• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.827-829
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• 2014

This paper presents a design methodology for improving dynamic stiffness of an inspection robot frame to prevent resonance. Finite element models of robot frame are developed for natural frequency analysis. Natural frequency analysis of robot frame is conducted to compare with sub-span oscillation which is excitation frequency. Reinforcement beams are applied to the sensitive parts of the robot frame to improve dynamic stiffness using case study. To reduce mass of the robot frame, thickness optimization of the robot frame is carried out by utilizing response surface method. The result of optimization show that dynamic stiffness of robot frame is increased. As a result, natural frequency of an optimal model is not included in range of frequencies of the sub-span oscillation.

• The Journal of Korea Robotics Society
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• v.6 no.4
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• pp.323-333
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• 2011

Due to the limited pendulum motion range, the conventional one-pendulum driven spherical robot has limited driving capability. Especially it can not drive parallel direction with center horizontal axis to which pendulum is attached from stationary state. To overcome the limited driving capability of one-pendulum driven spherical robot, we introduce a spherical robot, called KisBot II, with a new type of curved two-pendulum driving mechanism. A cross-shape frame of the robot is located horizontally in the center of the robot. The main axis of the frame is connected to the outer shell, and each curved pendulum is connected to the end of the other axis of the frame respectively. The main axis and pendulums can rotate 360 degrees inside the sphere orthogonally without interfering with each other, also the two pendulums can rotate identically or independent of each other. Due to this driving mechanism, KisBot II has various motion generation abilities, including a fast steering, turning capability in place and during travelling, and four directions including forward, backward, left, and right from stationary status. Experiments for several motions verify the driving efficiency of the proposed spherical robot.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.745-746
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• 2009

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.804-809
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• 2004

This paper introduces a link-type tracked vehicle which is developed for demining operations. The vehicle consists of three parts - front frame, rear frame and body. The front frame is connected to the rear frame by a rotational passive adaptation mechanism which is a driving mechanism of the vehicle. Additionally, the demining system which is adaptable to mobile robot is developed to clear small Anti-Personnel(AP) mines with inexplosive method. In other words, assembled rakes unearth mines by their opposite rotation to the direction of the robot. Finally, the motions of demining rakes and design parameters of the demining system are analyzed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.169-175
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• 2015

This study aims to improve the dynamic stiffness of an inspection robot frame to prevent derailment from transmission lines. Finite element models for the transmission lines and robot frame are developed for the multi-body dynamic simulation. Natural frequency analysis was conducted using the FE models. Three types of spacer damper clamps installed on 4-conductor transmission lines are used to evaluate the derailment of the robot. Multi-body dynamic simulations with FE models are demonstrated for sub-span oscillation. When the robot operates, derailment of inspection robot from the transmission lines is determined because of resonance. To prevent the resonance, body position was changed and thickness optimization was conducted. The results show that derailment was not occurred because of the natural frequency improvement.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.65-72
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• 2013

This paper describes a finite element analysis (FEA) of the body frame of a subsea robot, Crabster200 (CR200). CR200 has six legs for mobility instead of screw type propellers, which distinguishes it from previous underwater robots such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs). Another distinguishing characteristic is the body frame, which is made of carbon fiber reinforced plastic (CFRP). This body frame is designed as a rib cage structure in order to disperse the applied external loads and reduce the weight. The frame should be strong enough to support many devices for exploration and operation underwater. For a reasonable FEA, we carried out specimen tests. Using the obtained material properties, we performed a modal analysis and FEA for CR200 with a ready posture. Finally, this paper presents the FEA results for the CFRP body frame and the compares the characteristics of CFRP with conventional material, aluminum.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.313-319
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• 2023

In this study, we propose a method to improve the accuracy of acoustic odometry using optimal frame interval selection for Fourier-based image registration. The accuracy of acoustic odometry is related to the phase correlation result of image pairs obtained from the forward-looking sonar (FLS). Phase correlation failure is caused by spurious peaks and high-similarity image pairs that can be prevented by optimal frame interval selection. We proposed a method of selecting the optimal frame interval by analyzing the factors affecting phase correlation. Acoustic odometry error was reduced by selecting the optimal frame interval. The proposed method was verified using field data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.335-336
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• 2010

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.12
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• pp.1033-1041
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• 2003

A new visual tracking scheme is proposed for a mobile robot that tracks a moving object in 3D space in real time. Visual tracking is to control a mobile robot to keep a moving target at the center of input image at all time. We made it possible by simplifying the relationship between the 2D image frame captured by a single camera and the 3D workspace frame. To precisely calculate the input vector (orientation and distance) of the mobile robot, the speed vector of the target is determined by eliminating the speed component caused by the camera motion from the speed vector appeared in the input image. The problem of temporary disappearance of the target form the input image is solved by selecting the searching area based on the linear prediction of target motion. The experimental results have shown that the proposed scheme can make a mobile robot successfully follow a moving target in real time.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.132-138
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• 2009

In this paper, control of an omni-directional mobile robot is presented. Relying on encoder measurements to define the azimuth angle yields the dead-reckoned situation which the robot fails in localization. The azimuth angle error due to dead-reckoning is compensated and corrected by the magnetic compass sensor. Noise from the magnetic compass sensor has been filtered out. Kinematics and dynamics of the omni-directional mobile robot are derived based on the global coordinates and used for simulation studies. Experimental studies are also conducted to show the correction by the magnetic compass sensor.