基于加速度区间判断的坡道识别方法

介绍了坡道识别的原理;在功率谱分析的基础上,设计了纵向加速度滤波算法,通过比较汽车在坡道上行驶时用加速度传感器测得的加速度数值与汽车纵向速度经差分后获得的加速度数值之间的差异,进行了基于加速度区间判断的坡道识别方法研究;完成了水平道路的加速度比较试验和坡道识别的实车试验,并在此基础上进行了基于坡道识别的换挡规律设计。实车试验结果表明:该方法能够进行坡道识别,并具有简单、实用、高效的优点;这种基于行驶环境识别的控制是未来汽车控制技术发展的方向。     

Longitudinal Tire Dynamics

This article begins with a brief review of the traditional concept of lateral relaxation length. The review illustrates that this concept yields a useful approximation which can be used with semi-empirical tire models which assume lateral forces are a function of steady-state slip angles. The article then presents an analogous derivation for longitudinal slip. Like its lateral counterpart, the derivation yields an approximation for transient longitudinal slip which can be used with tire models which assume longitudinal forces are a function of steady-state longitudinal slip. It is shown that, like the relaxation-length-based lateral slip angle, this formulation for longitudinal slip yields the ability to compute shear forces at the tire/road interface for either high or low speed applications, a necessary feature of simulations which support human in the loop driving simulation. Like traditional kinematically-based longitudinal slip, the transient formulation presented here is coupled with the wheel spin equation, and it shares the characteristic that it is very stiff compared to the equations of vehicle motion. This characteristic is a challenge impeding the real-time calculations required for driving simulation. The paper shows that local linearization of the wheel spin equations coupled with analytical solutions of the transient longitudinal slip formulation provide the basis for both insight into the longitudinal dynamics of the tire and for integrating the model in real-time.     

液罐汽车横向稳定性的研究

对液罐车非满载工况下在水平道路上转弯行驶以及在侧坡道路上直线行驶和转弯行驶时的液体质心坐标和横向稳定性进行了分析研究。在水平道路上转弯行驶时，质心的转移及侧倾程度主要与转弯半径，车速等有关；在侧坡道路上直线行驶时，质心的转移及侧倾程度主要与坡道的角度有关，在侧坡上转弯行驶时，质心的转移及侧倾程度除与侧坡角度有关外，还与转弯半径和车速等有关。为了减少液体质心的转移对汽车横向稳定性的影响，可在罐内增加纵向隔板，来抑制液体质心的转移。     

Longitudinal Tire Dynamics

SUMMARY

This article begins with a brief review of the traditional concept of lateral relaxation length. The review illustrates that this concept yields a useful approximation which can be used with semi-empirical tire models which assume lateral forces are a function of steady-state slip angles. The article then presents an analogous derivation for longitudinal slip. Like its lateral counterpart, the derivation yields an approximation for transient longitudinal slip which can be used with tire models which assume longitudinal forces are a function of steady-state longitudinal slip. It is shown that, like the relaxation-length-based lateral slip angle, this formulation for longitudinal slip yields the ability to compute shear forces at the tire/road interface for either high or low speed applications, a necessary feature of simulations which support human in the loop driving simulation. Like traditional kinematically-based longitudinal slip, the transient formulation presented here is coupled with the wheel spin equation, and it shares the characteristic that it is very stiff compared to the equations of vehicle motion. This characteristic is a challenge impeding the real-time calculations required for driving simulation. The paper shows that local linearization of the wheel spin equations coupled with analytical solutions of the transient longitudinal slip formulation provide the basis for both insight into the longitudinal dynamics of the tire and for integrating the model in real-time.     

Human Control of Road Vehicles

This paper reviews the present state of knowledge of human control of road vehicles. Lateral and longitudinal control of motorcycles and automobiles are discussed, whenever information is available. Although knowledge has increased greatly in the last decade, the major part of this concerns lateral control and most is of an ad hoc nature. Adequate mathematical models for longitudinal motion of the vehicle are yet to be developed. Their development is a necessary step in the attainment of a complete understanding of longitudinal control.     

激光断面仪计量检定技术研究

针对目前缺少激光断面仪的计量检定方法,且传统比对试验方法可靠性低的情况,基于激光断面仪的工作原理,分解国际平整度指数的计算过程,在数据试验分析的基础上,采用在同一试验平台道路条件下,应用模块化高程变换技术,通过不同位置点高程的有序变化实现了检定激光断面仪动态特性所需要的不同路面平整度试验条件,消除了道路环境对试验结果的影响,借助高精度水准仪和激光测距仪的溯源途径解决了国际平整度指数溯源的要求。所建计量标准试验道路提供的检验量值重复性达到了设计要求,经过半年时间的稳定性考核,量值稳定可靠,不确定度分析结果证明整套检定装置的相对不确定度为1%。     

Friction coefficient measurement for autonomous winter road maintenance

Real-time measurement of tyre–road friction coefficient is extremely valuable for winter road maintenance operations, since knowledge of tyre–road friction coefficient can be used to optimise application of deicing chemicals to the roadway. In this paper, a wheel-based tyre–road friction coefficient measurement system is developed for snowploughs. Unlike a traditional Norse meter, this system is based on measurement of lateral tyre forces, has minimal moving parts and does not use a brake actuator. Hence, it is reliable and inexpensive. A key challenge is quickly detecting changes in the estimated tyre–road friction coefficient while rejecting the high levels of vibratory noise in the measured force signal. Novel filtering and signal processing algorithms are developed to address this challenge, including a biased quadratic mean filter and an accelerometer-based vibration removal filter. Detailed experimental results are presented on the performance of the friction estimation system on different types of road surfaces. It is also shown that disturbances due to lateral and longitudinal vehicle manoeuvres on the estimated friction coefficient can be removed by using accelerometer-based filtering.     

Human Control of Road Vehicles

SUMMARY

This paper reviews the present state of knowledge of human control of road vehicles. Lateral and longitudinal control of motorcycles and automobiles are discussed, whenever information is available. Although knowledge has increased greatly in the last decade, the major part of this concerns lateral control and most is of an ad hoc nature. Adequate mathematical models for longitudinal motion of the vehicle are yet to be developed. Their development is a necessary step in the attainment of a complete understanding of longitudinal control.     

SBS改性沥青SMA-13混合料在长大纵坡路段旧路面层改造中的应用

重载作用下长大纵坡沥青路面常出现车辙、推移、开裂等病害。以鞍隆线二级公路长大纵坡病害路段的治理工程为研究对象,调查其交通状况,路面工作状况,分析该段路面损坏的影响因素和破坏机理,提出用于旧路维修的路面结构设计方案,对面层SMA混合料进行设计,检验其动稳定度、渗水系数、劈裂强度、构造深度等性能,并铺筑了试验路段,后期观测结果良好。     

A curving ACC system with coordination control of longitudinal car-following and lateral stability

The paper presents a curving adaptive cruise control (ACC) system that is coordinated with a direct yaw-moment control (DYC) system and gives consideration to both longitudinal car-following capability and lateral stability on curved roads. A model including vehicle longitudinal and lateral dynamics is built first, which is as discrete as the predictive model of the system controller. Then, a cost function is determined to reflect the contradictions between vehicle longitudinal and lateral dynamics. Meanwhile, some I/O constraints are formulated with a driver permissible longitudinal car-following range and the road adhesion condition. After that, desired longitudinal acceleration and desired yaw moment are obtained by a linear matrix inequality based robust constrained state feedback method. Finally, driver-in-the-loop tests on a driving simulator are conducted and the results show that the developed control system provides significant benefits in weakening the impact of DYC on ACC longitudinal car-following capability while also improving lateral stability.     

基于横向安全距离模型的主动避障算法

现有的安全距离模型是基于纵向相对车速或减速度值建立的,没有考虑移动目标的横向运动特性。本文利用移动目标横穿马路的速度、相对位置,建立横向安全距离模型,并提出一种基于横向安全距离模型的主动避障算法。首先,根据横向移动目标横穿马路的速度、相对位置和自车的制动距离建立横向安全距离模型,设计主动避障算法。接着,为计及路面条件对制动效果的影响,引入当前行驶路面估算的附着系数峰值估算最大制动减速度,约束目标避障减速度,并调整制动强度,以适应不同路况的安全避障行驶。最后,以典型横向移动目标骑行者作为研究对象,通过PreScan/Simulink/CarSim联合仿真验证避障算法的有效性。结果表明:基于横向安全距离模型的主动避障算法能有效避免与骑行者碰撞,提高行车的主动安全性。     

On model-based longitudinal feed-forward motion control for low velocities on known road profiles

ABSTRACT

So far, longitudinal motion control has focused on situations like highway driving, where disturbances of the road profile can be neglected. In this paper, we show how the Two Point Tire Model can be used to derive a novel feed-forward control law for a vehicle's longitudinal motion that considers the effects of the road profile and can complement existing control approaches. For this purpose, we recapitulate the basic model assumptions and equations and briefly discuss how it can be used on arbitrary road profiles. Two approaches for implementation in a real vehicle are presented. Comparisons of these approaches in simulation and to a human driver of an experimental vehicle show that the controller can deal with stepped obstacles of up to 14?cm in height. However, the control performance is essentially limited by the actuator delay and human drivers outperform the controller due to their ability of sensing subtle vehicle motions. The results indicate that the control performance can be further improved by using a preview on the necessary drive torque, which can be provided by the solution that we propose.     

基于道路线形的智能汽车事故多发路段预判模型

分析了道路线形对智能汽车行驶安全性的影响,分别使用数据驱动的机器学习方法和模型驱动的经典数学建模方法,建立了以道路线形技术指标为输入的神经网络模型和多元数学模型,预测事故多发路段;计算了各个道路线形技术指标与事故率之间的偏相关系数,从中挑选出与事故率相关程度较大的道路线形特征,使用T检验和F检验验证了道路线形特征组合和...     

Model-Based Road Friction Estimation

The tire/road friction coefficient, μ, has a significant role in vehicle longitudinal and lateral control, and there has been associated efforts to measure or estimate the road surface condition to provide additional information for stability augmentation systems of automobiles. In this paper, a model based road friction estimation algorithm is proposed from easily measured signals such as yaw rate and wheel speed. For the development of the estimator, a low order vehicle model incorporated with simple but effective tire model. Field tests of the estimator using actual vehicle measurements show promising results.     

Velocity and normal tyre force estimation for heavy trucks based on vehicle dynamic simulation considering the road slope angle

A precise estimation of vehicle velocities can be valuable for improving the performance of the vehicle dynamics control (VDC) system and this estimation relies heavily upon the accuracy of longitudinal and lateral tyre force calculation governed by the prediction of normal tyre forces. This paper presents a computational method based on the unscented Kalman filter (UKF) method to estimate both longitudinal and lateral velocities and develops a novel quasi-stationary method to predict normal tyre forces of heavy trucks on a sloping road. The vehicle dynamic model is constructed with a planar dynamic model combined with the Pacejka tyre model. The novel quasi-stationary method for predicting normal tyre forces is able to characterise the typical chassis configuration of the heavy trucks. The validation is conducted through comparing the predicted results with those simulated by the TruckSim and it has a good agreement between these results without compromising the convergence speed and stability.     

Optimisation of railway crossing geometry considering a representative set of wheel profiles

A numerical method for robust geometry optimisation of railway crossings is presented. The robustness is achieved by optimising the crossing geometry for a representative set of wheel profiles. As a basis for the optimisation, a crossing geometry is created where rail cross-sectional profiles and longitudinal height profiles of both wing rails and crossing nose are parameterised. Based on the approximation that the two problems are decoupled, separate optimisations are performed for the cross-sectional rail profiles and the longitudinal height profiles. The rail cross sections are optimised to minimise the maximum Hertzian wheel–rail contact pressure. The longitudinal height profiles are optimised to minimise the accumulated damage in the wing rail to crossing nose transition zone. The accumulated damage is approximated using an objective criterion that accounts for the angle of the wheel trajectory reversal during the transition from the wing rail to the crossing nose as well as the distribution of transition points for the utilised wheel profile set. It is found that small nonlinear height deviations from a linear longitudinal wing rail profile in the transition zone can reduce the objective compared to the nominal design. It is further demonstrated that the variation in wheel profile shapes, lateral wheel displacements and the feasible transition zone length of the crossing will determine the longitudinal height profiles of the wing rail and crossing nose if all wheel profiles are to make their transition within the transition zone.     

公路排水系统设计参数研究

为了解决非单一纵坡条件下沟渠设计纵坡的确定问题，提出了沟渠名义设计纵坡的概念，给出了相应的计算公式。根据各类沟渠的结构重要性、损坏后果、修复可易性、使用要求以及国外的相关规定，提出了路界表面排水设施的设计降雨重现期和安全高度建议值。此外，讨论了沟管冲淤条件和允许最小纵坡的关系，对现行公路排水设计规范中的相应规定提出了修改建议。该成果可用于公路排水设计，也可为以后的规范修订提供技术支持。     

隧道下穿松散高填土路堤的沉降规律及其影响范围研究

为解决下穿隧道施工对既有高填土路堤的影响问题，依托成贵铁路大方隧道下穿杭瑞高速工程建立三维有限元模型，研究隧道施工对上覆地层位移影响、地表纵向变形特征以及下穿施工对地表各特征位置的主要影响范围。研究结果表明： 1）隧道下穿施工造成高填土路堤层发生显著沉降变形，上覆地层向隧道正中方向产生明显横向位移； 2）大方隧道下穿施工产生的地表纵向变形可划分为微变形区（洞口浅埋沉降区）、强变形区（高填土路堤沉降区）和弱变形区（地表沉降区）3个区域； 3）大方隧道施工分别开挖至洞口、挡墙和公路路面等特征位置时的地表纵向影响范围分别为开挖前方的75、52、65 m，在此影响范围内地层位移变化强烈； 4）拱顶动态沉降曲线均呈反“S”形特征。结合现场监测数据进行对比分析，得出模拟计算值与监测值变化趋势基本吻合，并最后给出相关施工建议措施。     

eTS fuzzy driver model for simultaneous longitudinal and lateral vehicle control

In this paper, evolving Takagi-Sugeno (eTS) fuzzy driver model is proposed for simultaneous lateral and longitudinal control of a vehicle in a test track closed to traffic. The developed eTS fuzzy driver model can capture human operator’s driving expertise for generating desired steering angle, throttle angle and brake pedal command values by processing only information which can be supplied by the vehicle’s on-board control systems in real time. Apart from other fuzzy rule based (FRB) models requiring human expert knowledge or off-line clustering, the developed eTS driver model can adapt itself automatically, even ‘from scratch’, by an on-line learning process using eTS algorithm while human driver is supervising the vehicle. Proposed eTS fuzzy driver model’s on-line human driver identification capability and autonomous vehicle driving performance were evaluated on real road profiles created by digitizing two different intercity express ways of Turkey in IPG© CarMaker® software. The training and validation simulation results demonstrated that eTS fuzzy driver model can be used in product development phase to speed up different tests via realistic simulations. Furthermore eTS fuzzy driver model has an application potential in the field of autonomous driving.     

3D brush model to predict longitudinal tyre characteristics

A 3D tyre brush model, which aims to predict the longitudinal tyre characteristic under steady-state conditions by modelling the occurring physical effects in the tyre–road contact patch, is presented. The model includes an analytical method to describe the tyre footprint geometry, the pressure distribution, the slip due to the lateral tyre contour, the slip due to braking or traction and the longitudinal as well as the lateral shear stresses on a flattened tyre. The presented development tool offers a method to investigate different rubber friction data (caused by different tread compounds and/or surface textures) and to analyse its influence on longitudinal tyre characteristics. The tyre design is fixed (same casing, dimension and pattern). The results include the shear stresses as well as the different sliding velocities in the contact patch for different slip conditions. The model was developed for a standard summer pattern design and a standard tyre dimension (205/55R16). It can also be adapted to other tread designs and tyre dimensions. To offer a good comparability between model results and test bench measurements, the surface curvature of an internal test rig is considered.