越野车辆机动性研究

为研究越野车辆行驶在不平路段机动性问题,通过偏频试验识别车辆部分特征参数,测量试验车辆悬架位移,计算行驶路段路面不平度,监测驾驶员座椅Z加速度在不平试验路段时序信号,据人体疲劳特性计算人体吸入功率,并建立"人体-车身-车轮"三自由度振动模型;用傅里叶逆变换生成不平路段的时序信号作为仿真输入,利用Simulink仿真试验车辆驾驶员座椅Z向加速度在不平路段的时序信号;提出人体吸入功率为6 W时对应的车速作为评判越野车在不平路段的机动性能。     

车辆四轮相关路面非平稳随机输入通用时频模型

车辆非匀速行驶时路面的随机输入模型是汽车非平稳动力学分析研究的重要基础.首先应用等效协方差方法建立了单轮随机输入非平稳时域模型.根据时间-空间一、二阶微分关系,成功地解决了前后轮变时差相关的问题,并由各向同性假设直接得到了与车辆轮距有关的左右轮相干函数,无需实测相干函数,因此适合各种车辆.本文还应用Wigner-Ville谱分析了路面非平稳随机输入的瞬时功率谱.分析表明Wigner-Ville谱很好地反映了频率特征和路面波形特征.     

面向性能需求的动态调节消扭悬架参数匹配与动力学研究

为协调越野车辆抗侧倾性能和通过性能,研究一种新型动态调节消扭悬架系统(DTS)。该系统可提高车辆抗侧倾能力,消除车身的扭转,增强车轮接地性,提高越野性能和安全性。在阐述DTS系统结构和原理的基础上,利用MATLAB建立该系统的动力学模型以及整车14自由度动力学模型;同时提出一种新的悬架参数匹配方法:面向抗侧倾性能和消扭性能需求匹配DTS系统的关键参数;设计蛇形试验、前轮角阶跃输入试验和扭曲路面工况研究装有DTS系统的车辆的动力学性能,并验证参数合理性。结果表明:应用面向性能需求的匹配方法能有效平衡车辆相关性能;该悬架系统能有效减少车辆侧倾角以及消除车身扭转载荷,对车辆越野性和舒适性有一定改善,并且在车辆转向时能增大其不足转向度,提高车辆安全性。     

无人多轴车辆通过性仿真分析

在越野环境中,车辆会遇到各种各样的复杂路面,比如树桩、台阶、砾石等,所以车辆的通过性显得至关重要.本文中设计了一种无人多轴车辆理论模型,并建立出样机模型,利用样机模型进行仿真分析,验证了无人多轴车辆通过垂直障碍的可行性,为生产研制新一代无人越野车辆提供理论依据.     

基于虚拟样机模型的车辆蓄能悬架联合仿真研究

基于机电系统相似性理论,设计了一种采用惯性蓄能器的车用蓄能悬架系统。运用PrO/E软件建立了机械式惯性蓄能器的三维实体模型,通过接口程序Mech/Pro将蓄能器三维模型导入到动力学仿真软件ADAMS中,与弹性元件、阻尼器连接,构建了1/4车辆蓄能悬架虚拟样机模型。在ADAMS和Matlab/Simulink联合仿真环境中,分别对正弦输入、随机路面输入和阶跃输入作用下的蓄能悬架动态性能进行仿真分析。结果表明,蓄能器具有"通高频、阻低频"的性能特点,与传统的被动悬架相比,蓄能悬架可有效降低车身垂直振动加速度,提高了车辆的行驶平顺性。     

基于虚拟样机模型的车辆蓄能悬架联合仿真研究※

基于机电系统相似性理论,设计了一种采用惯性蓄能器的车用蓄能悬架系统。运用PrO/E软件建立了机械式惯性蓄能器的三维实体模型,通过接口程序Mech/Pro将蓄能器三维模型导入到动力学仿真软件ADAMS中,与弹性元件、阻尼器连接,构建了1/4车辆蓄能悬架虚拟样机模型。在ADAMS和Matlab/Simulink联合仿真环境中,分别对正弦输入、随机路面输入和阶跃输入作用下的蓄能悬架动态性能进行仿真分析。结果表明,蓄能器具有“通高频、阻低频”的性能特点,与传统的被动悬架相比,蓄能悬架可有效降低车身垂直振动加速度,提高了车辆的行驶平顺性。     

基于车辆振动响应反向分析的路面等级辨识方法

提出一种利用希尔伯特黄变换和概率神经网络进行车辆振动响应反向分析的路面等级辨识方法,为主动悬架控制提供有效信息。建立车辆模型和随机输入路面模型,利用希尔伯特黄变换对不同等级路面下的车辆振动响应仿真数据进行分解变换,得到车辆振动响应的瞬时能量;提取瞬时能量的敏感特征参数,利用概率神经网络训练路面分类器,确定路面等级与特征参数范围的映射关系,完成路面等级分类器的设计;利用加速度传感器采集车辆在典型路面下的振动响应数据,提取试验数据的特征参数,并将其输入到训练完成的路面分类器中,实现试验路面等级辨识。辨识结果表明,基于车辆振动响应的反向分析法,结合希尔伯特黄变换和概率神经网络,可以实现对车辆当前行驶路面等级的辨识。     

基于车辆振动响应反向分析的路面等级辨识方法EI北大核心CSCD

提出一种利用希尔伯特黄变换和概率神经网络进行车辆振动响应反向分析的路面等级辨识方法,为主动悬架控制提供有效信息。建立车辆模型和随机输入路面模型,利用希尔伯特黄变换对不同等级路面下的车辆振动响应仿真数据进行分解变换,得到车辆振动响应的瞬时能量;提取瞬时能量的敏感特征参数,利用概率神经网络训练路面分类器,确定路面等级与特征参数范围的映射关系,完成路面等级分类器的设计;利用加速度传感器采集车辆在典型路面下的振动响应数据,提取试验数据的特征参数,并将其输入到训练完成的路面分类器中,实现试验路面等级辨识。辨识结果表明,基于车辆振动响应的反向分析法,结合希尔伯特黄变换和概率神经网络,可以实现对车辆当前行驶路面等级的辨识。     

履带车辆不平路面越野平均速度预测方法研究

为了研究路面不平度对履带车辆越野平均速度的影响规律,本文建立了履带车辆多体动力学模型,提出了振动响应指标并通过试验验证了模型的可信性;根据试验设计进行仿真计算,建立振动响应与车速、路面不平度间的近似模型;以振动响应指标的门限值为约束条件,采用目标寻优方法拟合了路面不平度与车速间的数学关系,提出了随机不平路面条件下的越野速度预测方法。应用该方法计算了车辆通过某试验场综合路面,结果表明：所建模型可以反映路面不平度对车速的影响,为车辆机动性预测提供了有效的量化手段。     

履带车辆不平路面越野平均速度预测方法研究

为了研究路面不平度对履带车辆越野平均速度的影响规律,本文建立了履带车辆多体动力学模型,提出了振动响应指标并通过试验验证了模型的可信性;根据试验设计进行仿真计算,建立振动响应与车速、路面不平度间的近似模型;以振动响应指标的门限值为约束条件,采用目标寻优方法拟合了路面不平度与车速间的数学关系,提出了随机不平路面条件下的越野速度预测方法。应用该方法计算了车辆通过某试验场综合路面,结果表明：所建模型可以反映路面不平度对车速的影响,为车辆机动性预测提供了有效的量化手段。     

主动悬架与EPS集成控制系统操纵稳定性试验

在主动悬架与EPS集成控制系统动力学模型建立、控制策略设计及其仿真计算分析基础上,为进一步验证集成控制系统车辆的抗侧倾能力,进行了车速为50 km/h和60 km/h的蛇行试验,试验结果表明,相对于被动系统,车速为50 km/h时经过集成控制后的侧向加速度峰值和标准差分别下降了21.4 %和15.9 %,车身侧倾角峰值和标准差分别下降了13.4 %和15.1 %,有效提高了车辆转弯时的操纵稳定性能。     

Effect of vehicle speed on shock and vibration levels in truck transport

An update on the nature of shock and vibration in truck transport was obtained by measuring and analysing the shock and vibration levels separately that occur during truck transportation in Japan. The effect of truck speed on the shock and vibration levels was mainly analysed. A significant difference was observed between the acceleration of vibration, and the acceleration including shock and vibration as a result of truck speed. The results indicated that the effect of truck speed on root mean square acceleration (Grms), including shock and vibration, was strong at a lower speed, but slight at a higher speed. The highest Grms, including shock and vibration, was found at 45–59.9 km/h on local roads, which was higher than that during highway driving. When the speed was below 45 km/h, the peak power spectral density (PSD) of acceleration including shock and vibration increased as truck speed increased; when the speed was above 45 km/h, no significant changes in peak PSD were found because of truck speed. At the same time, the effect of vehicle speed on the vibration acceleration was also studied. It was found that the higher the vehicle speed, the higher the Grms and peak PSD value of vibration in both the vertical and lateral directions. Copyright © 2010 John Wiley & Sons, Ltd.     

Concurrent processing of vehicle lane keeping and speech comprehension tasks

With the growing prevalence of using in-vehicle devices and mobile devices while driving, a major concern is their impact on driving performance and safety. However, the effects of cognitive load such as conversation on driving performance are still controversial and not well understood. In this study, an experiment was conducted to investigate the concurrent performance of vehicle lane keeping and speech comprehension tasks with improved experimental control of the confounding factors identified in previous studies. The results showed that the standard deviation of lane position (SDLP) was increased when the driving speed was faster (0.30 m at 36 km/h; 0.36 m at 72 km/h). The concurrent comprehension task had no significant effect on SDLP (0.34 m on average) or the standard deviation of steering wheel angle (SDSWA; 5.20° on average). The correct rate of the comprehension task was reduced in the dual-task condition (from 93.4% to 91.3%) compared with the comprehension single-task condition. Mental workload was significantly higher in the dual-task condition compared with the single-task conditions. Implications for driving safety were discussed.     

冲击载荷下永磁式电涡流减振器设计及动态特性分析

为研究轮式车辆的电涡流减振器在行进间冲击载荷下的动态特性,结合电涡流理论设计了一种永磁式电涡流减振器,并基于等效磁路模型和麦克斯韦方程分析了其导体筒表面空气间隙处磁感应强度与阻尼力之间的关系;同时,利用有限元法对永磁式电涡流减振器的静、动态磁场分布进行了研究,并分析了不同结构参数对其阻尼特性的影响及不同运动速度下的示功特性曲线。通过建立1/4车辆悬架动力学模型和基于高斯滤波白噪声的随机路面激励模型,对车辆行进间冲击载荷下永磁式电涡流减振器的动态特性进行了分析。结果表明：永磁式电涡流减振器的磁场在动态条件下会发生退磁以及磁感线趋速聚集现象,各结构参数对其阻尼特性的影响较大;永磁式电涡流减振器的响应速度快,压缩、复原阻尼力恒定且平稳,可以高效、快速地消除轮式车辆越野时受到的路面激励和车载武器射击时的冲击载荷,能够有效抑制车体振动。研究结果对提高轮式车辆的越野机动性以及车载武器的射击精度具有重要意义。     

汽车主动悬架模糊自适应控制研究

在建立的整车主动悬架系统动力学模型基础上,利用自适应模糊控制方法,分别设计了前轮和后轮的主动悬架模糊自适应控制系统,将前轮的路面激励信号引入到后轮处主动悬架控制策略之中,使得主动悬架可以根据路面和车身姿态的变化而改变特性,以适应当前车辆运行工况的需求,分别进行了随机路面输入和正弦波凸起输入的仿真计算和分析,结果表明,相对于传统的被动悬架系统,模糊自适应控制主动悬架系统车辆的质心垂直加速度峰值和标准差分别下降了38.9%和36.5%;车辆以5m/s速度驶过正弦波凸起时,主动悬架的后轮处车身加速度峰值比被动系统减少了43.9%,有效提高了汽车的行驶平顺性。     

Older driver distraction: A naturalistic study of behaviour at intersections

This study examined older driver engagement in distracting behaviours (secondary activities) at intersections using naturalistic driving data from a larger study based in Melbourne, Australia. Of interest was whether engagement in secondary activities at intersections was influenced by factors such as driver gender and situational variables, in particular, those relating to the complexity of the driving environment. Specifically we expected that when making left/right turns, older drivers would reduce the proportion of time engaged in secondary behaviours at intersections which required gap judgements (partly controlled or uncontrolled) compared with intersections that were fully controlled by traffic signals. Consideration was given to engagement in secondary activity with hands off the wheel and when the vehicle was moving versus stationary. Older drivers aged between 65 and 83 years drove an instrumented vehicle (IV) on their regular trips for approximately two weeks. The IV was equipped with a video camera system, enabling recording of the road environment and driver and a data acquisition unit, enabling recording of trip distance, vehicle speed, braking, accelerating, steering and indicator use. Driving experience and demographics were collected and functional abilities were assessed using the Useful Field of View (UFOV), Trail Making Test B, Mini Mental Status Examination (MMSE), visual acuity and contrast sensitivity. The study yielded a total of 371 trips with 4493 km (99.8 h) of naturalistic driving data including 1396 left and right turns. Trips were randomly selected from the dataset and in-depth analysis was conducted on 200 intersection manoeuvres (approximately 50% left turns, 50% right turns). The most frequently observed secondary activities were scratching/grooming (42.5%), talking/singing (30.2%) and manipulating the vehicle control panel (12.2%). Glances “off road” 2 s or longer were associated with reading, reaching and manipulation of the vehicle control panel. Hands off the wheel was associated with reading. Key parameters associated with the percent of intersection time that drivers engaged in secondary activities were intersection complexity, vehicle status (moving vs. stationary) and traffic density. In conclusion, older drivers appeared to engage selectively in secondary activities according to roadway/driving situations, supporting the notion that drivers self-regulate by engaging in secondary tasks less frequently when the driving task is more challenging compared with less challenging manoeuvres.     

基于路面等级匹配的重卡包装物运输激励研究

目的利用传感器搭配数据采集卡收集路面不平频谱,将路面信息匹配标准路面等级以及车辆行驶速度。方法通过Matlab将标准PSD与随机激励匹配路面等级,同时建立1/2四轴重卡动力学模型,并用能量法建立动力学方程。将收集的路面不平频谱对应到相应的路面等级,再结合车辆速度的设定,最后求解得到车辆受激励后轮胎的动载位移频谱,分析得出被运输包装物的半挂车平板动载位移。结果重卡运输前轴轮胎在A级路面以60 km/h的车速经过该路面的动载位移量在0.8和9.8 s时达到峰值,且路面响应位移不超过6 cm。结论求得被运输包装物的所受激励频谱,为被包装物的运输振动安全性研究提供支撑,可结合具体被运输包装物的脆值理论,提供被运输物品发生运输损坏的数值仿真。     

The impact of hands-free message reception/response on driving task performance

A series of closed-course driving experiments were conducted in which 41 drivers ranging in age from 19 to 70 were put through a series of increasingly challenging driving performance tasks both in the presence and absence of audible messages. The messages required specific responses and these, along with driving performance measures based on driver/vehicle response characteristics, were recorded. The results clearly showed a negative impact of the message task on driver decision-making performance when this involved the more complex tasks of weaving and especially left-turning. Such decision-making decrements in the presence of the messages were exacerbated by adverse pavement surface conditions.     

车轮结构对转向架区域噪声的影响

为了解车轮结构对转向架区域噪声的影响,基于RAYNOISE软件平台,建立转向架区域噪声预测模型。利用该模型,预测了转向架区域内侧及外侧各场点的噪声,分析了动/拖车车轮、车轮制动盘以及低噪声阻尼车轮对转向架区域各场点噪声的影响。预测结果表明：动车车轮、拖车车轮两种车轮结构对钢轨噪声的影响很小,而车轮噪声及转向架区域的噪声影响显著,直型辐板的动车车轮结构能较好地降低轮轨噪声及转向架区域噪声,有利于降低车外噪声。当车辆运行速度为200 km/h、250 km/h时,安装车轮制动盘有利于减小转向架区域各场点噪声,场点4位置降噪量分别达到0.4 dB(A)和0.9 dB(A)。低噪声阻尼车轮可以在一定程度上降低转向架区域各场点的噪声,三种阻尼车轮分别使场点4位置的降噪量达到8.0 dB(A)、8.0 dB(A)、4.6 dB(A)。