• Journal of the Ergonomics Society of Korea
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• v.16 no.3
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• pp.11-21
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• 1997

The purpose of this study is to obtain 3-dimensional isocomfort workspace using the robot kinematics, which is based on perceived discomfort in varying postures for manipulating four types of controls. Fifteen healthy male subjects participated in the experiment where their perceived discomfort in the given postures was measured, in which L32 orthogonal array was adopted. The shoulder flexion and adduction-abduction, elbow flexion, types of controls, and right/left hands were selected as experimental variables. The results showed that the shoulder flexion and adduction-abduction, elbow flexion, and types of controls significantly affected the perceived discomfort at .alpha. =0.01. Depending upon the types of control used, regression equations predicting perceived dis- comfort and three dimensional isocomfort workspace were suggested based on the experiemntal cata. Using the equations, driver's isocomfort workspace in his/her cabin for pushing operation was illustrated, in which the robot kinematics was employed to describe the translational relationships between the upper arm and the lower arm/hand. It was ecpected that isocomfort workspace could be used as a valuable guideline to design workplaces ergonomically.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.14-21
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• 1993

Pneumatic actuators have greater power to weight ratio than electric ones, but they have been rarely used as robotic actuators because of poor accuracy resulted from nonliearity of air. On the other hand, electric servo motors have glld controllability, but they have poor power to weight ratio. For the heavy load handling robot a combined actuating method was developed for vertical and horizontal axes of RISTBOT-ll which handles up to 250kgf load. In this paper, the control method is implemented and analyzed for the manufactured heavy load handling robot.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.575-578
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• 1995

In general, the control of robot manipulator is classified into position control and force control. Position controllers give adequate performance when a manipulator is following a trajectory through space and end-effector has no contact with environment. However for most tasks performed by robot manipulator in industry, contact is made between the end-effector and manipulator's environment, so position control may not suffice. The objective of this study is to control both position of a manipulator and the contact forces generated at the hand by using a conceptually simple control law. Position and force control problem is decoupled into subtasts via taskspace formulation and inverse dynamics. Then, the position controllers are designed for the task space variable which represent tangent motion and the forte controllers are designed for the lash space variables which represent normal force.

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.351-356
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• 2011

Stroke patients should exercise for the rehabilitation of their fingers, because they can't use their hand and fingers. Their hand and fingers are fixed on the hand fixing system for rehabilitation exercise of them. But the hands clenched the fist of stroke patients are difficult to fix on it. In order to fix the hands and fingers, their palms are pressed with pressing bars and are controlled by reference force. The fixing system must have a five-axis force/moment sensor to force control. In this paper, the five-axis force/moment sensor was developed for the hand fixing system of finger-rehabilitation exercising system. The structure of the five-axis force/moment sensor was modeled, and designed using finite element method(FEM). And it was fabricated with strain-gages, then, its characteristic test was carried out. As a result, the maximum interference error is less than 2.43 %.

• Journal of Digital Convergence
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• v.18 no.2
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• pp.361-366
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• 2020

The purpose of this study is to find out user preference on personification of the public service robot. Public service robot services in public places is increasing, which is expected to continue to increase. Proper anthropomorphism of robots has positive effect on user experience. On the other hand, when the level of likeness exceeds a certain point, it provokes strangeness and a sense of unease. Therefore, it is necessary to prepare standards for anthropomorphism required for public service robots. In order to find it, a survey and an in-depth interview were conducted. According to the analysis, people prefer verbal interaction with the robot, and the proper age for the voice is in their 20s and 30s. It is recommended that no biological signals appear on the robot and there is a need for personalized services. Through this research, it is expected that it will contribute to design of public service robots that enhance user experience.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.191-194
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• 1995

This paper evaluates the influences of sex on the human emotions while coexisting with robots. When we consider human vision, robot's motion is the most important parameter which influences human emotions and must be well controlled for males and females emotions. On the other hand, when we consider human touch of sense, which is effective for cooperation transmitting mutual forces, the softness of robot is an important parameter for human emotions and must be also well controlled for males and females emotions. From these points of view, at first, we evaluate robot's motion under four different shapes of velocity pattern while handing over a cup to humans. Second, we evaluate robot's softness realized by impedance control. From the first experiment, we concluded that the conditions of choosing an adequate maximum velocity value and locating the velocity peak at the center or the first half of the duration are necessary for male's emotions. In addition, the smooth velocity decrease in the last part of the velocity pattern's duration is desired for female's emotions. From the second experiment, we concluded that females prefer lighter values of virtual impedance characteristics than males and any small increase on the heaviness of virtual impedance values is followed by the negative exponential change on human emotions.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.9
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• pp.840-845
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• 2010

This paper proposes the method indirectly measuring the operating force of the end-effect tip of surgical robot instrument which conducts the surgical operation in the body on behalf of the surgeon's hand. Due to the size and safety obligation to the surgical robot instrument, it is difficult to measure the operation force of its tip like grasping force. However the instrument is driven by cable-pulley torque transmission mechanism and when some force is occurred at the tip, then the reaction force appears on the cable as additional tension. Based on this phenomenon, this paper proposes a method to estimate the operating force from measuring reaction force against the driving motor by using a loadcell. And it induces mathematical equation to calculate the force from loadcell by approaching the modulus of elasticity to high order polynomial. And this paper proves the validity of proposed mechanism by experimental test.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.60-69
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• 2010

Lookup-Table (LUT) based fuzzy controller for obstacle avoidance enhances operations faster in multiple obstacles environment. An LUT based fuzzy controller with Positive/Negative (P/N) fuzzy rule base consisting of 18 rules was introduced in our paper$^1$ and this paper shows a 50-rule P/N fuzzy controller for enhancing performance in obstacle avoidance. As a rule, the more rules are necessary, the more buffers are required. This paper suggests LUT sharing method in order to reduce LUT buffer size without significant degradation of performance. The LUT sharing method makes buffer size independent of the whole fuzzy system's complexity. Simulation using MSRDS(MicroSoft Robotics Developer Studio) evaluates the proposed method, and in order to investigate its performance, experiments are carried out to Pioneer P3-DX in the LabVIEW environment. The simulation and experiments show little difference between the fully valued LUT-based method and the LUT sharing method in operation times. On the other hand, LUT sharing method reduced its buffer size by about 95% of full valued LUT-based design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.18-25
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• 2003

A haptic hand controller (HHC) operated by the user’s hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. In this paper, a 3-DOF hand controller is first presented, in which all the actuators are mounted on the fixed base by combining a 5-bar linkage and a gimbal mechanism. The 6-DOF HHC is then designed by connecting these two 3-DOF devices through a handle which consists of a screw and nut. Analysis using performance index is carried out to determine the dimensions of the device. The HHC control system consists of the high-level controller for kinematic and static analysis and the low-level controller for position sensing and motor control. The HHC used as a user interface to control the mobile robot in the virtual environment is given as a simple application.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.2
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• pp.172-177
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• 2013

With Brain Computer Interface (BCI) system, a person with disabled limb could use this direct brain signal like electroencephalography (EEG) to control a device such as the artifact arm. The precise force control for the artifact arm is necessary for this artificial limb system. To understand the relationship between control EEG signal and the gripping force of hands, We proposed a study by measuring EEG changes of three grades (25%, 50%, 75%) of hand grip MVC (Maximal Voluntary Contract). The acquired EEG signal was filtered to obtain power of three wave bands (alpha, beta, gamma) by using fast fourier transformation (FFT) and computed power spectrum. Then the power spectrum of three bands (alpha, beta and gamma) of three classes (MVC 25%, 50%, 75%) was classified by using PCA (Principal Component Analysis) and LDA (Linear Discriminant Analysis). The result showed that the power spectrum of EEG is increased at MVC 75% more than MVC 25%, and the correct classification rate was 52.03% for left hand and 77.7% for right hand.