• Proceedings of the KSR Conference
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• 2004.10a
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• pp.357-362
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• 2004

Maglev vehicles, which are levitated and propelled by electromagnets, often run on elevated guideways comprised of steel, aluminum and concrete. Therefore, an analysis .of the dynamic interaction between the Maglev vehicle and the guideway is needed in the design of the critical speed, ride, controller design and weight reduction of the guideway. This study proposes a dynamic interaction simulation technique using a flexible beam model based on multi-body dynamics. The vehicle and the elevated guideway are represented as a multi-body dynamics model and a two-dimensional flexible beam, respectively. The proposed model was applied to an urban transit Maglev vehicle, UTM01, which is undergoing test drive. As a result of the proposed method, we concluded that it is possible to analyze the dynamic interaction between the Maglev vehicle and the guideway.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.217-222
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• 2007

This paper describes a static gait generation process and a mechanical design process of leg mechanisms for quadruped robots. Actually robot walking is realized with the joint motion of leg mechanisms. In order to calculate the time-angle trajectories for each joint of leg mechanisms, we generate end-tip trajectories with time for each leg in the global inertial coordinate system intuitively, followed by coordinate transformations of the trajectories into the local coordinates system fixed in each leg, finally the angle-time trajectories of each joint of leg mechanisms are obtained with inverse kinematics. The stability of the gait generated in this paper was verified by a multi-body dynamic analysis using the commercial software $ADAMS^{(R)}$. Additionally the mechanical specifications such as gear reduction ratio, electrical specifications of motor and electrical power consumption during walking have been confirmed by the multi-body dynamic analysis. Finally we constructed a small quadruped robot and confirmed the gait.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.2
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• pp.409-425
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• 2015

In this paper, we employ a dynamics modeling method for investigating a multi-body dynamics system of semi-submersible autonomous underwater vehicles consisting of a towing vehicle operated near the water surface, a tow cable, and a towfish. The towfish, which is towed by a marine cable for the purposes of exploration or mine hunting, is modeled with a Six-Degree-of-Freedom (6-DOF) equation of motion that reflects its hydrodynamics characteristics. The towing cable, which can experience large displacements and deformations, is modeled using an absolute nodal coordinate formulation. To reflect the hydrodynamic characteristics of the cable during motion, the hydrodynamic force due to added mass and the drag force are imposed. To verify the completeness of the modeling, a few simple numerical simulations were conducted, and the results confirm the physical plausibility of the model.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.120-125
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• 2010

This paper proposes an intelligent PID/Fuzzy control system for two humanoid robots to transport objects stably. When a robot transports an object while walking, a whole body system of a robot may not be stable due to vibration or external factors from a different departure speed error and a body movement of walking robots. Therefore, it is necessary to measure the horizontal and vertical locations and speeds of object, then calibrate the difference of departure speed between robots with PID/Fuzzy control. The results of simulation with two robots indicated that a proposed controller makes robots to transport an object stably.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.132-138
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• 2004

In a vacuum circuit breaker mechanism, a spring-actuated linkage system is used to satisfy the desired opening and closing characteristics of electric contacts. If the type and structure of the linkage system required to the circuit breaker is predetermined, the stiffness, free length and attachment points of a spring become the important design parameters. In this paper, based on the energy conservation that the total system energy is constant throughout the operating range of the mechanism, a systematic procedure for optimizing the spring design parameters is developed and applied to the simplified mechanism of a circuit breaker. Then, in order to consider the complex dynamics of the circuit breaker mechanism rather well, the developed procedure is converted to the environment of a multi-body dynamics program ADAMS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.564-568
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• 2005

As functional requirements of automatic office machines like printers, ATMs, copying machines are on a trend for the higher speed and precision, extensive technical advances are being developed and implemented in the industry. Media transport system is a device to convey a sheet of paper in ATMs and printers. The stability of media transport system is a matter of concern as their operating throughput rapidly increases. And defects of belts or rollers in a transport system directly affect the level of stability of the system. Therefore an automatic diagnostic system for predicting various defects is necessary for the stable operation of the media transport system. A simulation based on multi-body dynamics has been done for a feasibility study of a system design for the defect anticipation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.6 s.123
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• pp.524-530
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• 2007

This paper presents a friction model to realize self-excited vibration of multi-body systems. The friction coefficient is modeled with a spline function in most commercial codes. Even if such a function resolves the problem of discontinuity in friction force, it cannot realize self-excited vibration phenomena. Furthermore, as the relative velocity approaches zero, the friction coefficient approaches zero with the conventional model. So, slip occurs when small force is applied to the system. To avoid these problems a new friction model is proposed in this study. With the new friction model, the self-excited vibration can be realized since the friction coefficient changes with the relative velocity. Furthermore, the slip phenomena could be reduced significantly with the proposed model.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.441-451
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• 2019

When a store is launched, the umbilical plug should be separated from the launcher without any physical interference and fragments. In order to satisfy these conditions, an umbilical plug and an umbilical separating device were designed. The plug is separated from the receptacle of the store while moving along inclined planes by the store thrust and the spring force connected from the launcher to the plug. As a result of the prototype test, the hanger on the store collided with the plug. Several tests were conducted after some actions were taken to prevent the collision. However, not only the same phenomenon was repeated, but also fragmentation occurred. In this study, the non-colliding conditions were analyzed through rigid and flexible multi-body dynamics analysis.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.836-843
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• 2018

In this paper, dynamic model of 120mm self-propelled mortar is developed, and multi flexible body dynamics analysis is performed to analyze stresses occurring in the mount during mortar fire. For this, vehicle dynamic system, mortar dynamic system, and finite element mount model are proposed. The commercial program Recurdyn is used in the analysis. As a result of the analysis, the maximum stress(146.9MPa) occurred at the mount side plate. In order to analyze the validity of the analysis results, we performed strain measurement tests by selecting three major points, and the errors of results were 7.91%, 11.15%, and 18.23%, respectively. It is confirmed that the tendency of analysis and test is similar.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.89-97
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• 2007

COMS(Communication, Oceanography, and Meteorology Satellite) is the first Korean multi-purpose satellite which is planned to be deployed at the altitude of geosynchronous orbit above the Korean peninsular. Noting that COMS is composed of the main BUS structure, two deployable solar panels, one yoke, five reactions wheels, COMS is treated as a collection of 9 bodies and its nonlinear equations of motion are obtained using the multi-body dynamics approach. Also, a computer program is developed to analyze the COMS motion during the various mission phase. Quite often, the equations of motion have to be derived repeatedly to reflect the fact that the spacecraft dynamics change as its configuration, and therefore its degree of freedom varies. However, the equations of motion and simulation software presented in this paper are general enough to represent the COMS dynamics of various configurations with a minimum change in input files. There is no need to derive the equations of motion repeatedly. To show the capability of the simulation program, the spacecraft motion during the solar array partial and full deployment has been simulated and the results are summarized in this paper.