Vehicle Energy Dissipation Due to Road Roughness

Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.     

Dynamics of Pneumatic Tire Vehicles with Connected Suspension Systems

SUMMARY

A vehicle model, with 10 degrees of freedom is used to investigate the skidding conditions of any wheel of the vehicle in motion. Equations for the load transfer and equations for the pneumatic tire spring and shock absorber are derived. Parameters such as gradual cornering, U-curve cornering, the wavy road surface of different wave lengths and cases of independent and connected suspension systems are inputs to the system. The tire calculated forces and their corresponding maximum resistance forces are the outputs of the systems. A connected suspension system is found to resist skidding better than the independent suspension system. The system is non-linear, and numerical solutions are obtained.     

Messungen von Fahrbahn-Unebenheiten paralleler Fahrspuren und Anwendung der Ergebnisse

Measurement of two track road inputs and theoretical application of the results

The calculation of vehicle response to road-surface irregularity inputs requires the spectral densities of the left and right longitudinal track and their statistical dependence

This paper presents some resluts of parallel profile measurements, three typical german roads have been chosen

Random vibration of two vehicle types are digital-simulated. The dynamic tire load shows that independent suspension systems are more advantageous than beam axles, because by wheel tramp this type increases the dynamic tire load.     

Method for measuring force transmitted from road surface to tires and its applications

The force transmission from road surface to a rolling tire has been successfully measured by force measurements on suspension parts and correction for interia forces of suspension parts. The results of the measurement have shown that the force from road to tire has a sharp directivity, which is inclined rearward in side view, within the frequency range between 5 and 15 Hz. And the inclination angle of the direction of action has been found to be dependent on the vehicle velocity. As the application of the finding, the optimal wheel center locus inclination in side view has been studied, to minimize the longitudinal force transmission. And the optimum angle has been confirmed to exist.     

多自由度双轴车辆模型在波形路面上的动力分析

为了分析车辆以不同速度和不同载质量行驶于不同波长、振幅和坡度的波形路面时,车辆对路面的动载荷作用,根据綦万高速公路路面平整度的实测结果,得到描述波形路面的参数即波长和振幅,编制路面文件,在ADAMS中模拟波形路面,并以现有某红岩重型卡车为研究对象,利用ADAMS多体动力学分析软件建模仿真,建立其车架、悬架和驾驶室等的多体动力学模型,对整车模型进行仿真计算,揭示了车辆动载与路面不平度之间的关系,提出了降低车轮动载荷的方法。     

考虑弹性支撑边界条件的电动汽车-路面系统机电耦合振动特性分析

轮毂电机驱动电动汽车的簧下质量大导致轮胎动载荷增加,并且电机电磁力和转矩波动对车轮造成电机激励,进一步加剧车轮振动引起垂向振动负效应的问题。鉴于此,考虑电机的电磁激励,建立了电动汽车-路面系统的机电耦合动力学模型,推导了弹性支撑边界条件下路面结构的模态频率和振型表达式,以及路面振动引起的二次激励。计算了简支与弹性支撑边界条件下的路面模态频率,根据频率分布进行了截断阶数选取,并分析了边界条件、电机激励和车速对路面响应的影响。在此基础上,研究了不同行驶速度、路基反应模量及路面不平顺幅值下,激励形式对汽车车身加速度、悬架动挠度和轮胎动载荷的影响。结果表明：路面不平顺幅值越小,弹性支撑对路面响应的影响越大,弹性支撑边界条件下的路面响应较小,电机激励会引起路面响应的增加;弹性支撑边界条件下,路面不平顺幅值和路基反应模量越小,考虑路面不平顺、路面二次激励和电机激励的三重综合激励对电动汽车响应的影响越大,激励形式对轮胎动载荷的影响最大,对车身加速度的影响次之,对悬架动挠度的影响最小;电机激励导致轮胎动载荷增加,对路面破坏和寿命产生的负效应不容忽视。所建电动汽车-路面系统机电耦合模型及研究思路可为电动汽车垂向动力学分析提供参考与理论支持。     

路面抗滑性能影响弯道行车安全的仿真分析

为研究车辆制动工况下路面抗滑性能对弯道行车安全的影响,以车辆动力学分析软件AD-AMS为仿真平台,提出采用轮胎解析参数、整车参数、路面抗滑值构建耦合关联的车辆-轮胎-路面模型,在此基础上研究不同湿滑路面状态下弯道行驶车辆的运动学参数值变化情况,探索路面抗滑性能与表征行车安全风险的运动学参数值之间的关系.研究结果表明,路面抗滑性能影响车辆运动学参数值变化是诱发交通事故的主要因素.较低的弯道路面抗滑性能易使车辆在制动时出现急速横摆、甚至侧翻的交通事故;车辆两侧轮胎接地面抗滑值不均衡对弯道行车安全的影响高于对直道行车安全的影响,车辆极易在弯道制动时出现因抗滑值不均衡而无法保持有效转弯半径、进而冲出车道的交通事故.研究可为制定弯道行车安全的保障措施提供理论依据.      

汽车轮胎滚动阻力试验机测试方法分析

为了对汽车轮胎滚动阻力测试方案的可行性进行预先评估,基于检测设备的结构模型,提出了一种运用位移量对轮胎滚动阻力进行仿真分析的新方法。在简述滚动阻力有限元测试模型构建过程的基础上,通过改变轮胎的外部使用参数,分析传感器板在不同工况下位移场的分布情况,制定了设备的测试方案。以传感器的安装位置作为目标检测点,建立轮胎滚动阻力位移场与控制参数之间的关系曲线。最后将采集的数据经过平均滤波处理,与实验室的实测数据进行了趋势性对比。结果表明：采用该测试方法,轮胎滚动阻力随着轮胎负载和速度的增加而增大,随着气压的变大而减小;仿真结果和试验数据在相同工况下的变化趋势基本一致;该测试方法合理、可行。     

Road roughness estimation based on discrete Kalman filter with unknown input

ABSTRACT

The road roughness acts as a disturbance input to the vehicle dynamics, and causes undesirable vibrations associated with the ride and handing characteristics. Furthermore, the accurate measurement of road roughness plays a key role in better understanding a vehicle dynamic behaviour and active suspension control systems. However, the direct measurement by laser profilometer or other distance sensors are not trivial due to technical and economic issues. This study proposes a new road roughness estimation method by using the discrete Kalman filter with unknown input (DKF-UI). This algorithm is built on a quarter-car model and uses the measurements of the wheel stroke (suspension deflection), and the acceleration of the sprung mass and unsprung mass. The estimation results are compared to the measurements by laser profilometer in-vehicle test.     

In-plane Dynamics of Tires on the Road Based on an Experimentally Verified Rolling Ring Model

SUMMARY

The dynamic behavior of tires rolling on the road is predicted based on a ring model that is experimentally verified to well represent a real tire. The road contact is kinematically represented by two displacement constraints, one in radial and one in tangential direction. The displacement constraints are enforced via the receptance theory. The receptance matrix developed for the rolling tire is found to be Hermitian. Numerical results show that the natural (or eigen-) frequencies of the rolling tire with road contact are, as expected, higher than those of the tire with no contact. The influence of the rotating speed to the eigen-frquencies of the tire is also shown. Analytic expressions for the mode shapes of a rolling tire with ground contact are derived.     

车辆噪声与城市道路路面平整度关系的试验研究

主要研究了城市道路平整度可能对机动车辆噪声级产生的影响。采用IRI作为道路平整度的计量单位,并在上海的一些城市道路上组织了沥青路面和水泥路面两类试验。首先,在满足试验条件的道路上进行平整度的量测;其次,在试验道路的测点上采集车辆以特定速度驶过的最大噪声级。通过对试验数据的分析,发现车辆以相同速度行驶在平整度不同的城市道路上时,其噪声级是不同的,而且随着平整度指数的增加,机动车辆噪声级也呈上升趋势,因此城市道路平整度确实会对机动车辆噪声级产生影响。在20~50 km/h速度范围内,对于平整度相同的水泥路面和沥青路面,前者的车辆匀速行驶噪声要高于后者。     

Random Response of Tractor-Semitrailer System

SUMMARY

This work describes an analytical study of the dynamic behaviour of a tractor-semitrailer vehicle. A digital computer simulation was used to describe the longitudinal, vertical, and pitching motions of the vehicle travelling over a stationary random road surface. A man-seat model was also incorporated into the simulation. Vehicle response to road irregularities has been studied by assuming two different roads for loaded and unloaded cases.

Numerical results are presented for vehicle, showing system eigenvalues, power spectral densities and root mean square values of the linear and angular accelerations and displacements. Vehicle acceleration response is compared with the ISO riding comfort standard. All results for the loaded and unloaded cases and for smooth and rough roads indicated that an uncomfortable ride would result from vehicle response.     

Dynamics of Pneumatic Tire Vehicles with Connected Suspension Systems

A vehicle model, with 10 degrees of freedom is used to investigate the skidding conditions of any wheel of the vehicle in motion. Equations for the load transfer and equations for the pneumatic tire spring and shock absorber are derived. Parameters such as gradual cornering, U-curve cornering, the wavy road surface of different wave lengths and cases of independent and connected suspension systems are inputs to the system. The tire calculated forces and their corresponding maximum resistance forces are the outputs of the systems. A connected suspension system is found to resist skidding better than the independent suspension system. The system is non-linear, and numerical solutions are obtained.     

The Development and Implementation of Adaptive Semi-Active Suspension Control*

SUMMARY

Using adjustable shock absorbers within vehicle suspension systems, it is possible to improve ride comfort significantly when a control strategy is applied based on the so-called skyhook principle. However, the drawback is a poorly damped wheel-hop mode which makes the road holding ability worse. Using adaptive semi-active suspension control based on the tire load variations as introduced in this paper, the trade-off between road holding and ride comfort can be relaxed. Implementation of adaptive skyhook control requires the determination of a number of important and difficult to measure states of the vehicle. This can either be accomplished by several sensors and filters or by a state estimator in combination with less sensors and an internal model of the vehicle. Both methods are discussed. Finally some preliminary test results are discussed.     

Experimental Study of System Optimization for Suppression of Vehicle Vibration

SUMMARY

The improvements of ride comfort and vehicle maneuverability in the vehicle design can be achieved by using an active suspension. However, the problems in such a control are the complex control logic because of the control laws incompatible with the improvements of ride comfort and maneuverability, and the cost increase because of various sensors to be attached. Therefore, we examined the control abilities of ride comfort and maneuverability on a unique control law using frequency shaped LQ, and controlled the characteristic of the contact between tire and road without a road displacement sensor     

Energy Dissipation Due to Vehicle/Track Interaction

SUMMARY

The effects of track irregularities and wheel profile on the amount of energy dissipated in railroad freight vehicles is examined. A nonlinear computational model is used to determine the average dissipation in the vehicle suspension and the wheel/rail contact patches. This dissipation is a component of the total resistance force acting on the vehicle. Parametric results are presented showing the effects of track geometry, wheel profile, suspension design, and hunting on train resistance. Track geometry studies consider the effects of track quality and curving. The AAR 1:20 wheel profile and the Heumann wheel profile are compared under various operating conditions. Compared with the Heumann profile, the AAR 1:20 profile is shown to have lower average resistance on good quality tangent track, but higher average resistance in steady curves. A trade-off exists between the two profiles when dynamic curve entry is considered.     

Adaptive Control of Vehicle Suspension

SUMMARY

An adaptive control scheme for a two-degree-of-freedom vehicle model with active suspension is proposed. The performance goal is to minimize the variance of vehicle body acceleration under inequality constraints imposed on the variance of either tire or suspension deflection. An active suspension is adapted to the changes in vehicle velocity and the type of road (or terrain) surface which is assumed to be reconstructable from the accelerometer measurements. The control gain factors are obtained by the iterative method taking advantage of stochastic linear control theory. The performance of the system is evaluated and compared to that of an active system with constant gain factors and a passive system with adjustable parameters.     

台试与路试轮胎滚动阻力关联性研究

分析了台试与路试轮胎滚动阻力影响因素的内在联系；建立了台试与路试轮胎滚动阻力关联性模型；揭示了台试与路试轮胎滚动阻力之间的差异；解决了通过台试试验求解道路滚动阻力问题。     

电控空气悬架系统综述

随着车辆控制技术的发展,电控空气悬架系统逐步取代了传统空气悬架.文章介绍了电控空气悬架系统的结构组成及其功能特点,概述了国内外电控空气悬架的发展情况,简要分析了其发展趋势.与传统弹簧悬架相比,电控空气悬架系统具有较优越的动态传递特性,能降低车轮与路面之间的相对动载,减少汽车对路面的冲击损坏,较好地改善汽车的行驶平顺性和操纵稳定性.     

商用车轮胎花纹对车辆燃油经济性的影响

轮胎作为车辆唯一与地面接触的元件,轮胎状态是整车性能表现关键的一环。轮胎花纹对汽车动力性、操控稳定性、整车舒适性和燃油经济性都存在一定影响。其中,轮胎花纹对燃油经济性的影响主要体现在对轮胎滚阻系数的影响,理清轮胎花纹形式和燃油经济性的关系对整车轮胎选型有着重要的意义。