• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.84-90
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• 2009

The bi-modal tram is under development as a new public transportation. The features of the tram are an extended wheel base and its length. This features result in difficulties for drivers on maneuvering the tram. Therefore, the all wheel steering system is applied to the articulated vehicle. The AWS system enables the vehicle to steer all the rear wheels independently and improves its driving characteristics. However, the bi-modal tram has a problem to move backward in the limited place because of its geometric feature and the AWS system. Hence, the reverse parking assistant algorithm for articulated vehicle is developed to solve the problems of the reverse parking. Using the vehicle model which includes the reverse parking assistant algorithm, the dynamic analysis is performed for several parking cases. By the result of the analysis, the stability and validity of the reverse parking assistant algorithm is verified.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.59-67
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• 2014

A numerical model and a controller of Active Front wheel Steer (AFS) system are designed in this study. The AFS model consists of four sub models, and the AFS controller uses sliding mode control and PID control methods. To test this model and controller an Integrated Dynamics Control with Steering (IDCS) system is also designed. The IDCS system integrates an AFS system and an ARS (Active Rear wheel Steering) system. The AFS controller and IDCS controller are compared under several driving and road conditions. An 8 degree of freedom vehicle model is also employed to test the controllers. The results show that the model of AFS system shows good kinematic steering assistance function. Steering ratio varies depends on vehicle velocity between 12 and 24. Kinematic stabilization function also shows good performance because yaw rate of AFS vehicle tracks the reference yaw rate. IDCS shows improved responses compared to AFS because body side slip angle is also reduced. This result also proves that AFS system shows satisfactory result when it is integrated with another chassis system. On a split-m road, two controllers forced the vehicle to proceed straight ahead.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.16-22
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• 2010

Various programs for dynamic simulation of the railway vehicle have advantages and disadvantages. These programs have limitation that cannot express a large deformable body for an wire of the railway vehicle. In this study, a program for dynamic simulation of the railway vehicle is developed. And the rigid, flexible and large deformable body can be simulated using this program. Its reliability is verified by comparison with a commercial program. Also, a wire is considered as the large deformable body and a sliding joint which connects the rigid body to the large deformable body is included. Moreover, as the wheel-rail contact module is added, the dynamic simulation of the railway vehicle can be analyzed using the developed program.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.180-187
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• 2007

This paper presents a mathematical vehicle model that is designed to analyze the dynamic performance and to develop various safety control systems. Wheel slip controllers for ABS is also formulated to improve the vehicle response and to increase the safety on slippery road. Validation of the model and controller is performed by comparison with a commercial software package, CarSim. The result shows that performances of developed vehicle model are in good accordance with those of the CarSim on various driving conditions. Developed ABS controller is applied to the vehicle model and CarSim model, and it achieves good control performance. ABS controller improves lateral stability as well as longitudinal one when a vehicle is in turning maneuver on slippery road. A driver model is also designed to control steer angle of the vehicle model. It also shows good performance because the vehicle tracks the desired lane very well.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.9
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• pp.881-887
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• 2015

The hardware-in-the-loop simulation (HILS) of a railway vehicle is crucial for overcoming the limitation of field tests of a railway vehicle. A brake HILS system for a railway vehicle was previously not able to test the performance of a speed-sensing system of a railway vehicle, since wheelset speeds were generated only by computer simulations. In this paper, we present a novel wheelset speed implementation of a brake HILS system for a railway vehicle. Four wheelset speeds of a brake HILS system for a car of a railway vehicle are implemented using four small-sized servomotors, whereas the speed sensors and pole wheels used in the brake HILS system are the actual ones of the railway vehicle. According to the simulated speeds of four wheelsets in the dynamic equations of motion, four servomotors generate wheel speeds in real time, and then the measured wheelset speeds are fed back to the computer simulation model. Moreover, in this paper, we improve the performance of wheelset speed measurement via the T method instead of the M method presently used in the field. The performances of wheelset speed implementation and speed-sensor operation are demonstrated by experimental works using a HILS system.

• Structural Engineering and Mechanics
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• v.51 no.2
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• pp.315-331
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• 2014

The present study investigated the effect of the correlation of the measured road roughness profiles corresponding to the left and right wheels of a vehicle on the vibration of a vehicle-bridge coupling system. Four sets of road roughness profiles were measured by a laser road-testing vehicle. A correlation analysis was carried out on the four roughness samples, and two samples with the strongest correlation and weakest correlation were selected for the power spectral density, autocorrelation and cross-correlation analyses. The scenario of a three-axle truck moving across a rigid-frame arch bridge was used as an example. The two selected road roughness profiles were used as inputs to the vehicle-bridge coupling system. Three different input modes were adopted in the numerical analysis: (1) using the measured road roughness profile of the left wheel for the input of both wheels in the numerical simulation; (2) using the measured road roughness profile of the right wheel for both wheels; and (3) using the measured road roughness profiles corresponding to left and right wheels for the input corresponding to the vehicle's left and right wheels, respectively. The influence of the three input modes on the vibration of the vehicle-bridge system was analyzed and compared in detail. The results show that the correlation of the road roughness profiles corresponding to left and right wheels and the selected roughness input mode both have a significant influence on the vibration of the vehicle-bridge coupling system.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.76-85
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• 1997

The understeer characteristics of four wheel steering system(4WS system) in a high speed region have a negative effect upon the yaw velocity, leading to a decrease in the handling ability of vehicle. As a result, even if the side slip angle of vehicle can be kept up a minimum, a driver must compensate a decrease in yaw velocity by increasing the steering wheel angle in order to track the desired vehicle path. In this study, to keep the side slip angle of vehicle at zero and achieve a suitable yaw velocity in vehicle motion, a full active 4WS system(FA 4WS system) with actively steerable front and rear wheels is presented based on a nonlinear vehicle model and a model following control of yaw velocity. And the analysis results show the fat that, besides the excellent stability of vehicle, the FA 4WS system is able to realize better handling performance of vehicle than the previous 4WS systems in the high speed region.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.64-68
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• 1998

본 연구의 목적은 수도권 지하철차량의 소음과 진동에 방음차륜(또는 탄성차륜)이 어느 정도의 효과를 가져오는가를 평가하기 위한 것이다. 실차시험을 통하여 일체차륜이 장착된 차량과 방음차륜이 장착된 차량의 차내소음 및 차체진동을 비교하여 보았다. 그 결과 방음차륜은 지하철차량의 소음과 진동에 효과가 있음을 알 수 있었다. 그러나 실제 적용은 소음과 진동 이외에도 여러 가지 측면에서의 검토가 이루어져야만 가능할 것이다.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.115-118
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• 2007

The geometry of wheel and rail profiles is the primary contributor to wheel and rail interaction. These profiles interact to influence truck steering, vehicle lateral stability, wheel/rail wear and surface damage. Maintaining good control of the profiles is one of the keys to ensuring preferred wheel and rail interaction. Transportation Technology Center, Inc., Pueblo, Colorado, is developing an automated measurement system for wheel/rail contact condition inspections supported by AAR(Association of American Railroads). The system uses a modified version of $WRTOL^{TM}$ (Wheel/Rail Tolerances)--software that performs extensive analysis of wheel and rail contact conditions

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.1-8
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• 2012

Wheelset dynamic analysis is a key element to determine the degree of accuracy of railway vehicle dynamics. In this study, a three-dimensional wheelset dynamic analysis is presented in such a way that the precise wheel-rail contact analysis in three-dimension is implemented into the dynamic equations of a wheelset. A numerical procedure that can be used for the analysis of a wheelset dynamics when the wheel-rail two point contact occurs in a cornering maneuver is developed. Numerical solutions of the constraint equations and the dynamics equations of a wheelset are achieved by using Runge-Kutta method. The proposed wheelset dynamic analysis is validated by comparison against results obtained from VI-RAIL analysis.