• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.130-140
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• 2000

In this paper the reference model following control(RMFC) scheme through the optimal control theory is investigated for the independent rear wheel steering(IRWS) vehicle. RMFC vehicle follows the dynamic performance of a virtual vehicle as a reference model deisgned in the controller. Linear vehicle model of two degres-of-freedom is used to derive control scheme which is applied to full vehicle for evaluating handling performances. And 4WS vehicle through RMFC is compared to the conventional 2WS vehicle and 4WS vehicle in the J-turn test. The RMFC logic is also extended to IRWS vehicle, IRWS with RMFC shows not only the excellent handling performance but salso some advantages in terms of the directional stability and responsiveness from the simulation results.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.934-939
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• 2004

Railway wheel/rail contact conditions have an influence on dynamic behavior of rolling stock. If there are problems of incompatibility between wheel and rail, damages like wheel wear, wheel spalling, rail wear, etc are occurred. Especially wheel and rail profiles are important factor of vehicle curving performance, so compatibility study between wheel and rail has to be carried out preferentially, In this study, we have analyzed the compatibility between wheel and rail of KNR conventional line to improve the maintenance efficiency of wheel and rail. Thus we showed the results relating to wheel/rail geometric contact, vehicle running performances as the change of wheel/rail combination.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.174.4-174
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• 2001

Vehicle stability control system can enhance the vehicle stability and handling in the emergency situations through the control of traction and braking forces at the individual wheels. To achieve the desired performance, the wheel slip controller manages the hydraulic braking system to generate the desired braking force at each wheel. In this study, we propose the wheel slip controller for the generation of the braking forces based on multiple sliding mode control theory with the pulse width modulation. The proposed controller follows to the slip ratio and the brake pressure the desired ones so that the vehicle stability controller can Intervene braking force at each wheel. We show the validity and usefulness of the proposed controller through computer simulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.309-314
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• 2011

Outer rotor type in-wheel switched reluctance motor for Welfare neighborhood electric vehicle is researched. In-wheel system is to drive the electric vehicle without mechanical transmission, shaft, differential gears or other mechanical system. To calculate drive power for each wheels, the elder's and disable's safety driving conditions are considered. The designed outer rotor SRM has a 6-stator and 8-rotor pole. The determined dimensions as well as the stator and rotor pole arc are simulated and tested with CAD and finite element analysis to verify the performance of the proposed motor.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.17-24
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• 2006

Anti-lock brake system(ABS) are designed to prevent wheel lock on all wheels of the vehicle by sensing wheel angular speed, processing the speed sensor signals in suitable digital electronic control circuits and comanding electrohydraulic actuators to control brake pressure. This study considers a control of ABS using wheel circumferential acceleration thresholds which avoids dangerous wheel locking due to excessive brake pressure during the vehicle braking and discusses the 3-channels, 3-sensors ABS system that employs "independent control" technique for the front wheels and "select low" technique for the rear wheels. The validities of the ABS such as vehicle stability, steerability and stopping distance during braking are assured through the vehicle tests on uniform asphalt straight roads.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.759-764
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• 2014

Lateral force of wheel is important parameter when we evaluate the safety of a railway vehicle on curved track. The lateral force of wheel is influenced by the steering performance of wheelsets. Generally, in passive type vehicles, the steering performance of wheelsets is influenced by the parameters like primary spring stiffness, wheel base, conicity of the wheel profile, etc. But, the steering performance of passive type vehicle has its limit. To overcome the limit of the steering performance of passive type vehicle, active steering technology is being developed. In this paper, we analyze the lateral force of wheel and the safety of the railway vehicle on curved track by adopting the active steering technology. As results of dynamic analysis for vehicle model equipped with active steering system, the lateral force of wheel is reduced and the safety is improved remarkably.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.547-555
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• 2016

The wheel wear of a railway vehicle is mainly generated when maneuvering on a curved track. The change in the wheel profile affects the dynamic stability of the vehicle. In this analysis, the wheel wear volume was calculated while changing the velocity and radius of the curve to analyze the wear characteristics of a wheel at a curved section. The wear index was calculated from a vehicle dynamic analysis based on a multibody dynamics analysis and wear volume from a wear model by British Rail Research. The wear volume at a radius of 300 m is dominant compared with other radii. The wear volume was calculated by assigning different coefficients of friction to the tread and flange of the wheel to investigate the effect of lubrication on the wear characteristics. The effect of the improvement by lubrication is calculated by varying the radius of the track, and is assessed on an actual urban railway section.

• Journal of the Korean Society for Railway
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• v.8 no.5
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• pp.483-489
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• 2005

Railway wheel/rail contact conditions have influences on dynamic behavior of the rolling stock. If there are incompatibility problems between the wheel and rail, damages like wheel wear, wheel spalling, rail wear, etc are occurred. Especially wheel and rail profiles are important factors of vehicle curving performance, so compatibility studies between wheel and rail profiles have to be carried out preferentially. In this study, we have studied the compatibility between wheel and rail profiles of KNR conventional line to analyze the dynamic performances of the rolling-stock. Thus we showed the results relating to wheel/rail geometric contact, vehicle running performances as the change of wheel/rail combination.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.28-34
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• 2010

Railway wheel and axle is the most critical components in railway system. A wheel and axle failure can cause a derailment with its attendant loss of life and property. The service conditions of railway vehicles have become severe in recent years due to a general increase in operating speeds. Therefore, more precise evaluate of wheelset strength and safety has been desired. Fracture mechanics characteristics such as dynamic fracture toughness, fatigue threshold and charpy impact energy with respect to the tread, plate, disc hole of wheel and the surface of press fitted axle are evaluated. This paper describes the difference of fracture toughness, fatigue crack growth and fatigue threshold at the locations of wheel and axle. The results show that the dynamic fracture toughness, $K_{ID}$, is obviously lower than static fracture toughness, $K_{IC}$ and the fracture mechanics characteristics are difference to the location of wheel tread and hole.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.537-542
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.