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

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.8
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• pp.824-832
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• 2011

An essential consideration to differentiate prosthetic hand from robot hand is its convenience and usefulness rather than high resolution or multi-function of the robot hand. Therefore, this study proposes a myoelectric hand with a 2 DOF auto wrist module which has 6 essential functions of the human hand such as open, grasp, pronation, supination, extension, flexion, which improves the convenience of the daily life. It consists of the 3 main parts, the myoelectric sensor for input signal without additional attachment to operate the prosthetic hand, hand mechanism with high-torqued auto-transmission mechanism and self-locking module which guarantee the safety under the abrupt emergency and minimum power consumption, and dual threshold based controller to make easy for adopting the multi-DOF myoelectric hand. We prove the validity of the proposed system with experimental results.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.4
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• pp.16-21
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• 2007

Robotic applications, such as automatic fish cutting, require online trajectory planning because the material properties of the object, such as the bone or flesh conditions, are not known in advance. Different trajectories are required when the material properties vary. An effective online trajectory-planning algorithm is proposed using quaternions to determine the position and orientation of a robot manipulator with a spherical wrist. Quaternions are free of representation singularities and permit computationally efficient orientation interpolations. To prevent singular configurations, the exact locations of the kinematic singularities of the PUMA 560 manipulator are derived and geometrically illustrated when a forearm offset exists and the third link length is not zero.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.2
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• pp.36-43
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• 1992

In this paper, a robot assembly wrist, which is able to assemble chamferless parts, has been developed. The RCC (Remote Center Compliance) structure is used as a basic structure. 5 position sensors and 4 pneumatic actuators are installed additionally to measure the deformation of RCC structure and correct the errors actively. Due to the restricted direction of actuation, a decision rule which selects the suitable actuator according to the position sensor signals is needed. For this purpose, a neural network is used and it is experimentally shown that the nerual network overcomes system's nonlinearity. This paper presents fundamental experiment results for the insertion of parts with several clearance.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1929-1930
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• 2006

Human like robot arm posture for grasping by considering the shape of the target object is quite a challenge in the field of robotics. In this paper, an optimized grasp posture with respect to the shape of the object considering the wrist joint angle and elbow elevation angle, in order to verify that the grasp posture is human like has been proposed. Given a target object, the candidates for grasp are computed by the method described in this paper. For each candidate, the closed loop inverse kinematics has been solved for the corresponding hand position and orientation. From the obtained joint angles through inverse kinematics, the elbow elevation angle has been computed and compared with the elbow elevation angle obtained through human movement data by the characteristic equation. After considering all the candidates, the hand position and orientation with minimum wrist joint and difference in elbow elevation angles has been utilized as the optimized grasp posture. Simulation results are presented.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.241-244
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• 2002

Recently, the size of glass panel is increased to $1250 mm{\times}1100 mm{\times}0.7 mm$, whose mass is 2.65 kg, which requires much stiffer robot structure. In addition to the high stiffness, the robot hands and wrists for glass panel handling should have miller surface finishing of its outer surface to prevent particles and dusts from adhering on the surface. The maximum height of the robot structure should not be larger than 1500 mm because other automated guided vehicles (AGV) and transfer equipments have been designed within this size limit. The difference of maximum deflections of the four ends of the hands before and after loading the glass panel should be less than 2.0 mm. In this work, the robot hands and wrists for handling large glass panel displays were designed based on the axiomatic design using the finite element method along with optimization routine.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.9-17
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• 1999

This paper presents a method of grinding and polishing automation of precision die after CNC machining. The method employs a robot system equipped with a pneumatic spindle and a special abrasive film pad. The robot program is automatically generated off-line program form a PC and downloaded to robot controller. Position and orientation data for the program is supplied form cutter contact (CC) data of NC machining process. This eliminates separate robot teaching process. This paper aims at practical automation of die finishing process which is very time consuming and suffering from shortage of workpeople. Time loss due to changeover from one product to another is eliminated by PC off-line programming exploiting appropriate NC machining data. Dextrous 6-axis robot with rigid wrist and simple tooling enables the process applicable to larger, rather complex 3 dimensional free surfaces.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.5
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• pp.488-497
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• 1984

In the assembling process by industrial robots, many difficulties stem from the fact that the assembly operation is impossible or the parts to be assembled can be damaged by reaction forces due to even little misalignment in part mating. In this paper a flexible and sensible robot wrist is developed to make possible the precision insertion operation. The flexibility of the developed wrist were evaluated both analytically and experimentally in actual insertion process. The results show that without the use of feedback control the wrist is capable of doing insertion operations with a small clearance at a low inserting force. For smaller clearance the assembly process was devised involving insertion force feedback and a control algorithm for this active accommodation was developed. The simulation results show that if the active feedback control is used the insertion action can be performed with much less force, as compared with a passive accommodation method.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.26-34
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• 1998

In this paper, a force control algorithm for edge following task is suggested. Through the contact state modeling between rigid part and end-effector of robot, contact force and contact angle that are essencial parameters to build the control strategies for following movement of end-effector are derived. From these two parameters, we discriminate the every contact state into 8 cases and calculate the new moving position and direction simply. For the experiment. RX90 robot from Staubli with robot language V$^{+}$ is applied and F/T sensor is attached to the wrist of robot with RCC. Finally, 3 edge following experiments including the following of corner point are executed with successful results.s.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.164-171
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• 2022

Recently, interest of a dual arm robot which can replace humans is increasing in order to improve the working environment and solve the labor shortage. Various studies related with design and analysis of dual-arm robots have been conducted because dual arm robots can have various kinematic configurations according to the objective task. It is necessary to evaluate the work performance according to various kinematic structures of the dual arm robot to maximize its effectiveness. In the paper, the performance analysis is studied according to the shoulder configuration and the wrist configuration of the dual-arm robot by using main performance indices such as manipulability, condition number, and minimum singular value by assigning proper weight values to each objective motion. Performance analysis for the robotic assembly process is effectively carried out for each representative dual arm robot configuration.