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”。     

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。     

对汽车平顺性评价方法的探讨与建议

首先分析了现行国家标准GB4970-1996<汽车平顺性随机输入行驶试验方法>与国际上通行的人体振动评价标准ISO2631-1997的区别.通过道路试验测量了驾驶员坐垫、靠背和脚部的平移振动以及坐垫的旋转振动共lO个方向的振动.分析发现汽车中人体振动的峰值因子一般小于9;而按照GB4970和ISO2631的试验数据对比表明,GB4970在一定程度上低估了人体振动.分析各方向振动所占的比例发现,坐垫垂向振动、靠背前后振动和坐垫侧倾振动影响最大.最后提出了对汽车平顺性评价方法的建议.     

基于人机工程学的山区公路桥头跳车分析评价

桥头跳车是山区公路小桥涵运营中的一种常见现象,它影响了行车的舒适与安全。选取了人机工程学指标,包括汽车振动加速度和驾驶员心率,作为桥头跳车对行车安全影响的评价指标;通过行车实验和对比实验,从乘车舒适性和振动知觉两方面,并结合ISO2631全身振动的相关规定,对内蒙古S203线山区某路段桥头跳车的严重程度进行分析评价,并给出了改善建议。     

Subjective absolute discomfort threshold due to idle vibration in passenger vehicles according to sitting posture

Idle vibration, occurring when a vehicle comes to a stop while the engine is on, is known to be a main cause of discomfort for passengers, and the customer effect has been recently growing. The frequency of idle vibration is determined by the engine type. To lower the vibration, various technologies have been applied to optimize the engine mount and vehicle body structure. In addition to the technological developments, research on human response with a consideration of idle vibration is needed to effectively reduce the level of discomfort experienced by passengers. Seats aimed at enhancing static comfort influence the sitting posture of passengers; sitting posture is a factor affecting human body characteristics that response to idle vibration. This study examined the absolute discomfort threshold of idle vibration according to the sitting postures of 13 taxi drivers. The four sitting postures of subjects on a rigid-body seat without a backrest were variables in the determination of absolute discomfort threshold of idle vibration. The absolute discomfort threshold curves obtained in this experiment were less sensitive to frequency changes than the frequency weighting function of ISO 2631-1.     

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.     

Discomfort of vertical whole-body shock-type vibration in the frequency range of 0.5 to 16 Hz

Shock-type vibrations are frequently experienced in vehicles excited by impulsive input, such as bumps in the road, and cause discomfort. Current national and international standard weightings were primarily developed for assessing exposure to sinusoidal or random vibrations and not impulsive excitations or shocks. In this experimental study, various shock signals were systematically produced using the response of a one degree-of-freedom vibration model to hanning-windowed half-sine force input. The fundamental frequency of the shock was varied from 0.5 to 16 Hz at a step of 1/3 of an octave. The magnitude estimation method was used for fifteen subjects to compare the discomfort of shocks with various unweighted vibration dose values between 0.35 ms^−1.75 and 2.89 ms^−1.75 at each frequency. The equivalent comfort magnitude of shock showed greater sensitivity at frequencies less than 0.63 Hz and at the resonance frequency of the human body between 5.0 Hz and 6.3 Hz. The frequency weighting constructed by using both the equivalent comfort magnitude and the growth rate of discomfort obtained in this study was compared with the current standard weightings, W_b of BS 6841 and W_k of ISO 2631. The derived weightings for shock were applied to the acceleration of the shocks, and an enhanced correlation was proved between the magnitude estimations and the weighted physical magnitude of shock.     

Parameters optimisation of a vehicle suspension system using a particle swarm optimisation algorithm

The purpose of this paper is to determine the lumped suspension parameters that minimise a multi-objective function in a vehicle model under different standard PSD road profiles. This optimisation tries to meet the rms vertical acceleration weighted limits for human sensitivity curves from ISO 2631 [ISO-2631: guide for evaluation of human exposure to whole-body vibration. Europe; 1997] at the driver's seat, the road holding capability and the suspension working space. The vehicle is modelled in the frequency domain using eight degrees of freedom under a random road profile. The particle swarm optimisation and sequential quadratic programming algorithms are used to obtain the suspension optimal parameters in different road profile and vehicle velocity conditions. A sensitivity analysis is performed using the obtained results and, in Class G road profile, the seat damping has the major influence on the minimisation of the multi-objective function. The influence of vehicle parameters in vibration attenuation is analysed and it is concluded that the front suspension stiffness should be less stiff than the rear ones when the driver's seat relative position is located forward the centre of gravity of the car body. Graphs and tables for the behaviour of suspension parameters related to road classes, used algorithms and velocities are presented to illustrate the results. In Class A road profile it was possible to find optimal parameters within the boundaries of the design variables that resulted in acceptable values for the comfort, road holding and suspension working space.     

四轮独立驱动电动汽车电动轮影响研究

为了分析轮毂电机驱动电动汽车簧下质量变大导致的垂向振动负效应问题,根据自主研发可以四轮独立驱动的轮毂电机电动汽车,建立集中电机和轮毂电机驱动汽车的1/4动力学模型,在相同路面输入下,对汽车平顺性评价指标进行对比分析,说明轮毂电机驱动下电动轮结构对车辆垂向性能的影响。研究结果证明,轮毂电机驱动汽车的车身垂向加速度和轮胎动载荷都有所增加,这种变化将对车辆的行驶平顺性造成一定程度的恶化。     

基于Simulink车辆舒适性和行驶安全性仿真分析

根据国标GB／T7031—2005机械振动道路路面谱测量数据报告,在MatLab中编写了随机路面激励谱仿真程序;利用拉格朗日方程建立了1／2车辆动力学模型,并用Simulink对其进行了仿真;以不同等级路面和不同车速下的随机路面激励谱作为输入,分析了车辆在不同等级路面、不同车速下的车身加速度均方根值和后轮的动载荷均方根值。这对满足汽车行驶舒适性和行驶安全性的情况下优化悬架参数具有重要意义。     

New level of vehicle comfort and vehicle stability via utilisation of the suspensions anti-dive and anti-squat geometry

In this article a novel vehicle dynamics control concept is designed for a vehicle equipped with wheel individual electric traction machines, electronically controlled brakes and semi-active suspensions. The suspension's cross-couplings between traction forces and vertical forces via anti-dive and anti-squat geometry is utilised in the control concept to improve driving comfort and driving stability. The control concept is divided into one main and two cascaded branches. The main controller consists of a multivariable vehicle dynamics controller and a control allocation scheme to improve the vehicle's driving comfort. The cascaded feedback loops maintain the vehicle's stability according to wheel slip and vehicle sideslip. The performance of the combined vehicle dynamics controller is compared to a standard approach in simulation. It can be stated that the controller piloting semi-active suspensions together with brake and traction devices enables a superior performance regarding comfort and stability.     

基于Simulink的轮边驱动电动车振动分析与仿真

为解决轮边驱动电动车安全性和平顺性低的问题,文章以基于吸振原理的轮边驱动电动车垂向3自由度系统为例,运用机械振动学原理建立动力学微分方程,采用状态空间法将此系统的微分方程转化为便于Matlab/Simulink软件仿真的模型。通过分析和仿真可以直接获得轮边驱动电动车沿垂直地面方向的运动曲线图,在正弦激励作用下,动力吸振器、车轮及车身均作周期性运动。将机械振动学和Simulink软件相结合能够准确方便地对轮边驱动电动车的振动进行分析与仿真,为处理类似的汽车振动系统仿真提供了参考。     

Vossloh300扣件阻尼频变对高铁高频振动的影响研究

以Vossloh300扣件胶垫为研究对象，利用配备温度箱的万能试验机测得其在-60℃~20℃的耗能刚度。在试验基础上结合温频等效原理及车辆-轨道垂向耦合Timoshenko梁模型，在频域内探究该型扣件频变阻尼对高铁轮轨系统动力特性的影响。结果表明:Vossloh300扣件胶垫在20℃，4 Hz激振频率下阻尼系数约152.2 kN/（m·s-1）。Vossloh300扣件频变阻尼主要影响车辆-轨道垂向耦合系统1/3倍频中心频率22 Hz以上的振动响应，即:①增大车辆和轨道系统22~56 Hz的中高频振动，同时减小其60~256 Hz的高频振动；②在512~1 500 Hz范围内，钢轨垂向1/3倍频加速度振级最大值增大了5 dB，同时，扣件力1/3倍频幅值最大值减小了92%。因此，为精确预测高速铁路车辆及轮下结构随机振动响应，需考虑扣件胶垫的阻尼频变特性。     

Out-of-round railway wheels—a study of wheel polygonalization through simulation of three-dimensional wheel–rail interaction and wear

The objective of this study is to develop a tool for investigation of wheel tread polygonalization with radial irregularities including 1 to 20 wavelengths around the circumference of the wheel. Therefore, an existing multibody system model for simulation of general three-dimensional train–track interaction (accounting for frequencies up to several kHz) is extended with rolling contact mechanics according to FASTSIM. Furthermore, the model is also modified to allow for general wheel–rail profiles. The numerical model uses the concept of an iteration scheme including simulation of dynamic train–track interaction in the time domain coupled with a long-term wear model. A demonstration example including a bogie of a subway train travelling on a straight track is presented. In the example, an initial wheel out-of-roundness (OOR) is applied to the wheels. This irregularity is based on an amplitude spectrum derived from measurements on new wheels. Simulation results show that the most important wavelength-fixing mechanisms of the wheel OOR are (i) the vertical resonance of the coupled train–track system at approximately 40 Hz (the P2 resonance) and (ii) the frequency region including the lowest vertical track antiresonance at 165 Hz, where the dynamic track stiffness is high. Only a straight track is studied, but the model allows for asymmetric train motion on such a track.     

大跨度人行斜拉桥TMD减振分析

为避免人行桥发生共振,以新金牛(岛型)公园C、D地块人行斜拉桥为例,通过数值仿真和脉动试验得到了人行斜拉桥的一阶自振频率。进一步地,选取人行激励荷载,确定舒适度评价标准。最后,数值分析了原桥的振动响应,并根据原桥动力分析结果设计了调谐质量阻尼器(TMD)减振方案。研究结果表明：本桥端跨的一阶竖弯频率为2.73 Hz,跨中频率为1.51 Hz；安装TMD后,端跨和跨中的加速度峰值符合舒适度标准,TMD减振效果最大可达到60%。     

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.     

A novel fuzzy logic correctional algorithm for traction control systems on uneven low-friction road conditions

The traction control system (TCS) might prevent excessive skid of the driving wheels so as to enhance the driving performance and direction stability of the vehicle. But if driven on an uneven low-friction road, the vehicle body often vibrates severely due to the drastic fluctuations of driving wheels, and then the vehicle comfort might be reduced greatly. The vibrations could be hardly removed with traditional drive-slip control logic of the TCS. In this paper, a novel fuzzy logic controller has been brought forward, in which the vibration signals of the driving wheels are adopted as new controlled variables, and then the engine torque and the active brake pressure might be coordinately re-adjusted besides the basic logic of a traditional TCS. In the proposed controller, an adjustable engine torque and pressure compensation loop are adopted to constrain the drastic vehicle vibration. Thus, the wheel driving slips and the vibration degrees might be adjusted synchronously and effectively. The simulation results and the real vehicle tests validated that the proposed algorithm is effective and adaptable for a complicated uneven low-friction road.     

A two-stage-training support vector machine approach to predicting unintentional vehicle lane departure

Advanced driver assistance systems, such as unintentional lane departure warning systems, have recently drawn much attention and efforts. In this study, we explored utilizing the nonlinear binary support vector machine (SVM) technique to predict unintentional lane departure, which is innovative, as the SVM methodology has not previously been attempted for this purpose in the literature. Furthermore, we developed a two-stage training scheme to improve SVM's prediction performance in terms of minimization of the number of false positive prediction errors. Experiment data generated by VIRTTEX, a hydraulically powered, 6-degrees-of-freedom moving base driving simulator at Ford Motor Company, were used. All the vehicle variables were sampled at 50 Hz and there were 16 drowsy drivers (about 3 hours of driving per subject) and six control drivers (approximately 20 minutes f driving each). In total, 3,508 unintentional lane departures occurred for the drowsy drivers and 23 for the control drivers. Our study involving these 22 drivers with a total of more than 7.5 million prediction decisions demonstrates that (a) excellent SVM prediction performance, measured by numbers of false positives (i.e., falsely predicted lane departures) and false negatives (i.e., lane departures failed to be predicted), was achieved when the prediction horizon was 0.6 seconds or less, (b) lateral position and lateral velocity worked the best as SVM input variables among the nine variable sets that we explored, and (c) the radial basis function performed the best as the SVM kernel function.     

Driver recognition of a run-over accident

If a driver passes over a pedestrian lying on the road and flees, it is considered a crime. In several cases, even if the driver fled and was arrested, he/she often asserts that they did not know that the victim was a human being. However, the investigation agency often believes that a driver can certainly recognize when he/she passes over a person. Accordingly, such cases frequently lead to disputes due to the lack of criteria for recognizing when a driver was involved in run-over accidents. In this study, tests were conducted both to identify if drivers can recognize whether their vehicles passed over a person and to examine how they feel at the time. A silicon dummy, which was manufactured to have the same characteristic as the human chest, was used in this study. According to the method specified in ISO2631, the vibration delivered to the driver was measured, and eighteen participants drove a vehicle over the silicon dummy to experience how the vibrations felt. When the passenger car for the test ran over the dummy at speeds ranging from 10 km/h to 60 km/h, all participants recognized the delivered vibration, and the VDV that was delivered to the participants ranged from 1.81 m/s ^1.75 to 2.38 m/s ^1.75. The participants thought that the object they drove over was a stone or a piece of wood. This indicates that the driver certainly can recognize the vibrations generated from passing over a human chest even though it feels like a solid object.