轿车八自由度平顺性动力学仿真与实验研究

建立了轿车八自由度平顺性动力学模型,推导了八自由度轿车模型拉格朗日方程,并应用仿真软件MATLAB/S imu link建立了轿车平顺性的仿真模型,对驾驶员座椅、副驾驶员座椅和后排左侧座椅的垂直加速度信号进行了仿真,得出了频域内的仿真结果,并与实验结果进行了对比。     

基于人机工程设计的某履带急救车伤病员装载仿真分析

通过建立数字化人体模型和车厢内部布局三维模型,基于人机工程学原理完成了某履带急救车上层担架伤痛员装栽的仿真分析。结果表明：在驻车条件下装载上层担架伤病员的持重仿真分析较好地反映了该任务的安全性和可达性;医护人员装载操作的舒适性程度达到了91．7％,为该履带急救车的布局设计提供了重要依据。     

Embedded system to evaluate the passenger comfort in public transportation based on dynamical vehicle behavior with user’s feedback

This paper shows the development of a system (Hardware, Firmware and Software) focused to assess the dynamic motion factors that affect the comfort in public transportation systems. The data is collected, on-board processed and transported using the public transportation system vehicles as mobile smart sensors. Therefore, the acceleration measurement using a tri-axial accelerometer, the position detection using Global Positioning System (GPS) and the appropriate algorithms allow the system to detect rude driver styles and defects on the pavement. The firmware is composed by two algorithms. The first one is based on the detection of acceleration and Jerk magnitudes out of the comfort range, which is called Jerk-Acceleration Threshold Detection (JATD). An algorithm to compute the Jerk with comparable results to prior researches is proposed in this paper. The second algorithm, called Comfort Index with Acceleration Threshold Detection (CI-ATD), is based on the detection of acceleration values out of comfort range and the average ride comfort. The average ride comfort is supported by the recommendation of the international standard ISO2631-1. The comfort range or threshold values can be set using the user’s perception. A software developed in LabVIEW™ interface, visualizes discomfort event in online maps for geographic location of each event. Also, the software implements road unevenness detection, which is based on the collected data analysis. The system was successful tested in a conventional bus line on its daily ride, the results reveals that most of the events are due to vertical acceleration disturbances. Also, a preliminary test indicates higher sensibility for vertical than longitudinal or transversal accelerations.     

A new stretcher design for easy manoeuvreability on narrow staircases and rough ground for developing countries

Rough terrains with obstacles, narrow staircases and inadequate space to position the ambulance conveniently in relation to the exit door of houses, often encountered in developing countries like India, make it difficult if not impossible to carry patients using conventional stretchers. A novel two-wheeled stretcher to overcome the limitations has been designed, fabricated and tested for a decade. The special features allow even one stretcher operator to transport a patient over all types of ground, down staircases with landings so small as not to provide space for a regular stretcher to turn into and out from the ambulance. This wide range of facilities has been obtained by incorporating very simple and low-cost devices such as a metal guard over two wheels, friction belts and an ergonomically designed tie bar system. Usage in handling various medical and surgical emergency cases has proven the efficacy and acceptability of the design.     

Whole-body vibration analysis for assessment of railway vehicle ride quality

In this paper, a whole-body vibration analysis using a three-dimensional human biodynamic model is presented, and the dynamic behavior of the body exposed to vibration by a railway vehicle is investigated with respect to ride quality. Since a subject in a railway vehicle is exposed to multi-axial excitation conditions, the acceleration of the body is calculated by summing the accelerations in three directions. The equations for the acceleration response of the body are formulated as complex transfer functions multiplied by input accelerations from the three axes in the form of a frequency response function. Body behavior when exposed to random acceleration inputs measured at the floor of the railway vehicle is investigated across a frequency domain. Root Mean Square (RMS) values of the acceleration magnitudes in the body regions are calculated from the power spectral density (PSD) values of the acceleration responses. The absolute magnitude of the accelerations of the body is compared with the ride index, which is calculated using the input accelerations and standard methods. It is shown that the absolute magnitudes in the body regions are proportional to the standard ride index and that the ride index accurately reflects vibration damage to the body. A proposed seat design using the vibration magnitudes calculated with the human biodynamic model also is presented.     

A design tool to evaluate the vehicle ride comfort characteristics: modeling, physical testing, and analysis

A greater need to enhance comfort characteristics during vehicle design process has recently forced the manufacturers to develop simulation-based approaches. In this study, a simulation-based model of a full-car suspension system is proposed to predict the ride comfort. A simulation model was created for calculating ride comfort effectively. This simulation uses seat-back, seat-surface, and feet acceleration values collected from four different road vehicles which were run on six different roads. Parameters which effect ride comfort were also investigated. Using these parameters, a simulation-based model of a full-car suspension system including engine and seat is created for predicting the ride comfort. The correlation between the results of physical tests and the simulation is very promising. It was found that the effect of an engine has a substantial influence on the ride comfort. To find the optimum values of each parameter, an optimization process was executed properly and added in the model. Using this model, the best ride comfort values were computed without the need of physical prototypes. The developed algorithm can be very helpful as an assistant tool for engineers during vehicle design and manufacturing process.     

Damping collaborative optimization of five-suspensions for driver-seat-cab coupled system

Both the seat and cab system of truck play a vital role in ride comfort. The damping matching methods of the two systems are studied separately at present. However, the driver, seat, and cab system are one inseparable whole. In order to further improve ride comfort, the seat suspension is regarded as the fifth suspension of the cab, a new idea of“Five-suspensions”is proposed. Based on this idea, a 4 degree-of-freedom driver-seat-cab coupled system model is presented. Using the tested cab suspensions excitations as inputs and seat acceleration response as compared output, the simulation model is built. Taking optimal ride comfort as target, a new method of damping collaborative optimization for Five-suspensions is proposed. With a practical example of seat and cab system, the damping parameters are optimized and validated by simulation and bench test. The results show the seat vertical frequency-weighted RMS acceleration values tested for the un-optimized and optimized Five-suspensions are 0.50 m/s2 and 0.39 m/s2, respectively, with a decrease by 22.0%, which proves the model and method proposed are correct and reliable. The idea of “Five-suspensions” and the method proposed provide a reference for achieving global optimal damping matching of seat suspension and cab suspensions.     

Automotive seat vibration control via hydraulic semiactive vibration absorbers (SAVA)

The paper examines the ride performance enhancement that can be obtained by applying hydraulic semiactive vibration absorbers (SAVA) to alter the compliance characteristics of the seat/wheel suspension system. The work relies on a consistent model of the (nonlinear) hydraulics of the SAVA. A recently developed Lyapunov control scheme is used for regulation. The performance is examined assuming a quarter car with a seat/seat mounted mass. The paper then employs a quarter car/seat with a two mass ISO model of the seated human. Two road conditions are employed in the simulations; a ride swell and a road surface with a white noise velocity profile. The results show 45% reduction of of the vertical acceleration.     

集成主被动式安全带的性能评估及优化分析

针对高级驾驶员辅助系统（ADAS）功能多、集成度低的情况,提出了将可逆预紧式安全带与车道偏离预警系统、前方碰撞预警系统和疲劳驾驶监测系统集成为一体的集成式主被动安全系统。在探讨了该集成系统的工作原理和控制策略基础上,通过开展志愿者实车道路实验研究了前方预警系统的碰撞时间阈值、安全带预紧力以及安全带预紧时产生的噪声三个因素对乘员主观感受的影响。对志愿者的主观评价和实验数据的对比分析表明：该集成系统的控制策略逻辑合理,在各个工况下能够主动触发以提醒和约束乘员;但是初期由于预警提醒的频次过高和噪声较大影响了乘员的驾驶体验。经过降低预警系统碰撞时间阈值和优化调整安全带的传动结构,提高了乘员的驾驶体验。该集成式主动安全系统可有效地辅助驾驶员驾驶,且满足乘员的主观可接受度。     

基于响应面方法的某智能SUV平顺性优化

为了在良好操纵稳定性的基础上,实现对车辆平顺性的最优化,以某智能四驱SUV为研究对象,利用ADAMS/CAR软件建立刚柔耦合的平顺性虚拟样机模型,在随机路面下进行仿真计算。根据仿真结果对影响平顺性的因素进行灵敏度分析,确定座椅刚度、前悬刚度、前悬阻尼、后悬阻尼为优化变量,座椅平面3个轴向的总加权加速度为优化目标,运用D-最优设计理论进行试验设计。根据实验数据,运用响应面方法(RSM)拟合出回归模型,得到最优值。研究结果表明,优化后得到的加权加速度均方根值减小了20%。     

变节距悬架弹簧对方程式赛车平顺性的影响

针对大学生方程式赛车座椅与车架为刚性连接,行驶过程中车架振动对驾驶员造成很大影响的问题,分析了赛车变节距悬架弹簧的弹性特性曲线拟合方法,得出了变节距悬架弹簧节距随载荷的变化规律;通过随机输入实验和确定输入实验,对比分析了赛车前悬架分别采用线性弹簧和变节距弹簧对平顺性的影响。实验结果表明：随着车速的提高,车身各测点的最大垂直振动加速度都增大,但采用变节距弹簧的各测点值都小于采用线性弹簧的各测点值;当实验车速为50km/h时,采用变节距弹簧,前轴测点和座椅底板测点的垂直振动加速度均方根值较采用线性弹簧分别减小了11.02％和20.16％,平顺性得到提高。     

基于遗传算法的厢式货车平顺性优化

在RecurDyn中建立某厢式货车的整车多体动力学模型。基于离散梁法,建立整车模型中的钢板弹簧动力学模型,在板簧模型中,采用用户自定义子程序的方法为弹簧片间定义的三向力,可有效模拟簧片间的接触力和摩擦力,应用基于元模型的优化方法,对钢板弹簧模型的参数进行辨识;基于AR模型开发的路面不平度重构程序,可生成能够被RecurDyn调用的路面文件;进行该厢式货车整车平顺性试验,仿真和实车试验结果验证了所建整车模型的正确性;采用试验设计方法分析了悬架参数及驾驶室悬置参数对平顺性的影响,为平顺性优化时变量范围的选取提供了依据;提出一种采用批处理方式,通过ProcessNet集成AForge.Genetic组件实现遗传算法进行整车平顺性优化的方法,优化后驾驶员脚部地板处总加权加速度均方根值下降了9.35%,提高了厢式货车的平顺性能。     

手扶拖拉机非线性座椅的研究

给出一种预紧的非线性座椅,用以改善手扶拖拉机驾驶员的乘坐舒适性,并对该座椅进行了理论分析,测定了它的静态特性、手扶拖拉机在凹凸不平道路上行驶时的隔振性能,同时与手扶拖拉机原海棉弹簧座垫及ＩＳＯ２６３１中的振动规范曲线进行了比较。     

农用三轮摩托车平顺性仿真及优化设计研究

利用Adams/View建立三轮车的多刚体动力学模型,并在其中添加驾驶员模型,通过驾驶员控制方向把的转角对跑偏现象进行实时的反馈和调节,从而精确模拟实际车辆在道路上的行驶情况。然后对车辆的平顺性能进行仿真分析,得其振动的加速度,参考汽车的平顺性评价指标,对其平顺性进行评价。在此基础上,以驾驶员座椅垂向加速度均方根值作为目标函数,对三轮车的行驶平顺性进行优化设计,得到前后减振器的刚度、阻尼的最优值,使其乘坐舒适性得到大幅度提高。     

The transmission of translational seat vibration to the head: the effect of measurement position at the head.

Head motion has been measured in six axes on twelve subjects exposed to vertical seat vibration in the frequency range 0.5-25 Hz. The subjects sat on a rigid flat seat in two postures: 'back-off' (no backrest) and 'back-on' (subject's back in contact with the seat backrest). Translational acceleration has been calculated for various locations on the head and transmissibilities between vertical seat vibration and translational head motion determined for each location and all axes. The translational motion of the head was most affected by pitch motion of the head. This caused variations in fore-and-aft motion with position along the vertical axis of the head and variations in vertical motion with position along the fore-and-aft axis of the head. These variations are illustrated for each subject in both postures. The individual data allow the identification of various modes of vibration and show that seat-to-head transmissibility is greatly affected by pitch modes of the head and neck. The magnitude of motion occurring in some modes is dependent on body posture.     

基于不确定性和模糊理论的汽车平顺性优化

以整车八自由度振动模型为对象,建立某车行驶平顺性的MATLAB/SMULINK模型,根据仿真结果构建了Kriging模型。以座椅加权加速度均方根值为目标函数,以悬架的刚度和非线性阻尼系数、座椅的刚度和阻尼为设计变量,以簧上质量、轮胎的刚度和阻尼为不确定模糊变量,运用模糊理论和多种群遗传算法对该仿真模型进行双层嵌套的不确定性优化。对比表明:不确定性量在一定范围变化时,确定性优化的目标函数恶化到2.0 m/s2,远远大于不确定性优化时目标函数的最小值(1.5 m/s2),即不确定性优化的结果对行驶过程中的不确定性量变化更加不敏感,适应性更好。     

磁悬浮车辆随机振动响应分析及其平稳性研究

以德国Transrapid磁悬浮系统为原型，建立了磁悬浮车辆/线路相互作用模型，高速磁悬浮线路随机不平顺则引入了分段功率谱表述模型。运用数值积分法和时频转换法对磁悬浮车/线、车/桥系统随机响应进行了仿真分析，并以先进地面交通车辆走行品质UTACV规范和铁道车辆Sperling平稳性指标对磁悬浮车辆运行平稳性进行评价。     

基于MEMS技术的疲劳驾驶预警系统设计

因疲劳驾驶造成的交通事故逐渐增多,疲劳驾驶预警系统的研究有着重要的意义和应用价值。本文则是基于MEMS加速度传感器,通过采集驾驶员头部加速度数据,把得到的加速度数据送到处理器进行处理从而进行疲劳检测。若判定为疲劳驾驶,则通过处理器驱动语音系统发出报警信号,提示驾驶员保持清醒或休息,从而减低因疲劳驾驶造成的交通事故的发生机率。     

EVA-625在电梯乘运质量测量中的应用

EVA-625电梯综合性能测试仪可以一次性完成电梯运行加速度、速度、加加速度、振动峰峰值、声音等乘运质量指标的数据采集和数据分析,广泛用于电梯乘运质量测量。本文简要介绍了EVA-625的结构组成,详细描述了利用EVA-625测量电梯乘运质量的步骤,并利用随机软件对测量结果进行了图形显示和数据分析,结合有关电梯技术标准给出了评价依据,最后对利用EVA-625提升电梯检验服务能力提出了建议。     

Adaptive control of a vehicle-seat-human coupled model using quasi-zero-stiffness vibration isolator as seat suspension

We propose the quasi-zero-stiffness (QZS) vibration isolator as seat suspension to improve vehicle vibration isolation performance. The QZS vibration isolator is composed of vertical spring and two symmetric negative stiffness structures used as stiffness correctors. A vehicle-seat-human coupled model considering the QZS vibration isolator is established as a three degree-of-freedom (DOF) model; it is composed of a quarter car model and a simplified 1 DOF model combined vehicle seat and human body. This model considers the changing mass of the passengers and sets the total mass of the vehicle seat and human body as an uncertain parameter, which investigates the overload and unload conditions in practical engineering. To further improve the vehicle ride comfort, a constrained adaptive backstepping controller law based on the barrier Lyapunov function (BLF) is presented. The dynamic characteristic of the active vehicle-seathuman coupled model under shock excitation was analyzed using numerical method. The results show that the designed controller law can isolate the shock excitation transmitted from the road to the passengers effectively, and both the vehicle and seat suspension strokes remain in the allowed stroke range.