• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.43-52
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• 2010

In this study, the shapes of the wheel and rail are represented by using 3-dimensional surface functions with surface parameters and a 3-dimensional wheel-rail contact analysis is presented. A whole numerical solution of wheel-rail contact at tread and flange including 2-point contacts can be achieved with the proposed numerical algorithm. Kinematic characteristics such as variances of vertical displacement and roll angle, and variance of wheel radius difference for arbitrary yaw and lateral displacement of wheelset, are determined for the KTX wheel-rail pair as an example. The condition of yaw and lateral displacement occurring 2-point contacts to analyze derailment are compared between standard and worn wheels. Differences of contact characteristics between curved and straight rails are also analyzed.

• Superconductivity and Cryogenics
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• v.12 no.2
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• pp.15-19
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• 2010

원문이미지 참조

• Ceramist
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• v.1 no.2
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• pp.74-82
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• 1998

• Superconductivity and Cryogenics
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• v.7 no.2
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• pp.17-20
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• 2005

• Journal of Drive and Control
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• v.7 no.2
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• pp.33-41
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• 2010

• Electrical & Electronic Materials
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• v.14 no.10
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• pp.35-43
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• 2001

• Superconductivity and Cryogenics
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• v.2 no.1
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• pp.41-46
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• 2000

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.5
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• pp.514-523
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• 2008

This paper presents a single-axis simulator developed to verify the attitude control algorithm of KAUSAT-2 satellite. Named KAUSatSIM, the simulator is composed of a single-axis rotation table using an air-bearing that simulates a frictionless environment, as well as sensors and momentum wheel that was used on KAUSAT-2. The simulator can be utilized for verification of KAUSAT-2 attitude control algorithm, development of new algorithms, and verification of performance. Tests were performed on the single-axis rotation simulator using the momentum wheel in order to verify the attitude control algorithm of KAUSAT-2. Satisfactory test results were obtained by designing a wheel controller that employs the proportional-derivative control method. In addition, a propulsion system was added and tested for development of a new satellite attitude control algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.11
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• pp.934-943
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• 2018

In these days, demand for agile spacecraft is gradually increasing, due to the fact that agile spacecraft can improve mission capability. In this paper, an attitude control logic based on reaction wheels that can enhance agility of spacecraft is proposed. Three methods are suggested, and all three or part of them can be integrated to the existing attitude control system. First, a feedforward/feedback controller is introduced, and its pros and cons are provided, compared to the conventional feedback controller. Second, an attitude command generation method that fully utilizes torque/momentum capacities of reaction wheels is proposed. Third, a torque (current) control mode for internal wheel control is introduced. Numerical results verify that the settling time can be significantly reduced by employing the feedforward/feedback control method, especially for large angle maneuver.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.386-394
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• 1997

In this study, a few of the modeling methods for flexible spacecraft were introduced and adopted to the modeling of a 3-axes stabilization satellite. The generated model was put into pre-built rigid body attitude control loop. A Lumped Parameter Model(Global Mode Model: GMM) was recommended for the absence of the Finite Element Method(FEM) model. Finally, GMM was compared with FEM in terms of designing a control filter. A 1st-order filter was designed to meet requirements of the controller since the new flexible model was applied, and that filter was added to motor controller and axis controller. MATLAB/Simulink was used as a tool for design and simulation of the control loop and filter.