共查询到20条相似文献,搜索用时 15 毫秒
1.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(4):231-260
SUMMARY This article begins with a brief review of the traditional concept of lateral relaxation length. The review illustrates that this concept yields a useful approximation which can be used with semi-empirical tire models which assume lateral forces are a function of steady-state slip angles. The article then presents an analogous derivation for longitudinal slip. Like its lateral counterpart, the derivation yields an approximation for transient longitudinal slip which can be used with tire models which assume longitudinal forces are a function of steady-state longitudinal slip. It is shown that, like the relaxation-length-based lateral slip angle, this formulation for longitudinal slip yields the ability to compute shear forces at the tire/road interface for either high or low speed applications, a necessary feature of simulations which support human in the loop driving simulation. Like traditional kinematically-based longitudinal slip, the transient formulation presented here is coupled with the wheel spin equation, and it shares the characteristic that it is very stiff compared to the equations of vehicle motion. This characteristic is a challenge impeding the real-time calculations required for driving simulation. The paper shows that local linearization of the wheel spin equations coupled with analytical solutions of the transient longitudinal slip formulation provide the basis for both insight into the longitudinal dynamics of the tire and for integrating the model in real-time. 相似文献
2.
A semi-empirical dynamic tire model for combined-slip forces 总被引:1,自引:0,他引:1
Jacob Svendenius Magnus G fvert 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2006,44(2):189-208
This article presents a semi-empirical combined-slip tire model including transient behavior. It is assumed that the transient behavior is a result from the dynamic deformation of the tire carcass and that the interaction between the lateral and longitudinal slip, and forces can be explained by the deformation of the rubber treads. The deformation of the tire carcass makes the tread slip deviate from the wheel-rim motion in a way that may be described by differential equations. A method based on brush-model tire mechanics is used to construct the combined-slip forces as nonlinear scalings of corresponding pure-slip forces. 相似文献
3.
E. Velenis P. Tsiotras C. Canudas-de-Wit M. Sorine 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2005,43(1):3-29
An extension to the LuGre dynamic friction model from longitudinal to longitudinal/lateral motion is developed in this paper. Application of this model to a tyre yields a pair of partial differential equations that model the tyre-road contact forces and aligning moment. A comparison of the steady-state behaviour of the dynamic model with existing static tyre friction models is presented. This comparison allows one to determine realistic values of the parameters for the new dynamic model. Via the introduction of a set of mean states we reduce the partial differential equations to a lumped model governed by a set of three ordinary differential equations. Such a lumped form describes the aggregate effect of the friction forces and moments and it can be useful for control design and online estimation. A method to incorporate wheel rim rotation is also proposed. The proposed model is evaluated by comparing both its steady-state as well as its dynamic characteristics via numerical simulations. The results of the simulations corroborate steady-state and dynamic/transient tyre characteristics found in the literature. 相似文献
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5.
This paper describes a design of a real-time conversion system of wheel linear accelerations into tire lateral forces. Though the tire lateral forces are important elements for analyzing vehicle dynamic control performances, they cannot be easily measured in real-time owing to the non-linearities of tire dynamics, friction, and slippage on road. In this paper, we propose a practical direct method using wheel linear accelerations in order to estimate tire lateral forces transmitted into the vehicle in real-time. A simplified vehicle model based on force-acceleration analysis is proposed to assure the real-time performance. The acceleration values are obtained using three-axis accelerometers attached on each wheel location. For conditioning and rectifying the acceleration signals, a signal transducer is designed using a digital filter. And in order to investigate the feasibility and real-time performance, a prototype of signal transducer is fabricated using a digital signal processor. The experimental results and performance are validated with the road test results using six-component wheel force transducers. 相似文献
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7.
轮胎附着极限下差动制动对汽车横摆力矩的影响 总被引:20,自引:3,他引:20
本文以纵滑-侧偏联合工况的稳态轮胎模型为基础,分析了汽车极限转向条件下制动作用于不同车轮时对汽车横摆力矩的影响,并通过整车动力学仿真进行了验证,研究结果为利用差动制动控制提高汽车的高速操纵稳定性提供了动力学依据。 相似文献
8.
Nonlinear Dynamics of Vehicle Traction 总被引:3,自引:0,他引:3
B. J. Olson S. W. Shaw G. St p n 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2003,40(6):377-399
Summary The purpose of this study is to understand the nonlinear dynamics of longitudinal ground vehicle traction. Specifically, single-wheel models of rubber-tired automobiles under straight-ahead braking and acceleration conditions are investigated in detail. Customarily, the forward vehicle speed and the rotational rate of the tire/wheel are taken as dynamic states. This paper motivates an alternative formulation in which wheel slip, a dimensionless measure of the difference between the vehicle speed and the circumferential speed of the tire relative to the wheel center, replaces the angular velocity of the tire/wheel as a dynamic state. This formulation offers new insight into the dynamic behavior of vehicle traction. The unique features of the modeling approach allow one to capture the full range of dynamic responses of the single-wheel traction models in a relatively simple geometric manner. The models developed here may also be useful for developing and implementing anti-lock brake and traction control control schemes. 相似文献
9.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(6):377-399
Summary The purpose of this study is to understand the nonlinear dynamics of longitudinal ground vehicle traction. Specifically, single-wheel models of rubber-tired automobiles under straight-ahead braking and acceleration conditions are investigated in detail. Customarily, the forward vehicle speed and the rotational rate of the tire/wheel are taken as dynamic states. This paper motivates an alternative formulation in which wheel slip, a dimensionless measure of the difference between the vehicle speed and the circumferential speed of the tire relative to the wheel center, replaces the angular velocity of the tire/wheel as a dynamic state. This formulation offers new insight into the dynamic behavior of vehicle traction. The unique features of the modeling approach allow one to capture the full range of dynamic responses of the single-wheel traction models in a relatively simple geometric manner. The models developed here may also be useful for developing and implementing anti-lock brake and traction control control schemes. 相似文献
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The electric vehicle with four direct-driven in-wheel motors is an over actuated system. A three-level control strategy of electronic stability control (ESC) is proposed to achieve optimal torque distribution for four in-wheel motors. The first level is a gain-scheduled linear quadratic regulator which is designed to generate the desired yaw moment command for ESC. Control allocation is the second level which is used to distribute the desired longitudinal tire forces according to the yaw moment command while satisfying the driver’s intent for acceleration and deceleration. The associated weighting matrix is designed using the work load ratio at each wheel to prevent saturating the tire. The third level is slip ratio control (SRC) which is employed at each wheel to generate the desired longitudinal tire force based on a combined-slip tire model. Simulation results show that the proposed method can enhance the ESC performance for the test maneuvers. Since the tire model is often unknown for practical implementation, the effectiveness of the SRC is studied using the sine with dwell test. It is found that the SRC is not crucial for achieving performance similar to the proposed method with SRC, if the slip ratio can be maintained in the stable region using traction control system/anti-lock braking system. 相似文献
12.
A hierarchical control structure is a more suitable structural scheme for integrated chassis control. Generally, this type of structure has two main functions. The upper layer manages global control and force allocation, while the bottom layer allocates realized forces with 4 independent local tire controllers. The way to properly allocate these target forces poses a difficult task for the bottom layer. There are two key problems that require attention: obtaining the nonlinear time-varying coefficient of friction between the tire and different road surfaces and accurately tracking the desired forces from the upper layer. This paper mainly focuses on longitudinal tire-road friction allocation and control strategies that are based on the antilock braking system (ABS). Although it is difficult to precisely measure longitudinal tire-road friction forces for frequently changing road surface conditions, they can be estimated with a real-time measurement of brake force and angular acceleration at the wheels. The Magic Formula model is proposed as the reference model, and its key parameters are identified online using a constrained hybrid genetic algorithm to describe the evolution of tire-road friction with respect to the wheel slip. The desired wheel slip, with respect to the reference tire-road friction force from the top layer, is estimated with the inverse quadratic interpolation method. The tire-road friction controller of the extended anti-lock braking system (Ext-ABS) is designed through use of the nonlinear sliding mode control method. Simulation results indicate that acceptable modifications to changes in road surface conditions and adequate stability can be expected from the proposed control strategy. 相似文献
13.
Kiyoshi Wakamatsu Yoshimitsu Akuta Manabu Ikegaya Nobuyoshi Asanuma 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,27(5):305-326
This paper proposes an adaptive yaw rate feedback control system for a four-wheel-steering (4WS) vehicle which involves a tire/road friction coefficient estimator. The adaptive 4WS system has been developed so that the vehicle possesses desirable lateral characteristics even on slippery roads and in critical driving situations. The friction coefficient is estimated on real time from the yaw rate response of the controlled vehicle with the least squares. The control system adopts a two degree of freedom structure which consists of a feedforward compensator and a feedback control subsystem. The feedforward compensator is determined with the estimated friction coefficient to minimize the steady-state and transient vehicle slip angle in spite of changes in tire/road conditions. The feedback subsystem adopts the Internal Model Control (IMC) structure in order to compensate for nonlinearities and to realize robustness against modelling and estimation errors. 相似文献
14.
In a dynamic vehicle simulation, longitudinal tire force is primarily based on the longitudinal slip (ratio). In the longitudinal
slip formula, state variables are used in the denominator. This causes a divergence problem for numerical simulations of vehicle
dynamics. To avoid this numerical singularity, a differential slip calculation method was developed for use in dynamic vehicle
simulations. However, this method also causes a singularity when the wheel velocity approaches zero in a pure slip state,
such as during sudden braking. In this paper, a new longitudinal slip calculation method, which can overcome singularities
in all velocity conditions, is proposed. For this purpose, the Taylor series is adapted to the slip formula and the idea of
virtual wheel rotation stiffness is introduced for the development of the slip equation. The physical phenomenon at the zero
slip state is analyzed. Finally, the proposed slip formula is used to solve the numerical singularity problem, and the non-singular
slip (NSS) calculation method is proposed. The proposed NSS method is applied to tire model performance test (TMPT) simulations
to validate its performance. 相似文献
15.
This paper describes a drive controller designed to improve the lateral vehicle stability and maneuverability of a 6-wheel
drive / 6-wheel steering (6WD/6WS) vehicle. The drive controller consists of upper and lower level controllers. The upper
level controller is based on sliding control theory and determines both front and middle steering angle, additional net yaw
moment, and longitudinal net force according to the reference velocity and steering angle of a manual drive, remotely controlled,
autonomous controller. The lower level controller takes the desired longitudinal net force, yaw moment, and tire force information
as inputs and determines the additional front steering angle and distributed longitudinal tire force on each wheel. This controller
is based on optimal distribution control and takes into consideration the friction circle related to the vertical tire force
and friction coefficient acting on the road and tire. Distributed longitudinal/lateral tire forces are determined as proportion
to the size of the friction circle according to changes in driving conditions. The response of the 6WD/6WS vehicle implemented
with this drive controller has been evaluated via computer simulations conducted using the Matlab/Simulink dynamic model.
Computer simulations of an open loop under turning conditions and a closed-loop driver model subjected to double lane change
have been conducted to demonstrate the improved performance of the proposed drive controller over that of a conventional DYC. 相似文献
16.
制动—驱动工况下的轮胎侧偏特性理论研究 总被引:2,自引:0,他引:2
本文通过考虑制动和驱动工况下的轮胎印迹内垂直载荷分布的不同,建立了比以往模型更完善的制动-驱动工况下的轮胎侧偏特性理论模型,以6.50R16轮胎为例,分析了滑移率,侧偏角和垂直载荷分布形状参数等对其侧特性的影响。 相似文献
17.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(11):1685-1704
ABSTRACTThe handling characteristic is a classical topic of vehicle dynamics. Usually, vehicle handling is studied by analyzing the understeer coefficient in quasi-steady-state maneuvers. In this paper, experimental tests are performed on an electric vehicle with four independent motors, which is able to reproduce front-wheel-drive, rear-wheel-drive and all-wheel-drive (FWD, RWD and AWD, respectively) architectures. The handling characteristics of each architecture are inferred through classical and new concepts. The study presents a procedure to compute the longitudinal and lateral tire forces, which is based on a first estimate and a subsequent correction of the tire forces that guarantee the equilibrium. A yaw moment analysis is performed to identify the contributions of the longitudinal and lateral forces. The results show a good agreement between the classical and new formulations of the understeer coefficient, and allow to infer a relationship between the understeer coefficient and the yaw moment analysis. The handling characteristics vary with speed and front-to-rear wheel torque distribution. An apparently surprising result arises at low speed: the RWD architecture is the most understeering configuration. This is discussed by analyzing the yaw moment caused by the longitudinal forces of the front tires, which is significant for high values of lateral acceleration and steering angle. 相似文献
18.
Masao Nagai Yutaka Hirano Sachiko Yamanaka 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,27(5):357-370
An integrated control system of active rear wheel steering (4WS) and direct yaw moment control (DYC) is presented in this paper. Because of the tire nonlinearity that is mainly due to the saturation of cornering forces, vehicle handling performance is improved but limited to a certain extent only by steering control. Direct yaw moment control using braking and/or driving forces is effective not only in linear but also nonlinear ranges of tire friction circle. The proposed control system is a model matching controller which makes the vehicle follow the desired dynamic model by the state feedback of both yaw rate and side slip angle. Various computer simulations are carried out and show that vehicle handling performance is much improved by the integrated control system. 相似文献
19.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(5-6):357-370
SUMMARY An integrated control system of active rear wheel steering (4WS) and direct yaw moment control (DYC) is presented in this paper. Because of the tire nonlinearity that is mainly due to the saturation of cornering forces, vehicle handling performance is improved but limited to a certain extent only by steering control. Direct yaw moment control using braking and/or driving forces is effective not only in linear but also nonlinear ranges of tire friction circle. The proposed control system is a model matching controller which makes the vehicle follow the desired dynamic model by the state feedback of both yaw rate and side slip angle. Various computer simulations are carried out and show that vehicle handling performance is much improved by the integrated control system. 相似文献
20.
Dynamic Friction Models for Road/Tire Longitudinal Interaction 总被引:5,自引:0,他引:5
Carlos Canudas-de-Wit Panagiotis Tsiotras Efstathios Velenis Michel Basset Gerard Gissinger 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2003,39(3):189-226
Summary In this paper we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles. The model is based on a dynamic friction model developed previously for contact-point friction problems, called the LuGre model. By assuming a contact patch between the tire and the ground we develop a partial differential equation for the distribution of the friction force along the patch. An ordinary differential equation (the lumped model) for the friction force is developed, based on the patch boundary conditions and the normal force distribution along the contact patch. This lumped model is derived to approximate closely the distributed friction model. Contrary to common static friction/slip maps, it is shown that this new dynamic friction model is able to capture accurately the transient behaviour of the friction force observed during transitions between braking and acceleration. A velocity-dependent, steady-state expression of the friction force versus the slip coefficient is also developed that allows easy tuning of the model parameters by comparison with steady-state experimental data. Experimental results validate the accuracy of the new tire friction model in predicting the friction force during transient vehicle motion. It is expected that this new model will be very helpful for tire friction modeling as well as for anti-lock braking (ABS) and traction control design. 相似文献