• 대한기계학회논문집A
• /
• 제37권3호
• /
• pp.379-385
• /
• 2013

차량의 제동시 쏠림 현상은 크게 타이어에 의한 원인과 현가시스템, 조향시스템 등의 차량구조의 이유로 발생한다. 그 중 차량구조의 원인은 드래그링크 방식의 조향시스템과 판스프링 형태의 현가 스프링 때문으로 볼 수 있다. 본 연구에서는 차량동역학 해석 프로그램인 ADAMS/CAR 를 사용하여 제동시 쏠림의 발생 원인에 대해 분석하였다. 제동시 드래그링크와 판스프링의 거동을 확인하고 그로 인해 발생하는 쏠림을 최소화 시키기 위해 최적화 프로그램인 Visual DOC 를 사용하여 쏠림을 감소시키기 위한 조향 연결점의 위치를 결정하였다. 설계 변경된 차량의 K&C (Kinematic & Compliance) Test 시뮬레이션을 통해서 다른 특성에 미치는 영향이 없음을 보였고, 전차량 제동시뮬레이션을 통해 제동시 쏠림이 감소함을 확인하였다.

• Steel and Composite Structures
• /
• 제25권4호
• /
• pp.403-413
• /
• 2017

The fabric braided braking hose that delivers the driver's braking force to brake cylinder undergoes the large deformation cyclic motion according to the steering and bump/rebound motions of vehicle. The cyclic large deformation of braking hose may give rise to two critical problems: the interference with other adjacent vehicle parts and the micro cracking stemming from the fatigue damage accumulation. Hence, both the hose deformation and the fatigue damage become the critical issue in the design of braking hose. In this context, this paper introduces a multi-objective optimization method for minimizing the both quantities. The total length of hose and the helix angles of fabric braided composite layers are chosen for the design variables, and the maximum hose deformation and the critical fatigue life cycle are defined by the individual single objective functions. The trade-off between two single objective functions is made by introducing the weighting factors. The proposed optimization method is validated and the improvement of initial hose design is examined through the benchmark simulation. Furthermore, the dependence of optimum solutions on the weighting factors is also investigated.

• Journal of Electrical Engineering and Technology
• /
• 제11권3호
• /
• pp.653-661
• /
• 2016

This paper proposes a capacitance estimation method of the dc-link capacitor for brushless DC motor (BLDCM) drive systems. In order to estimate the dc-link capacitance, the BLDCM is operated in quadrant-II or -IV among four-quadrant operation. Quadrant-II and -IV are called reverse braking and forward braking, respectively. During the braking operation of the BLDCM, the capacitor is charged by the phase current and then the voltage is increased during the braking operation time. The capacitor current and voltage can be obtained by using the phase current sensor of BLDCM and the dc-link voltage sensor. The capacitance and be easily obtained by the voltage equation of the capacitor. The proposed method guarantees the reliable and simple calculation of the dc-link capacitance without additional hardware system except several the sensors already installed for the motor control system. The effectiveness of the proposed method is verified through both the simulation and experimental results.

• 자동차안전학회지
• /
• 제5권1호
• /
• pp.56-61
• /
• 2013

This paper presents a development of the Advanced Emergency Braking (AEB) Algorithm for passenger vehicles. The AEB is the system to slow the vehicle and mitigate the severity of an impact when a rear end collision probability is increased. To mitigate a rear end collision, the AEB comprises of a millimeter wave radar sensor, CCD camera and vehicle parameters of which are processed to judge the likelihood of a collision occurring. The main controller of the AEB algorithm is composed of the two control stage: upper and lower level controller. By using the collected obstacle information, the upper level controller of the main controller decides the control mode based not only on parametric division, but also on physical collision capability. The lower level controller determines warning level and braking level to maintain the longitudinal safety. To decide the braking level, Last Ponit To Brake and Steer (LPTB/LPTS) are compared with current driving statues. To demonstrate the control performance of the proposed AEBS algorithm's, closed-loop simulation of the AEBS was conducted by using the Matlab simlink and CarSim software.

• 동력기계공학회지
• /
• 제21권4호
• /
• pp.5-17
• /
• 2017

This study focuses on the application of the PEM Fuel Cell(PEMFC) hybrid system, which includes a regenerative braking system with supercapacitor(SC) and battery. The purpose of this study is to evaluate the characteristics of regenerative energy and to propose solutions to increase regenerative energy via vehicle simulation. To achieve this target, we set the rated motor speed to 3,000/2,500/2,000 rpm. Because the flywheel is directly connected to the motor, the generator activates regenerative braking by using the rotational momentum of the flywheel when the flywheel reaches the set speed after the motor stops. We could then measure the characteristics of regenerative braking of voltage, current, power, energy change, etc. Meanwhile, we calculate the storage efficiency of the SC or the battery. Our results show that the SC stores 18% of the regenerative energy, while battery stores 15% of the energy. Since the regenerative energy decreases with the decrease of the motor rotating speed that 5,027 J and 2,915 J are restored at 3,000 and 2,500 rpm, respectively. The experimental results also prove that regenerative braking energy is able to be obtained if and only if the speed of flywheel is over 2,500 PRM, and the efficiency of the system can be further improved.

• 한국항행학회논문지
• /
• 제24권4호
• /
• pp.280-284
• /
• 2020

현재 공기제동의 문제점을 보완하기 위한 유지보수와 환경문제, 효율성, 경제성 등을 개선하기 위하여 정지에서 고속영역까지의 전 영역에서 전기 브레이크의 모든 주행 범위와 관련된 제동력을 제시하였다. 결과적으로 는 제동력의 효율과 첨단 기술은 에너지 활용을 확장 시켰으며, 본 논문을 통하여 모든 주행 범위에서의 소음이 저감되며, 유지 보수 비용의 절감 효과가 있었다. 트랙션 모터는 인버터의 최대 전압을 제어하는 고속 운전 특성 구동을 위해 트랙션 모터의 가변 속도와 트랙션 모터의 단자 전압을 가져 와야 한다. 따라서 시뮬레이션을 통한 구동 및 브레이크 변경에 대해 연구하였다.

• 한국자동차공학회논문집
• /
• 제6권5호
• /
• pp.222-227
• /
• 1998

Collision warning systems have been an active research and development area as the interests and demands for ASV's (Advanced Safety Vehicles) have increased. This paper presents an experimental investigation of a collision warning system for automobiles. A collision warning HiLS(Hardware-in-the-Loop Simulation) system has been designed and used to test the collision warning algorithm, radar sensors, and warning displays under realistic operating conditions in the laboratory. the collision warning algorithm is operated by a warning index, which is a function of the warning distance and the braking distance. The computer calculates velocities of the preceding vehicle and following vehicle, relative distance and relative velocity of the vehicles using vehicle simulation models. The relative distance and the relative velocity are applied to the vehicle simulator controlled by a DC motor.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.98-103
• /
• 2002

In this paper, static analysis of eddy current brake's frame, which is one of key structural components of brake system for high speed train, was performed in order to evaluate the design by computer simulation. Calculation was carried out in general for the driving modes 'braking' and 'frame in upper position(Brakes inactive)'. Several yield stress load cases and fatigue load cases were analysed for each of the driving modes. The fatigue load resulting from the Multi Body System simulation was also taken into consideration. The simulation results shows that some of structural part should be improved for more increasing reliability of frame.

• 한국정밀공학회지
• /
• 제13권8호
• /
• pp.120-127
• /
• 1996

Anti-lock Brake System has been developed to reduce tendency for wheel lock and improve vehicle control during sudden braking on slippery road surfaces. This is achieved by controlling the braking pressure, avoiding wheel lock, while retaining handling and brake performance. This paper is concerned about pressurecharacteristics of hydraulic modulator. Experimental sets which is consists of hydraulic modulator, duty controller, pressure regulator, pressure senset is consuructed. System modelling and computer simulation are performed for comparison with experimental results. Brake wheel pressure are measured under various driving pulse. The result of experiment show fairly agreement with the simulation. As a result, it is known that wheel pressure is affected by duty ratio, orifice diameter through computer simulation.

• International Journal of Aeronautical and Space Sciences
• /
• 제18권4호
• /
• pp.623-640
• /
• 2017

The full nonlinear equations of an unmanned aerial vehicle ground taxiing mathematical dynamic model are built based on a type of unmanned aerial vehicle data in LMS Virtual.Lab Motion. The flexible landing gear model is considered to make the aircraft ground motion more accurate. The electric braking control system is established in MATLAB/Simulink and the experiment of it verifies that the electric braking model with the pressure sensor is fitted well with the actual braking mechanism and it ensures the braking response speediness. The direction rectification control law combining the differential brake and the rudder with 30% anti-skid brake is built to improve the directional stability. Two other rectifying control laws are demonstrated to compare with the designed control law to verify that the designed control is of high directional stability and high braking efficiency. The lateral displacement increases by 445.45% with poor rectification performance under the only rudder rectifying control relative to the designed control law. The braking distance rises by 36m and the braking frequency increases by 85.71% under the control law without anti-skid brake. Different landing conditions are simulated to verify the good robustness of the designed rectifying control.