Reconstruction of road defects and road roughness classification using vehicle responses with artificial neural networks simulation

The road damage assessment methodology in this paper utilizes an artificial neural network that reconstructs road surface profiles from measured vehicle accelerations. The paper numerically demonstrates the capabilities of such a methodology in the presence of noise, changing vehicle mass, changing vehicle speeds and road defects. In order to avoid crowding out understanding of the methodology, a simple linear pitch-plane model is employed. Initially, road profiles from known roughness classes were applied to a physical model to calculate vehicle responses. The calculated responses and road profiles were used to train an artificial neural network. In this way, the network renders corresponding road profiles on the availability of fresh data on model responses. The results show that the road profiles and associated defects can be reconstructed to within a 20% error at a minimum correlation value of 94%.     

考虑胎路多点接触的电动汽车?路面耦合系统振动分析

轮毂电机驱动电动汽车的簧下质量大, 使得轮胎动载荷增加, 且电机激励进一步加剧车轮振动. 同时, 轮胎与路面单点接触的简化模型, 其动力学计算结果与实际存在差别. 鉴于此, 考虑电机的电磁激励、胎路多点接触和非线性地基, 建立了电动汽车?路面系统机电耦合动力学模型, 通过Galerkin法推导了非线性地基梁的垂向振动, 利用积化和公式推导了非线性地基梁中非线性项积分的精确表达式, 提出了路面截断阶数选取的简易方法, 并通过路面位移响应的收敛性进行了验证. 在此基础上, 研究了胎路多点接触、非线性地基、电机激励、车速、路面不平顺幅值等对路面及车辆响应的影响. 结果表明, 非线性地基及多点接触对车辆响应的影响中, 轮胎动载荷的影响最大, 车身加速度和悬架动挠度的影响较小, 且考虑电机激励时, 二者对车辆响应的影响显著增大. 从对路面响应的影响看, 电机激励的影响最大, 非线性地基的影响次之, 多点接触的影响较小. 所建模型及研究方法可为电动汽车的垂向动力学分析提供一种新思路.      

基于逆动力学分析的路面不平度测试研究

通过分析一个简化的履带车辆单扭力轴-负重轮力学模型,建立了扭力轴扭转角与路面不平度的联系方程,基于该方程可以由路面不平度求出扭力轴扭转角,如已知扭转角则可以通过逆动力学分析得到路面不平度.数值算例结合ADAMS仿真结果验证了该方法用于路面不平度测试的可行性.     

履带车辆路面激励响应的简化计算

为了快速计算履带车辆在路面不平度激励下的动力学响应,基于合理假设采用理论力学方法建立了某履带车辆的简化动力学模型,用ADAMS 软件建立了同种工况下的履带车辆动力学模型,并把两种模型的求解结果进行了对比,验证了简化模型的合理性. 研究结果为基于简化模型的动力学方程对车辆悬挂系统进行优化和逆动力学分析奠定了基础.     

Rural road characteristics and vehicle operating costs in developing countries

The primary phase of transportation at the smallholder level, from village to local market, is a particularly important aspect of increasing agricultural production in developing countries. The realistic prediction of vehicle operating costs on the (largely) unsurfaced roads in this sector is a useful input to development planning and a computer program has been developed to produce such predictions from first principles. When compared with survey results obtained by the Transport and Road Research Laboratory in Kenya, it is found that correlation is satisfactorily close. The program can also be used to predict the effects, on the operating costs of various vehicles, of changing road characteristics (gradient, curvature, roughness, rolling resistance and traction). It is found that rolling resistance and road roughness are the factors most likely to influence operating costs, due to their effects on vehicle speeds, fuel consumption and service/repair costs. Small, cheap machines are not necessarily superior to larger vehicles in terms of costs per tonne kilometre and fuel, particularly where the available load is sufficient to allow the larger vehicle to be utilized reasonably fully.     

Evaluation of fractal terrain model for vehicle dynamic simulations

Fractals are a popular method for modeling terrains that include various scales. This paper investigates the effectiveness of using fractals for generating artificial terrains which can be used for vehicle simulations. The 3-D Weierstrass–Mandelbrot function was used to generate surfaces based on experimentally measured terrains. There is an exponential relationship between the root means squared elevation of the surfaces and the fractal scaling parameter. This relationship was used to determine the required fractal parameters to generate a surface with a desired roughness. A light detection and ranging (LiDAR) sensor coupled with a global positioning system (GPS) and inertial navigation system (INS) was used to measure two off road surfaces. The experimental terrain was then compared to the simulated terrain. Based on the comparison, the fractal model can capture the general roughness of the experimentally measured terrains as determined by the dynamic response of a suspension model. However, the fractal model fails to capture some of the nuances and non-periodic events observed in experimental terrains.     

Development of a criterion for road surface roughness based on power spectral density function

This study has demonstrated that the non-contact acoustical transducer is a reasonable sensor for reflecting the road roughness profile, and the procedure is much faster in detecting the road surface roughness as compared to other measurement devices. Thus, it is a very promising sensor with regard to road roughness measurement. Furthermore, the ISO may be employed to classify the road grade. However, the assumed linearity in the PSD on a log-log graphical representation may not be true in reality, especially in the lower frequency band. Therefore, a new approach to classify road surface roughness is to be developed.     

Stochastic optimal active control of a half-car nonlinear suspension under random road excitation

The random response analysis and the stochastic optimal active control of a half-car model with nonlinear suspension stiffness and damping traversing a rough road are studied in this paper. The road roughness height is modeled as the output of a first-order linear filter to Gaussian white noise. Considering the hysteretic nonlinear stiffness and the square damping of the vehicle model, the response statistics of the nonlinear suspension with active control are obtained by using the equivalent linearization method. The performance indexes of the active suspension are evaluated and compared with those of the corresponding passive suspension. It is found that the nonlinear active suspension gives a better vehicle performances like ride comfort, suspension stroke and overall performance. Finally, the theoretical results are verified through Monte Carlo simulation.     

车辆纵振路面谱及其应用

对车辆纵振路面谱及其在地面-车辆系统中的应用进行了探讨,计算了行车纵剪力及其作用下的路面应力强度因子．与垂向路面谱相比,纵振路面谱代表的路面等级较高．行车纵剪力为均值等于0的平稳随机过程,在它的作用下,路面荷载型裂纹从上到下扩展的速度明显大于从下往上扩展的速度,扩展速度与力的 4次幂成正比．行车纵剪力对路面的裂纹损伤远远大于轮胎路面压力导致的裂纹损伤．     

Spectrum analysis of road roughness for earthmoving machinery

The power spectral density functions of roughness of road surfaces for earthmoving machines such as tractors, scrapers and dumpers were determined by use of an accelerometer mounted on a towed fifth wheel of which the frequency-response function had previously been known. From obtained data, a range of power spectral density curves of the road roughness for these earthmoving machines was derived and expressed mathematically.     

桥梁表面不平顺对车-桥耦合振动系统动力效应的影响

利用模态分析法以及时变力学系统的求解方法,考虑桥面不平顺产生的随机激励,以简支梁桥为对象,计算了四自由度模型车辆-桥梁耦合系统的动力效应,讨论了不同等级桥面平整度情况下桥梁冲击系数、车辆垂直加速度、车轮对桥的作用力的变化规律。结果表明,随着不平整度系数逐渐增大,冲击系数逐渐增大;平整度较差等级的桥面,车辆垂直加速度较大,车轮对桥的作用力也较大。     

基于SHAP-RF框架的越野车辆路面识别算法研究

根据越野车辆在不同路面上行驶时的动力学响应特征, 可以实现路面类型的在线识别, 为面向路面特征调整底盘控制子系统参数从而获取更好的行驶性能奠定基础. 但越野环境地面特征复杂, 车辆响应机理分析困难, 给基于车辆动力学响应进行路面准确识别带来挑战. 提出了一种SHAP-RF路面识别算法设计框架, 通过SHAP (Shapley additive explanations)模型解释方法实现高维随机森林(random forest, RF)路面识别模型的降维化: 首先采集了试验车在压实土路、沙地、良好沥青路与冰雪路4种路面上的行驶数据并计算了3个次级行驶特征; 进一步计算了行驶数据的共计105个时域特征和频域特征, 并以此为输入特征建立了高维随机森林路面识别模型; 利用SHAP解释法分析高维模型输入特征对识别结果的影响从而提炼出各个特征与路面类型的关联性, 完成特征筛选; 最后, 利用筛选后的特征设计降维随机森林路面分类器. 基于实车数据的算法验证试验表明, 设计的降维路面识别模型对4种路面的识别精确率在94%以上, 召回率在93%以上, 相比高维的随机森林路面识别模型, 各种路面上的精确率和召回率最大降幅不超过3.2%, 证明本文提出的SHAP-RF路面识别算法设计框架能够在选用较少特征的情况下依然保证车辆行驶路面类别的准确识别.      

Development of a simplified method for evaluating agricultural tractor’s operator whole body vibration

Whole body vibrations (WBV) are one of the risk factors causing the onset of professional diseases in agricultural tractors operators: a method for assessing vehicle’s properties in terms of vibrations turns out to be fundamental for comfort and safety improvement. Studying agricultural tractor operator exposure to vibrations has always been difficult for the several topics to the tractor is used. Studies have pointed out that the combination of vehicle speed and surface roughness induces a transformation of part of vehicle forwarding speed in vertical accelerations acting as a series of impulses exciting the elastic parts of the tractor to have similar shapes in the frequency domain. Following this consideration the CREA-ING has developed three simplified test track, one for each axis of solicitation, for investigating the possibility of defining tractor’s comfort level with a simplified test.     

OPTIMAL DAMPING MATCHING Of SHOCK ABSORBER FOR A LIGHT TRUCK SUSPENSION SYSTEM

阻尼匹配是制约车辆悬架系统减振器设计的关键问题.以某轻型卡车为研究对象,利用MATLAB软件建立了悬架阻尼优化设计的半车模型.采用车体垂向加速度、俯仰角加速度和车轮动载均方根值作为评价指标,利用线性加权和法建立了悬架阻尼优化设计的目标函数.在随机路面激励下,对悬架系统阻尼进行了优化匹配和分析,并通过实车实验验证了优化效果.研究结果表明,悬架阻尼的匹配优化可有效提高车辆的行驶平顺性,从而为车辆悬架的动态设计提供有益参考.     

随机车辆冲击作用下简支梁桥疲劳可靠度评估

为了研究考虑随机车辆冲击效应的简支梁桥疲劳安全水平,提出了基于车-桥耦合振动与随机车流的桥梁疲劳应力谱模拟方法,并应用于疲劳可靠度评估。基于某高速公路桥梁动态称重数据建立随机车流模型,采用小样本车辆数据拟合桥梁等效疲劳应力范围的插值响应函数,最后由高斯混合模型拟合大样本随机车流作用于桥梁构件的疲劳应力谱。分析了25 m标准跨径简支T梁桥底部普通钢筋的疲劳应力谱,评估了考虑路面劣化与交通量增长的桥梁疲劳可靠度。数值分析结果表明,基于随机车流模拟的疲劳应力谱具有典型的多峰分布特征,包含了超载车辆产生的疲劳应力;车辆对桥梁的冲击效应致使等效疲劳应力放大系数略大于冲击系数,当路面等级为一般时,采用规范冲击系数将低估车辆冲击效应的疲劳损伤;路面劣化与交通量增长均会导致桥梁运营期内的疲劳可靠指标显著降低,由路面劣化导致车辆对简支梁桥的冲击效应不可忽略。     

Response of vehicle accelerating over random profile

Summary Certain aspects of the complex dependence on parameters of the non-stationary random response of a simple model of a vehicle to road roughness are investigated numerically. Although the method is applicable to an arbitrarily varying traversal velocity, attention has been restricted to uniformly accelerated motion. The mean square velocity response is found to be strongly dependent on acceleration and relatively independent of road roughness spectral density at low wave-numbers. The fact that the non-stationary displacement response is independent of acceleration would thus seem to be an exceptional case, since the mean square acceleration response is known to depend markedly on acceleration.

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übersicht Gewisse Aspekte der komplizierten Parameterabh?ngigkeiten der durch Stra?enunebenheiten erzeugten nichtstation?ren Zufallsschwingungen eines einfachen Modells eines Stia?enfahrzeuges werden numerisch untersucht. Obwohl das L?sungsverfahren keine Annahmen über die Fahrgeschwindigkeit voraussetzt, wird die Untersuchung auf eine konstante Beschleunigung beschr?nkt. Die Ergebnisse zeigen, da? bei niedrigen Geschwindigkeiten die mittlere quadratische Ansprechgeschwindigkeit stark von der Beschleunigung abh?ngt, jedoch relativ unabh?ngig vom Spektrum der Stra?enunebenheiten bei kleinen Wellenzahlen ist. Die relative Unabh?ngigkeit der mittleren quadratischen Ansprechverschiebung stellt einen Ausnahmefall dar, da schon bekannt ist, da? die Transportbeschleunigung einen erheblichen Einflu? auf den quadratischen Mittelwert der Ansprechbeschleunigung hat.

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Dedicated to Prof. Dr. H. Ziegler on the occasion of his seventieth birthday     

Maneuver analysis methodology to predict vehicle impacts on training lands

Tactical mobility analysis techniques were merged with land management strategies to assess potential impacts of vehicle operations on training areas for rangeland planning and management. A vehicle mobility analysis was performed for a suite of vehicle types using the NATO Reference Mobility Model (NRMM II). Input parameters include terrain information (soil type, slope, vegetation, surface roughness, soil strength), terrain surface condition based on climate (terrain strength, freeze–thaw, moisture content, snow cover), and vehicle specifications (tire, power train, weight on each axle, ground clearance, dimensions, ride). The vehicle performance was spatially mapped over the terrain for different seasons of the year and used to calculate the maneuverable acreage, which was compared to acreage needed for training requirements. This can be related to land capability based on expected training impact (Maneuver Impact Miles, MIM) and Land Condition Curves which link training density to land condition. This methodology can be used to determine the suitability of training lands and the degree of land management or rehabilitation expected. The methodology was applied to the transformation of the Alaska training lands to support a new brigade unit called the Stryker Brigade Combat Team (SBCT3), but is equally useful for other training areas and military units. For summer use, Alaska training lands are capable of supporting four times the projected training requirements. For winter, when the ground is frozen, more than 10 times the area needed was available.     

A method for real-time condition monitoring of haul roads based on Bayesian parameter estimation

Current haul road management techniques, such as routine, periodic and urgent maintenance have shortcomings in many complex haul road environments. Real-time road condition monitoring may significantly reduce maintenance costs, both to the road and to the vehicles. A recent idea is that vehicle on-board data collection systems could be used to monitor haul roads on a real-time basis by means of vibration signature analysis. This paper proposes a methodology based on Bayesian regression to isolate the effect of varying vehicle speed on the measured vehicle response metric. A key feature of the proposed methodology is that it avoids the costly need to generate analytical or empirical vehicle models.