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。     

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。     

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.     

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。     

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.     

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.     

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.     

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.     

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.     

Multi-axle/articulated bus dynamics modeling: a reconfigurable approach

This paper proposed a unified model including yaw and roll dynamics for any axle or articulation configuration of buses by using a reconfigurable approach. First, all the possible existing configurations of buses are introduced, including the axle/articulation configuration, powertrain configuration, and active chassis control configuration. Consequently, the research is motivated by a key question: how can we develop a unified model that is inclusive and configurable to all of the above bus configurations? To develop the model, three layers of the modeling process are presented step by step. The magic formula and vertical load transfer are discussed to formulate the tyre model. It is noted that the case of the articulated bus is presented in an independent section but how it is included and unified in a general form is also explained. Finally, a modeling validation of axle or articulation configuration cases is performed and the comparative results to high-fidelity models show the feasibility, efficiency, and convenience of the reconfigurable approach. As the crucial feature, the resulting model can be potentially applied to model-based controller design in any buses without reformulating the model. This will greatly benefit the vehicle dynamics control and also future autonomous buses. Although the focus of this paper is buses, the proposed approach actually covers any multi-axle/articulated vehicles, like trucks, tractor-trailers.     

Nonlinear PI front and rear steering control in four wheel steering vehicles

Vehicle steering dynamics show resonances, which depend on the longitudinal speed, unstable equilibrium points and limited stability regions depending on the constant steering wheel angle, longitudinal speed and car parameters.

The main contribution of this paper is to show that a combined decentralized proportional active front steering control and proportional-integral active rear steering control from the yaw rate tracking error can assign the eigenvalues of the linearised single track steering dynamics, without lateral speed measurements, using a standard single track car model with nonlinear tire characteristics and a non-linear first-order reference model for the yaw rate dynamics driven by the driver steering wheel input. By choosing a suitable nonlinear reference model it is shown that the responses to driver step inputs tend to zero (or reduced) lateral speed for any value of longitudinal speed: in this case the resulting controlled vehicle static gain from driver input to yaw rate differs from the uncontrolled one at higher speed. The closed loop system shows the advantages of both active front and rear steering control: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres, enlarged stability regions, reduced lateral speed and improved manoeuvrability; in addition comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced.

For the designed control law a robustness analysis is presented with respect to system failures, driver step inputs and critical car parameters such as mass, moment of inertia and front and rear cornering stiffness coefficients. Several simulations are carried out on a higher order experimentally validated nonlinear dynamical model to confirm the analysis and to explore the robustness with respect to unmodelled dynamics.     

Asymptotic sideslip angle and yaw rate decoupling control in four-wheel steering vehicles

This paper shows that, for a four-wheel steering vehicle, a proportional-integral (PI) active front steering control and a PI active rear steering control from the yaw rate error together with an additive feedforward reference signal for the vehicle sideslip angle can asymptotically decouple the lateral velocity and the yaw rate dynamics; that is the control can set arbitrary steady state values for lateral speed and yaw rate at any longitudinal speed. Moreover, the PI controls can suppress oscillatory behaviours by assigning real stable eigenvalues to a widely used linearised model of the vehicle steering dynamics for any value of longitudinal speed in understeering vehicles. In particular, the four PI control parameters are explicitly expressed in terms of the three real eigenvalues to be assigned. No lateral acceleration and no lateral speed measurements are required. The controlled system maintains the well-known advantages of both front and rear active steering controls: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres and improved manoeuvrability. In particular, zero lateral speed may be asymptotically achieved while controlling the yaw rate: in this case comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced. Also zero yaw rate can be asymptotically achieved: in this case additional stable manoeuvres are obtained in obstacle avoidance. Several simulations, including step references and moose tests, are carried out on a standard small SUV CarSim model to explore the robustness with respect to unmodelled effects such as combined lateral and longitudinal tyre forces, pitch, roll and driver dynamics. The simulations confirm the decoupling between the lateral velocity and the yaw rate and show the advantages obtained by the proposed control: reduced lateral speed or reduced yaw rate, suppressed oscillations and new stable manoeuvres.     

Active roll control for rollover prevention of heavy articulated vehicles with multiple-rollover-index minimisation

This paper presents the application of a nominal control design algorithm for rollover prevention of heavy articulated vehicles with active anti-roll-bar control. This proposed methodology is based on an extension of linear quadratic regulator control for ‘state derivative-induced (control coupled) output regulation’ problems. For heavy articulated vehicles with multiple axles, a performance index with multiple rollover indices is proposed. The proposed methodology allows us to compare the usefulness of various control configurations (i.e. actuators at different axles of the vehicle) based on the interaction of this control configuration with vehicle dynamics. Application of this methodology to a specific heavy articulated vehicle with a tractor semi-trailer shows that a single active anti-roll-bar system at the trailer unit gives better performance than multiple-axle actuators at tractor and trailer together with the single lane change manoeuvre as the external disturbance. Thus, the proposed methodology of this paper not only highlights the importance of the interactions between control and vehicle dynamics in rollover prevention problems but, in fact, proposes a novel technique to exploit the benefits of these interactions judiciously.     

Coordinated control strategies for active steering,differential braking and active suspension for vehicle stability,handling and safety improvement

ABSTRACT

In this paper, a coordinated control strategy is proposed to provide an effective improvement in handling stability of the vehicle, safety, and comfortable ride for passengers. This control strategy is based on the coordination among active steering, differential braking, and active suspension systems. Two families of controllers are used for this purpose, which are the high order sliding mode and the backstepping controllers. The control strategy was tested on a full nonlinear vehicle model in the environment of MATLAB/Simulink. Rollover avoidance and yaw stability control constraints have been considered. The control system mainly focuses on yaw stability control. When rollover risk is detected, the proposed strategy controls the roll dynamics to decrease rollover propensity. Simulation results for two different critical driving scenarios, the first one is a double lane change and the other one is a J-turn manoeuvre, show the effectiveness of the coordination strategy in stabilising the vehicle, enhancing handling and reducing rollover propensity.