• The Journal of Korea Robotics Society
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• v.18 no.4
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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.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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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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• 1991.10a
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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.

• The Journal of Korea Robotics Society
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• v.14 no.4
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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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.33-38
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• 2013

The general purposed control system for driving a motion of many different typed robot end-effector, which consists of a controller based on ARM Cotex M3-11017 MCU and an application software for generating a motion of end-effector, was developed. Experimental results show that a positioning error is nearly negligible and a repeatability error is 0.04%. Accordingly the developed control system can be applied practically to actuate a robot end-effector for inspection and maintenance of steam generator heat pipe in nuclear power plant.

• Proceedings of the KIEE Conference
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• 2003.07d
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.361-367
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• 2015

This paper presents the design concept of an intrinsic continuum robot for safe man-machine interface and characteristic behaviors of its end-effector based on real experiments. Since pneumatic artificial muscles having similar antagonistic actuation to human muscles are used for main backbones of the proposed robot as well as in the role of the actuating devices, variable stiffness of robotic joints can be available in the actual environment. In order to solve the inherent shortcoming of an intrinsic continuum robot due to bending motion of the backbone materials, a Kalman filter scheme based on a triaxial accelerometer and a triaxial gyroscope was proposed to conduct an attitude estimation of the end-effector of the robot. The experimental results verified that the proposed method was effective in estimating the attitude of the end-effector of the intrinsic continuum robot.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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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.

• Journal of the Korean Society of Systems Engineering
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• v.18 no.2
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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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• v.37 no.1
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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.