• 로봇학회논문지
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• 제18권4호
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• pp.376-384
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• 2023

In this paper, we introduce an upper extremity rehabilitation robot, NREH (NRC End-effector based Rehabilitation arm at Home). Through NREH, stroke survivors could continuously exercise their upper extremities at home. NREH allows a user to hold the handle of the end-effector of the robot arm. NREH is a end-effector-based robot that moves the arm on a two-dimensional plane, but the tilt angle can be adjusted to mimic a movement similar to that in a three-dimensional space. Depending on the tilting angle, it is possible to perform customized exercises that can adjust the difficulty for each user. The user can sit down facing the robot and perform exercises such as arm reaching. When the user sits 90 degrees sideways, the user can also exercise their arms on a plane parallel to the sagittal plane. NREH was designed to be as simple as possible considering its use at home. By applying error augmentation, the exercise effect can be increased, and assistance force or resistance force can be applied as needed. Using an encoder on two actuators and a force/torque sensor on the end-effector, NREH can continuously collect and analyze the user's movement data.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1998년도 추계학술대회 및 정기총회
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• pp.120-123
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• 1998

In animating an articulated entity with motion capture data, especially when the reconstruction is based on forward kinematics, there could be large discrepancies at the end effector. The small errors in joint angles tend to be amplified as the forward kinematics positioning progresses toward the end effector. In this paper, we present an algorithm that enhances the motion capture data to reduce positional errors at the end effector. The process is optimized so that the characteristics of the original joint angle data is preserved in the resulting motion. The frames at which the end-effector position needs to be accurate are designated as“keyframes”(e.g. starting and ending frames). In the algorithm, corrections by inverse kinematics are performed at sparse keyframes and they are interpolated with a cubic spline which produces a curve best approximating the measured joint angles. The experiment proves that our algorithm is a valuable tool to improve measured motion especially when end-effector trajectory contains a special goal.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.174-178
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• 1991

In this paper, we present a unified approach for the control of manipulator motions and active forces based on the operational space formulation. The end-effector dynamic model is used in the development of a control system in which the generalized operational space end-effector forces are selected as the command vector. A "generalized position and force specification matrix" is used for the specification of space of motions and forces in which manipulator is to be controlled. Flexibility in the force sensor, end-effector, and environment are discussed.discussed.

• 로봇학회논문지
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• 제14권4호
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• pp.311-317
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• 2019

Direct teaching is an essential function for collaborative robots for easy use by non-experts. For most robots, direct teaching is implemented only in joint space because the realization of Cartesian space direct teaching, in which the orientation of the end-effector is fixed while teaching, requires a measurement of the end-effector force. Thus, it is limited to the robots that are equipped with an expensive force/torque sensor. This study presents a Cartesian space direct teaching method for torque-controlled collaborative robots without either a force/torque sensor or joint torque sensors. The force exerted to the end-effector is obtained from the external torque which is estimated by the disturbance observer-based approach with the friction model. The friction model and the estimated end-effector force were experimentally verified using the robot equipped with joint torque sensors in order to compare the proposed sensorless approach with the method using torque sensors.

• 한국산학기술학회논문지
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• 제14권1호
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• pp.33-38
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• 2013

여러 종류의 증기발생기 검사정비 로봇의 엔드이펙터 모션 구동에 전부 사용할 수 있도록 ARM Cotex M3-107 MCU 기반의 제어기와 엔드이펙터 모션 프로그램 생성 응용소프트웨어로 구성된 범용 엔드이펙터 모션구동 제어시스템을 개발하였다. 범용 제어시스템을 적용하여 엔드이펙터의 직선이송 및 회전이송의 위치 결정의 오차는 무시할만한 수준이며, 재현성은 0.04% 오차를 보여줌으로써 실제로 사용 가능한 범용 엔드이펙터 모션구동 제어시스템을 개발하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2468-2470
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• 2003

비주얼 서보잉이란 로봇팔 등과 같은 제어기의 폐루프에서 입력단에 영상을 이용하는 것이다. 영상에 나타난 정보는 특징점을 통해 얻을 수 있으며, 매시간 이 특징점의 위치를 추적함으로써 제어기의 출력값을 결정한다. Optical flow를 이용하는 가나데 특징점 추적기는 특징점 추적기 중에서 성능이 우수하다고 알려져 있다. 본 논문에서는 가나데 특징점 추적기를 이용하여 실시간으로 로봇팔을 제어하고 결과를 분석하도록 한다. 실험에 이용되는 로봇팔은 전체 6축이며 기존의 5축 상용로봇의 end-effector에 ccd카메라를 좌우로 회전가능하도록 기구부를 추가하였다. 6DOF를 갖도륵 변형된 로봇팔을 기구적으로 분석하고 자코비안을 획득한 후, 로봇팔의 end-effector에 설치된 카메라를 통하여 특정 영상이 얻어지도록 로봇의 end-effector의 속도를 생성해내고, 자코비안의 역행렬을 통해 로봇의 각 관절을 제어하는 과정을 기술하고 분석한다.

• 대한기계학회논문집A
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• 제39권4호
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• pp.361-367
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• 2015

논문에서는 인간과의 안전한 접촉이 가능한 내부형 연속체로봇에 대한 설계개념과 로봇 말단장치의 운동특성실험을 제시한다. 인간의 근육과 유사한 상극구동방식으로 작동하는 공압인공근육을 연속체로봇의 백본 및 구동장치로 사용하기 때문에, 외부환경과의 부드러운 접촉과 강한 접촉을 선택적으로 제어할 수 있는 로봇 관절에서의 가변강성이 가능하다. 그러나 내부형 연속체로봇은 백본소재의 굽힘운동을 예측하기 어렵기 때문에 로봇 말단장치에서의 자세를 추정하기 어렵다. 이를 해결하기 위해 3 축 가속도계와 3 축 자이로스코프를 이용한 칼만필터 방법을 제안하고 개발된 내부형 연속체 로봇의 자세추정에 적용하여 실제 실험을 통해서 제안된 방법의 효율성을 검증하였다.

• 한국기계가공학회지
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• 제12권6호
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• pp.132-141
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• 2013

Robotic Drilling Systems(RDSs) set the standard for the factory automation systems in aerospace manufacturing. With the benefits of cost effective drilling and predictive maintenance, RDSs can provide greater flexibility in the manufacturing process. The system can be easily adopted to manage very complex and time-consuming processes, such as automated fastening hole drilling processes of large aircraft sections, where it would be difficult accomplished by workers following teaching or conventional guided methods. However, in order to build an RDS based on a CAD model, the precise calibration of the Tool Center Point(TCP) must be performed in order to define the relationships between the fastening-hole target and the End Effector(EEF). Based on the kinematics principle, the robot manipulator requires a new method to correct the 3D errors between the CAD model of the reference coordinate system and the actual measurements. The system can be called as a successful system if following conditions can be met; a. seamless integration of the industrial robot controller and the IO Level communication, b. performing pre-defined drilling procedures automatically. This study focuses on implementing a new technology called iGPS into the fastening-hole-drilling process, which is a critical process in aircraft manufacturing. The proposed system exhibits better than 100-micron 3D accuracy under the predefined working space. Based on the proposed EEF fastening-hole machining process, the corresponding processes and programs are developed, and its feasibility is studied.

• 시스템엔지니어링학술지
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• 제18권2호
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• pp.126-139
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• 2022

The need for synthetic automation is increasing in preparation for a gradual decrease in laboratory research manpower due to low birth rate and aging. In this study, the existing laboratory synthesis method is analyzed based on the systems engineering technique. Then, it led to the derivation of the system requirements for a fixed-based robot manipulator capable of recognition, decision and control. The robot is equipped with replaceable modular end-effectors and designed depending on the purpose and process of the synthesis. The robot with an end-effector was implemented as PoC(Proof-of-Concept), and the functions for pipetting automation was verified.

• Journal of Biosystems Engineering
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• 제37권1호
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• pp.65-74
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• 2012

Purpose: An autonomous robot was developed for harvesting strawberries cultivated in bench-type systems. Methods: The harvest robot consisted of four main components: an autonomous vehicle, a manipulator with four degrees of freedom (DOF), an end effector with two DOFs, and a color computer vision system. Strawberry detection was performed based on 3D image and distance information obtained from a stereo CCD color camera and a laser device, respectively. Results: In this work, a Cartesian type manipulator system was designed, including an intermediate revolute axis and a double driven arm-based joint axis, so that it could generate collision-free motions during harvesting. A DC servomotor-driven end-effector, consisting of a gripper and a cutter, was designed for gripping and cutting the strawberry stem without damaging the strawberry itself. Real-time position tracking algorithms were developed to detect, recognize, trace, and approach strawberries under natural light conditions. Conclusion: The developed robot system could harvest a strawberry within 7 seconds without damage.