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P. E. Pfeffer M. Harrer D. N. Johnston 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2008,46(5):413-428
For the on-centre handling behaviour of vehicles the steering system is absolutely important. To investigate the interaction of the vehicle and steering system a validated, especially tailored simulation model was developed. Some meaningful vehicle and steering system parameters are altered to show the influence on steering wheel torque, steering feel and understeer. The results underline the importance of an accurate steering system model. Identified measures to improve the centre feel and steering response were a stiffer torsion bar, a higher cornering stiffness or a lower overall steering ratio. The steering response, however, suffers when the centre feel is improved by a higher trail. The steering rack friction reduces mainly the steering response while the steering column friction decreases the centre feel whereas a stiffer torsion bar lessens the understeer tendency. 相似文献
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F. Bucchi F. Frendo 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(6):831-847
The handling behaviour of vehicles is an important property for its relation to performance and safety. In 1970s, Pacejka did the groundwork for an objective analysis introducing the handling diagram and the understeer coefficient. In more recent years, the understeer concept is still mentioned but the handling is actively managed by direct yaw control (DYC). In this paper an accurate analysis of the vehicle handling is carried out, considering also the effect of drive forces. This analysis brings to a new formulation of the understeer coefficient, which is almost equivalent to the classical one, but it can be obtained by quasi-steady-state manoeuvres. In addition, it relates the vehicle yaw torque to the understeer coefficient, filling up the gap between the classical handling approach and DYC. A multibody model of a Formula SAE car is then used to perform quasi-steady-state simulations in order to verify the effectiveness of the new formulation. Some vehicle set-ups and wheel drive arrangements are simulated and the results are discussed. In particular, the handling behaviours of the rear wheel drive (RWD) and the front wheel drive (FWD) architectures are compared, finding an apparently surprising result: for the analysed vehicle the FWD is less understeering than for RWD. The relation between the yaw torque and the understeer coefficient allows to understand this behaviour and opens-up the possibility for different yaw control strategies. 相似文献
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三轴汽车前后轮角输入时的响应特性 总被引:5,自引:0,他引:5
本文详细推导了三轴汽车线性二自由度模型的运动微分方程,分析了汽车对前后轮角输入时的移居记响应特性。从汽车动力学的角度讨论了前后轮转应具备的比例关系。该方法同样适用于其它多轴汽车的建模分析。 相似文献
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汽车操纵稳定性与前轮摆振的非线性仿真分析 总被引:3,自引:0,他引:3
以某轿车为例,建立3自由度整车系统动力学模型,利用常微分方程稳定性理论和数值仿真计算,详细研究整车的稳态转向特性和系统失稳后的前轮摆振特性。阐明汽车的操纵稳定性与前轮摆振特性同属汽车整车稳定性问题,前者是负刚度系统,后者是负阻尼系统。在一定的参数组合下,具有不同转向特性的汽车都或多或少地存在摆振现象,这与实际情况相符,建议适当增加转向系阻尼和刚度以减小甚至消除摆振的发生。 相似文献
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E. N. Smith E. Velenis D. Tavernini D. Cao 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2018,56(2):221-248
In this paper, the effect of both passive and actively-modified vehicle handling characteristics on minimum time manoeuvring for vehicles with 4-wheel torque vectoring (TV) capability is studied. First, a baseline optimal TV strategy is sought, independent of any causal control law. An optimal control problem (OCP) is initially formulated considering 4 independent wheel torque inputs, together with the steering angle rate, as the control variables. Using this formulation, the performance benefit using TV against an electric drive train with a fixed torque distribution, is demonstrated. The sensitivity of TV-controlled manoeuvre time to the passive understeer gradient of the vehicle is then studied. A second formulation of the OCP is introduced where a closed-loop TV controller is incorporated into the system dynamics of the OCP. This formulation allows the effect of actively modifying a vehicle's handling characteristic via TV on its minimum time cornering performance of the vehicle to be assessed. In particular, the effect of the target understeer gradient as the key tuning parameter of the literature-standard steady-state linear single-track model yaw rate reference is analysed. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(10):1575-1596
Steering feel, or steering torque feedback, is widely regarded as an important aspect of the handling quality of a vehicle. Despite this, there is little theoretical understanding of its role. This paper describes an initial attempt to model the role of steering torque feedback arising from lateral tyre forces. The path-following control of a nonlinear vehicle model is implemented using a time-varying model predictive controller. A series of Kalman filters are used to represent the driver's ability to generate estimates of the system states from noisy sensory measurements, including the steering torque. It is found that under constant road friction conditions, the steering torque feedback reduces path-following errors provided the friction is sufficiently high to prevent frequent saturation of the tyres. When the driver model is extended to allow identification of, and adaptation to, a varying friction condition, it is found that the steering torque assists in the accurate identification of the friction condition. The simulation results give insight into the role of steering torque feedback arising from lateral tyre forces. The paper concludes with recommendations for further work. 相似文献
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Y. Marumo M. Nagai 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2007,45(5):445-458
This study proposes a steering control method to improve motorcycle handling and stability. Steer-by-wire (SBW) technology is applied to the motorcycle's steering system to remove characteristic difficulties of vehicle maneuvers. By examining computer simulation using a simplified motorcycle model, the actual rolling angle of the SBW motorcycle is controlled to follow the desired rolling angle intended by the rider. A state feedback control such as linear quadratic control gives the SBW vehicle a good follow-through performance compared with proportional-derivative control because it can decouple rolling motion from the other motions, which affect the rolling motion in the strongly coupled motorcycle system. 相似文献
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《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
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Y. G. Cho 《International Journal of Automotive Technology》2009,10(4):431-439
In this paper, an analytical model with suitable vehicle parameters, together with a multi-body model is proposed to predict
steering returnability in low-speed cornering with what is expected to be adequate precision as the steering wheel moves from
lock to lock. This model shows how the steering response can be interpreted in terms of vertical force, lateral force with
aligning moment, and longitudinal force. The simulation results show that vertical steering rack forces increase in the restoring
direction according to steering rack displacement for both the inner and outer wheels. As lateral forces due to side-slip
angle are directed toward the medial plane of the vehicle in both wheels, the outer wheel pushes the steering wheel in the
returning direction while the inner wheel does not. In order to improve steering returnability, it is possible to increase
the total steering rack force in both road wheels through adjustments to the kingpin axis and steering angle. This approach
is useful for setting up a proper suspension geometry during conceptual chassis design. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(9):1521-1532
The steady-state handling properties of a rigid vehicle with a tandem rear axle configuration are developed. This work uses conventions resulting in a parsimonious characterisation of steady-state handling of such three-axle vehicles that is shown to be a simple extension of the well-known two-axle bicycle model. Specifically the concepts of understeer and wheelbase are developed for a three-axle vehicle, and shown to play the same role in characterising vehicle handling as they do in the well-known two-axle vehicle model. An equivalent wheelbase of a three-axle vehicle is expressed in terms of vehicle geometry and cornering stiffness of each axle. The model developed in this work is reconciled with previous models that make use of simplifying assumptions found in the literature. 相似文献
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A. Mortazavi A. Eskandarian R. A. Sayed 《International Journal of Automotive Technology》2009,10(3):391-404
Driver drowsiness is a major safety concern, especially among commercial vehicle drivers, and is responsible for thousands
of accidents and numerous fatalities every year. The design of a drowsiness detection system is based on identifying suitable
driver-related and/or vehicle-related variables that are correlated to the driver’s level of drowsiness. Among different candidates,
vehicle control variables seem to be more promising since they are unobtrusive, easy to implement, and cost effective. This
paper focuses on in-depth analysis of different driver-vehicle control variables, e.g., steering angle, lane keeping, etc.
that are correlated with the level of drowsiness. The goal is to find relationships and to characterize the effect of a driver’s
drowsiness on measurable vehicle or driving variables and set up a framework for developing a drowsiness detection system.
Several commercial drivers were tested in a simulated environment and different variables were recorded. This study shows
that drowsiness has a major impact on lane keeping and steering control behavior. The correlation of the number and type of
accidents with the level of drowsiness was also examined. Significant patterns in lateral position variations and steering
corrections were observed, and two phases of drowsiness-related degradation in steering control were identified. The two steering
degradation phases examined are suitable features for use in drowsiness detection systems. 相似文献
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电动助力转向系对汽车角输入响应影响的仿真 总被引:8,自引:0,他引:8
详细地分析和推导出了具有不同控制方式的EPS系统的传递函数,在Matlab环境中进行了仿真计算并对结果进行了分析,定性地说明了EPS系统的控制方式和结构参数对汽车转向盘角阶跃输入下的稳态、瞬态和频率响应特性的影响。 相似文献