• Title, Summary, Keyword: Understeer

Search Result 20, Processing Time 0.031 seconds

Stochastic Analysis for Vehicle Dynamics using the Monte-Carlo Simulation (Monte-Carlo 시뮬레이션을 이용한 확률적 차량동역학 해석)

  • Tak, Tae-Oh;Joo, Jae-hoon
    • Journal of Industrial Technology
    • /
    • v.22 no.B
    • /
    • pp.3-12
    • /
    • 2002
  • Monte-Carlo simulation technique has advantages over deterministic simulation in various engineering analysis since Monte-Carlo simulation can take into consideration of scattering of various design variables, which is inherent characteristics of physical world. In this work, Monte-Carlo simulation of steady-state cornering behavior of a truck with design variables like hard points and busing stiffness. The purpose of the simulation is to improve understeer gradient of the truck, which exhibits a small amount of instability when the lateral acceleration is about 0.4g. Through correlation analysis, design variables that have high impacts on the cornering behavior were selected, and significant performance improvement has been achieved by appropriately changing the high impact design variables.

  • PDF

A Study on the Effects of Suspension Design Parameters on Cornering Performances of a Vehicle (차량의 선회성능에 미치는 현가장치 설계인자의 영향에 관한 연구)

  • 이장무;윤중락;강주석;정종혁;탁태오
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.4 no.4
    • /
    • pp.27-37
    • /
    • 1996
  • In this paper the effects of suspension design parameters on the steady-state cornering performance of vehicles are studied. To investigate the understeer characteristics of vehicles, steady-state cornering equatons are derived from a two-track model which is expanded from a simple one track model. The effects of the suspension design parameters as well as those of lateral load transfer are taken into consideration. To verify the equation, a skid pad test was carried out with a domestic passenger car. The design parameters of the vehicle are measured using a Suspension Parameter Measuring Device(SPMD). Based on these results, parameter studies are carried out to determine the effect of design parameters on the cornering performance of a vehicle, both in low and high acceleration region.

  • PDF

A Study on the DYC 4WS Control Method for Improving the Dynamic Characteristics of Vehicle (자동차의 주행성능 향상을 위한 DYC 4WS 제어방법에 관한 연구)

  • 김형내;김석일;김동룡;김건상
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.6 no.2
    • /
    • pp.1-11
    • /
    • 1998
  • The 4WS system is usually developed to improve the maneuverability at low speed and the straight line stability at high speed, but it is found to have the severe understeer characteristics at high speed. Therefore a 4WS vehicle requires to turn the steering wheel much more than a 2WS vehicle at high speeds even a driver goes through the same curved road. In this study, to enhance the cornering performance of the 4WS vehicle at high speed, a DYC 4WS system is proposed based on the nonlinear 4WS system and direct yaw moment control system. Especially the proposed DYC 4WS system is able to realize a zero side slip angle for vehicles and a cornering performance similar to the 2WS vehicle at high speed.

  • PDF

Optimal Design of Shock Absorber using High Speed Stability (고속 안정성을 고려한 쇽업소버 최적 설계)

  • 이광기;모종운;양욱진
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.6 no.4
    • /
    • pp.1-8
    • /
    • 1998
  • In order to solve the conflict problem between the ride comfort and the road holding, the optimal design of shock absorber that minimizes the r.m.s. of sprung mass vertical acceleration and pitch rate with the understeer characteristics constraints in the high speed stability is proposed. The design of experiments and the nonlinear optimization algorithm are used together to obtain the optimal design of shock absorber. The second order regression models of the input variables(front and rear damping coefficients) and the output variables (ride comfort index and road holding one) are obtained by the central composite design in the design of experiments. Then the optimal design of shock absorber can be systematically adjusted with applying the nonlinear optimization algorithm to the obtained second order regression model. The frequency response analysis of sprung mass acceleration and pitch rate shows the effectiveness of the proposed optimal design of shock absorber in the sprung mass resonance range with the understeer characteristics constraints.

  • PDF

A Study on the Steady-State Cornering of a Vehicle Considering Roll Motion (롤 운동을 고려한 차량의 정상상태 선회주행에 관한 연구)

  • 이장무;윤중락;강주석;배상우;탁태오
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.5 no.6
    • /
    • pp.89-102
    • /
    • 1997
  • In this study, the steady state cornering behavior of a vehicle is investigated by using a numerical model that has parameters associated with roll motion. The nonlinear characteristics of tire cornering forces and aligning torques are presented in analytical forms using the magic formula. The sets of nonlinear algebraic equations that govern the cornering motion are solved by the Newton-Raphson iteration method. The vehicle design parameters are measured by SPMD(Suspension Parameter Measuring Device), and its results are verified by carrying out a skid pad test. The design parameters that are most affecting the steady state cornering behavior are classified into four factors, and the contributions of the factors to understeer gradient are then calculated.

  • PDF

A Study on the Full Active 4WS Control Method Using Nonlinear Tire Model (비선형 타이어모델을 이용한 완전능동형 4WS 제어방법에 관한 연구)

  • 김형내;김석일;김동룡;김건상
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.5 no.3
    • /
    • pp.76-85
    • /
    • 1997
  • The understeer characteristics of four wheel steering system(4WS system) in a high speed region have a negative effect upon the yaw velocity, leading to a decrease in the handling ability of vehicle. As a result, even if the side slip angle of vehicle can be kept up a minimum, a driver must compensate a decrease in yaw velocity by increasing the steering wheel angle in order to track the desired vehicle path. In this study, to keep the side slip angle of vehicle at zero and achieve a suitable yaw velocity in vehicle motion, a full active 4WS system(FA 4WS system) with actively steerable front and rear wheels is presented based on a nonlinear vehicle model and a model following control of yaw velocity. And the analysis results show the fat that, besides the excellent stability of vehicle, the FA 4WS system is able to realize better handling performance of vehicle than the previous 4WS systems in the high speed region.

  • PDF

Development of a Control Method of Traction Control System Using Vehicle Model (차량 모델을 이용한 구동력 제어 시스템 (TCS)의 제어 방법 개발)

  • Song Jeonghoon;Kim Heungseob;Lee Dae Hee;Son Minhyuk
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.28 no.8
    • /
    • pp.1203-1211
    • /
    • 2004
  • A traction control systems (TCSs) composed of either a wheel slip controller or a throttle valve controller or an integrated controller of both systems are proposed in this study. To validatethe dynamic characteristics of a vehicle and TCS, a full car model that can simulate the responses of both front wheel drive (2WD) and four wheel drive (4WD) vehicle is also developed. The wheel slip controller uses a sliding mode control scheme and the throttle valve is controlled by a PID controller. The results shows that tHe brake TCS and the engine TCS achieve rapid acceleration, and reduce slip angle on slippery road. When a vehicle is cornering and accelerating maneuver with the brake or engine TCS, understeer or oversteer occur, depending on the driving conditions. The integrated TCS prevents most of these problems and improves the stability and controllability of the vehicle.

Effects of an actuator attached to roll stabilizer bar on vehicle performance (롤안정바에 부착된 엑츄체이터가 차량의 성능에 미치는 영향 분석)

  • Sung, In-Chol;Kim, Keun-Soo;Yoo, Wan-Suk
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.649-654
    • /
    • 2000
  • To analyze the effects of the front and rear roll stabilizer bar, five different models of roll stabilizer bar are simulated in this paper. It is shown that the stiffness change of the roll stabilizer bar is an effective way to alter the vehicle's roll gradient. Attaching an actuator at the roll stabilizer bar the vehicle's roll gradient can be controlled within error limits.

  • PDF

Dynamic Analysis and Optimization of 1ton Commercial Truck Using ADAMS/Insight (ADAMS/Insight를 이용한 1톤 상용트럭의 동역학 해석 및 최적화)

  • Chun, Hung-Ho;Tak, Tae-Oh
    • Journal of Industrial Technology
    • /
    • v.23 no.A
    • /
    • pp.15-20
    • /
    • 2003
  • Stochastic simulation technique has advantages over deterministic simulation in various engineering analysis, since stochastic simulation can take into consideration of scattering of various design variables, which is inherent characteristics of physical world. In this work, Monte-Carlo simulation mothod in ADAMS/Insight for steady-state cornering and J-turn behavior of a truck with design variables like hard points and busing stiffnesses have performed to achieve better dynamic performance. The main purpose is to improve understeer gradient at steady-state cornering and minimize peak lateral acceleration and peak yaw rate at J-turn. Through correlation analysis, design variables that have high impacts on the cornering behavior were selected, and significant performance improvement has been achieved by appropriately changing the high impact design variables.

  • PDF

A Study on the 4WS Control Method with the Effect of Steering Wheel Angular Velocity (핸들조향속도를 고려한 4WS 제어방법에 관한 연구)

  • 이영화;김석일;김대영;김동룡
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.4 no.3
    • /
    • pp.168-175
    • /
    • 1996
  • Except the collision avoidance performance related to the rapid lane change, the 4WS vehicle has better dynamic stability and handling performance than the conventional 2WS vehicle which has close relation with the driver's safety, a 4WS conrol method with the effect of steering wheel angular velocity is proposed based on the fact that the driver steers abruptly the steering wheel to avoid the collision. And the effects of the proposed 4WS control method are investigated on the dynamic stability and handling performance by using the ISO lane change test code.

  • PDF