• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.69-74
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• 1997

In this paper we derive relations which describe the geometry and kinematics of contact between the travelling wheel and stepped comb joint. From which we can obtain the impulse, impulsive force and its time interval due to travelling wheel impact which can not be taken from Carter's model or Newland and Cassidy's. The calculated transient responses of the comb joint structure to travelling wheel impact reveals that the proposed wheel contact model and Carter's give very similar results but Newland Cassidy's model make a quite different results from the others.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.328-333
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• 2002

When vehicle travelling along the track which has irregularity such as vertical profile, dynamic forces arise at the Wheel/Rail contact patch by wheel/rail interaction. In particular short wavelength irregularities on dipped joint and small stiffness of connecting rail bring about intense wheel/rail dynamic effects at higher speed. In the paper, a new model for dipped joint rail is developed to study dynamic behavior of track. A cusp behavior on dipped joint was defined by its amplitude and decay factor, which was presented by FRA track classes. The result of case study are presented, which show wheel rail contact force in each track classes, train operation speed and bending flexible rigidity ratio of fishplates which are connecting the rail.

• 대한토목학회논문집
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• 제28권3A호
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• pp.357-366
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• 2008

본 연구는 교량 신축이음에 대해서 윤하중 재하실험을 통해 윤하중 재하 특성을 분석하고 이를 토대로 신축이음에서의 윤하중 재하기준을 마련하는 기초데이터를 확보하고자 실시하였다. 이를 위해 국내에서 많이 사용되고 있는 레일신축이음과 핑거신축이음에 대하여 시험체를 제작하고 실제 타이어 바퀴를 사용한 정적 윤하중 재하실험을 실시하였다. 윤하중에 접촉된 레일과 핑거에서 윤하중 분배율을 파악하였는데, 레일신축이음에서 중앙 레일이 지지하는 분담율은 윤하중 크기가 증가함에 따라 감소하는 것으로 나타났고 핑거신축이음에서는 접촉 면적 증가에 따라 거의 증가하지 않고 일정하게 됨을 알 수 있었다. 윤하중 재하 특성이 기존 설계기준과 많은 차이를 나타내고 있으므로 신축이음 설계를 위한 윤하중 접지압력 분포에 대한 합리적인 기준 마련이 필요하다고 판단되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(I)
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• pp.204-209
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• 2003

The railway vehicle is composed of many suspension components, such as 1st springs, 2nd dampers, that have an influence on the dynamic characteristics of high speed train. Also, the wheel/rail shapes and its contact mechanism affect the dynamic behavior of high speed train. but these geometric contact characteristics are nonlinear functions of the wheelset lateral displacement and it do not exact dynamic analysis for high speed train. there is a need to develop a new wheel/rail contact module for dynamic behavior and wheelset model is divided motor box, wheel box and wheel body. This wheel is moved by motor box and constrained by joint. It is almost same a train and its result is more exactly.

• International Journal of Automotive Technology
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• 제7권7호
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• pp.833-839
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• 2006

In this paper, roll behavior of three planar half car models are compared. The first model is a simple model whose contact point between a wheel and the ground is assumed to be fixed with a revolute joint. The second model is a modified model of the fIrst model, whose wheel tread width can vary. In this model, the instant center of a wheel with respect to the ground, which is crucial to find the roll center, is assumed to be at the contact point of a wheel and the ground. The last model uses the pole of a wheel with respect to the ground for small displacement as the instant center of a wheel with respect to the ground. Loci of the center of gravity point, the fixed and the moving centrodes which are traces of roll center position in the ground and the body frame respectively, wheel contact points, and instant centers of a wheel with respect to the ground are calculated.

• 로봇학회논문지
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• 제6권3호
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• pp.284-291
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• 2011

This paper presents the estimation of the frictional coefficient of the wheel-legged robot with hip joint actuation producing maximum tractive force. Slip behavior for wheel-legged robot is analytically explored and physically understood by identification of the non-slip condition and derivation of the torque limits satisfying it. Utilizing results of the analysis of slip behavior, the frictional coefficients of the wheel-legged robot during stance phase are numerically estimated and finally this paper suggests the pseudo-algorithm which can not only estimate the frictional coefficients of the wheel-legged robot, but also produce the candidate of the touch down angle for the next stance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.337.2-337
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• 2002

When vehicle travelling along the track which has irregularity such as vortical profile, dynamic forces arise at the Wheel/Rail contact patch by wheel/rail interaction. In particular short wavelength irregularities on dipped joint and small stiffness of connecting rail bring about intense wheel/rail dynamic effects at higher speed. In the paper, a new model for dipped joint rail is developed to study dynamic behavior of track. (omitted)

• 한국정밀공학회지
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• 제16권10호
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• pp.118-125
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• 1999

In the grinding process, generally, the exciting forces with high frequency can be generated due to the wheel wear and the grinding process. As the grinding speed increases, the precise investigation about the wheel dynamic characteristics is required. Conventionally the wheel-spindle has been considered with lumped model in dynamic modeling. With this lumped model, the significant mode resulted from the shell mode of wheel can be readily ignored. This paper suggests the new analysis model which includes the shell mode of wheel in modeling the wheel-spindle assembly. Furthermore, based on the suggested model, the effects of the bolt tightening force and the taper tightening force on the dynamic properties are investigated by the finite element modal analysis and the experimental method. As a result of investigation, the shell mode vibration of wheel affects the dynamic characteristics of the spindle assembly. Also, the vibration modes of the spindle assembly are significantly affected by the joint tightening forces.

• 로봇학회논문지
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• 제17권4호
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• pp.500-507
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• 2022

In this study, a motion planning method based on the integer representation of contact status between wheels and the ground is proposed for planning swing motion of a 6×6 wheel-legged robot to cross large obstacles and gaps. Wheel-legged robots can drive on a flat road by wheels and overcome large obstacles by legs. Autonomously crossing large obstacles requires the robot to perform complex motion planning of multi-contacts and wheel-rolling at the same time. The lift-off and touch-down status of wheels and the trajectories of legs should be carefully planned to avoid collision between the robot body and the obstacle. To address this issue, we propose a planning method for swing motion of robot legs. It combines an integer representation of discrete contact status and a trajectory optimization based on the direct collocation method, which results in a mixed-integer nonlinear programming (MINLP) problem. The planned motion is used to control the joint angles of the articulated legs. The proposed method is verified by the MuJoCo simulation and shows that over 95% and 83% success rate when the height of vertical obstacles and the length of gaps are equal to or less than 1.68 times of the wheel radius and 1.44 times of the wheel diameter, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.72-75
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• 2001

In this paper, the kinematic model and motion control of a joint-actuated mobile robot are analyzed. To take an efficient approach to the wheeled mobile robots, the relationship between wheel rotation and the contact point of the wheel is considered. It is shown that each addition of a joint to a mobile robot increases the degree of freedom(DOF) of mobile robot, and the way of joint attachment to a mobile robot is proposed. To get a solution of inverse kinematics of mobile robot, two types of approaches are proposed.