Comparison of Ride Comfort Criteria for Computer Optimization of Vehicles Travelling on Randomly Profiled Roads

This paper discusses and compares some ride comfort criteria which may be suitable for randomly vibrating vehicles. The criteria consider single-figure measures based on response mean square spectral densities for plane linear combined vehicle-passenger models. Eight different measures divided into three groups are studied. The two vehicle suspension damper stiffnesses are numerically optimized with respect to the eight measures of ride comfort. The results are compared and discussed. Two optimizations with respect to five vehicle parameters are also reported.     

Experimental Study of System Optimization for Suppression of Vehicle Vibration

SUMMARY

The improvements of ride comfort and vehicle maneuverability in the vehicle design can be achieved by using an active suspension. However, the problems in such a control are the complex control logic because of the control laws incompatible with the improvements of ride comfort and maneuverability, and the cost increase because of various sensors to be attached. Therefore, we examined the control abilities of ride comfort and maneuverability on a unique control law using frequency shaped LQ, and controlled the characteristic of the contact between tire and road without a road displacement sensor     

Advanced Control Methods of Active Suspension

SUMMARY

This paper describes new control methods for the active suspension. For improving ride comfort further, preview control rule is proposed. For improving stability further, roll stiffness distribution control rule is examined by the test vehicle. Simulations and vehicle driving tests are conducted to confirm the effect of these new control methods. The results of simulations and vehicle driving tests show in our research phase that preview control can achieve a substantial improvement in ride comfort and application of roll stiffness distribution control provides a large improvement in stability     

The Development and Implementation of Adaptive Semi-Active Suspension Control*

SUMMARY

Using adjustable shock absorbers within vehicle suspension systems, it is possible to improve ride comfort significantly when a control strategy is applied based on the so-called skyhook principle. However, the drawback is a poorly damped wheel-hop mode which makes the road holding ability worse. Using adaptive semi-active suspension control based on the tire load variations as introduced in this paper, the trade-off between road holding and ride comfort can be relaxed. Implementation of adaptive skyhook control requires the determination of a number of important and difficult to measure states of the vehicle. This can either be accomplished by several sensors and filters or by a state estimator in combination with less sensors and an internal model of the vehicle. Both methods are discussed. Finally some preliminary test results are discussed.     

I. Minutes of the IAVSD Board Meetings

SUMMARY

A theoretical analysis is presented to model a hydromechanical, semi-active suspension system, first as a single wheel station and then as fitted to each wheel of an off-road vehicle. Predicted results show that two benefits are obtained by comparison with the equivalent passive system. First, vehicle attitude is controlled for changes in body forces arising from static loads or braking/cornering inputs. Second, a significant improvement in ride comfort is obtained because low suspension stiffnesses can be used.     

基于虚拟样机技术的扭杆悬架汽车平顺性仿真

运用面向整车系统的数字化虚拟样机技术和大型机械系统动力学仿真软件ADAMS建立了包括前后悬架、轮胎、转向系统及整车的多体动力学模型。用Visual Basic编制路面生成文件，生成不同等级的随机路面。对整车进行了随机输入平顺性仿真分析，把仿真数据输入编制的平顺性仿真程序中，发现结果满足国家规定的汽车平顺性评价标准。     

Random Response of Tractor-Semitrailer System

SUMMARY

This work describes an analytical study of the dynamic behaviour of a tractor-semitrailer vehicle. A digital computer simulation was used to describe the longitudinal, vertical, and pitching motions of the vehicle travelling over a stationary random road surface. A man-seat model was also incorporated into the simulation. Vehicle response to road irregularities has been studied by assuming two different roads for loaded and unloaded cases.

Numerical results are presented for vehicle, showing system eigenvalues, power spectral densities and root mean square values of the linear and angular accelerations and displacements. Vehicle acceleration response is compared with the ISO riding comfort standard. All results for the loaded and unloaded cases and for smooth and rough roads indicated that an uncomfortable ride would result from vehicle response.     

汽车平顺性时域仿真分析

采用虚拟试验场技术进行了汽车行驶平顺性的时域仿真。建立了面向汽车平顺性分析的整车刚弹耦合有限元模型,同时建立了脉冲输入路面模型和随机输入路面模型。采用1/3倍频带分布加速度均方根值方法及总加权方法对试验车辆的平顺性进行了评价。试验结果表明,运用虚拟试验场技术能够真实地反映汽车的行驶平顺性,仿真分析结果可靠。     

换道操作对智能车辆乘客舒适性的影响研究

乘坐舒适性是决定乘客对智能车辆接受度的重要因素之一。为了提升智能车辆的舒适性,服务智能驾驶控制算法的设计和优化,开展了基于乘客主观感知的实车乘坐舒适性试验,试验中驾驶人驾驶传统车辆执行多次换道操作,获取了60名被试乘客对换道操作的舒适性评价数据,并采集了车辆的运动数据。选取换道时横向最大加速度、回正时横向最大加速度、横向最大加加速度、横向加速度转换幅值以及横向加速度转换频率这5个车辆运动参数作为研究对象。采用二元Logistic回归单因素分析法分析了这5个车辆运动参数对乘坐舒适性的影响,采用接收者操作特征(ROC)曲线分析法为不同晕车易感性的乘客分别确立了这5个车辆运动参数的舒适性阈值,并根据岭回归分析法确定了不同参数对乘坐舒适性的影响权重。结果表明：所选取的5个车辆运动参数对乘坐舒适性具有显著影响,易晕乘客的舒适性阈值小于不易晕乘客的舒适性阈值,在换道过程中,换道时横向最大加速度、回正时横向最大加速度和横向加速度转换幅值是影响乘坐舒适性的主要因素。最后根据车辆运动参数和乘客生理特征参数建立了基于动态时间归整(DTW)和K最近邻(KNN)算法的乘坐舒适性预测模型,该模型对乘坐舒适性的预测准确率为84%,可用于智能车辆控制算法的舒适性判断。     

Intra-Platoon Collision Behavior during Emergency Operations

SUMMARY

This paper presents current research regarding intra-platoon collision dynamics for rapid decelerations. Measures of ride quality and impact severity are introduced to allow comparisons between different collision scenarios. In this study, the disturbance input to the platoon is assumed to be a rapid braking of the lead vehicle. Several deceleration rates are used to assess the overall platoon behavior and the effect of the intra-platoon collisions on the platoon passengers. The role of the desired headway spacing on preventing the occurrence of intra-platoon collisions and improving rider comfort is discussed.     

基于行驶舒适性的路桥过渡段差异沉降控制标准

从人车路相互作用出发,建立了人车路系统振动方程和路桥过渡段路面不平整模型,并通过编制的RCBP程序分析了车辆行驶舒适性的影响因素,最后确定了基于行驶舒适性的路桥过渡段差异沉降控制标准。结果不仅可以用于路桥过渡段差异沉降控制标准的相关规范,也可用于一般路基差异沉降标准的制定,对桥头跳车问题的处治和路桥过渡段路面的养护维修提供了科学决策依据。     

基于柔性模型的多轴汽车平顺性的仿真研究

基于弹性梁弯曲振动理论和模态分析法建立了多轴汽车平顺性分析的柔性模型。按照汽车行驶平顺性评价方法，运用建立的柔性模型，分析了车速、路面等级、悬挂质量的分布、车架刚度以及悬架系统的刚度和阻尼对多轴汽车平顺性的影响。分析结果表明：悬挂质量的弯曲振动是影响多轴汽车行驶平顺性的一个不可忽略的重要因素；常用的刚体模型不能准确地描述多轴汽车的平顺性，不适合用于多轴汽车平顺性的分析。     

Magneto-rheological suspensions for improving ground vehicle’s ride comfort,stability, and handling

ABSTRACT

A state-of-the-art discussion on the applications of magneto-rheological (MR) suspensions for improving ride comfort, handling, and stability in ground vehicles is discussed for both road and rail applications. A historical perspective on the discovery and engineering development of MR fluids is presented, followed by some of the common methods for modelling their non-Newtonian behaviour. The common modes of the MR fluids are discussed, along with the application of the fluid in valve mode for ground vehicles’ dampers (or shock absorbers). The applications span across nearly all road vehicles, including automobiles, trains, semi-trucks, motorcycles, and even bicycles. For each type of vehicle, the results of some of the past studies is presented briefly, with reference to the originating study. It is discussed that Past experimental and modelling studies have indicated that MR suspensions provide clear advantages for ground vehicles that far surpasses the performance of passive suspension. For rail vehicles, the primary advantage is in terms of increasing the speed at which the onset of hunting occurs, whereas for road vehicles – mainly automobiles – the performance improvements are in terms of a better balance between vehicle ride, handling, and stability. To further elaborate on this point, a single-suspension model is used to develop an index-based approach for studying the compromise that is offered by vehicle suspensions, using the H₂ optimisation approach. Evaluating three indices based on the sprung-mass acceleration, suspension rattlespace, and tyre deflection, it is clearly demonstrated that MR suspensions significantly improve road vehicle’s ride comfort, stability, and handling in comparison with passive suspensions. For rail vehicles, the simulation results indicate that using MR suspensions with an on-off switching control can increase the speed at which the on-set of hunting occurs by as much as 50% to more than 300%.     

Investigating the influence of rail grinding on stability,vibration, and ride comfort of high-speed EMUs using multi-body dynamics modelling

ABSTRACT

High-speed electric multiple units (EMUs) have been popularised rapidly all around the world and have become a major transportation method. Increases in running velocity and wheel-rail deterioration lead to excessive vibration and reduced ride comfort, which are common issues encountered in the operation of high-speed EMUs. While built-in sensors on a car body are able to detect abnormal vibrations in the car body itself, they cannot effectively reflect the ride comfort of passengers. Wheel-rail profile matching can improve the wheel-rail interaction, and rail grinding has thus been introduced as a practical solution to alleviating the aforementioned problems. Nonetheless, the working mechanism of rail grinding has not been investigated theoretically. This study develops flexible car body and human body models based on the rigid-flexible coupled method to systematically study the effects of wheel-rail wear and rail grinding on passenger ride comfort. Case studies show that the proposed models can predict the ride comfort of passengers accurately. It is also demonstrated that rail grinding can significantly alleviate excessive vibration and improve passenger ride comfort in the long term. A long-term investigation reveals that rail grinding can improve the smoothness of the rail surface and reduce the damage to the rail.     

汽车行驶平顺性评价方法研究及仿真分析

汽车平顺性是汽车NVH性能的评价指标之一。系统介绍了汽车行驶平顺性的客观评价方法,并结合某车型搭建整车行驶平顺性虚拟样机,进行了仿真分析评价。该方法可用于指导汽车行驶平顺性的改善以及悬架参数的优化。     

Semi-Active Attitude and Vibration Control

SUMMARY

The paper discusses the attitude and vibration control of a passenger car on the basis of a full vehicle model. The analysis presented consists of two parts: (I) The introduction of a newly developed semi-active anti-roll/pitch system, (ii) An example of an actively suspended full vehicle model using a simple control strategy to improve ride comfort. The attitude control using semi-actively generated compensation forces prevents the car from rolling in curves and pitching during braking or accelerating. The strength of the system is the small energy consumption. The performance of the combination of both attitude and vibration control can compete with a fully active suspension system.     

Optimal Linear Preview Control of Active Vehicle Suspension

SUMMARY

The problem of linear preview control of vehicle suspension is considered as a continuous time stochastic optimal control problem. In the proposed approach minimal a priori information about the road irregularities is assumed and measurement errors are taken into account. It is shown that estimation and control issues can be decoupled. The problem formulation and the analytical solution are given in a general form and hence they apply to other problems in which the system disturbances are unknown a priori, even in a stochastic sense, but some preview information is possible.

The solution is applied to a two-degree-of-freedom (2-DOF) vehicle model. The effects of preview information on ride comfort, road holding, working space of the suspension and power requirements are examined in time and frequency domains. The results show that the greatest potential is for improving road holding properties. This effect could not have been observed in previous studies based on a 1-DOF vehicle model. It is also demonstrated that the presence of preview drastically reduces power requirements, thus relieving the performance versus actuator power dilemma.     

Modelling Combined Ride and Handling Manœuvres for a Vehicle with Slow-Active Suspension

SUMMARY

The computer modelling of vehicle ride and handling has been widely reported, but often only one or other of these functions is considered. This is especially true in the design of active suspension controllers, where the effects that improvements in the performance of one aspect have on the other are often not presented. This paper initially describes a combined ride and handling model for a large executive saloon fitted with a slow-active suspension. Separately derived ride and roll control strategies are combined and the effects on both ride and handling considered for straight running and various handling man?uvres on rough roads. The results are compared to the original passively suspended vehicle and the effect of running each strategy separately.