• Title/Summary/Keyword: Lateral slip angle

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A Study on Integrated Control of AFS and ARS Using Fuzzy Logic Control Method (Fuzzy Logic 제어를 이용한 AFS와 ARS의 통합제어에 관한 연구)

  • Song, Jeonghoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.65-70
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    • 2014
  • An Integrated Dynamics Control system with four wheel Steering (IDCS) is proposed and analysed in this study. It integrates and controls steer angle of front and rear wheel simultaneously to enhance lateral stability and steerability. An active front steer (AFS) system and an active rear steer (ARS) system are also developed to compare their performances. The systems are evaluated during brake maneuver and several road conditions are used to test the performances. The results showed that IDCS vehicle follows the reference yaw rate and reduces side slip angle very well. AFS and ARS vehicles track the reference yaw rate but they can not reduce side slip angle. On split-${\mu}$ road, IDCS controller forces the vehicle to go straight ahead but AFS and ARS vehicles show lateral deviation from centerline.

Autonomous Vehicle Driving Control Considering Tire Slip and Steering Actuator Performance (타이어 슬립과 조향작동장치의 성능을 고려한 무인자동차 자율주행 제어)

  • Park, C.H.;Gwak, G.S.;Jeong, H.U.;Hong, D.U.;Hwang, S.H.
    • Journal of Drive and Control
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    • v.12 no.3
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    • pp.36-43
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    • 2015
  • An autonomous vehicle control algorithm based on Ackerman Geometry is known to be reliable in low tire slip situation. However, vehicles at high speed make lateral errors due to high tire slip. In this paper, considering the tire slip of vehicles, the steering angle is determined based on the Ackerman Geometry and is supplemented tire slip angle by the Stanley steering algorithm. In addition, to prevent the tire slip, the algorithm, which restricts steering if a certain level of slip occurs, is used to reduce the lateral error. While many studies have been extended to include vehicle slip, studies also need to be carried out on the tire slip depending on hardware performance. The control algorithm of autonomous vehicles is compensated considering the sensor noise and the performance of steering actuator. Through the various simulations, it was found that the performance of steering actuator was the key factor affecting the performance of autonomous driving. Also, it was verified that the usefulness of steering algorithm considering the tire slip and performance of steering actuator.

A Study on Lateral Stability Enhancement of 4WS Vehicle with Active Front Wheel Steer System (능동전륜조향장치를 채택한 사륜조향차량의 횡방향 안정성 강화에 대한 연구)

  • Song, Jeong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.2
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    • pp.15-20
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    • 2012
  • This study is to propose and develop an integrated dynamics control system to improve and enhance the lateral stability and handling performance. To achieve this target, we integrate an AFS and a 4WS systems with a fuzzy logic controller. The IDCS determines active additional steering angle of front wheel and controls the steering angle of rear wheel. The results show that the IDCS improves the lateral stability and controllability on dry asphalt and snow paved road when double lane change and step steering inputs are applied. Yaw rate of the IDCS vehicle tracks reference yaw rate very well and body slip angle is reduced about by 50%. Response time of the IDCS vehicle is also decreased.

Design of a Robust Controller to Enhance Lateral Stability of a Four Wheel Steer Vehicle with a Nonlinear Observer (비선형 관측기를 이용한 사륜조향 차량의 횡방향 안정성 강화를 위한 강인 제어기 설계)

  • Song, Jeong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.6
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    • pp.120-127
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    • 2007
  • This paper describes the development of a nonlinear observer for four wheel steer (4WS) vehicle. An observer is designed to estimate the vehicle variables difficult to measure directly. A brake yaw motion controller (BYMC), which uses a PID control method, is also proposed for controlling the brake pressure of the rear and inner wheels to enhance lateral stability. It induces the yaw rate to track the reference yaw rate, and it reduces a slip angle on a slippery road. The braking and steering performances of the anti-lock brake system (ABS) and BYMC are evaluated for various driving conditions, including straight, J-turn, and sinusoidal maneuvers. The simulation results show that developed ABS reduces the stopping distance and increases the longitudinal stability. The observer estimates velocity, slip angle, and yaw rate of 4WS vehicle very well. The results also reveal that the BYMC improves vehicle lateral stability and controllability when various steering inputs are applied.

Static and seismic active lateral earth pressure coefficients for c-ϕ soils

  • Keshavarz, Amin;Pooresmaeil, Zahra
    • Geomechanics and Engineering
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    • v.10 no.5
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    • pp.657-676
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    • 2016
  • In this paper, the active lateral earth pressure is evaluated using the stress characteristics or slip line method. The lateral earth pressure is expressed as the lateral earth pressure coefficients due to the surcharge, the unit weight and cohesion of the backfill soil. Seismic horizontal and vertical pseudo-static coefficients are used to consider the seismic effects. The equilibrium equations along the characteristics lines are solved by the finite difference method. The slope of the ground surface, the wall angle and the adhesion and friction angle of the soil-wall interface are also considered in the analysis. A computer code is provided for the analysis. The code is capable of solving the characteristics network, determining active lateral earth pressure distribution and calculating active lateral earth pressure coefficients. Closed-form solutions are provided for the lateral earth pressure coefficients due to the surcharge and cohesion. The results of this study have a good agreement with other reported results. The effects of the geometry of the retaining wall, the soil and soil-wall interface parameters are evaluated. Non-dimensional graphs are presented for the active lateral earth pressure coefficients.

Monitoring System Design for Estimating Lateral Velocity and Sideslip Angle (감지시스템을 통한 차량의 횡 속도 및 슬립각 추정)

  • Han, Sang-Oh;Huh, Kun-Soo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.1
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    • pp.51-57
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    • 2011
  • Information of the lateral velocity and the sideslip angle in a vehicle is very useful in many active vehicle safety applications such as yaw stability control and rollover prevention. Because cost-effective sensors to measure the lateral velocity and the sideslip angle are not available, reliable algorithms to estimation them are necessary. In this paper, a sliding mode observer is designed to estimate the lateral velocity. The side slip angle is estimated using the recursive least square with the disturbance observer and the pseudo integral. The estimated parameters from the combined estimation method are updated recursively to minimize the discrepancy between the model and the physical plant, and any possible effects caused by disturbances. The performance of the proposed monitoring system is evaluated through simulations and experiments.

Development and Evaluation of ESP Systems for Enhancement of Vehicle Stability during Cornering (II) (차량의 선회시 주행 안정성 강화를 위한 ESP 시스템 개발 및 성능 평가 (II))

  • Song, Jeong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.12 s.255
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    • pp.1551-1556
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    • 2006
  • Two yaw motion control systems that improve a vehicle lateral stability are proposed in this study: a rear wheel steering yaw motion controller (SESP) and an enhanced rear wheel steering yaw motion controller (ESESP). A SESP controls the rear wheels, while an ESESP steers the rear wheels and front outer wheel to allow the yaw rate to track the reference yaw rate. A 15 degree-of-freedom vehicle model, simplified steering system model, and driver model are used to evaluate the proposed SESP and ESESP. A robust anti-lock braking system (ABS) controller is also designed and developed. The performance of the SESP and ESESP are evaluated under various road conditions and driving inputs. They reduce the slip angle when braking and steering inputs are applied simultaneously, thereby increasing the controllability and stability of the vehicle on slippery roads.

Analysis on the Shift Characteristics of Semi-Spherical CVT using 2-dimensional Friction Model (2차원 마찰모델을 이용한 구면무단변속기의 변속특성해석)

  • Kong, Jin-Hyung;Lim, Won-Sik;Park, Yeon-Gil;Kim, Jung-Yun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.4
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    • pp.103-109
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    • 2008
  • Semi-spherical CVT(SS-CVT) is one of friction drives, which transmits power via the friction force between a spherical shaped variator and output disks. The variator varies the speed ratio of SS-CVT continuously as well as transmits input power into the output shaft. Therefore two friction forces are normally applied on the variator; one is the longitudinal friction force for power transmission and the other is the lateral for shifting. In order to investigate the dynamic behavior of SS-CVT, we introduced a numerical model of 2-dimensional friction force using a function of slip ratio and slip angle. And a dynamic model, which describes the shifting mechanism of SS-CVT, is developed through 3-dimensional vector analysis. Finally we presented numerical results of the shift characteristics focused on the transient behavior of the variator's slip ratio and slip angle. The numerical results also show the typical CVT shifting characteristics of SS-CVT and stable shifting behaviors of the variator.

The Study on PRAT Performance due to Tire Pattern Shapes using Steady State Rolling Analysis Method (정상 상태 롤링 해석 기법 적용을 통한 타이어 패턴 형상에 따른 PRAT 특성 연구)

  • Sung, Ki-Deug;Park, Hyun-Man;Koo, Byong-Kook;Cho, Choon-Tack
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.5
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    • pp.15-21
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    • 2008
  • It is generally known that the PRAT(Plysteer Residual Aligning Torque) is one of indicating a performance factors of a tire for assessing the vehicle pull, also tire pattern shape, which means lateral groove angle, is very important tire design factor in relation to the PRAT. Lateral grooves of tire pattern are widely divided into center and shoulder parts. So, this paper has studied the correlation between the PRAT and their lateral groove angles using FEM. Especially, the steady state rolling analysis among tire rolling analysis methods has been used for the PRAT performance study. Firstly, analysis result data have been compared with the experimental data to validate FE analysis for PRAT. Next, the PRAT due to the lateral groove angle about PCR(Passenger Car Radial) tire and SUV tire has been analyzed. The tendency of the PRAT due to the lateral groove angles can be used as a guide line for the tire design in relation to vehicle pull.

Development of an Integrated Control System between Active Front Wheel System and Active Rear Brake System (능동전륜조향장치 및 능동후륜제동장치의 통합제어기 개발)

  • Song, Jeong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.6
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    • pp.17-23
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    • 2012
  • An integrated dynamic control (IDCF) with an active front steering system and an active rear braking system is proposed and developed in this study. A fuzzy logic controller is applied to calculate the desired additional steering angle and desired slip of the rear inner wheel. To validate IDCF system, an eight degree of freedom, nonlinear vehicle model and a sliding mode wheel slip controller are also designed. Various road conditions are used to test the performance. The results show that the yaw rate of IDCF vehicle followed the reference yaw rate and reduced the body slip angle, compared with uncontrolled vehicle. Thus, the IDCF vehicle had enhanced lateral stability and controllability.