基于横摆角速度的汽车ABS控制策略的研究

研究汽车制动系统中,为了保证缩短制动距离的同时,改善汽车在附着系数分离的非对称路面上行驶制动的方向稳定性,结合单轮独立控制与低选控制方式,以横摆角速度为控制参数,提出一种兼顾制动距离和方向稳定性的ABS整车控制策略:ABS混合控制策略.建立汽车制动相关模型,对4种控制方式进行仿真分析.比较4种不同控制策略的仿真结果,表明以横摆角速度为控制参数的ABS混合控制策略能在制动距离与制动方向稳定性中找到合理的平衡点,既能充分利用每 个车轮的路面附着系数,又能防止汽车在非对称路面行驶时产生较大的制动跑偏量,提高汽车制动时的方向稳定性.综合考虑制动距离和制动方向稳定性两项指标,以横摆角速度为控制参数的ABS混合控制方式制动效果最优.     

十一自由度汽车转弯防抱制动系统仿真的研究

防抱制动系统（ABS）仿真的目的是建立汽车动力学仿真模型,并在此模型上加载防抱制动控制器模型,以观察不同控制策略在不同工况条件下的控制效果。采用解析法建立的十一自由度汽车转弯制动数学模型,并用MATLAB／SIMULINK建立仿真模型。用PID控制器对防抱制动系统的制动过程进行了仿真分析,针对PID控制器抗干扰能力不强的缺点,设计了抗干扰能力更强的模糊控制器,对仿真结果进行了对比分析。仿真结果表明模糊控制器在理想工况条件下控制效果不如PID控制器,但抗干扰能力更强。本实验为进一步硬件在线实时仿真做好准备。     

防抱死制动系统的滑模变结构控制

针对汽车防抱死制动系统(ABS)的强非线性,采用基于滑移率的滑模变结构控制策略建立了ABS的仿真模型.由于引入了制动系统执行的时间延迟,导致滑模控制出现颤振现象.为了消除控制中出现的颤振,采用边界层方法来克服滑模控制的缺陷.通过对ABS在干、湿和冰路面情况下的制动仿真试验和对结果进行的分析,可以认为基于边界层的滑模控制能够获得良好的控制效果,并可用于ABS控制器的设计.     

基于车轮加速度和滑移率的EBD控制策略

ABS控制并不适用于所有制动工况,由此进一步发展衍生出了电子制动力分配系统(Electric Brake force Distribution,EBD)。针对EBD的功能将EBD的工况分为轻制动、强制动和ABS故障,并分别设计控制策略,实现了一种以车轮加速度和滑移率为门限值的逻辑控制策略。控制策略通过增压、减压和保压调整轮缸制动压力,优先保证制动过程的稳定性,并且在轻制动时注重舒适性,强制动时减缓后轮压力上升速率,ABS故障时EBD代替ABS对后轮进行制动控制。基于车辆动力学仿真软件ve-DYNA的仿真测试和基于ve-DYNA与dSPACE构建的车辆底盘开发平台的硬件在回路测试表明,此EBD控制策略既能防止后轮先于前轮抱死,又能保证制动舒适性和较高的制动效率。     

汽车转向/防抱死制动协同控制

为了解决汽车转向过程中防抱死制动稳定性问题,提出一种新的协同控制系统.该协同控制结构由转向控制器和制动控制器组成.在转向控制中设计滑模鲁棒自适应控制器和横摆力矩控制器力求改善汽车动态响应,鲁棒自适应性和稳定性.此外定义协同误差,建立汽车协同误差模型并设计汽车防抱死制动鲁棒自适应控制系统.为了减少转向系统和制动系统之间的补偿控制律难以确定的困难,提出耦合误差补偿原理与同一给定控制相结合的新的耦合控制策略.最后用仿真结果验证所设计控制算法的有效性.     

基于模糊滑模控制的HEV再生制动控制策略

为了提高混合动力汽车制动能量回收率,根据镍氢电池快速充电特性和集成启动电机(Integrated starter/generator,ISG)发电特性,确定了电机与电池联合高效工作曲线.根据上述曲线,提出了一种无级自动变速传动(Continuously variabletransmission,CVT)速比控制的混合动力汽车再生制动模糊滑模控制策略.利用滑模控制方法对永磁同步电机的转矩进行控制,此外,给被控对象加上一个外界干扰,并对干扰采取模糊控制策略,使电机运行点处于联合高效曲线附近.在MATLAB/ADVISOR中搭建再生制动模糊滑模控制仿真模型.仿真结果表明,与Advisor控制策略相比,所设计的模糊滑模控制策略有效地提高电机制动过程中的能量回收率.     

基于模糊神经网络的汽车ABS控制系统联合仿真

对防抱死制动系统的原理进行总结分析,在ADAMS中建立了一个包含前后悬架系统、动力系统、转向系统、稳定系统、制动系统、车身系统以及轮胎模型、道路模型的整车模型.针对汽车ABS的非线性系统,在MATLAB/Simulink中采用模糊神经网络控制策略设计ABS控制器.通过接口设置进行联合仿真,验证了所提算法的可行性,结果表明基于模糊神经网络的控制方法可以获得良好的控制效果.     

基于ADAMS与MATLAB的汽车ABS控制策略的联合仿真

在分析现阶段ABS仿真技术的基础上,利用ADAMS搭建整车模型,利用MATLAB搭建ABS控制策略模型以及气压调节控制单元模型。通过ADAMS/Control模块接口将建立的整车动力学模型与控制模型连接起来,组成ABS实时闭环控制模型,最终实现两者的联合仿真。对高附着系数路面的汽车ABS进行联合仿真研究,由仿真结果可知ABS系统在整车的制动过程中起到了很好的制动防抱死效果,验证了ABS制动的可靠性以及联合仿真方法的可行性。     

ISG混合动力汽车制动力动态协调控制策略研究

本文针对混合动力汽车的制动过程能量回馈效率不足进行分析.以ISG技术的中度混合动力汽车为平台,通过分析混合动力汽车前、后轮制动力分配以及摩擦制动力和再生制动力的合理分配,建立了基于制动安全性和高效制动能量回收的动态协调再生制动控制策略模型,并在不同的路况下进行仿真分析和修正.仿真结果表明,制动力动态协调控制策略与原有传...     

刹车系统自适应控制研究

关于汽车制动器仿真试验台设计问题,为了试验制动系统的性能,对汽车制动器试验台电惯量性能进行研究。针对波形振荡严重等缺点,为改善控制效果,提出了Hopfield PID参考自适应控制的电惯量模拟系统。首先计算出应达到的电磁力矩,产生电流控制环节的速度指令,然后在速度环中加入Hopfield PID自适应控制。实验结果表明,改进设计的控制系统与传统控制系统相比响应速度快,波动小,相对能量误差少,并且在制动角加速度和末速度上与路试时更为接近。实验证明,自适应控制策略是有效的,为汽车制动器的优化设计提供了参考。     

Vehicle longitudinal motion modeling for nonlinear control

The problem of modeling vehicle longitudinal motion is addressed for front wheel propelled vehicles. The chassis dynamics are modeled using relevant fundamental laws taking into account aerodynamic effects and road slop variation. The longitudinal slip, resulting from tire deformation, is captured through Kiencke's model. A highly nonlinear model is thus obtained and based upon in vehicle longitudinal motion simulation. A simpler, but nevertheless accurate, version of that model proves to be useful in vehicle longitudinal control. For security and comfort purpose, the vehicle speed must be tightly regulated, both in acceleration and deceleration modes, despite unpredictable changes in aerodynamics efforts and road slop. To this end, a nonlinear controller is developed using the Lyapunov design technique and formally shown to meet its objectives i.e. perfect chassis and wheel speed regulation.     

线控转向系统动力学模型的研究

准确简单的线控转向系统动力学模型是研究线控转向的各种控制策略和参数匹配的基础.建立了线控转向系统的人-车-路闭环动力学模型,包括道路模型、驾驶员模型、控制器模型、转向盘总成模型、整车模型(包括车身模型、轮胎模型)及前轮转向总成模型等.基于以上模型,研究了驾驶员模型参数:驾驶员的补偿转向增益和认知时间延迟引起的死区时间变化对实际侧向偏移到目标侧向偏移的传递函数频率响应的影响.结果表明,选择不同的参数对线控转向系统的操纵稳定性影响较大,应合理选择相关参数.     

汽车横摆的动态模型

建立横摆动态模型是汽车横摆稳定控制的基础．本文根据汽车横摆稳定控制的特点,综合车身横摆动态,车轮动态和轮胎的非线性特性,建立了非线性离散横摆动态模型,其中轮胎摩擦力为时变参数．为了估计本模型中的时变参数,本文进而设计了离散滑模估计器估计轮胎摩擦力．最后,在一个高精度的汽车动力学仿真环境中,证实了本估计方法可有效地估计车轮摩擦力,所建立模型较为准确地反映汽车横摆动态．     

Disturbance Observer Based Control for Four Wheel Steering Vehicles With Model Reference

This paper presents a disturbance observer based control strategy for four wheel steering systems in order to improve vehicle handling stability. By combination of feedforward control and feedback control, the front and rear wheel steering angles are controlled simultaneously to follow both the desired sideslip angle and the yaw rate of the reference vehicle model. A nonlinear three degree-of-freedom four wheel steering vehicle model containing lateral, yaw and roll motions is built up, which also takes the dynamic effects of crosswind into consideration. The disturbance observer based control method is provided to cope with ignored nonlinear dynamics and to handle exogenous disturbances. Finally, a simulation experiment is carried out, which shows that the proposed four wheel steering vehicle can guarantee handling stability and present strong robustness against external disturbances.      

Evaluation of antilock braking system with an integrated model of full vehicle system dynamics

Antilock braking system (ABS), traction control system, etc. are used in modern automobiles for enhanced safety and reliability. Autonomous ABS system can take over the traction control of the vehicle either completely or partially. An antilock braking system using an on–off control strategy to maintain the wheel slip within a predefined range is studied here. The controller design needs integration with the vehicle dynamics model. A single wheel or a bicycle vehicle model considers only constant normal loading on the wheels. On the other hand, a four wheel vehicle model that accounts for dynamic normal loading on the wheels and generates correct lateral forces is suitable for reliable brake system design. This paper describes an integrated vehicle braking system dynamics and control modeling procedure for a four wheel vehicle. The vehicle system comprises several energy domains. The interdisciplinary modeling technique called bond graph is used to integrate models in different energy domains and control systems. The bond graph model of the integrated vehicle dynamic system is developed in a modular and hierarchical modeling environment and is simulated to evaluate the performance of the ABS system under various operating conditions.     

Integrated stability and traction control for electric vehicles using model predictive control

In this paper, an integrated vehicle and wheel stability control is developed and experimentally evaluated. The integrated structure provides a more accurate solution as the output of the stability controller is not altered by a separate unit, therefore its optimality is not compromised. Model predictive control is used to find the optimal control actions. The proposed control scheme can be applied to a wide variety of vehicle driveline and actuation configurations such as: four, front and rear wheel drive systems. Computer simulations as well as experiments are provided to show the effectiveness of the proposed control algorithm.     

Evaluation of antilock braking system with an integrated model of full vehicle system dynamics

Antilock braking system (ABS), traction control system, etc. are used in modern automobiles for enhanced safety and reliability. Autonomous ABS system can take over the traction control of the vehicle either completely or partially. An antilock braking system using an on–off control strategy to maintain the wheel slip within a predefined range is studied here. The controller design needs integration with the vehicle dynamics model. A single wheel or a bicycle vehicle model considers only constant normal loading on the wheels. On the other hand, a four wheel vehicle model that accounts for dynamic normal loading on the wheels and generates correct lateral forces is suitable for reliable brake system design. This paper describes an integrated vehicle braking system dynamics and control modeling procedure for a four wheel vehicle. The vehicle system comprises several energy domains. The interdisciplinary modeling technique called bond graph is used to integrate models in different energy domains and control systems. The bond graph model of the integrated vehicle dynamic system is developed in a modular and hierarchical modeling environment and is simulated to evaluate the performance of the ABS system under various operating conditions.     

Integrated vehicle control through the coordination of longitudinal/lateral and vertical dynamics controllers: Flatness and LPV/‐based design

This paper deals with global chassis control of automotive vehicles. It focuses on the coordination of suspension and steering/braking vehicle controllers based on the interaction between the vertical and lateral behaviors of the vehicle. It is shown that the lateral acceleration and resulting roll motion of the car generate load transfers that considerably affect vehicle stability. A control law is designed in hierarchical way to improve the overall dynamics of the vehicle and cope with coupled driving maneuvers like obstacle avoidance using steering control and stop‐and‐go control using braking or driving wheel torque. This global control strategy includes two types of controllers. The first one is the longitudinal/lateral nonlinear flatness controller. Based on an appropriate choice of flat outputs, the flatness proof of a 3 DOF two‐wheel nonlinear vehicle model is established. Then, the combined longitudinal and lateral vehicle control is designed using algebraic estimation techniques to provide an accurate estimation of the derivatives and filtering of the reference flat outputs. The second part of the proposed strategy consists of a linear parameter‐varying/ suspension controller. This controller uses lateral acceleration as a varying parameter to account for load transfers that directly affect the suspension system. The coordination between the vehicle vertical and lateral dynamics is highlighted in this study, and the linear parameter‐varying/ framework ensures a specific collaborative coordination between the suspension and the steering/braking controllers, to achieve the desired performance. Simulations on a complex full vehicle model have been validated using experimental data obtained on‐board a real Renault Mégane Coupé. Copyright © 2017 John Wiley & Sons, Ltd.     

Control aspects of a tracked magnetic levitation high speed test vehicle

The paper deals with the control system of the high speed test vehicle KOMET. The control hardware configuration consisting of digital computer, interface, sensors, magnet drivers and magnets is described. Control system synthesis is performed based on the state space approach and the classical approach of the z-transform. It leads to various control concepts, which are evaluated with regard to their responses to guideway irregularities, external forces and their sensitivity to plant parameter variations. The measurements used to reconstruct the state vector are magnet gaps, vehicle accelerations and/or magnet currents. To be efficient, the magnets have to be operated on small magnet gaps. This demands a fast system response to external disturbances and guideway inputs. This in turn may lead to the excitation of the elastic modes of the system. The higher order modes of vehicle and guideway are therefore included in the control synthesis. The speed range of the KOMET extends to 400 km/hr. Results from high speed testing are evaluated with regard to system responses, power requirements, and loss in magnetic force due to eddycurrents.     

Effect of tangent track buckle on vehicle derailment

In order to investigate the effect of a tangent track buckle on the dynamic derailment of a railway vehicle, a coupled vehicle/track dynamics model is developed, in which the vehicle is modeled as a 35 D.O.F. multibody system and the track is modeled as a 3-layer discrete elastic support model. Rails are assumed to be Timoshenko beams supported by discrete sleepers, and the effects of vertical and lateral motions and rolling of the rail on the wheel/rail creepages are taken into account. The sleepers are treated as Euler beams on elastic foundation for the vertical vibration, while as lumped masses in the lateral direction. A moving sleeper support model is developed to simulate the effect of the periodical discrete sleepers on the vehicle/track interaction. The vehicle and the track are coupled by wheel/rail contacts whereas the normal forces and the creep forces are calculated using the Hertzian contact theory and the nonlinear creep theory by Shen et al., respectively. The equations of motion of the coupled vehicle/track system are solved by means of an explicit integration method. A tangent track buckle is simulated with a cosine function, which describes the misalignment of the track with different lengths due to its buckling. In the analysis the effects of the buckle wavelength and amplitude and of the vehicle speed on the dynamic behavior of the coupled vehicle/track system are considered. The present paper analyzes in detail the conventional derailment coefficients which include the ratio of the wheel/rail lateral force to the vertical force, the wheel load reduction, and the new criteria indicating the wheel/rail contact point traces and the wheel rise with respect to the rail. These criteria are simultaneously used to evaluate the risk of derailment of the whole vehicle. The numerical results obtained indicate that the track misalignment caused by the buckle and the vehicle speed have a great influence on the whole vehicle running safety when the vehicle passes through the buckled tangent track.