• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2356-2361
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• 2005

In this paper, we present a complete isotropy analysis of a caster wheeled omnidirectional mobile robot(COMR) with nonredundant/redundant actuation. The motivation of this work is that the omnidirectional mobility loses significance in motion control unless the isotropy characteristics is maintained well. First, with the characteristic length introduced, the kinematic model of a COMR is obtained based on the orthogonal decomposition of the wheel velocities. Second, a general form of the isotropy conditions of a COMR is given in terms of physically meaningful vector quantities which describe the wheel configurations. Third, for all possible nonredundant and redundant actuation sets, the algebraic expressions of the isotropy conditions are derived to completely identify the isotropic configurations of a COMR. Fourth, the number of the isotropic configurations and the characteristic length required for the isotropy are discussed.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.10
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• pp.1014-1020
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• 2009

This work deals with navigation of an omni-directional mobile robot with active caster wheels. Initially, the posture of the omni-directional mobile robot is calculated by using the odometry information. Next, the position accuracy of the mobile robot is measured through comparison of the odometry information and the external sensor measurement. Finally, for successful navigation of the mobile robot, a motion planning algorithm that employs kinematic redundancy resolution method is proposed. Through experiments for multiple obstacles and multiple moving obstacles, the feasibility of the proposed navigation algorithm was verified.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.137.4-137
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• 2001

Omni-directional mobile robots have been employed popularly in several application areas. However, the optimal design has not been considered yet. This paper introduces an optimal design methodology for omni-directional mobile robots. Optimal design parameters such as the offset distance and the wheel radius are identified with respect to isotropy. Furthermore, the force transmission ratio and actuator sizing problem are treated. Conclusivel, three cases are compared minimum actuation, two active caster wheel, and three active caster wheel, we claim that the redundantly actuated mobile robot with three active caster wheel has the best performance.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.1
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• pp.38-44
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• 2006

The omnidirectional mobility of a mobile robot may lose significance in motion control, unless the isotropy characteristics of the mechanism is maintained well. This paper investigates the local and global isotropy of an omnidirectional mobile robot with three caster wheels. All possible actuations with different number and combination of rotating and steering joints are considered. First, the kinematic model based on velocity decomposition and the algebraic conditions for the local isotropy are obtained. Second, the geometric conditions for the local isotropy are derived and all isotropic configurations are fully identified. Third, the global isotropy index is examined to determine the optimal parameters in terms of actuation set, characteristic length, and steering link length.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.4
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• pp.214-220
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• 2006

This paper presents the systematic isotropy analysis of a fully actuated caster wheeled omnidirectional mobile robot (COMR) with the steering link offset different from the wheel radius, which can be considered as the generalization of the previous analysis. First with the characteristic length introduced, the kinematic model of a COMR is obtained based on the orthogonal decomposition of the wheel velocities. Second, the necessary and sufficient conditions for the isotropy of a COMR are derived and examined to categorize there different groups, each of which can be dealt with in a similar way. Third, for each group, the isotropy conditions are further explored so as to identify four different sets of all possible isotropic configurations. Fourth, for each set the expressions of the isotropic characteristic length required for the isotropy of a COMR are elaborated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1529-1530
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• 2013

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.240-241
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• 2003

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.319-323
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• 1996

A new steel-making process, strip-casting, is introduced. The strip-casting is a new technique making the thin steel strip from the molten steel directly without resorting to repetitive reheating and hot-rolling required in a conventional steel-making method. This paper derives the mathematical model of strip caster, proposes a control strategy for stable startup operation and a fuzzy decision making rule for automatic control mode change in strip-casting process.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.325-328
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• 1997

In this paper the modeling and control of a twin roll strip caster is investigated. Mathematical models for the strip casting process are obtained by analyzing five critical areas such that the molten steel level in the pool, solidification process, roll separating force and torque, roll dynamics including hydraulic actuators, and roll drive system. A two-level control strategy is proposed. At lower level, three local subsystems are independently feedback-controlled by suitable local controllers which perform well to the behaviors of each subsystem. They are a variable structure control of the molten steel level in the pool, an adaptive predictive control of the roll gap which is directly related to the strip thickness, and an $H^{\infty}$ control of the roll drive system. At higher level, all reference signals to the lower level subsystems are generated by an optimal controller in the perspective of regulating the strip thickness and roll separating force. Simulations are provided..

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.181-185
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• 2001

Three-dimensional finite-element-based numerical model of turbulent flow, heat transfer, macroscopic solidification and inclusion trajectory in a continuos steel slab caster was developed Turbulence was incorporated using the Improved Low-Re turbulence model with positive preserving approach. The mushy region was modeled as the porous media with average effective viscosity. A series of simulations was carried out to investigate the effects of the casting speed, the slab size, the delivered superheat the immersion depth of the SEN on the transport phenomena. In the absence of any known experimental data related to velocity profiles, the numerical predictions of the solidified profile on a caster was compared with breakouts data and a good agreement was found.