Lateral Dynamics of Commercial Vehicle Combinations A Literature Survey

SUMMARY

This paper presents a review of theoretical and experimental works relative to the handling performance of commercial vehicle combinations. A commercial vehicle combination (road train) is defined as a tractor unit and an arbitrary number of trailers. The review contains literature corresponding the most widely used types of trains: tractor-semitrailer, truck-trailer and tractor-semitrailer-semitrailer (doubles). The vehicle dynamic performance has been investigated taking into consideration the following features: directional performance, roll dynamics, braking performance and combined braking and directional performance. With the aim of evaluating the present state of research activities in the field of lateral dynamics of articulated commercial vehicles, the author has compiled some 250 references.     

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.     

Directional performance issues in evaluation and design of articulated heavy vehicles

This review of the dynamics of heavy road-vehicle systems emphasizes directional performance. The review presents information on the following topics: why are articulated vehicles used; units, hitches, and combination vehicles; multiple axle suspensions and steering systems; important performance issues; models and simulation tools; and controlling directional performance. The concluding section summarizes the material presented and provides ideas regarding the application of vehicle system dynamics concepts in developing controllers for road trains.     

Improvement of Vehicle Dynamics by Rear Braking Force Control

A study on effective use of rear braking force to improve a brake performance and vehicle dynamics are carried out. On a ordinary condition, the rear braking force could be more increased to a conventional braking force distribution. Based on this thought, the brake performances are estimated. The results show the effects not only improve the brake performance but also reduce a pitching at braking and moderate a vehicle OS behavior in a turn during braking. These are verified by experimental test vehicle equipped with a rear braking force control system.     

Improvement of Vehicle Dynamics by Rear Braking Force Control

SUMMARY

A study on effective use of rear braking force to improve a brake performance and vehicle dynamics are carried out. On a ordinary condition, the rear braking force could be more increased to a conventional braking force distribution. Based on this thought, the brake performances are estimated. The results show the effects not only improve the brake performance but also reduce a pitching at braking and moderate a vehicle OS behavior in a turn during braking. These are verified by experimental test vehicle equipped with a rear braking force control system.     

汽车防抱死制动系统的自抗扰控制研究

汽车防抱死制动系统(Anti-lock Braking System,ABS)的作用是确保汽车制动时行驶方向的稳定性、可靠性,但是目前仍存在非线性、时变性以及参数不确定性等问题.为保证汽车制动行驶过程中的操纵稳定性和安全性,进一步实现各工况下防抱死制动系统的优化控制,以影响整车稳定的变量滑移率为研究对象,分析所设计策略...     

Braking Force Distribution Control for Improved Vehicle Dynamics and Brake Performance

This paper describes the feasibility of improving the braking performance of a commercial vehicle by using an electronic braking system. An electronic braking system enables the braking force at each wheel to be independently controlled. Braking force distribution control makes the braking force at each wheel proportional to each wheel's load. Results of computer simulation and vehicle test showed that the proposed control laws can eliminate the effects of a laden condition on the braking distance and can increase the degree of deceleration at which wheel lock occurs, resulting in improved vehicle attitude stability during a critical maneuver.     

Braking Force Distribution Control for Improved Vehicle Dynamics and Brake Performance

SUMMARY

This paper describes the feasibility of improving the braking performance of a commercial vehicle by using an electronic braking system. An electronic braking system enables the braking force at each wheel to be independently controlled. Braking force distribution control makes the braking force at each wheel proportional to each wheel's load. Results of computer simulation and vehicle test showed that the proposed control laws can eliminate the effects of a laden condition on the braking distance and can increase the degree of deceleration at which wheel lock occurs, resulting in improved vehicle attitude stability during a critical maneuver.     

基于MATLAB GUI的商用汽车持续制动模拟系统开发

近年来,随着道路情况的进一步改善,商用汽车不断向着重型化、高速化发展。持续制动系统可以在不使用传统制动系统的情况下,实现能量转化,为汽车提供持续的制动效果。避免由于持续使用传统摩擦式制动装置而引起的热衰退,提高汽车的安全性。本文通过分析国内外对于持续制动系统的研究,提出使用计算机模拟的方法来分析持续制动系统和车辆匹配的问题。选择合适的程序平台,进一步开发后得到了一套商用汽车持续制动模拟计算系统。     

基于TruckSim的商用车操稳性能验证

为了在产品开发前端有效评估设计样车性能,识别性能风险点,提升产品开发效率,利用多体动力学软件TruckSim进行商用车操稳性能建模、仿真验证。首先遵循整车-子系统-零部件逐级建模思维分别完成整车、车身、转向、悬架、轮胎、动力总成、制动系统等模型建立,在此基础上,基于GB 6323试验方法对其进行稳态回转、低速回正、蛇形绕桩等性能仿真。仿真结果表明:所开发的样机操稳性能能够满足项目既定指标要求,为产品开发提供了依据。     

8×4重型自卸车制动性能分析

以某8×4重型自卸车为分析对象,建立了四轴汽车的制动力学模型,对该车在满载、超载情况下进行各轴载荷的计算,前、中、后桥制动力矩和制动力分配分析,在此基础上,提出了多轴汽车的行车制动性能分析方法,并与该车制动性能O型试验结果数据进行对比。实例分析结果表明,该方法简单、实用,能对四轴汽车行车制动性能进行有效分析。     

Extended-Kalman-filter-based regenerative and friction blended braking control for electric vehicle equipped with axle motor considering damping and elastic properties of electric powertrain

Because of the damping and elastic properties of an electrified powertrain, the regenerative brake of an electric vehicle (EV) is very different from a conventional friction brake with respect to the system dynamics. The flexibility of an electric drivetrain would have a negative effect on the blended brake control performance. In this study, models of the powertrain system of an electric car equipped with an axle motor are developed. Based on these models, the transfer characteristics of the motor torque in the driveline and its effect on blended braking control performance are analysed. To further enhance a vehicle's brake performance and energy efficiency, blended braking control algorithms with compensation for the powertrain flexibility are proposed using an extended Kalman filter. These algorithms are simulated under normal deceleration braking. The results show that the brake performance and blended braking control accuracy of the vehicle are significantly enhanced by the newly proposed algorithms.     

BAS系统的设计和开发

为保证整车具有更好更快的制动性能,将制动系统的管路布置由三通道改为四通道,在现有制动系统DBC7.4ABS模块的基础上附带PBA功能,增加制动辅助（BAS）装置。通过对相应的零部件进行设计变更,对整车制动系统重新进行标定,并针对整车的技术条件进行了常温和冬季性能试验,确保整车制动性能满足欧盟法规要求,并顺利通过了E-mark认证。此制动系统的开发设计无须额外增加传感器,不会增加太多的生产成本,也不会增加整车的质量及安装空间。     

Vehicle dynamics integrated control for four-wheel-distributed steering and four-wheel-distributed traction/braking systems

In this article, vehicle dynamics integrated control algorithm using an on-line non-linear optimization method is proposed for 4-wheel-distributed steering and 4-wheel-distributed traction/braking systems. The proposed distribution algorithm minimizes work load of each tire, which is controlled to become the same value. The global optimality of the convergent solution of the recursive algorithm can be proved by extension to convex problems. This implies that theoretical limited performance of vehicle dynamics integrated control is clarified. Furthermore, the effect of this vehicle dynamics control for the 4-wheel-distributed steering and 4-wheel-distributed traction/braking systems is demonstrated by simulation to compare with the combination of the various actuators.     

制动管路对整车制动系统的影响

针对商用车整车制动系统的管路进行了分析,对不同材料的制动管路进行了试验,在试验的基础上分析了制动管路对整车制动系统的影响因素,通过对整车试验结果的分析研究,找出了因制动管路的原因对整车制动的影响。并采取措施解决了整车制动的某些问题。     

Fault-tolerant braking control with integerated EMBs and regenerative in-wheel motors

This paper presents a fault-tolerant brake torque controller for four-wheel-distributed braking systems with in-wheel motors and Electro-Mechanical Brakes (EMB). Mechanical and electrical faults can degrade the performance of the EMB actuators and, thus, their effects need to be compensated in vehicle dynamics level. In this study, the faults are identified as performance degradation and expressed by the gains of each actuator. Assuming the brake force distribution and the regenerative braking ratios, the over-actuated braking system is simplified into a two-input system. A sliding mode controller is designed to track the driver’s braking and steering commands, even if there exist faults in EMBs. In addition, adaptive schemes are constructed to achieve the fault-tolerant control in braking. The proposed controller and strategies are verified in the EMB HILS (Hardware-in-loop-simulation) unit for various conditions.     

基于ADAMS与Matlab的ABS模糊控制仿真研究

将多体系统动力学与智能控制理论相结合对汽车制动防抱死控制系统进行了研究，利用ADAMS／CAR建立了汽车整车的多体力学模型，模型包含了前后悬架、动力总成、转向系统、稳定杆、制动系、轮胎力学模型以及车身，同时也考虑了轮胎、衬套、弹簧、减震器等部件的非线性，准确地表达了车辆的动态特性；利用Matlab／Simulink模糊控制工具箱建立了制动防抱死控制系统的模糊控制策略，利用ADAMS／Control接口进行模型的集成、协同仿真，并将仿真结果与另一种控制策略一逻辑门限值控制的仿真结果进行了比较和分析，仿真反映出模糊控制在整车制动防抱死控制系统上的应用效果，结果表明该控制算法稳定好并具有较强的鲁棒性。     

基于模糊解耦控制的车辆转向制动系统研究

车辆转向系统和制动系统之间存在着很强的速度耦合关系,造成两个系统之间的性能相互影响,使得车辆在转向制动这一工况成了汽车最危险的工况之一。本文结合实际车辆参数建立转向系统的二自由度模型和制动系统的单车轮模型,针对车辆转向制动工况设计了模糊解耦控制器,实现了车辆的转向与制动同时控制。经验证含有模糊解耦控制的车辆转向制动系统具有很好的动态控制效果,并且有很强的鲁棒性和自适应性。     

分布式驱动电动汽车回馈制动失效的液压补偿控制

分布式驱动电动汽车各驱动轮转速和转矩可以单独精确控制,便于实现整车动力学控制和制动能量回馈,从而提升车辆的主动安全性和行驶经济性。但车辆在回馈制动过程中,一旦1台电机突发故障,其他电机产生的制动力矩将对整车形成附加横摆力矩,从而造成车辆失稳,此时虽可通过截断异侧对应电机制动力矩输出来保证行驶方向,但会使车辆制动力大幅衰减或丧失,同样不利于行车安全。为了解决此问题,提出并验证一种基于电动助力液压制动系统的制动压力补偿控制方法,力图有效保证整车制动安全性。以轮毂电机驱动汽车为例,首先建立了整车动力学模型以及轮毂电机模型,通过仿真验证了回馈制动失效的整车失稳特性以及电机转矩截断控制的不足;然后,建立了电动助力液压制动系统模型,并通过原理样机的台架试验验证了模型的准确性;接着,基于滑模控制算法设计了制动压力补偿控制器,并在单侧电机再生制动失效后的转矩截断控制基础上完成了液压制动补偿控制效果仿真验证;最后,通过实车试验证明了所提控制方法的有效性和实用性。研究结果表明：在分布式驱动电动汽车单侧电机再生制动失效工况下,通过异侧电机转矩截断控制和制动系统的液压主动补偿,能够使车辆快速恢复稳定行驶并满足制动强度需求。