined by interpolation of a 3rd order polynomial. The solutions were verified through computer simulations and ultimately implemented on the hardware. Owing to the feedback from the built-in sensors, it is possible to correct the positioning error due to loading effects. The proposed solution offers an efficient and cost-effective platform to study the trajectory planning as well as dynamics of the manipulator.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1045-1049
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• 2005

In this paper, the dynamic crawling of a five-bar planar mechanism is investigated. One complete cycle of the crawling selected in this study consists of four different steps, i) sliding at one contact point between the mechanism and the ground, ii) changing its configuration without sliding at two contact points, iii) sliding at the other contact point, and iv) again changing its configuration without sliding at two contact points. In this type of crawling, the crawling mechanism maintains the shape of the parallel structure throughout a complete crawling cycle. The modeling algorithm for serial manipulators proposed by M. Thomas and et al.[1] is employed by introducing imaginary joints and links which represent the contact interfaces between the one end of the mechanism and the ground, while the other end of the mechanism is regarded as an end-effector of the imaginary serial manipulator which treats the reaction force and torque at the contact point as external forces. Then, a complete cycle of dynamic crawling of the mechanism is investigated through various computer simulations. The simulation result show that the stable crawling characteristics of the mechanism could be secured when the proper configurations depending on specified frictional constraints are met.

• 생물환경조절학회지
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• 제18권2호
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• pp.87-94
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• 2009

본 연구는 식물체 캘러서의 접종공정을 자동화하기 위한 로봇개발을 위하여 수행되었으며, 본 보에서는 로봇의 주요구성부인 엔드이펙터 및 전체 로봇시스템의 성능에 대한 연구결과를 소개하였다. 이에 본 보에서 소개한 연구결과를 요약하면, 캘러스 접종을 위하여 흡인식 엔드이펙터와 기계식 엔드이펙터를 제작하였으며, 흡인식은 분리 및 치상의 겸용, 기계식은 분리 분할 치상용으로 각각 분리하여 제작하였으며, 흡인식 엔드이펙터의 성능시험 결과, 평균 8.2kPa의 흡인압에서 캘러스가 깨끗이 분리되었으며 분리된 캘러스를 새배지로 치상 고정히는데 소요되는 적정 배출압은 12kPa로 나타났다. 또한 기계식 엔드이펙터를 이용한 접종공정 자동화 시스템의 성능시험으로서 분할, 파지, 이송 및 치상 작업 성능을 시험한 결과 분할에서는 97%, 분할된 캘러는 모두 정확하게 파지되었으나, 치상하기 위하여 새로운 배양용기로 이송하는 과정에서는 일부 미끄러지는 현상이 발생하여 95%의 성능을 보였고 이송된 캘러스는 모두 정확하게 치상이 기능하였다. 따라서 분할하여 치상할 총 80개의 캘러스 가운데 74개가 정확하게 작업되는 것으로 나타나 전체 성공율은 92%였다. 또한 식물 조직 배양 자동화 공정에 사용되는 로봇에 있어서 엔드 이펙터를 장착하게 되는 매니퓰레이터로서는 6자유도의 매니퓰레이터를 선정하였다.