Roll and pitch independently tuned interconnected suspension: modelling and dynamic analysis

In this paper, a roll and pitch independently tuned hydraulically interconnected passive suspension is presented. Due to decoupling of vibration modes and the improved lateral and longitudinal stability, the stiffness of individual suspension spring can be reduced for improving ride comfort and road grip. A generalised 14 degree-of-freedom nonlinear vehicle model with anti-roll bars is established to investigate the vehicle ride and handling dynamic responses. The nonlinear fluidic model of the hydraulically interconnected suspension is developed and integrated with the full vehicle model to investigate the anti-roll and anti-pitch characteristics. Time domain analysis of the vehicle model with the proposed suspension is conducted under different road excitations and steering/braking manoeuvres. The dynamic responses are compared with conventional suspensions to demonstrate the potential of enhanced ride and handling performance. The results illustrate the model-decoupling property of the hydraulically interconnected system. The anti-roll and anti-pitch performance could be tuned independently by the interconnected systems. With the improved anti-roll and anti-pitch characteristics, the bounce stiffness and ride damping can be optimised for better ride comfort and tyre grip.     

车辆半主动悬架与助力转向集成控制的仿真研究

为协调车辆操纵稳定性和行驶平顺性,基于底盘系统动力学原理,建立了半主动悬架和电动助力转向的综合模型,对半主动悬架和电动助力转向系统进行集成控制.运用二次反馈法和PID策略分别对悬架的可调阻尼和转向系统的助力进行控制.仿真结果表明,在集成控制情况下,车辆的操纵稳定性和平顺性均优于悬架或转向单独控制的效果.     

Heavy vehicle pitch dynamics and suspension tuning. Part I: unconnected suspension

The influence of suspension tuning of passenger cars on bounce and pitch ride performance has been explored in a number of studies, while only minimal efforts have been made for establishing similar rules for heavy vehicles. This study aims to explore pitch dynamics and suspension tunings of a two-axle heavy vehicle with unconnected suspension, which could also provide valuable information for heavy vehicles with coupled suspensions. Based on a generalised pitch-plane model of a two-axle heavy vehicle integrating either unconnected or coupled suspension, three dimensionless measures of suspension properties are defined and analysed—namely the pitch margin (PM), pitch stiffness ratio (PSR), and coupled pitch stiffness ratio (CPSR)—for different unconnected suspension tunings and load conditions. Dynamic responses of the vehicle with three different load conditions and five different tunings of the unconnected suspension are obtained under excitations arising from three different random road roughness conditions and a wide range of driving speeds, and braking manoeuvres. The responses are evaluated in terms of performance measures related to vertical and pitch ride, dynamic tyre load, suspension travel, and pitch-attitude control characteristics of the vehicle. Fundamental relationships between the vehicle responses and the proposed suspension measures (PM, PSR, and CPSR) are established, based on which some basic suspension tuning rules for heavy vehicles with unconnected suspensions are also proposed.     

铰接式自卸车橡胶弹簧悬架系统试验研究

采用模拟随机输入路面谱激励室内台架试验的方法,对装有新型橡胶弹簧悬架系统的某型号铰接式自卸车进行台架试验研究,以评价橡胶弹簧悬架系统的减振性能和整车行驶平顺性。试验结果表明由于橡胶弹簧悬架系统某些参数匹配不合理导致该车行驶平顺性很不理想,通过优化悬架及座椅的刚度和阻尼参数,可提高整车行驶平顺性,并给出了座椅弹簧的优化结果。     

工程车辆非线性橡胶悬架动力学建模与优化

以AD250铰接式自卸车的非线性变刚度橡胶悬架为研究对象,应用模态综合法和多柔体系统动力学理论,并通过整车试验建立了整车刚柔耦合动力学模型。以行驶平顺性和操纵稳定性为优化目标,采用序列二次规划法,对不同载荷、不同等级路面和不同车速下的悬架特性参数进行优化,得到了不同工况下的最优悬架特性参数。通过最小二乘法拟合得到了橡胶悬架刚度参数的理想非线性特性曲线。仿真结果表明,优化后的橡胶悬架系统能使车辆保持良好的行驶平顺性。     

悬架弹性元件最佳刚度分布的工程设计方法

基于车辆系统动、静力学分析及优化设计原理,提出了一种旨在揭示汽车悬架弹性元件最佳刚度分布的工程设计新方法,可确定满足整车平顺性和操纵稳定性协调设计要求的悬架弹性元件的刚度特性,从而为弹性元件的结构优化设计提供了目标依据,并通过一个工程实例验证了所提方法的有效性。     

橡胶元件在汽车悬架中的应用分析

介绍了橡胶元件在汽车悬架中的应用现状,分析了橡胶衬套力学特性的理论研究方法和试验技术,并对某汽车悬架橡胶衬套进行了有限元分析和试验验证。阐述了橡胶衬套对汽车平顺性、操纵稳定性及高频NVH特性的影响,并通过实例讨论了橡胶衬套对悬架运动学性能的作用和衬套刚度优化方法。指出,需进一步研究橡胶元件对汽车高频动态性能的影响。     

多体动力学仿真分析在乘用车底盘调校中的应用

针对某乘用车开发FT阶段乘坐舒适性太差的问题,在该车型底盘调校过程中,通过灵敏度分析对底盘参数进行了优化。首先对减震器阻尼特性进行了调整,提出了多个优化方案,其次通过多体动力学建模及分析方法对优化方案进行了预测,最后通过实车的主、客观测评验证了参数优化方案的实际效果。结果表明,调校后的车辆在保证操控性的前提下,乘坐舒适性得到了改善。     

基于LQR控制的现代客车自适应空气悬架

长期在不良工况的道路上驾驶会降低驾驶员的乘坐舒适性。随着人们对乘坐舒适性需求不断提升,空气弹簧的优势尤为明显。文章提出了一种基于LQR控制策略的自适应空气悬架系统的创新设计方案,提出的LQR控制器采用粒子群算法进行优化。以客车空气悬架为研究对象,采用MATLAB软件对空气悬架系统的被动和自适应动力学模型进行了设计和仿真。仿真结果表明,自适应空气悬架系统在保证车辆稳定性的同时,降低了车辆在随机道路上的最大位移幅值,从而提高了车辆的平顺性。     

基于正交试验的虚拟样车平顺性分析及参数选择

利用多体力学理论,在机械系统动力学分析软件ADAMS中建立了某车的整车多体力学模型。将虚拟样车在三维空间道路上进行平顺性仿真试验,通过正交试验方法研究了前、后悬架弹簧刚度及相关主要衬套等性能参数对汽车行驶平顺性的影响,并根据正交试验的结果优选了相应的设计参数。     

某乘用车平顺性调校及虚拟验证研究

基于某乘用车前期平顺性目标设定与分解,详细地介绍了其平顺性调校的方法和过程,运用主观评价手段对车辆的平顺性进行了调校,并对调校前后的参数指标建立了动力学虚拟样机。利用仿真方法展开定性验证,结果表明车辆平顺性在调校后满足前期平顺性目标,为底盘调校及悬架设计提供了较好的工程参考。     

Structured H2 Optimization of Vehicle Suspensions Based on Multi-Wheel Models

Summary Various control techniques, especially LQG optimal control, have been applied to the design of active and semi-active vehicle suspensions over the past several decades. However passive suspensions remain dominant in the automotive marketplace because they are simple, reliable, and inexpensive. The force generated by a passive suspension at a given wheel can depend only on the relative displacement and velocity at that wheel, and the suspension parameters for the left and right wheels are usually required to be equal. Therefore, a passive vehicle suspension can be viewed as a decentralized feedback controller with constraints to guarantee suspension symmetry. In this paper, we cast the optimization of passive vehicle suspensions as structure-constrained LQG/H2 optimal control problems. Correlated road random excitations are taken as the disturbance inputs; ride comfort, road handling, suspension travel, and vehicle-body attitude are included in the cost outputs. We derive a set of necessary conditions for optimality and then develop a gradient-based method to efficiently solve the structure-constrained H2 optimization problem. An eight-DOF four-wheel-vehicle model is studied as an example to illustrate application of the procedure, which is useful for design of both passive suspensions and active suspensions with controller-structure constraints.     

基于舒适性和轮胎动载的车辆悬架参数优化

为了改善汽车行驶的舒适性并减小轮胎对路面的动载，以某载货汽车为研究对象，建立了多目标优化模型，并采用统一目标函数法对车辆悬架参数进行优化。优化结果表明：优化后悬架刚度减小而阻尼增大，且前悬架参数变化较小，后悬架参数变化较大；相比于优化前，车身垂直方向加速度均方根值减小了20％，前轮动栽均方根值减小了40％，后轮变化更显著，减小了49％；采用多目标优化设计方法不仅可提高车辆自身的舒适性，而且可减小轮胎对路面的动载。     

基于多动力总成的六点悬置匹配计算

发动机悬置系统性能的好坏是影响车辆乘坐舒适性的重要因素,而悬置软垫的刚度又是关键。本文以某新能源客车动力总成的悬置系统设计为例,介绍多动力总成的悬置系统的弯矩校核、系统解耦、软垫刚度计算,以及悬置系统设计的基本方法和步骤。     

Design of passive vehicle suspensions for maximal least damping ratio

This paper studies the use of the least damping ratio among system poles as a performance metric in passive vehicle suspensions. Methods are developed which allow optimal solutions to be computed in terms of non-dimensional quantities in a quarter-car vehicle model. Solutions are provided in graphical form for convenient use across vehicle types. Three suspension arrangements are studied: the standard suspension involving a parallel spring and damper and two further suspension arrangements involving an inerter. The key parameters for the optimal solutions are the ratios of unsprung mass to sprung mass and suspension static stiffness to tyre vertical stiffness. A discussion is provided of performance trends in terms of the key parameters. A comparison is made with the optimisation of ride comfort and tyre grip metrics for various vehicle types.     

Rollover mitigation for a heavy commercial vehicle

A heavy commercial vehicle has a high probability of rollover because it is usually loaded heavily and thus has a high center of gravity. An anti-roll bar is efficient for rollover mitigation, but it can cause poor ride comfort when the roll stiffness is excessively high. Therefore, active roll control (ARC) systems have been developed to optimally control the roll state of a vehicle while maintaining ride comfort. Previously developed ARC systems have some disadvantages, such as cost, complexity, power consumption, and weight. In this study, an ARC-based rear air suspension for a heavy commercial vehicle, which does not require additional power for control, was designed and manufactured. The rollover index-based vehicle rollover mitigation control scheme was used for the ARC system. Multi-body dynamic models of the suspension subsystem and the full vehicle were used to design the rear air suspension and the ARC system. The reference rollover index was tuned through lab tests. Field tests, such as steady state cornering tests and step steer tests, demonstrated that the roll response characteristics in the steady state and transient state were improved.     

基于ADAMS的空气悬架客车平顺性仿真与试验

以多体系统动力学理论为基础,应用机械系统仿真分析软件ADAMS,创建空气悬架客车前悬架、后悬架的多体系统动力学模型,包括转向系、发动机、车身、前后轮胎等在内的整车虚拟样机模型。并通过编制路面谱文件对虚拟模型进行平顺性仿真和悬挂系统固有频率仿真试验,结果显示该车的平顺性能比较理想。将仿真结果与样车道路试验结果进行对比,发现二者比较吻合,从而验证了所创建的虚拟样机模型的可靠性。研究结果表明虚拟试验可以有效地分析汽车的平顺性。     

轻型商用车悬架匹配

为优化某轻卡乘坐舒适性,首先对悬架系统的刚度、阻尼匹配过程进行了分析总结,给出了悬架刚度、阻尼的匹配流程。然后针对某些受开发周期及资源限制,无法进行实车调校及精确仿真的车型给出了基于理论计算及统计数据的悬架阻尼匹配方法。从阻尼比选择,各速度段阻尼比分布,双向比分布等方面分析,总结了方便、快速,且实车验证切实有效的悬架系统阻尼匹配方法。