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Kim J.-T.,Korea Institute of Robot and Convergence | Kim D.,Pohang University of Science and Technology
Advanced Robotics

This paper proposes a novel way of carrying out manipulator motion planning with unconstrained end-effector (MMP-UE) under an obstacle environment, where an unconstrained end-effector implies that the end-effector can be displaced from the target object. We introduce two kinds of manipulator motion planning methods: the-based MMP-UE method and the-based MMP-UE method. The former finds a solution path for manipulator motion planning in the configuration space iteratively by extending the terminal trees in the constraint-satisfying subspace and a messenger tree in the configuration space and by connecting the terminal trees and the messenger tree to each other. The latter finds a solution path for manipulator motion planning in the task space by incrementally and randomly generating an extended point that can be added to the current master tree, finding the nearest point in the current master tree from the generated extended point, generating a set of reachable configurations that corresponds to the generated extended point, checking whether two consecutive sets of reachable configurations and are connectable, and finally extending the current slave and master tree if the consecutive sets of reachable configurations are connectable. We evaluated the performance of the two proposed methods in terms of the number of iterations, number of samples, number of generated nodes, and the total computation time through three different experiments: a toy train tunnel passing simulation, a wheel turning simulation, and a basket tunnel passing experiment using a real robot. The experimental results indicate that the two proposed methods succeed in finding the solution paths in all the experiments and that the-based MMP-UE method is faster and requires less storage than the-based MMP-UE method. © 2014 Taylor & Francis and The Robotics Society of Japan. Source

Jee S.C.,Korea Institute of Robot and Convergence | Lee H.J.,Inha University
Journal of the Franklin Institute

An H-/H∞ sensor fault detection and isolation problem is investigated for continuous- and discrete-time Takagi-Sugeno fuzzy systems with state delay and immeasurable premise variables. A bank consisting of the sensor's number of fuzzy observers is adopted. A fuzzy observer gain and a fuzzy residual gain in each observer are designed such that the residual is sensitive to a certain partial group of faults and robust against disturbance. Sufficient design conditions are derived in nonlinear matrix inequality format and a numerically tractable algorithm involving a convex optimization is presented based on the cone complementary linearization technique. A simulation is provided to verify the effectiveness of the proposed technique. © 2015 The Franklin Institute. Source

Jeon K.-W.,Korea Institute of Robot and Convergence | Shin K.-B.,Hanbat National University | Kim J.-S.,Korea Railroad Research Institute
Advanced Composite Materials

The fatigue strength and life of a GFRP composite bogie frame for urban subway trains were evaluated in this study. The GEP224 glass fabric/epoxy was selected as the structural material of a composite bogie frame to save its weight. In order to obtain the fatigue characteristics of the GEP224 glass/epoxy composite material, the tension-compression fatigue test was done with three different stacking sequences of warp direction, fill direction, and warp/fill direction, respectively. A fatigue test was conducted with a stress ratio, R of 0.1 and-1, and up to endurance limit of 107 with frequency of 5 Hz. The fatigue strength of the GFRP composite bogie frame was evaluated on the basis of the S-N curve and Goodman diagrams obtained from GEP224 glass/epoxy composites according to the JIS E 4207 and UIC 515/615-4. The result shows that fatigue strength of the GFRP composite bogie has satisfied the design requirements. Also, the GFRP composite bogie frame had a good fatigue performance in comparison with conventional metal bogie frame, considering its weight. © 2013 Japan Society for Composite Materials, Korean Society for Composite Materials and Taylor & Francis. Source

Li J.-H.,Korea Institute of Robot and Convergence
International Journal of Control

This article considers the path tracking problem for underactuated ships with general form of dynamics including uncertainties. By introducing certain two polar coordinate transformations, the ship's tracking kinematics and dynamics can be transformed into certain two-inputs-Two-outputs nonlinear strict-feedback form. To avoid possible singularity problem in the backstepping control design, we introduce an asymptotic modification of orientation concept. Presented tracking scheme can guarantee the uniformly ultimately boundedness of closed-loop system in terms of polar coordinates. For the convenience of comparison with previous related works, where all tracking schemes were discussed in the Cartesian frame, we carry out some case studies to investigate the conditions under which the proposed tracking method can guarantee the same stability and convergence properties of tracking errors in the Cartesian frame. Numerical simulation studies are also carried out to demonstrate the effectiveness of presented tracking scheme. © 2015 Taylor & Francis. Source

Moon J.H.,Inha University | Jee S.C.,Korea Institute of Robot and Convergence | Lee H.J.,Inha University
International Journal of Control, Automation and Systems

This paper addresses an output-feedback control problem of an underwater glider. The buoyancy and the pitching moment that are generated by the net mass variation and the elevator control, respectively, are used as control inputs. Additional forces induced by the elevator control increase nonlinearity of the plant dynamics, which make controller design difficult. By using the feedback linearization technique, we convert the concerned nonlinear dynamics to a linear time-invariant model, and based on this, design an observer-based output-feedback controller. A simulation result is shown to verify the effectiveness of the proposed technique. © 2016, Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg. Source

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