Influencing driver chosen cornering speed by means of modified steering feel

This paper presents an investigation about influencing the driver's behaviour intuitively by means of modified steering feel. For a rollover indication through haptic feedback a model was developed and tested that returned a warning to the driver about too high vehicle speed. This was realised by modifying the experienced steering wheel torque as a function of the lateral acceleration. The hypothesis for this work was that drivers of heavy vehicles will perform with more margin of safety to the rollover threshold if the steering feel is altered by means of decreased or additionally increased steering wheel torque at high lateral acceleration. Therefore, the model was implemented in a test truck with active steering with torque overlay and used for a track test. Thirty-three drivers took part in the investigation that showed, depending on the parameter setting, a significant decrease of lateral acceleration while cornering.     

汽车转向感觉主观评价试验方法综述

传统的转向评价标准已经不能完全适应新兴的动力转向,如何系统的评价转向感觉,如何获得理想的转向感觉,已经成为国内外迫切需要解决的问题。分别对转向的移线性能、中间位置转向性能和转向的舒适性等主观感觉评价进行介绍,分析转向感觉主观评价中的几个基本问题,并探讨应用实车试验、驾驶员模型和驾驶模拟器进行转向感觉试验的主要方法,对今后转向感觉主观评价的发展具有一定指导性和借鉴意义。     

汽车操纵稳定性主客观评价数据的一种处理方法

汽车操纵稳定性主客观评价之间的相关性分析是汽车技术的重要课题。提出了汽车操纵稳定性主客观评价数据的一种处理方法．通过回归分析筛选客观参数,运用BP神经网络建立相关性模型,验证结果说明了该方法的可行性。     

A model of driver steering control incorporating the driver's sensing of steering torque

Steering feel, or steering torque feedback, is widely regarded as an important aspect of the handling quality of a vehicle. Despite this, there is little theoretical understanding of its role. This paper describes an initial attempt to model the role of steering torque feedback arising from lateral tyre forces. The path-following control of a nonlinear vehicle model is implemented using a time-varying model predictive controller. A series of Kalman filters are used to represent the driver's ability to generate estimates of the system states from noisy sensory measurements, including the steering torque. It is found that under constant road friction conditions, the steering torque feedback reduces path-following errors provided the friction is sufficiently high to prevent frequent saturation of the tyres. When the driver model is extended to allow identification of, and adaptation to, a varying friction condition, it is found that the steering torque assists in the accurate identification of the friction condition. The simulation results give insight into the role of steering torque feedback arising from lateral tyre forces. The paper concludes with recommendations for further work.     

Generalised multi-axle vehicle handling

The familiar two-axle bicycle model and associated basic concepts of vehicle handling are reviewed and used to introduce minor changes in convention from the literature. The two-axle model is extended to a three-axle vehicle to illustrate the effectiveness of the notation combined with a simplifying mathematical identity found in the two-axle vehicle literature. A generalised model is then developed that produces dynamic equations of motion by inspection for a vehicle with an arbitrary number of steerable and non-steerable axles. Furthermore, the vehicle dynamic concepts of understeer and wheelbase are generalised and can be directly computed for various arbitrary vehicle configurations.     

基于驾驶员在环的EPS试验台开发

汽车转向系统性能与汽车的操纵稳定性和舒适性有关,对汽车的行驶安全起着至关重要的作用。随着动力转向系统的发展,电动助力转向系统的优势逐渐突出。这里运用七自由度汽车模型,拟设计出一种基于驾驶员在环的转向测试试验台,将驾驶员操纵的油门踏板和转向信号实时采集,通过信号运算和汽车动力学模型实时仿真,实现转向力矩的模拟和车辆状态信息的输出,并可以快速进行EPS系统的开发验证。     

Lateral dynamics emulation via a four-wheel steering vehicle

In this paper, we examine the lateral dynamics emulation capabilities of an automotive vehicle equipped with four-wheel steering. We first demonstrate that the lateral dynamics of a wide range of vehicles can be emulated, either with little or with no modification on the test vehicle. Then we discuss a sliding mode controller for active front and rear wheel steering, in order to track some given yaw rate and side-slip angle. Analytically, it is shown that the proposed controller is robust to plant parameter variations by±10%, and is invariant to unmeasurable wind disturbance. The performance of the sliding mode controller is evaluated via computer simulations to verify its robustness to vehicle parameter variations and delay in the loop, and its insensitivity to wind disturbance. Finally, the emulation of a bus, a van, and two commercially available passenger vehicles is demonstrated in an advanced nonlinear simulator.     

线控汽车驾驶员特性辨识算法的研究

线控汽车相对于传统汽车具有较多的控制自由度,控制算法设计可将人的因素考虑在车辆集成控制中,进行人性化设计,变\"人适应车\"为\"车适应人\",最终实现车辆的安全、智能驾驶。文中确定了驾驶员特性辨识系统,以转向行为为例,对驾驶员特性进行分类,并采用神经网络方法建立了辨识模型,在驾驶模拟器上对所研究方法进行实验验证。结果表明,所建立的驾驶员特性辨识模型有较高精度,能对驾驶员特性进行预测,方法可行。     

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.     

Emergency steering control of autonomous vehicle for collision avoidance and stabilisation

ABSTRACT

Collision avoidance and stabilisation are two of the most crucial concerns when an autonomous vehicle finds itself in emergency situations, which usually occur in a short time horizon and require large actuator inputs, together with highly nonlinear tyre cornering response. In order to avoid collision while stabilising autonomous vehicle under dynamic driving situations at handling limits, this paper proposes a novel emergency steering control strategy based on hierarchical control architecture consisting of decision-making layer and motion control layer. In decision-making layer, a dynamic threat assessment model continuously evaluates the risk associated with collision and destabilisation, and a path planner based on kinematics and dynamics of vehicle system determines a collision-free path when it suddenly encounters emergency scenarios. In motion control layer, a lateral motion controller considering nonlinearity of tyre cornering response and unknown external disturbance is designed using tyre lateral force estimation-based backstepping sliding-mode control to track a collision-free path, and to ensure the robustness and stability of the closed-loop system. Both simulation and experiment results show that the proposed control scheme can effectively perform an emergency collision avoidance manoeuvre while maintaining the stability of autonomous vehicle in different running conditions.     

基于组合模型的纯电动汽车能耗预测

纯电动汽车的续驶里程低于同价位传统燃油车,续航问题严重限制了纯电动汽车在中国的推广,因此精确预测纯电动汽车能耗,可以准确估计续驶里程,降低司机里程焦虑,提升消费者购买意愿。文章基于纯电动汽车监控平台的实车采集数据,提出了一种多元线性回归和径向基函数神经网络组合能耗预测方法。首先系统分析纯电动汽车能量流向,其主要包括行驶阻力能耗、制动回收的能量和附件能耗三部分。在能量流向分析基础上,考虑温度对整车能耗的影响,利用实车采集数据,辨识回归模型参数,建立能耗预测多元线性回归模型,对比实际值得到非线性误差,最后利用 RBF 神经网络拟合回归模型的非线性残差。对比结果表明,该模型能够改善单一模型预测精度不足的问题,对估计纯电动汽车续驶里程具有工程应用意义。     

三自由度四轮转向系统的神经网络模型研究

车辆四轮转向的数学模型随着自由度的增加其非线性迅速增加。对于多自由度车辆模型而言,准确而迅速地求解出目标变量的值是研究的难点。针对车辆的三自由度模型,建立了带反馈的神经网络模型,通过有导师训练改变网络的权值和阈值,在输入参数后可以准确而迅速地求解出目标值。仿真结果表明,该神经网络能够很好地逼近该三自由度数学模型。     

极限工况下主动前轮转向汽车稳定性控制

轮胎对汽车稳定性有重要影响,研究和利用轮胎的非线性特性有助于扩展汽车的稳定域。本文基于非线性轮胎模型,提出一种改进型线性时变模型预测控制(LTV-MPC)方法。该方法能扩展主动前轮转向汽车的稳定范围,提高极限工况下主动前轮转向汽车的稳定性。仿真结果表明,该方法比传统的LTV-MPC方法具有更好的稳定性控制效果。     

基于神经网络的电动转向系统助力特性研究

基于综合目标函数的误差反向传播学习算法,设计了用于该离散化转向助力特性的BP神经网络结构,进行了离线训练,并在电动转向综合试验台上实现了在线控制。实现了全车速范围的非线性转向助力,克服了转向助力盲区。     

转向机构对驾驶员伤害的试验分析

通过GB11557试验中出现的情况,分析转向管柱、转向盘、转向盘轮缘下端与人体胸部模块基准线距离、转向管柱安装角等对人体模块作用力的影响,并指出GB11557中的不足和提出建议。     

A nonlinear virtual rider for motorcycles

This work presents a virtual rider for the guidance of a nonlinear motorcycle model. The target motion is defined in terms of roll angle and speed. The virtual rider inputs are the steering torque, the rear-wheel driving/braking torque and front-wheel braking torque. The virtual rider capability is assessed by guiding the nonlinear motorcycle model in demanding manoeuvres with roll angles of 50° and longitudinal accelerations up to 0.8 g. Considerations on the effective preview distance used by the virtual rider are included.