• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.1
• /
• pp.85-90
• /
• 2011

To maintain the safety and efficiency of railroad vehicles, it is important to understand the working of the brake system with anti-skid control unit (ASCU) for rolling stocks. In this paper, a HILS (Hardware In-the Loop Simulations) system with ASCU hardware (for logic) and a DSP board (for dynamics) is developed to analyze skidding of the Hanvit-200 train during the process of braking. Experimental results are presented for the case that the skid on one of the four wheels is artificially generated using a Simulink model. A convenient GUI is prepared using ControlDesk of dSPACE.

• Journal of the Korean Society for Railway
• /
• v.4 no.4
• /
• pp.131-137
• /
• 2001

The dynamic behavior of high speed train is very important because of its safety and passengers' ride comfort. The railway vehicle is composed of many suspension components, such as 1st springs, 1st dampers, 2nd springs and 2nd dampers, that have an influence on the dynamic characteristics of high speed train. Also, the wheel/rail shapes and the track geometry affect the dynamic behavior of high speed train. This paper reviews the dynamic behavior of KHST in the KTX test line. The VAMPIRE program is used for this simulation. The simulation results are within the limits of safety criteria. Thus the KHST can operate safely at 350 km/h in the KTX test line.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.811-816
• /
• 2008

Train dynamics affects significantly safe and efficient operation of a train, especially during traction or braking period. Train dynamics is intrinsically complex due to many DOF motions in a three-dimensional space, and its behavior during the braking stage is too complex to understand and design an effective braking logic of the train. In this paper, we present a two-dimensional model with three DOF motion in a longitudinal, vertical, and pitch direction for the Hanvit 200 tilting train, which is efficient to analyze a braking performance. Furthermore, we analyze the braking logic and simulate the braking process of the Hanvit 200 tilting train using Simulink.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.383-386
• /
• 2005

An integrated analytical model which should have essential dynamics on the longitudinal railway vehicle is developed. The model consists of translational movement, rotational movement, brake actuator, adhesion force between rail and wheel, and brake friction force between wheel and pad. Thus, during the deceleration for stopping, a feedback controller controlling the brake cylinder pressure is designed to improve ride quality and to release friction problems. Through the developed model, the feasibility of controlling the cylinder pressure is verified for the better performances during braking.

• Journal of the Korean Society for Railway
• /
• v.18 no.1
• /
• pp.15-24
• /
• 2015

In magnetic levitation vehicles, the clearance between the magnet and track should be maintained within an allowable range through a feedback control loop. The flexibility of the guideway would introduce additional modes in the overall suspension system, resulting in dynamic interaction between the guideway vibration and the electromagnetic suspension control system. This dynamic interaction can be a serious problem, particularly at very low speeds or standstill, and may cause airgap instability. To optimize the overall system dynamics, an integrated dynamic model including mechanical and electrical parts and a flexible guideway as well as a control loop was developed. With the proposed model, airgap simulations at standstill were performed while varying the control gains, specifically with the aim of understanding the effects of gains of the PID controller on the airgap variation. The findings may be used to achieve a stable levitation controller design.

• Journal of the Korean Society for Railway
• /
• v.14 no.3
• /
• pp.203-210
• /
• 2011

This study formulates the theoretical wheel-set model to evaluate wheel-climbing derailments of rolling stock due to collision, and verifies this theory with dynamic simulations. The impact forces occurring during collision are transmitted from a car body to axles through suspensions. As a result of combinations of horizontal and vertical forces applied to axles, rolling stock may lead to derailment. The derailment type will depend on the combinations of the horizontal and vertical forces, flange angle and friction coefficient. According to collision conditions, the wheel-lift, wheel-climbing or roll-over derailments can occur between wheel and rail. In this theoretical derailment model of wheelset, the wheel-climbing derailment types are classified into Climb-over, Climb/roll-over, and pure Roll-over according to derailment mechanism between wheel and rail, and we proposed the theoretical conditions to generate each derailment mechanism. The theoretical wheel-set model was verified by dynamic simulations.

• Journal of the Korean Society for Railway
• /
• v.18 no.3
• /
• pp.194-202
• /
• 2015

In this paper, dynamic modeling with viscoelastic properties of a human body resting on a seat is presented to quantitatively analyze ride quality of passengers exposed to vertical vibrations. In describing the motions of a seated body, a 5 degree-of-freedom multibody model from the literature is investigated. The viscoelastic characteristics of seats used in railway vehicles are mathematically formulated with nonlinear stiffness characteristics and convolution integrals representing time delay terms. Transfer functions for the floor input are investigated and it is found that these are different in accordance with the input magnitude due to nonlinear characteristics of the seat. Measured floor input at the railway vehicle is used to analyze realistic human vibration characteristics. Frequency weighted RMS acceleration values are calculated and the effects of the seat design parameters on the frequency weighted RMS acceleration values are presented.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.140-145
• /
• 2005

The dynamic performances of railway vehicles, such as ride comfort, stability and safety, have the opposite characteristics of response each other according to design changes of suspensions. For this reasons, it is necessary that multidisciplinary engineers join in design processes of the suspensions so as to satisfy the requirements of dynamic performance with design constraints. Sometimes iterative dynamic analyses are required so many times during the design processes. In this paper, the development of integrated process environments and the dynamic analyses of railway vehicles based on the environments are presented. Using agent and wrapping technologies, process managements about the work process and design parameters were set up under the distributed computing environments. Also, dynamic analyses on the sample railway vehicle were carried out and the efficiency and improvement in future work were discussed as results.

• Proceedings of the KSR Conference
• /
• 2003.10c
• /
• pp.455-460
• /
• 2003

180km/h 급 한국형 틸팅차량의 틸팅 메카니즘 기구동역학 해석을 통하여 얻어진 틸팅 대차를 형성하는 주요 파라메터들의 값을 기반으로 틸팅대차용 엑츄에이터의 성능과 용량을 계산하여 설계에 결과를 반영하고자 한다. 승객의 안락감을 유지하기 위해 차체 틸팅 각가속도에 Sine 연속 함수를 적용하여 차체의 틸팅 제어 패턴을 결정하였으며, 이를 통해 차체의 틸팅 각속도와 틸팅각의 패턴을 얻어내었다. 또한 이번 연구를 통해 틸팅 메카니즘의 파라메타를 변화하면서 각각의 틸팅각에 따른 Swing bar 와 엑츄에이터에 작용되는 반발력에 대한 영향력을 분석, 검토하였으며, 이에 따른 엑츄에이터의 출력과 변위 속도등의 변화를 조사하였다. 이러한 결과와 틸팅 메카니즘 기구동력학 해석의 결과를 토대로 틸팅차량이 요구하는 최적의 틸팅 운동을 수행하는 파라메타를 결정하였다.

• Journal of the Korean Society for Railway
• /
• v.10 no.5
• /
• pp.540-545
• /
• 2007

The tilting train is able to tilt its body towards the center of the turning radius, preventing roll-over of the train as it runs on a curved rail at high-speed. This train, widely accepted for commercial purpose internationally, is very beneficial in that the operating time is shortened without much capital investment to the infrastructure where there are many curved rails. Over several years, the Korea Railroad Research Institute (KRRI) has developed such a train. In this paper, the safety of the Korean tilting train express (TTX) is investigated using a dynamic simulation model. Since proper safety standards have not been established for the TTX, those for the Korean train express (KTX) is employed to analyze the safety and ride comfort of the TTX. This study is useful in predicting the behavior of the TTX and ride comfort, and conforms that designed TTX is stable enough to satisfy the safety standards. It would be useful to recommend proper normal operating speed and determine the maximum safety speed, according to the result. Furthermore, it would be possible to provide basic reference data when analyzing the dynamic effect of the catenary system and the fatigue of the bogie.