• Title, Summary, Keyword: Lateral Acceleration

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Evaluation of Tire Lateral Hydroplaning using Measured Vehicle Acceleration (가속도 계측을 이용한 타이어 선회 수막현상의 평가)

  • Kang, Young Kyu;Hwang, JangSoon;Oh, YagJeon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.623-625
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    • 2013
  • Tire hydroplaning is one of the most important tire performances, especially for safety on wet road surface. And nowadays various methods such as FEM and FVM analysis are being applied to design and improve tire hydroplaning performance, along with on-vehicle test of tire hydroplaning. Conventional evaluation of tire hydroplaning has been done by comparing peak lateral acceleration and vehicle speed in time domain. But in this paper, frequency domain analysis of lateral acceleration when hydroplaning at high speed has been carried out to get the quantitative comparison between test tires. And it is concluded that the frequency spectrum analysis of lateral acceleration gives much better discrimination, as compared to the conventional time domain analysis of lateral acceleration and vehicle speed.

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Experimental Study of Driving Load Conditions for the Wheel Bearing Hub Unit of Passenger Car (승용차용 Wheel Bearing Hub Unit 설계를 위한 주행 하중조건의 실험적 연구)

  • 김기훈;유영면;임종순
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.2
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    • pp.166-173
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    • 2002
  • The wheel bearing hub unit is developed type of wheel bearing unified with the hub parts. It has advantage of reducing the weight and the number of components. And, it also improves uniformity of manufacturing quality, In order to design the wheel bearing hub units, many techniques are used such as load analysis, structure analysis and bearing characteristics analysis and so forth. These techniques need highly accurate load conditions founded on service conditions. In this study, to design the wheel bearing hub units used widespread in passenger cars, the service load was measured through driving tests on the public roads and in the special events. The public roads are classified into highway, intercity road, rural road, urban road, and unpaved road so as to know what the characteristics of the road loads are. The results of the tests showed that the wheel force was relative to the lateral acceleration, and also could be calculated from the lateral acceleration. The lateral acceleration was measured from 0.0G to 0.6G in general driving on the public roads, with different distributions in each road type. In special events, the maximum lateral acceleration was measured from 0.8G to 1.3G.

Estimation of critical speed and running performance for swing motion bogie of railway freight car (화물수송용 스윙모션보기의 임계속도와 주행성능 평가)

  • 함영삼;오택열
    • Journal of the Korean Society for Railway
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    • v.6 no.4
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    • pp.215-220
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    • 2003
  • In this paper the dynamic characteristics of a Swing Motion Bogie, such as a critical speed and a carbody vibration, are investigated in reply to the request of the Meridian Rail Corporation in the United States. Also described are experimental results of the maximum speed, the derailment coefficient, the lateral force, the vertical force, the vibration acceleration and steady state lateral acceleration measured from main line tests.

Evaluation of critical speed & running performance for Swing Motion Bogie (스웡모션보기의 임계속도와 주행성능 평가)

  • 함영삼;허현무;오택열
    • Proceedings of the KSR Conference
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    • pp.892-897
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    • 2002
  • The research was requested by Meridian Rail Corporation in United States. The Swing Motion Bogie can application by Korea style if synthesize study result of bogie strength evaluation, bogie dynamic characteristics analysis, actual test(maximum speed, derailment coefficient, lateral force, vertical force, vibration acceleration, steady state lateral acceleration) etc..

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Decoupling Control of 2WS Cars Using Direct Yaw Moment (직접요오모멘트를 이용한 이륜조향차량의 비결합 제어기 설계)

  • Choi, Jae-Weon;Cho, Chung-Nae
    • Journal of Institute of Control, Robotics and Systems
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    • v.11 no.9
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    • pp.761-767
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    • 2005
  • There exists a structural limit of 2WS cars that drivers would not like simultaneously to follow the desired path and attenuate moments resulting from disturbances because lateral acceleration and yaw rate are coupled inherently. In order to overcome the limit, the 4WS cars that have rear wheel steering as an additional input have been introduced. But the 4WS cars have disadvantages that much cost is required due to structural alteration, it is difficult to be used to the driving circumstances and tire performances are not efficient in nonlinear or large lateral acceleration ranges. Therefore, it is proposed that, in this paper, a robust controller is easy to apply to 2WS cars by using direct yaw moment, decouples lateral acceleration from yaw motion and is robust against disturbances and uncertainties of system parameters, and thus the proposed control method has the advantages of 4WS cars which can be achieved in 2WS cars.

A study on the effects of active suspension upon vehicle handling (능동 현가장치가 차량의 핸들링에 미치는 영향에 관한 연구)

  • Lee, Jung-Sup;Kwon, Hyok-Jo;Oh, Chae-Youn
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.3
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    • pp.603-610
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    • 1998
  • This paper develops a 7 DOF vehicle model to study the effects of the active suspension on ride. The model is used to derive a control law for the active suspension using a full state linear optimal control technique. A wheelbase preview type active suspension is also considered in the control law derivation. The time delay between wheelbases is approximated using Pade approximation technique. The ride model is extended to a 14 DOF handling model. The 14 DOF handling model includes lateral, longitudinal, yaw and four wheel spin motions in addition to the 7 DOF ride model. A control law which is derived considering only ride related parameters is used to study the effects of the active suspension on a vehicle handling. J-turn maneuver simulation results show that the active suspension has a slower response in lateral acceleration and yaw rate, a bigger steady state lateral acceleration and an oversteer tendency. Lane changing maneuver simulation results show that the active suspension has a little bigger lateral acceleration but a much smaller roll angle and roll motion. Braking maneuver simulation results show that the active suspension has a much smaller pitch angle and pitch motion.

Climbing Angle Estimation in Yawing Motion by UIO (UIO를 이용한 선회 시 등판각 추정)

  • Byeon, Hyeongkyu;Kim, Hyunkyu;Kim, Inkeun;Huh, Kunsoo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.5
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    • pp.478-485
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    • 2015
  • Availability of the climbing angle information is crucial for the intelligent vehicle system. However, the climbing angle information can't be measured with the sensor mounted on the vehicle. In this paper, climbing angle estimation system is proposed. First, longitudinal acceleration obtained from gyro-sensor is compared with the actual longitudinal acceleration of the vehicle. If the vehicle is in yawing motion, actual longitudinal acceleration can't be approximated from time derivative of wheel speed, because lateral velocity and yaw rate affect actual longitudinal acceleration. Wheel speed and yaw rate can be obtained from the sensors mounted on the vehicle, but lateral velocity can't be measured from the sensor. Therefore, lateral velocity is estimated using unknown input observer with nonlinear tire model. Simulation results show that the compensated results using lateral velocity and yaw rate show better performance than uncompensated results.

Optimization of Suspension Under the Condition of Curved Track in Railway Vehicle

  • Choi, Jong Yoon;Li, Zheng Yuan;Baek, Seung Guk;Song, Ki Seok;Koo, Ja Choon;Choi, Yeon Sun
    • International Journal of Railway
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    • v.7 no.2
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    • pp.57-63
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    • 2014
  • This paper presents the optimization of suspension characteristics under the condition of curved track railway vehicles. Reducing lateral acceleration on curved track is an issue for high-speed railway vehicles. In terms of curved track running environments, reducing the lateral vibration of railway vehicles is critical to safety and curving performance. The properties of lateral damping and stiffness of both primary and secondary suspension show effect on wheel-set, bogie and car-body. Analysis for reducing the lateral vibration of rail vehicles with respect to the characteristics of both primary and secondary suspension has been developed using ADAMS/Rail. Response Surface Method has been chosen for the purpose of verifying correlation effects among design parameters. Also, this paper suggests the method for designing optimal suspension of railway vehicles on curved track. The optimization result indicates decrement of lateral acceleration on wheel-set by 3% and bogie by 1% on curved track. Finally, this paper comes to the conclusion that suspension system of railway vehicle (KTX I) is properly designed when regarding lateral vibration of railway vehicle on diverse curved track condition.

Seismic lateral earth pressure analysis of retaining walls

  • Ismeik, Muhannad;Shaqour, Fathi
    • Geomechanics and Engineering
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    • v.8 no.4
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    • pp.523-540
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    • 2015
  • Based on limit equilibrium principles, this study presents a theoretical derivation of a new analytical formulation for estimating magnitude and lateral earth pressure distribution on a retaining wall subjected to seismic loads. The proposed solution accounts for failure wedge inclination, unit weight and friction angle of backfill soil, wall roughness, and horizontal and vertical seismic ground accelerations. The current analysis predicts a nonlinear lateral earth pressure variation along the wall with and without seismic loads. A parametric study is conducted to examine the influence of various parameters on lateral earth pressure distribution. Findings reveal that lateral earth pressure increases with the increase of horizontal ground acceleration while it decreases with the increase of vertical ground acceleration. Compared to classical theory, the position of resultant lateral earth force is located at a higher distance from wall base which in turn has a direct impact on wall stability and economy. A numerical example is presented to illustrate the computations of lateral earth pressure distribution based on the suggested analytical method.

The Influence of Wedged Insole and Foot Progression Angle on Lateral Thrust of Knee During Walking (보행 시 Wedged 인솔과 보행진행 각이 슬관절 외측 밀림(Lateral Thrust)에 미치는 영향)

  • Jung, Do-Young;Kim, Moon-Hwan;Kwon, Oh-Yun
    • Physical Therapy Korea
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    • v.11 no.2
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    • pp.27-34
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    • 2004
  • The purpose of this study was to identify the influence of wedged insole and foot progression angle (FPG) on lateral thrust of knee in healthy subjects. Fifteen healthy male subjects were recruited from Suncheon First College, in Suncheon. The subjects randomly walked at the comfortable velocity under five conditions: bare footed, medio-lateral $10^{\circ}$ wedged insoles, toe-in and toe-out gait. The lateral thrust was measured by a accelerometer with telemeter during walking. Data was collected while each subject walked for about 10 gait cycle on a flat, level walkway at their normal speed. The middle three gait cycle were used for averaged peak value of lateral acceleration. The three averaged peak value of lateral acceleration were collected under each condition at heel strike. The results showed that averaged peak value of lateral acceleration increased significantly in medial wedged insole and toe-in gait and decreased significantly in lateral wedged insole and toe-out gait as compared with bare footed (p<.05). These results suggest that wedged insole as well as walking strategy, such as foot progression angle, may prevent progression of degenerative knee osteoarthritis.

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