• The Journal of Korea Robotics Society
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• v.12 no.2
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• pp.194-205
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• 2017

A redundantly actuated planar 3-degree-of-freedom parallel mechanism is analyzed to show its high application potential as a haptic device. Its structure along with the closed form forward position solutions is briefly discussed. Then its geometric and kinematic characteristics via singularity analysis, the kinematic isotropy index, and the input-output force transmission ratio are investigated both for the redundantly actuated cases and for the non-redundantly actuated case. In addition, comparative joint torque simulations of the mechanism with different number of redundant actuations as well as without redundant actuation are conducted to confirm the improved joint torque distribution characteristics. Through these analyses it is shown that the geometric and kinematic characteristics of the redundantly actuated mechanism are superior to the ones of the mechanism without redundant actuation. Thus, it can be concluded that the suggested planar mechanism with redundant actuation has a very high potential for haptic device applications.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.82-87
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• 1994

In this study, dynamic optimal design far a two degree-of-freedom anthropomorphic robot module is performed. Several dynamic design indices associated with the inertia matrix and the inertia power array are introduced. Analysis for the relationship between the dynamic parameters and the design indices shows that trade-offs exist between the isotropy and the dynamic design indices related to the actuator size. A composite design index is employed to deal with multi-criteria based design with different weighting factors, in a systematic manner. We demonstrate the fact that dynamic optimization is another significant step to enhance the system performances, followed by kinematic optimization.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1693-1696
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• 2003

In this paper, input-output velocity transmission characteristics of the Casing Oscillator, which is a constructional machine with 4 degree of freedom are examined. After the Jacobian matrix is decomposed into linear part and angular part, the linear and the angular velocity transmission characteristics are analyzed and visualized in easy way even in the case of 3 dimensional task space with 4 variables. Regarding the measure of dexterity of the Casing Oscillator, the kinematic isotropic index and the manipulability measures which are respectively represented the isotropy and the volume of the manipulability ellipsoid are combined. A performance of the Casing Oscillator is evaluated by the combined manipulability measure.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.225-228
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• 1999

In a plastically deformed body the formation of a shear band is widely observed in the engineering materials during rapidly forming process for a thermally rate-sensitive material. The localized shear bond stems from evolution of a narrow region in which intensive plastic flow occurs. The shear band often plays as a precursor of the ductile fracture during a forming process. The objectives of this study are to investigate the localization behaivor by using numerical method thus predict the failure. In this work the implicit finite difference scheme is preformed due to the ease of covergence and the numerical stability. This study is based on an analysised material with hardening as well as thermally softening behavior which includes isotropy strain hardening. Furthermore this paper suggests that an anticipated and suggested a kinematic hardening constitutive equation be requried to predicte a more accurate strain level wherein a shear band occurs.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.140-150
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• 2002

The planar tracked vehicle model used in this investigation consists of two kinematically decoupled subsystems, i.e., the chassis subsystem and the track subsystem. The chassis subsystem includes the chassis frame, sprocket, idler and rollers, while the track subsystem is represented as a closed kinematic chain consisting of rigid links interconnected by revolute joints. In this study, the recursive kinematic and dynamic formulation of the tracked vehicle is used to find the vertical terce and the distance of an arbitrary track moved in the driving direction along the track. These distances and vertical forces obtained are used to get the deformation and sinkage of a terrain. The FEM(Finite Element Method) is adopted to analyze the interaction between tracked vehicle and terrain. The terrain is represented by a system of elements wish specified constitutive relationships and considered as a piecewise linear elastic, plastic and isotropic material. When the tracked vehicle is moving with different speeds on the terrain, the elastic and plastic deformations and the maximum sinkage for the four different types of isotropic soils are simulated.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.185-190
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• 1993

The POSTECH Hand adopting coupled tendon driven technique with planar two fingers is developed. The hand is designed to emulate principal motions of the human hand which has two and three joints respectively. Its kinematic parameters are determined through a parameter optimizing technique to aim at improving the isotropy of fingertip motions with new criterion functions of design. For the control of the hand, tension and torque control algorithms are developed. Based on the virtual stiffness concept, we develop the stiffness control method of a grasped object with redundant finger mechnism and investigate experimentally.