• Title, Summary, Keyword: 다물체 동역학

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Path Tracking Control of 6X6 Skid Steering Unmanned Ground Vehicle for Real Time Traversability (실시간 주행 안정성 분석을 위한 6X6 스키드 조향 무인 자율 주행 차량의 경로 추종 제어)

  • Hong, Hyosung;Han, Jong-Boo;Song, Hajun;Jung, Samuel;Kim, Sung-Soo;Yoo, Wan Suk;Won, Mooncheol;Joo, Sanghyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.7
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    • pp.599-605
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    • 2017
  • For an unmanned vehicle to be driven on the off-road terrain, it is necessary to consider the vehicle's stability. This paper suggests a path tracking controller for simulation of real-time vehicle stability analysis. The path tracking controller uses the preview distance to track the given trajectory. The disturbance moment is estimated using the yaw moment observer, and this information is used for compensation in the yaw moment control. On a curved path, the vehicle's desired velocity is determined from the curvature of the path. Because the vehicle is equipped with six independent motor driven wheels, the driving torques are distributed on all the wheels. The effectiveness of the path tracking controller is verified using ADAMS/MATLAB co-simulation.

Study on the Dynamic Behavior Characteristics due to the Unbalance High Speed Railway Vehicle Wheel (고속철도차량용 차륜 불평형에 의한 동적 거동 특성 연구)

  • Lee, Seung-Yil;Song, Moon-Shuk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.175-181
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    • 2016
  • This occurs when the unbalanced rotating body is inconsistent with the mass center line axis geometric center line. Wheelsets are assembled by a single axle with two wheels and a rotating body of a running railway vehicle. Owing to non-uniformity of the wheel material, the wear, and error of the wheel and axle assembly may cause an imbalance. Wheelsets will suffer the effects of vibrations due to the unbalanced mass, which becomes more pronounced due to the thin and high-speed rotation compared to the shaft diameter This can affect the driving safety and the running behavior of a rail car during high-speed running. Therefore, this study examined this unbalanced wheel using a railway vehicle multibody dynamics analysis tool to assess the impact of the dynamic VI-Rail movement of high-speed railway vehicles. Increasing the extent of wheel imbalance on the analysis confirmed that the critical speed of a railway vehicle bogie is reduced and the high-speed traveling dropped below the vehicle dynamic behaviour. Therefore, the adverse effects of the amount of a wheel imbalance on travel highlight the need for management of wheel imbalances. In addition, the static and dynamic management needs of a wheel imbalance need to be presented to the national rail vehicles operating agency.

Analysis of braking characteristics of electric multiple unit for train control system (열차제어시스템을 위한 전동차 제동특성 분석)

  • Choi, Don Bum;Oh, Sehchan;Kim, Min-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.12
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    • pp.887-895
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    • 2018
  • This paper presents a braking model that can be used to design the safety distance of a train control system and a train braking system to increase the volume of traffic. For the braking model, a train set (electric multiple unit composed 6 cars) was tested. The factors that can affect the braking characteristics include the friction coefficient, braking pressure, and regenerative braking. The braking pressure was classified into service and emergency braking and reflected the characteristics of the vehicle. The external force acting on the running railway car was tested in accordance with KS R 9217, and the running resistance of the train is presented in the form of a polynomial. The dynamic behavior of the train running on a straight flat line was simulated using UM 8.3. The results were validated with experimental data, and the results were reasonable. With the validated model, a stopping distance was determined according to the initial braking speed and compared with the deceleration braking model. In addition, a safety distance for the train control system could be changed according to the frictional coefficient limits. These results are expected to be useful for analyzing the dynamic behavior of trains, and for analyzing various railway environments and improving the braking performance.

Analysis of Dynamic Interaction Between Maglev Vehicle and Guideway (자기부상열차/가이드웨이 동적상호작용 해석)

  • Kim, Ki-Jung;Han, Hyung-Suk;Yang, Seok-Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.12
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    • pp.1559-1565
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    • 2013
  • This study aims to investigate the dynamic interaction characteristics between Maglev vehicles and an elevated guideway. A more detailed model for the dynamic interaction of the vehicle/guideway is proposed. The proposed model incorporates a 3D full vehicle model based on prototyping, flexible guideway by a modal superposition method, and levitation electromagnets including the feedback controller into an integrated model. The proposed model was applied to an urban transit Maglev developed for a commercial application to analyze the dynamic response of the vehicle and guideway, and the effect of the surface roughness of the rail, mid-span guideway deflections, and air gap variations are then investigated from the numerical simulation.

A Study on Program Development for Static Design Factor of Automotive Suspension System (자동차 현가장치의 정적설계인자 계산을 위한 프로그램 개발에 관한 연구)

  • Kim, Kwang-Suk
    • Journal of the Korea Convergence Society
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    • v.8 no.12
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    • pp.283-289
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    • 2017
  • In this study, a general program has been developed to calculate the static design factor of a vehicle suspension system. The partial derivatives of Jacobians for constraint equations are calculated using the symbolic technique. In the commercial program, finite difference method is used to calculate the Jacobian matrix of Jacobian. But in this study, it is calculated by using the symbol calculation method to precisely consider it. The calculated Jacobian matrix for the system has proved its accuracy through the solution of the numerical example. A simulation was performed for a double wishbone suspension of a 1/4 vehicle. The result can be used to calculate the static design factor of the suspension, and also add a convergence module that can perform virtual tests.

Optimal Design of Stiffness of Torsion Spring Hinge Considering the Deployment Performance of Large Scale SAR Antenna (전개성능을 고려한 대형 전개형 SAR 안테나의 회전스프링 힌지의 강성 최적설계)

  • Kim, Dong-Yeon;Lim, Jae Hyuk;Jang, Tae-Seong;Cha, Won Ho;Lee, So-Jeong;Oh, Hyun-Ung;Kim, Kyung-Won
    • Journal of Aerospace System Engineering
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    • v.13 no.3
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    • pp.78-86
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    • 2019
  • This paper describes the stiffness optimization of the torsion spring hinge of the large SAR antenna considering the deployment performance. A large SAR antenna is folded in a launch environment and then unfolded when performing a mission in orbit. Under these conditions, it is very important to find the proper stiffness of the torsion spring hinge so that the antenna panels can be deployed with minimal impact in a given time. If the torsion spring stiffness is high, a large impact load at the time of full deployment damages the structure. If it is weak, it cannot guarantee full deployment due to the deployment resistance. A multi-body dynamics analysis model was developed to solve this problem using RecurDyn and the development performance were predicted in terms of: development time, latching force, and torque margin through deployment analysis. In order to find the optimum torsion spring stiffness, the deployment performance was approximated by the response surface method (RSM) and the optimal design was performed to derive the appropriate stiffness value of the rotating springs.

International Research Status on Spent Nuclear Fuel Structural Integrity Tests Considering Vibration and Shock Loads Under Normal Conditions of Transport (정상운반조건의 진동 및 충격하중을 고려한 사용후핵연료의 구조적 건전성 시험평가 해외연구현황)

  • Lim, JaeHoon;Cho, Sang Soon;Choi, Woo-seok
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.17 no.2
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    • pp.167-181
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    • 2019
  • Currently, the development of evaluation technology for vibration and shock load characteristics and spent nuclear fuel structural integrity under normal conditions of transport is being conducted in the Republic of Korea. This is the first such research conducted in the Republic of Korea and, thus, previous international studies need to be investigated and will be referred to in the ongoing project. Before 2000, several studies related to measurement of vibration and shock loads on spent nuclear fuel were conducted in the US. US national research institutes conducted uniaxial fuel assembly shaker tests, concrete block tests, and multi-axis fuel assembly tests between 2009 and 2016. In 2017, multi-modal transportation tests including road, sea, and rail transport were also performed by research institutes from the US, Spain and the Republic of Korea. Therefore, test preparation procedures, acceleration and strain measurement results, and finite-element and multi-body dynamics analysis were investigated. Based on the measured strain data, the preliminary conclusion was obtained that the measured strain was too small to cause damage to spent nuclear fuel rods. However, this conclusion is a preliminary conclusion that only reviews part of the results; a detailed review is being conducted in the US. The investigation of international studies on spent nuclear fuel structural integrity tests considering vibration and shock loads under normal conditions of transport in the US will be useful data for the project being conducted in the Republic of Korea.