一种较新的汽车行驶平顺性评价方法

本文详细地介绍了一种较新的汽车行驶平顺性评价方法，并对采用此方法试验所得结果进行了分析，进而将其与ＩＳＯ２６３１评价方法作了对比分析。     

汽车脉冲输入平顺性评价指标限值的研究

在分析了脉冲输入下人体所受到的振动速度响应到基础上，运用ＩＳＯ２６３１新草案对人体健康的评价指标和限值，提出了脉冲输入下汽车平顺性评价指标的限值，最后以东风ＥＱ２１０２Ｃ型军用越野汽车为例，说明了脉冲输入下汽车行驶平顺性的评价过程。     

关于国际标准ISO2631的认识和修改

现行国际标准ＩＳＯ２６３１《关于全身振动评价指南》（１９８５）一些重要概念的理解和实践，至今尚未完善和统一。本文对此提出一些新的认识和看法，并对ＩＳＯ２６３１及国家标准ＧＢ４９７０－８５提出部分修改方案。文中举例说明了原２６３１应用的不便和修改后的２６３１应用十分方便。     

斯达——斯太尔载货车振动试验分析

在数据分析的基础上，综合斯达－斯太尔车的整车振动特性，分析了座椅的振动特性，并用ＩＳＯ２６３１对平顺性作了评介，进行了计算分析，为整车开发设计打下了基础，并为坦步对悬架振动进行控制研究作了准备。     

汽车中人体振动的评价方法研究

对国际标准ＩＳＯ２６３１新草案进行了研究，应用新草案对各类汽车的人体振动进行了测试分析，确定了影响人体振动舒适性的主要振动轴向。比较了舒适性评价法与总加权值法的评价结果的差异。通过主观评价验证了舒适性评价法能真实地反映人对振动的感觉，并建立了总乘坐值指标的限值。     

频域快速调节半主动悬架

本文以最新的ＩＳＯ２６３１为舒适性标准，阐述了现有的被动悬架的缺陷及其各种改良措施的不实用性，并由此提出一种实用的半主动悬架控制逻辑，即频率调节逻辑，并给出了计算机模拟结果。     

汽车行驶平顺性评价方法研究及仿真分析

汽车平顺性是汽车NVH性能的评价指标之一。系统介绍了汽车行驶平顺性的客观评价方法,并结合某车型搭建整车行驶平顺性虚拟样机,进行了仿真分析评价。该方法可用于指导汽车行驶平顺性的改善以及悬架参数的优化。     

基于证据理论和模糊神经网络的汽车换挡平顺性评价方法

针对目前汽车换挡平顺性评价方法的不足,提出了一个基于证据理论和模糊神经网络的汽车换挡平顺性评价方法.运用证据理论对不同驾驶员给出的主观评价进行数据融合;通过模糊神经网络对由仪器测得的客观评价指标和经证据合成后的相应主观评价构成的样本向量进行学习和训练,建立了汽车换挡平顺性评价系统.计算和试验结果表明,该方法克服了主观评价和客观评价各自的缺点,能客观、准确、有效地评价汽车换挡平顺性.     

载货汽车行驶平顺性评价方法分析

本文详细地介绍了一种新的载货汽车行驶平顺性评价方法,并对采用该方法试验所得结果进行分析,进而对载货汽车行驶平顺性评价方法进行了对比分析。     

基于柔性模型的多轴汽车平顺性的仿真研究

基于弹性梁弯曲振动理论和模态分析法建立了多轴汽车平顺性分析的柔性模型。按照汽车行驶平顺性评价方法，运用建立的柔性模型，分析了车速、路面等级、悬挂质量的分布、车架刚度以及悬架系统的刚度和阻尼对多轴汽车平顺性的影响。分析结果表明：悬挂质量的弯曲振动是影响多轴汽车行驶平顺性的一个不可忽略的重要因素；常用的刚体模型不能准确地描述多轴汽车的平顺性，不适合用于多轴汽车平顺性的分析。     

平地机振动舒适性的测试与评估

介绍了国际标准ISO 2631和欧共体人体安全委员会法规89/391/EC有关车辆座椅振动的测试、分析和评估方法,对平地机在现场作业和路面行驶工况下的振动进行了测试和分析,并以试验中振动最严重的工况为例,按照ISO2631和89/391/EC对平地机振动舒适性及振动对人体健康的影响进行了分析评估。最后,对如何改善平地机的整车动态性能,提高座椅舒适性提出了建议。     

出租汽车驾驶员振动剂量监测与评价

通过对ISO2631、GB4970等振动舒适性评价标准的研究,建立手动变速器出租汽车驾驶员振动舒适性评价方法。通过实车振动监测和测量驾驶员生理指标,找到了重庆市出租汽车驾驶员在实际行驶工况下达到疲劳的时间;并对他们进行有关疲劳的主观问卷调查,调查统计与试验的结果相吻合,由此得到出租汽车驾驶员达到疲劳时的“振动剂量极限值”。     

Ride Quality and Dynamics of Rail Vehicle Models for Microcomputers

This paper describes mathematical and computer models for ride quality and dynamics of rail vehicles developed for running on personal computers. The purpose of the computer simulations is for prediction of ride quality in order to study the dynamic stability of the system and the effect of track quality and irregularities on ride quality.

In deriving the equations of motion for dynamic stability, the tangential forces acting on the contact areas between the wheels and rails are of fundamental importance in railway vehicles dynamics and are included in the analysis [1]. These forces are due to the creep phenomenon between the wheel and the rail on which it is rolling. Track irregularities are defined in terms of four components consisting of gauge, cross level, alignment and vertical surface profile [2]. Relation of allowable track irregularities versus speed is given by the FRA Track Safety Standards. Analytical representation of track irregularities should include both PSD (Power Spectral Density) for CWR (Continuous Welded Rail) as well as discrete inputs from track joints.

In this paper, the rail vehicle suspension analysis and dynamics mathematical and computer models are described. The computer models are written in Fortran 77 and designed to run on personal computer. The paper also discusses programming considerations that must be taken into account when programming for microcomputers under DOS (IBM's Disk Operating System) and MS or RM Fortran Compilers. Most of the considerations are however, valid in general with respect to engineering software development and programming for microcomputers.

Computer graphics is a powerful tool for visualization of the resulting solutions such as the display of the characteristic roots for the eigenvalues solution on a root locus plot and representation of acceleration levels versus the “Reduced Comfort Boundary” limits defined by the International Standards Organization” (ISO 2631-1985). In this paper some examples of these resulting outputs are presented and their significance discussed.     

Ride quality evaluation of a vehicle with a planar suspension system

The longitudinal connection between a chassis and a wheel in a conventional vehicle suspension system is commonly very stiff than the vertical connection. Such a mechanism can efficiently isolate vibrations and absorb shocks in the vertical direction but cannot sufficiently attenuate the impact in the longitudinal direction. In order to overcome such a limitation, a planar suspension system (PSS) with spring–damper struts in both the longitudinal and vertical directions is proposed so that the vibration along any direction in the wheel rotation plane can be isolated. In this paper, the dynamic responses of a vehicle with PSS due to a single bump and random road unevenness are investigated. The ride quality of the vehicle with PSS is evaluated in accordance with ISO 2631. A comparison with that of a similar conventional vehicle is conducted to demonstrate the promising potentials of the PSS in improving the vehicle ride quality.     

Assessment of wheel loader vibration on the riding comfort according to ISO standards

Vibration accelerations were measured on a compact wheel loader during 11 operations with two drivers and with/without the activated boom suspension system (BSS). Two standards, ISO 2631-1 (1985) and ISO 2631-1 (1997), were used to assess the effect of wheel loader vibration on comfort. The assessment results of ISO 2631-1 (1985) showed that vibration in the frequency range from 4 to 20 Hz in the vertical direction and in the frequency range from 1.6 to 3.15 Hz in the vertical and driving directions plays an important role in comfort assessment. The overall total values of vibration measured on the wheel loader in all operations exceeded the ‘uncomfortable’ boundary specified in ISO 2631-1 (1997). The speed had a larger influence on the vibration intensity than the bucket load, the BSS or the driver biodynamic response during driving. During driving and V-cycle, the difference of vibration intensity with two drivers in the z-direction is larger than that in the x- and y-direction.     

Comparison between different sets of suspension parameters and introduction of new modified skyhook control strategy incorporating varying road condition

This study examines the uncertainties in modelling a quarter car suspension system caused by the effect of different sets of suspension parameters of a corresponding mathematical model. To overcome this problem, 11 sets of identified parameters of a suspension system have been compared, taken from the most recent published work. From this investigation, a set of parameters were chosen which showed a better performance than others in respect of peak amplitude and settling time. These chosen parameters were then used to investigate the performance of a new modified continuous skyhook control strategy with adaptive gain that dictates the vehicle's semi-active suspension system. The proposed system first captures the road profile input over a certain period. Then it calculates the best possible value of the skyhook gain (SG) for the subsequent process. Meanwhile the system is controlled according to the new modified skyhook control law using an initial or previous value of the SG. In this study, the proposed suspension system is compared with passive and other recently reported skyhook controlled semi-active suspension systems. Its performances have been evaluated in terms of ride comfort and road handling performance. The model has been validated in accordance with the international standards of admissible acceleration levels ISO2631 and human vibration perception.     

Analytical Wheel Models for Ride Dynamic Simulation of Off-road Tracked Vehicles

This paper outlines various analytical approaches of varying complexities to model the wheel in the ride dynamic formulation of off-road tracked vehicles. In addition to a proposed model, four analytical models available in the literature are compared to study their effectiveness in modeling the wheel/track-terrain interaction for ride dynamic evaluation of typical high mobility tracked vehicles. The ride dynamic model used in this study describes the bounce-pitch plane motion of an armoured personnel carrier (Ml 13 APC) traversing over an arbitrary rigid terrain profile at constant speed. The ride dynamic response of the tracked vehicle is evaluated with different wheel models, and compared against field-measured ride data. The relative performance of different wheel models are assessed based on the accuracy of response prediction and associated computational time. The proposed wheel model is found to perform very well in comparison, and is equally applicable for the case of wheeled vehicles.     

A Two DOF Model for Jerk Optimal Vehicle Suspensions

Researchers have proposed various active suspension concepts to optimize the tradeoff between ride and handling in passenger vehicles. A few investigators suggested inclusion of the passenger jerk, the derivative of the passenger acceleration, as a measure of ride quality in the performance index. Minimization of a performance index then optimizes both the acceleration and jerk as well as other outputs representing handling quality and design constraints. This approach is called jerk optimal control.

This paper compares two different vehicle models of increasing complexity (the one and two DOF quarter car) using jerk optimal control. Different aspects of suspension performance are investigated, including the structure of the system transfer functions, the structure of the force control laws, and the tradeoffs between the various root mean square (rms) outputs defining system ride and handling performance. Tables compare the numerical results of the two models, allowing predictions of actual vehicle performance.

The results of the two models show the same basic trend for the tradeoff between ride and handling quality: at a constant level of rms passenger acceleration the rms passenger jerk can be reduced significantly, but only at a cost of increased rms tire deflections. In physical terms, a softer ride results in degraded handling performance. For a chosen level of ride improvement, the more realistic two DOF quarter car model predicts more severe degradation of handling. The latter nevertheless predicts a substantial increase in vehicle ride quality is possible through a 55% reduction in jerk. It is expected that actual suspensions could also produce significant increases in ride quality through jerk reduction. Jerk optimal suspensions could find use both in higher end passenger vehicles and in transports for vibration sensitive cargo.