• Journal of the Korean Society for Railway
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• v.10 no.4
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• pp.431-437
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• 2007

This paper describes the dynamic modeling of a railway vehicle when it is under braking force. It is important for the enhancement of braking performance to establish a proper dynamic model of a railway vehicle because the braking performance is affected by some dynamic forces generated by a railway vehicle when it undergoes braking. In this paper, a dynamic model for one vehicle is suggested to compute the dynamic behavior of a railway vehicle in the HILS(Hardware In-the-loop Simulation) system for the railway vehicle braking devices. To simplify the dynamic model, friction between a wheel and a rail is assumed that there exist only the static and the dynamic friction forces. Static friction coefficient is also assumed to be a function of the running speed. Some simulations are carried out with various braking forces, and the braking characteristics according to the change of the braking force are discussed. This study can provide some fundamental results to construct the HILS system for braking devices of a railway vehicle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1003-1008
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• 2012

The paper presents an Experimental Vehicle Model (EVM), that utilizes the kinematic characteristics of suspensions from SPMD test data. The relative displacement and orientation of a wheel with respect to the body are represented as a function of the vertical displacement of the wheel. The equations of motion of the vehicle are formulated in terms of local coordinates that do not require coordinate transformation, which improves the efficiency of dynamic analysis. The EOM was modularized for each suspension model, and a $6{\times}6$ vehicle model was obtained by combining six suspensions. The analysis results were compared with ADAMS to verify the accuracy of the EVM. This study also verifies the feasibility of real-time simulation with the developed EVM. For a vehicle simulation for 1 ms, the real simulation time required within 20% of the prescribed time. This result shows that the EVM meets the real-time simulation requirements.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.121-128
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• 2000

In this paper, the control algorithm fur an autonomous vehicle is studied and applied to an actual 2 wheel-driven vehicle system. In order to control a nonholonomic system, the kinematic model for an autonomous vehicle is constructed by relative velocity relationship about the virtual point at distance from the vehicle's frame. And the optimal controller that based on the kinematic model is operated on purpose to track a reference vehicle's path. The actual system is designed with named 'HYAVI' and the system controller is applied. Because all the results of simulation don't satisfy the driving conditions of HYAVI, a reformed control algorithm that satisfies an actual autonomous vehicle is applied at HYAVI. At the results of actual experiments, the path tracking works very well by the reformed control algorithm. An autonomous vehicle that applied this control algorithm can be easily used for a path generation algorithm.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.17-22
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• 2013

Design of braking system is one of the most critical subjects in vehicle stability. In this paper, optimal scheme for brake force proportioning of all-wheel-drive vehicle is proposed to guarantee the vehicle dynamic stability under plausible drive circumstances. A brake force distribution of generic $8{\times}4$ vehicle is calculated according to proposed scheme and braking stability of this vehicle is verified by using a commercial vehicle software, Trucksim.

• International Journal of Railway
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• v.5 no.4
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• pp.156-162
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• 2012

When a vehicle passes through turnout, it is required to minimize the changes of lateral force for running safety of vehicle. Therefore, it is necessary to analyze interaction between the vehicle and the turnout in order to estimate the lateral force and the derailment coefficient on the turnout. In this paper, analysis model of the vehicle and turnout are established and analysis is carried out when the vehicle passes through turnout in order to improve running safety of the vehicle on turnout. To verify the vehicle and turnout analysis model, the contact points between wheel and rail and the influence of changing cradle and tongue rail are also discussed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1184-1189
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• 2006

Railway vehicle have three translational motions-longitudinal, vertical and lateral, and three rotational motions-rolling, pitching and yawing caused by track irregularity, wheel and rail characteristic, dynamic behaviors etc. The rolling motion in vehicle mainly happens in cases of the vehicles stationary and running on canted track. When the vehicle positioned in stationary on canted track, vehicle is inclined toward inside of installed cant due to gravity component. When the vehicle has running on a track with cant deficiency, vehicle is inclined toward outside of installed cant due to centrifugal force. The roll coefficient(s) is defined as the ratio between the angle of inclination of the vehicle($\eta$) and the angle of the rail level($\alpha$). This paper has noted the test method, test result and analysis result to calculate the roll coefficient according to UIC505-5, international standard

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.129-139
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• 2010

To be satisfied with complex load condition of electric vehicle, fuzzy logic control (FLC) is applied to improve speed response and system robust performance of induction traction machine based on indirect rotor field orientation control. The proposed propulsion system consists of two induction motors (IM) that ensure the drive of the two back driving wheels of lightweight electric vehicle by means the vehicle used for passenger transportation. The electronic differential system ensures the robust control of the vehicle behavior on the road. It also allows controlling, independently, every driving wheel to turn at different speeds in any curve. Our electric vehicle fuzzy inference system control's simulated in Matlab SIMULINK environment, the results obtained present the efficiency and the robustness of the proposed control with good performances compared with the traditional PI speed control, the FLC induction traction machine presents not only good steady characteristic, but with no overshoot too.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.2
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• pp.107-117
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• 1998

As the traffic congestion and parking problems in urban areas are increased the tall and narrow commuter vehicles have interested as a means to increase the utilization of existing freewa- ys and parking facilities. However, in hard cornering those vehicles could reduce stability against overturning compared to conventional vehicles. This tendency can be mitigated by tilting the body toward the inside of the turn. In this paper those tilting vehicles are considered in which at speed at least, the tilt angle is controlled by steering the front wheels. In other word, if the driver turns the steering wheel the tilt controller automatically steers the road wheel to tilt the body inside of the turn. Also, the dynamic tilting vehicle model with tire slip angles is constructed by adding the roll degree of freedom. Finally, through computer simulation the behaviors of the tilting vehicles are investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1395-1400
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• 2007

Tire flat spot is a deformation which occurs around the contact patch during long-period parking and does hardly recovered even after driving. The deformation makes a tire self-excited and ride comfort gets worse. In this study, it is shown that the flat spot can be evaluated by measuring change in radial run out or force. Its effects on vibration at vehicle floor and steering wheel are also revealed. Finally it is shown that the flat spot is likely to occur if the inflation pressure is low and the tire is suppressed by a heavy load at a high temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.523-530
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• 2005

This paper addresses sliding mode control (SMC) of the anti-lock braking system (ABS) with a compensator of model uncertainties such as vehicle parameter variation, unmodeled dynamics, and external disturbances. A sliding mode controller (SMC) is designed with a nominal vehicle model to achieve a desired wheel slip ratio. A disturbance observer (DOB) is introduced to compensate the model uncertainties and is designed with a transfer function of a hydraulic brake dynamics. Through simulations on the model uncertainties, it is verified that the sliding mode control with the DOB can give the simulation results better than the sliding mode control without the DOB.