A New Method for Accurately Estimating the Weight of Moving Vehicles Using Piezoelectric Sensors and Adaptive-footprint Tire Model

Summary This paper presents new methods for estimating the axle weight of a moving vehicle, using two piezoelectric sensors and adaptive-footprint tire model. It is more difficult to weigh vehicles in motion accurately than to weigh standing vehicles. The difficulties in weighing moving vehicles result from sensor limitations as well as dynamic loading effects induced by vehicle/pavement interactions. For example, two identical vehicles with the same weight will generate sensor signals that differ in the shape and the peak value, depending the tire pressure, vehicle speed, road roughness, and sensor characteristics. This paper develops a method that is much less sensitive to these variable factors in determining the axle weight of a moving vehicle. In the developed method, first the piezoelectric sensor signal is reconstructed using the inverse dynamics of a high-pass filter representing the piezoelectric sensor. Then, the reconstructed signal, is normalized, using the nominal road/tire contact length obtained using an adaptive-footprint tire model, and then integrated. Experiments are performed with 3 vehicles of known weight ranging from 1,400 kg to 28,040 kg. The developed method is compared to two other algorithms. Results show that the developed method is most consistent and accurate.     

基于奇异谱分析的动态称重系统算法研究

针对目前动态称重系统称重误差较大的现状,设计了基于奇异谱分析的动态称重系统。在汽车综合试验场,根据设计的动态称重系统及所选用的压电石英称重传感器的特点,采用两轴车辆及多轴车辆在S形通过、高速行驶刹车通过、不同车速通过的三种情况下采集称重数据。利用车辆的轴重与采集的信号所包围的面积关系计算得到车重,并将奇异谱分析(SSA)算法应用于动态称重系统的数据处理中。试验结果表明:SSA算法与传统的小波分析算法相比能够明显降低称重误差,可广泛推广应用于动态称重系统中。     

基于图像识别轮胎变形的非接触式车辆称重方法

为了解决接触式车辆称重方法存在的安装和维修成本高、使用年限短、识别精度低等问题,创新性地提出一种基于计算机视觉获取轮胎变形的非接触式车重识别方法。首先,利用视频图像采集装置拍摄车辆轮胎图像信息,通过图像处理技术提取轮胎轮廓,并根据轮廓变形计算轮胎的垂向挠度。其次,通过胎压监测系统(TPMS)获取轮胎的真实胎压值,对于没有安装TPMS的车辆,则可以通过图像字符识别技术读取轮胎侧壁的胎压标识信息,再利用统计回归方式确定实际胎压值。在此基础上,将轮胎垂向挠度和胎压值代入推导的称重公式计算轮胎承受的重量,再将所有轮胎承受重量求和得到车辆总重量。最后,以现场的乘用车和重载货车为例,验证在不同胎压和重量变化下非接触式车辆称重方法的准确性,并对比分析3个称重公式的准确性。研究结果表明:车重识别准确率随着胎压增大而降低,随着车重增大而上升;轮胎刚度拟合公式的载重识别准确率达到95%以上,高于理论推导公式和半经验拟合公式。提出的非接触式车辆称重方法具有测量范围广、无需任何额外传感设备、不用封闭交通和易于信息集成等优势,有效地突破了现有接触式车重识别技术的瓶颈,具有很好的工程应用前景。     

Development of algorithms for commercial vehicle mass and road grade estimation

Estimation algorithms for road slope angle and vehicle mass are presented for commercial vehicles. It is well known that vehicle weight and road grade significantly affect the longitudinal motion of a commercial vehicle. However, it is very difficult to measure the weight and road slope angle in real time because of lack of sensor technology. In addition, the total weight of a commercial vehicles varies depending on the freight. In this study, the road grade and vehicle mass estimation algorithms are proposed using the RLS (Recursive Least Square) method and only the in-vehicle sensors. The proposed algorithms are verified in experiments using a commercial vehicle under various conditions.     

Vehicle Energy Dissipation Due to Road Roughness

Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.     

Vehicle Energy Dissipation Due to Road Roughness

SUMMARY

Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.     

Effectiveness of vehicle weight enforcement in a developing country using weigh-in-motion sorting system considering vehicle by-pass and enforcement capability

Vehicle overloading has been identified as one of the major contributors to road pavement damage in Malaysia. In this study, the weigh-in-motion (WIM) system has been used to function as a vehicle weight sorting tool to complement the exsiting static weigh bridge enforcement station. Data collected from the developed system is used to explore the effectiveness of using WIM system in terms of generating more accurate data for enforcement purposes and at the same time improving safety and reducing the number of vehicle weight violations on the roads. This study specifically focus on the effect of vehicle by-pass and static weigh station enforcement capability on the overall effectiveness of vehicle weight enforcement system in a developing country. Results from this study suggest that the WIM system will significantly enhance the effectiveness and efficiency of the current vehicle weight enforcement, thus generating substantial revenue that would greatly off-set the current road maintenance budget that comes from tax payers money. If there is substantial reduction in overloaded vehicles, the public will still gain through reduction in road maintenance budget, less accident risks involving heavy trucks, and lesser greenhouse gases (GHGs) emissions.     

基于“移动水坝”的高速公路雨天行车安全性研究

为了减少雨天交通安全隐患,保障高速公路行车安全,根据雨天高速公路实际行车状态、路面径流特点和车辆水膜相互作用探究雨天安全行车速度。首先,提出“移动水坝”概念,并分析“移动水坝”现象出现的原因和形成机理;依据水力学基本理论探究“移动水坝”现象中水膜厚度和车辆滑水限速值的变化规律;然后,利用Fluent软件仿真车辆对水流的阻挡作用,依据外侧车道大车行车间距的水压力探究连续“移动水坝”形成的条件,并确定外侧车道大车在不同行驶速度下相应的临界车头时距;最后,应用流体力学原理仿真分析车辆行驶速度和水膜厚度与轮胎受到的动水压力之间的关系,确定不同降雨强度下内侧车道小客车的滑水限速值。研究结果表明：雨天在高速公路外侧车道行驶的大车会对路面径流产生阻挡作用,出现“移动水坝”现象;“移动水坝”作用下水膜厚度较正常排水状态下增加,导致内侧车道行驶的小客车滑水限速值降低;设定试验条件下外侧车道大车间距40 m时,两车的水坝作用连续,增加大车车头时距可以减弱连续“移动水坝”作用;车辆行驶过程中轮胎受到的动水压力随水膜厚度及行驶速度的增加而增大,小客车在“移动水坝”作用下发生滑水的概率增加,根据轮胎动水压力值和滑水值确定不同降雨强度对应的临界滑水速度,可相应作为雨天高速公路小客车行驶速度限值。     

商用车双转向桥中间杆系优化设计

商用车双转向桥包含两个独立的转向梯形机构,它们之间的运动是通过中间杆系来传递的.在设计双转向桥转向系统时,为了避免转向桥轮胎异常磨损,需要两个转向桥的车轮转角协调变化.提出了一种对现有双转向桥中间杆系优化设计的方法,可协调车辆第一、第二转向桥的转角关系,避免了横向滑移导致的双前桥车轮转向时造成的轮胎异常磨损.     

Design and evaluation of sideslip angle observer for vehicle stability control

This paper presents a method for estimating the vehicle side slip angle, which is considered as a significant signal in determining the vehicle stability region in vehicle stability control systems. The proposed method combines the model-based method and kinematics-based method. Side forces of the front and rear axles are provided as a weighted sum of directly calculated values from a lateral acceleration sensor and a yaw rate sensor and from a tire model according to the nonlinear factor, which is defined to identify the degree of nonlinearity of the vehicle state. Then, the side forces are fed to the extended Kalman filter, which is designed based on the single-track vehicle model associated with a tire model. The cornering stiffness identifier is introduced to compensate for tire force nonlinearities. A fuzzy-logic procedure is implemented to determine the nonlinear factor from the input variables: yaw rate deviation from the reference value and lateral acceleration. The proposed observer is compared with a model-based method and kinematics-based method. An 8 DOF vehicle model and Dugoff tire model are employed to simulate the vehicle state in MATLAB/SIMULINK. The simulation results shows that the proposed method is more accurate than the model-based method and kinematics-based method when the vehicle is subjected to severe maneuvers under different road conditions.     

Vehicle-Generated Road Damage: A Review

The literature concerned with road damage caused by heavy commercial vehicles is reviewed. The main types of vehicle-generated road damage are described and the methods that can be used to analyse them are presented. Attention is given to the principal features of the response of road surfaces to vehicle loads and mathematical models that have been developed to predict road response. Also discussed are those vehicle features which, to a first approximation, can be studied without consideration of the dynamics of the vehicle, including axle and tyre configurations, tyre contact conditions and static load sharing in axle group suspensions. The main emphasis of the paper is on the dynamic tyre forces generated by heavy vehicles: their principal characteristics, their simulation and measurement, the effects of suspension design on the forces and the methods that can be used to estimate their influence on road damage. Some critical research needs are identified.     

轴重和胎压对车轮动荷载的影响

为研究重型运输车辆对路面作用的动荷载,建立车辆动力学模型,模型中将簧上质量处理为空载簧上质量与装载质量,将轮胎刚度表示为轴重和胎压的函数。研究了轴重和胎压对车辆动荷载的影响。结果发现,车轮动荷载随着轴重和胎压的增加而增加;动载系数随着胎压的增加而增加,但随着轴重的增加而减小;胎压越高,车轮动载随轴重增加速度越快;仅仅采用轴重不足以评价重载高压车辆对路面的破坏作用,在治理超载的同时也应进一步治理超压：空载车辆对路面的冲击作用较大,不能忽视空载车辆对路面的破坏作用;实际高速运行车辆对路面施加较大的附加动荷载,现有《公路沥青路面设计规范》没有考虑附加动荷载是引起路面结构发生早期破坏的原因之一。     

Design of a signal transducer for direct conversion of wheel linear accelerations into tire lateral forces

This paper describes a design of a real-time conversion system of wheel linear accelerations into tire lateral forces. Though the tire lateral forces are important elements for analyzing vehicle dynamic control performances, they cannot be easily measured in real-time owing to the non-linearities of tire dynamics, friction, and slippage on road. In this paper, we propose a practical direct method using wheel linear accelerations in order to estimate tire lateral forces transmitted into the vehicle in real-time. A simplified vehicle model based on force-acceleration analysis is proposed to assure the real-time performance. The acceleration values are obtained using three-axis accelerometers attached on each wheel location. For conditioning and rectifying the acceleration signals, a signal transducer is designed using a digital filter. And in order to investigate the feasibility and real-time performance, a prototype of signal transducer is fabricated using a digital signal processor. The experimental results and performance are validated with the road test results using six-component wheel force transducers.     

Rail Vehicles' Riding Quality and Comfort Related to Theoretical and Experimental Optimization Application to High Speed Trains

SUMMARY

The literature concerned with road damage caused by heavy commercial vehicles is reviewed. The main types of vehicle-generated road damage are described and the methods that can be used to analyse them are presented. Attention is given to the principal features of the response of road surfaces to vehicle loads and mathematical models that have been developed to predict road response. Also discussed are those vehicle features which, to a first approximation, can be studied without consideration of the dynamics of the vehicle, including axle and tyre configurations, tyre contact conditions and static load sharing in axle group suspensions. The main emphasis of the paper is on the dynamic tyre forces generated by heavy vehicles: their principal characteristics, their simulation and measurement, the effects of suspension design on the forces and the methods that can be used to estimate their influence on road damage. Some critical research needs are identified.     

Tire Lateral Force Estimation Using Kalman Filter

As for the tire analysis, lateral tire force is a fundamental factor that describes the stability of vehicle handling. Attempts to analyze the vehicle stability have been made based on various objective test methods and some specific factors such as yaw, lateral acceleration and roll angle. However, the problem to identify which axle is lack of the tire grip at a certain situation still remains. Since indoor tire force measurement system cannot represent a real road and vehicle conditions, tire force measurement through a real vehicle test is inevitable. Due to the high price of the tire force measurement device, tire force estimator can be an alternative toward cost reduction and device failure. In this paper, nonlinear planar full car model combined with tire model is proposed. Then, using discrete-time extended Kalman-Bucy filter (EKBF), individual tire lateral force are estimated with modified relaxation length model.     

车速和路面附着系数的滚动时域估计

基于Dugoff轮胎模型建立了车辆的非线性动力学方程,并给出了路面附着系数的约束条件.针对车速和路面附着系数约束的非线性估计,提出了一种基于滚动优化原理的滚动时域估计法(MHE),并给出了MHE法的具体步骤.在不同路面上对MHE法进行了多种工况的实验验证,并在同样条件下与扩展Kalman滤波法进行了比较.实验结果表明,MHE法的估计性能优于扩展Kalman滤波法.     

Estimation of maximum road friction coefficient based on Lyapunov method

With the real time and accurate information of motor torque and rotation speed of the four-in-wheel-motordrive electric vehicles, a slip based algorithm for estimating maximum road friction coefficient is designed using Lyapunov stability theory. Modified Burckhardt tire model is used to describe longitudinal slip property of the tire. By introducing a new state variable, a nonlinear estimator is proposed to estimate the longitudinal tire force and the maximum road friction coefficient simultaneously. With the appropriate selection of estimation gain, the convergence of the estimation error of the tire longitudinal force and maximum road friction coefficient is proved through Lyapunov stability analysis. In addition, the error is exponentially stable near the origin. Finally the method is validated with Carsim-Simulink co-simulation and real vehicle tests under multi working conditions in acceleration situation which demonstrate high computational efficiency and accuracy of this method.     

交通视频辅助的桥梁动态称重方法研究

为了进一步提升既有的桥梁动态称重技术，提出一种交通视频辅助的新型桥梁动态称重方法。首先介绍基于深度神经网络的计算机视觉目标检测技术和一种计算机视觉坐标转换方法，实现从交通监控视频中实时地探测与定位桥上行驶的车辆和车轴。然后引入桥梁应变分解方法和应变影响面识别方法，建立车重、车辆位置与桥梁应变之间的映射关系，从而建立一种综合利用时间和空间冗余信息对车辆进行称重的方法。该方法构建超定的影响面加载方程组，使用最小二乘法求解该方程组以得到桥上行驶车辆的轴重和总重。最后总结出一套交通视频辅助的桥梁动态称重方法框架。为验证以上方法，在某连续大箱梁桥的缩尺模型以及实桥上进行试验。试验包含单车、双车、跟车、并行、直行、变道、匀速、变速等复杂交通工况。模型试验结果表明：该方法的车辆总重识别误差均值为-2.02%，标准差为4.77%；车辆轴重的识别误差均值为4.77%，标准差为17.50%。实桥试验结果表明：该方法的车辆总重识别误差均值为0.21%，标准差为1.53%；车辆轴重的识别误差均值为-3.59%，标准差为42.67%。除此以外，所提出的方法还可用于识别桥上车辆的数量、类型、轴数、实时位置、运动轨迹、行驶速度等多粒度交通信息。     

人工神经网络在车辆行驶称重技术中的应用

车辆行驶称重技术是通过测量分析车辆轮胎与路面作用力,从而计算车辆的静态载荷和静态轴载等相关参数的车辆载荷检测技术。基于人工神经网络综合分析了影响轮胎作用力的各个因素的影响关系,通过自行研制的油管传感器式车辆行驶称重仪进行了相关试验验证,达到了预定的精度和实用要求。     

基于车路系统的事故现场轮胎印迹强度参数化研究

为明确事故现场可视轮胎印迹强度与车辆动力学特性、轮胎橡胶磨损特征及道路表面灰度之间的关联特性,提出基于车路耦合的事故现场轮胎印迹强度参数化研究方法。通过结合动态滑动摩擦因数模型及轮胎非线性模型,建立车辆路面9 DOF非线性系统动力学模型,运用VBOX惯性测量技术验证模型的有效性。运用胎面磨损能量模型,从车路系统角度确定车辆、轮胎和路面特性对轮胎全局摩擦力及胎面磨损特性的影响。结合印迹强度特征模型提出轮胎印迹强度参数研究方法,选取不同制动、转向角工况及3组路面、胎面特性对轮胎路面接地力学特性、胎面橡胶磨损量、可视轮胎印迹特征进行仿真分析。结果表明：印迹强度仅与全局摩擦力大小有关,与轮胎路面滑移方向无关;滑移工况下胎面橡胶磨损量随着全局摩擦力和滑移速度的增大而增大,而印迹强度变化不明显;制动力矩和道路表面灰度对产生可视轮胎印迹起决定作用,转向角主要影响不规则可视轮胎印迹的产生;前轮轮胎最先出现可视印迹,且可视印迹长度和强度均高于后轮轮胎;采取可视印迹起点作为事故车辆速度判定具有一定的误差,应根据具体情况进行具体分析;研究成果能够为基于可视轮胎印迹的交通事故重建提供理论基础。