铰接车辆在不平道路行驶的动力学仿真

本文将铰接车辆简化为一多体系统，把轮胎简化为三维分段性弹簧，通过引入刚性位移机制，考虑路面不平度及其产生的坡度对车辆动力性的影响。建立了铰接车辆在不平路面行驶的动力学模型，列出了运动微分方程，提出了铰接车辆在不平路面行驶的动力学仿真算法，并通过实验验证了此模型及仿真算法的正确性。     

铰接汽车转向器座可靠性分析

针对铰接式城市客车转向器座的受载特点,运用有限元分析方法计算了几种典型工况下某铰接汽车转向器座的疲劳强度,得到了转向器座接近实际工况的应力循环,然后利用其S-N曲线,基于Miner线性累计损伤准则计算其疲劳寿命。通过与成熟的产品疲劳分析结果的比较,获得了新车型的可靠性数据,减少了试验成本。     

大型车辆侧翻预测和控制技术研究进展

大型车辆引起的重特大侧翻事故频发会造成严重的人员伤亡和财产损失,因此,提高中国大型车辆防侧翻技术水平显得尤为重要.通过阐述国内外在车辆侧翻预警和稳定性控制方面开展的研究现状,详细描述基于静态门限值法和动态门限值法的侧翻预警技术研究进展,分析车辆半主动、主动转向控制、主动悬架控制、差动控制、电子稳定控制、联合控制等防侧翻控制技术发展现状,指出当前车辆侧倾预警领域主要研究方向在于提高侧翻指标的预测精度和响应实时性,特别是综合考虑道路环境因素对侧翻指标的影响.侧翻控制已逐步从半主动阶段提升到主动控制,控制方法更趋智能化、精确化.人-车-路-环境耦合作用、复杂非线性条件下的车辆侧翻预测模型,以及混沌条件下的优化控制将会是未来重点研究方向.     

基于主动转向技术的汽车防侧翻控制的研究

以汽车2自由度模型作为参考模型，建立了一种汽车防侧翻的控制方法。该方法采用主动转向技术来改变转向轮的转向角度，有效地减少了汽车的侧向加速度，提高了汽车的防侧翻的能力。在8自山度汽车动力学模型的基础上，运用主动转向技术的控制策略进行了汽车的性能仿真分析。与末采用汽车防侧翻控制系统的汽车动力学分析结果相比，汽车的主动安全性得到了增强。     

铰接工程车辆稳定性的固有模态

本文将铰接式工程车辆简化为多体系统，将轮胎简化为带有粘阻尼的分段线性弹簧，列出了系统的运动策方程，以ＺＬ１０装载机为例，测量了轮胎的三维动态刚度与阻尼，利用模态分析方法，求出前７阶固有上频率与固有振型，并以三维彩色动画显示于计算机屏幕，通过分析得出如下结论，第１阶固有频率与横向稳定性有关，第２阶固有频率与竖向稳定性有关。这一结论对于工程车辆稳定性的监测与控制具有重要参考价值。     

重型汽车转向侧翻稳定性浅析

重型汽车一般为非公路车辆,其质心高度较高,行驶的道路条件较为恶劣且装载质量大,车辆的行驶安全十分重要。重型汽车的侧翻试验是难以实施的,本文通过建立重型汽车侧翻的数学模型,进行计算机仿真,     

铰接车辆稳定性的监测与控制方法

本文将铰接车辆稳定性的理论研究成果应用于稳定性的监测与控制，提出了通过监测车轮接地正压力和设定接地压力门限来进行稳定性预警与控制的原理，及通过低通数字滤波来分辨真假失稳的方法，运用现代电子测试技术与计算机控制技术，研制成功了能够显示铰接车辆当前稳定程度，分级自动声光报警与控制的单片机稳定性监控系统，通过装机试验，证明装机试验，证明它是成功的，估计在全国范围内推广后，至少可降低翻车事故率４０％。     

车辆侧翻警示及控制系统的现状研究

乘用车领域,SUV由于质心较高,导致动态侧翻稳定性较差,易产生侧翻;商用车领域,重型车辆(尤其是重型半挂车)具有重量和尺寸大、质心高等特点,与其他公路车辆相比,其侧翻稳定极限较低。因此,提高车辆的侧倾稳定性是提高公路运输安全和减少交通事故的重要手段。本文阐述了车辆侧翻警示与控制系统的研究方法,比较出车辆侧翻警示与控制的优缺点,为车辆侧翻警示算法及控制策略的研究奠定了基础。     

混凝土搅拌运输车水平道路转向侧翻稳定性计算

根据国家特种车辆设计标准,选取混凝土搅拌运输车侧翻稳定性计算的各项参数,对水平路面不同转向和旋向车辆的侧翻稳定性进行计算,得到控制混凝土搅拌运输车转向侧翻的最高行驶车速,为规范二类通用底盘型混凝土搅拌运输车安全行驶车速提供了理论依据。     

高速紧急转向对大客车侧翻稳定性影响的研究

为了研究大型客车驾驶员不同的紧急转向操作对客车行驶安全性所产生的影响,利用Trucksim 软件,采用仿真建模的方法,选用轮胎载荷转移率 LTR 作为分析指标,通过多组不同路面条件、行驶速度和转角幅度下的车辆动力学的仿真试验,定量地比对分析了不同的紧急转向操作对大客车侧翻稳定性的影响。仿真结果表明,在干燥路面上,行驶速度和转角幅度与客车的侧翻稳定性呈负相关,即行驶速度越高,转角幅度越大,LTR 越趋向于1。而在湿滑路面上,行驶速度和转角幅度与客车的侧滑稳定性呈负相关,即行驶速度越高,转角幅度越大,车辆越易发生侧滑。此外,客车在第2次回转时的侧翻风险性或侧滑风险性显著高于第1次紧急转向时的风险。     

Method for control of steering angles for articulated vehicles using virtual rigid axles

Many methods we have been developed to control the rear wheels of a vehicle, but most of them are designed for automobiles with four wheels. The AWS (all wheel steering) control method for articulated vehicles is currently applied only to Phileas vehicles developed by APTS, but the control algorithm for this system has yet to be reported. In the present paper, a new algorithm is proposed after the AWS ECU (electronic control unit) of the Phileas vehicle was tested and analyzed in order to understand the existing steering algorithm. The new algorithm considers the vehicle geometry, stability of handling, and safety, and can be easily applied to multi-axle vehicles. In order to verify the AWS algorithm, the trajectory and steering angles of each algorithm were compared using the commercial software ADAMS. Turning radius, swing-out, and swept path width were also investigated to determine the turning performance of the proposed algorithm.     

A closed-loop dynamic simulation-based design method for articulated heavy vehicles with active trailer steering systems

This paper presents a closed-loop dynamic simulation-based design method for articulated heavy vehicles (AHVs) with active trailer steering (ATS) systems. AHVs have poor manoeuvrability at low speeds and exhibit low lateral stability at high speeds. From the design point of view, there exists a trade-off relationship between AHVs’ manoeuvrability and stability. For example, fewer articulation points and longer wheelbases will improve high-speed lateral stability, but they will degrade low-speed manoeuvrability. To tackle this conflicting design problem, a systematic method is proposed for the design of AHVs with ATS systems. In order to evaluate vehicle performance measures under a well-defined testing manoeuvre, a driver model is introduced and it ‘drivers’ the vehicle model to follow a prescribed route at a given speed. Considering the interactions between the mechanical trailer and the ATS system, the proposed design method simultaneously optimises the active design variables of the controllers and passive design variables of the trailer in a single design loop (SDL). Through the design optimisation of an ATS system for an AHV with a truck and a drawbar trailer combination, this SDL method is compared against a published two design loop method. The benchmark investigation shows that the former can determine better trade-off design solutions than those derived by the latter. This SDL method provides an effective approach to automatically implement the design synthesis of AHVs with ATS systems.     

Dynamic model and validation of an articulated steering wheel loader on slopes and over obstacles

This paper devotes both analytical and experimental efforts in developing a comprehensive dynamic model for an articulated steering wheel loader. The general motion of a wheel loader without suspension is described by seven degrees of freedom (DOF) (three for translation and four for rotation) in this model, which can be used to study the problem of wheel loader dynamics on slopes and over obstacles. A scale wheel loader was designed and manufactured to validate the dynamic model in three conditions (turning on level ground, turning on slopes, and passing over obstacles). The test results reasonably agree with the simulation results. The developed dynamic model was found to be useful and could serve as an important tool for analysing the stability of wheel loaders.     

An improvement in rollover detection of articulated vehicles using the grey system theory

A Rollover Index combined with the grey system theory, called a Grey Rollover Index (GRI), is proposed to assess the rollover threat for articulated vehicles with a tractor–semitrailer combination. This index can predict future trends of vehicle dynamics based on current vehicle motion; thus, it is suitable for vehicle-rollover detection. Two difficulties are encountered when applying the GRI for rollover detection. The first difficulty is effectively predicting the rollover threat of the vehicles, and the second difficulty is achieving a definite definition of the real rollover timing of a vehicle. The following methods are used to resolve these problems. First, a nonlinear mathematical model is constructed to accurately describe the vehicle dynamics of articulated vehicles. This model is combined with the GRI to predict rollover propensity. Finally, TruckSim^? software is used to determine the real rollover timing and facilitate the accurate supply of information to the rollover detection system through the GRI. This index is used to verify the simulation based on the common manoeuvres that cause rollover accidents to reduce the occurrence of false signals and effectively increase the efficiency of the rollover detection system.     

Design and validation of a robust active trailer steering system for multi-trailer articulated heavy vehicles

ABSTRACT

Multi-trailer articulated heavy vehicles (MTAHVs) are increasingly used around the world due to their economic and environmental benefits. However, MTAHVs exhibit poor maneuverability and low lateral stability, which may lead to fatal traffic accidents. Given the safety risks, it is necessary to solve the steering and stability problems of MTAHVs before they are safely mass deployed on our roads. To this end, active trailer steering (ATS) based on the linear quadratic regulator (LQR) technique has been explored. The LQR-based ATS demonstrates improved maneuverability and enhanced lateral stability. In the ATS design, the vehicle and operating parameters are assumed constant. Thus, it is natural to question the robustness of the ATS in presence of vehicle and operating parameter uncertainties. To address the problem, this paper proposes a robust ATS system. The robust ATS controller is designed using a linear matrix inequality (LMI) based LQR method. In the design, both vehicle and steering actuator parameter uncertainties are considered; to enhance the robustness of the ATS, the weighting matrices of the proposed controller are optimized. The robust controller is applied to an A-Train Double, one type of MTAHV. The effectiveness of the robust ATS is demonstrated using numerical and hardware-in-the-loop real-time simulations.     

A study on single lane-change manoeuvres for determining rearward amplification of multi-trailer articulated heavy vehicles with active trailer steering systems

The Society of Automotive Engineers issued a test procedure, SAE-J2179, to determine the rearward amplification (RA) of multi-trailer articulated heavy vehicles (MTAHVs). Built upon the procedure, the International Organization for Standardization released the test manoeuvres, ISO-14791, for evaluating directional performance of MTAHVs. For the RA measures, ISO-14791 recommends two single lane-change manoeuvres: (1) an open-loop procedure with a single sine-wave steering input; and (2) a closed-loop manoeuvre with a single sine-wave lateral acceleration input. For an articulated vehicle with active trailer steering (ATS), the RA measure in lateral acceleration under the open-loop manoeuvre was not in good agreement with that under the closed-loop manoeuvre. This observation motivates the research on the applicability of the two manoeuvres for the RA measures of MTAHVs with ATS. It is reported that transient response under the open-loop manoeuvre often leads to asymmetric curve of tractor lateral acceleration [Winkler CB, Fancher PS, Bareket Z, Bogard S, Johnson G, Karamihas S, Mink C. Heavy vehicle size and weight – test procedures for minimum safety performance standards. Final technical report, NHTSA, US DOT, contract DTNH22-87-D-17174, University of Michigan Transportation Research Institute, Report No. UMTRI-92-13; 1992]. To explore the effect of the transient response, a multiple cycle sine-wave steering input (MCSSI) manoeuvre is proposed. Simulation demonstrates that the steady-state RA measures of an MTAHV with and without ATS under the MCSSI manoeuvre are in excellent agreement with those under the closed-loop manoeuvre. It is indicated that between the two manoeuvres by ISO-14791, the closed-loop manoeuvre is more applicable for determining the RA measures of MTAHVs with ATS.     

Theory and experimental research on six-track steering vehicles

The structural characteristics and steering behaviour of a six-track vehicle are described in this paper. Kinematic analysis for skid steering of a six-track vehicle under steady-state conditions on firm ground is conducted, with the relationship between thrust force and speed instantaneous centre of the track–terrain interface taken into consideration. A mechanical model for steady steering of a six-track vehicle is also presented based on the kinematic analysis. In this model, the steering inaccuracy and efficiency are defined to evaluate steering performance. The steering performance of a six-track vehicle is numerically simulated to analyse the effect of the structural parameters and deflection angles on tracks. A virtual prototype model is established based on the multi-body dynamics software RecurDyn for steering simulation and the findings coincide well with theoretical results. The theory and the virtual prototype simulations presented are verified by a power test of a bucket-wheel excavator. The method for analysing the steering performance of a six-track vehicle proposed in this paper provides a basis for designing a six-track vehicle.     

Combined emergency braking and turning of articulated heavy vehicles

‘Slip control’ braking has been shown to reduce the emergency stopping distance of an experimental heavy goods vehicle by up to 19%, compared to conventional electronic/anti-lock braking systems (EBS). However, little regard has been given to the impact of slip control braking on the vehicle’s directional dynamics. This paper uses validated computer models to show that slip control could severely degrade directional performance during emergency braking. A modified slip control strategy, ‘attenuated slip demand’ (ASD) control, is proposed in order to rectify this. Results from simulations of vehicle performance are presented for combined braking and cornering manoeuvres with EBS and slip control braking with and without ASD control. The ASD controller enables slip control braking to provide directional performance comparable with conventional EBS while maintaining a substantial stopping distance advantage. The controller is easily tuned to work across a wide range of different operating conditions.     

Anti-jackknife reverse tracking control of articulated vehicles in the presence of actuator saturation

It is well known that backward motion control of an articulated vehicle is difficult because it is an open loop unstable system and such motion is also dangerous due to ‘jackknifing’. In this paper, an anti-jackknife reverse tracking control strategy for autonomous articulated vehicles is proposed based on the combined longitudinal and lateral control scheme. In the proposed lateral-longitudinal control scheme, the major task is to control the reverse heading of the trailer by automatic steering strategies that observe both the anti-jackknife condition and input limitations. The main contribution of this paper is the development of globally asymptotic anti-jackknife stabilising and tracking controls of heading angles with both state and input constraints considered a priori. The proposed control inherently has an anti-windup mechanism that prevents the hitch angle from going beyond any specified critical value to avoid jackknifing, during which time, the steering angle remains at its limit. Stability of the controller is theoretically proven via the Lyapunov argument. Effectiveness of the proposed approach is demonstrated by CarSim and Simulink joint simulations.     

铰接式自卸车液压转向系统的特性分析

介绍一种用于铰接式自卸车的转向流量阀,通过对其结构的分析,得出了其流量放大的原理,从而解决了铰接式自卸车使用普通的液压转向装置,无法为转向执行元件提供足够流量的难题,保证了铰接式自卸车正常安全实现转向.