• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.390-396
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• 2003

This paper is focused on an optimal block sectioning technique which are widely used in conventional railway system. We studied braking distance with pure train braking performance to generalize train braking. We tried to apply the braking distance to wayside signaling system to decide optimal block sectioning to reduce headway. The braking distances are obtained for 2 aspects, 3 aspects, 4 aspects and n aspects such that step speed control, are longer than the pure braking distance. We found an optimal solution with the generalized n aspects, and a minimum block distance for ATO mode.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.295-301
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• 2006

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS systems. In order to achieve the superior braking performance through the wheel-slip control, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance, stability enhancement, etc. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm. An adaptive law is formulated to estimate the longitudinal braking force in real-time. The wheel slip controller is designed using the Lyapunov stability theory and considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm is developed for the maximum braking force and searches the optimal target slip value based on the estimated braking force. The performance of the proposed wheel-slip control system is verified In simulations and demonstrates the effectiveness of the wheel slip control in various road conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.102-109
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• 2005

Wheel-slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS systems. But, in order to achieve the superior braking performance through the wheel-slip control, real-time information such as the tire braking force is required. For example, in the case of EHB (Electro-Hydraulic Brake) systems, the tire braking force cannot be measured directly, but can be approximated based on the characteristics of the brake disk-pad friction. The friction characteristics can change significantly depending on aging of the brake, moisture on the contact area, heat etc. In this paper, a wheel slip The proposed wheel slip control system is composed of two subsystems: braking force monitor and robust slip controller In the brake force monitor subsystem, the tire braking forces as well as the brake disk-pad friction coefficient are estimated considering the friction variation between the brake pad and disk. The robust wheel slip control subsystem is designed based on sliding mode control methods and follows the target wheel-slip using the estimated tire braking forces. The proposed sliding mode controller is robust to the uncertainties in estimating the braking force and brake disk-pad friction. The performance of the proposed wheel-slip control system is evaluated in various simulations.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.44-51
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• 2006

This paper addresses sliding mode control of the anti-lock braking system (ABS) with a disturbance observer for model uncertainties such as vehicle parameter variation, un-modeled dynamics, and external disturbances. By using a nominal vehicle model, a sliding mode controller is designed to achieve a desired wheel slip ratio for ABS control. To compensate the model uncertainties, a disturbance observer is introduced with the help of a transfer function of a hydraulic brake dynamics. A proposed sliding mode controller with a disturbance observer is evaluated through simulations for model uncertainties. The simulation results show that the disturbance observer can enhance performances of sliding mode control for ABS.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.78-85
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• 2013

This paper presents the sliding mode control methods for anti-lock brake system (ABS) with the friction force observer. Using a simplified quarter car model, the sliding mode controller for ABS is designed to track the desired wheel slip ratio. Here, new method to find the desired wheel slip ratio which produces the maximum friction force between road and tire is suggested. The desired wheel slip ratio is varying according road and tire conditions to produce maximum friction force. In order to find optimum desired wheel slip ratio, the sliding mode observer for friction force is used. The proposed sliding mode controller with observer is evaluated in simulation, and the control design is shown to have high performance on roads with constant and varying adhesion coefficients.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.12
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• pp.868-873
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• 1987

In this pater, we have proposed a synthetic main chopper circuit for the chopper controlled electric automobile. The proposed chopper circuit operates as a step-down chopper in powering mode and as a polarity reversion type chopper in regenerative braking mode. In this study, it was found that powering and regenerative braking operations using the separately excited D.C motor can be controlled continuously only by gate signals of the chopper without changing the connection of the circuit.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.733-736
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• 2002

This study was carried out to investigate the braking performances associated with the friction coefficients and temperature fluctuations. Friction coefficient stability and maximum temperature of brake drums, made of an Al-MMC and conventional cast iron, were tested by the inertial brake dynamometer during 15 braking operations. Also the temperature distribution was analyzed by the finite element analysis(FEA). In this experiment, both lower temperature rise near the drum surface and less variation of friction coefficient, compared to those of cast iron, were observed with Al-MMC drums during braking operations.

• Journal of Power Electronics
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• v.15 no.2
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• pp.469-478
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• 2015

In order to promote the application of switched reluctance machines (SRM) in electric vehicles (EVs), the braking torque closed-loop control of a SRM is proposed. A hysteresis current regulator with the soft chopping mode is employed to reduce the switching frequency and switching loss. A torque estimator is designed to estimate the braking torque online and to achieve braking torque feedback. A feed-forward plus saturation compensation torque regulator is designed to decrease the dynamic response time and to improve the steady-state accuracy of the braking torque. The turn-on and turn-off angles are optimized by a genetic algorithm (GA) to reduce the braking torque ripple and to improve the braking energy feedback efficiency. Finally, a simulation model and an experimental platform are built. The simulation and experimental results demonstrate the correctness of the proposed control strategy.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.954-958
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• 2004

본 논문은 부하에 대한 빠른 응답특성을 보이는 새로운 토폴로지를 제안하였다. PI제어기 출력이 포화될 때 windup 현상이 나타나고 그 결과로 성능이 저하된다. 따라서 전동기의 가변속 제어성능을 위해 가속시에는 개선된 Anti-windup PI제어기만을 사용하고, 감속시에는 추가로 부하의 특성을 고려하여 braking 동작을 사용하였다. 시뮬레이션 및 실험결과는 속도성능면에서 제안된 방식이 종래의 다른 제어방식에 비해 우수함을 보여 준다.