Robust design optimization of suspension system by using target cascading method

This study presents the robust design optimization process of suspension system for improving vehicle dynamic performance (ride comfort, handling stability). The proposed design method is so called target cascading method where the design target of the system is cascaded from a vehicle level to a suspension system level. To formalize the proposed method in the view of design process, the design problem structure of suspension system is defined as a (hierarchical) multilevel design optimization, and the design problem for each level is solved using the robust design optimization technique based on a meta-model. Then, In order to verify the proposed design concept, it designed suspension system. For the vehicle level, 44 random variables with 3% of coefficient of variance (COV) were selected and the proposed design process solved the problem by using only 88 exact analyses that included 49 analyses for the initial meta-model and 39 analyses for SAO. For the suspension level, 54 random variables with 10% of COV were selected and the optimal designs solved the problem by using only 168 exact analyses for the front suspension system. Furthermore, 73 random variables with 10% of COV were selected and optimal designs solved the problem by using only 252 exact analyses for the rear suspension system. In order to compare the vehicle dynamic performance between the optimal design model and the initial design model, the ride comfort and the handling stability was analyzed and found to be improved by 16% and by 37%, respectively. This result proves that the suggested design method of suspension system is effective and systematic.     

基于多目标粒子群优化算法的某轻型商用车操纵稳定性优化研究

针对某轻型商用车稳态回转时侧倾度偏大的问题对其悬架进行优化改进。基于ADAMS/car搭建整车多体动力学模型,通过前悬架反向平行轮跳试验、后悬架理论计算验证了悬架仿真模型的准确性。进行整车稳态回转工况和转向盘中间位置转向工况仿真分析,结果表明,车身侧倾度偏高。为实现操纵稳定性优化分析的流程自动化,提出了基于modeFRONTIER的联合仿真方法。以悬架设计参数为优化变量,以汽车的侧倾度与横摆角速度响应滞后时间为优化目标,采用拉丁超立方试验设计方法拟合得到混合代理模型,并结合多目标粒子群优化算法对悬架系统进行多目标优化,获得了悬架系统优化方案。优化结果显示,在不影响平顺性的前提下,汽车车身侧倾度降低了13.93%,横摆角速度响应滞后时间降低了2.75%,整车操纵稳定性得到了提升。     

分段式转向梯形断开点的优化设计

文章建立了某轮式车辆的前独立悬架和转向系统的参数化模型,阐述了分段式梯形断开点设计需要遵循的两点原则,分析了断开点三个方向坐标对阿克曼转向特性以及车轮跳动过程中前束角变化的影响,以实际外轮转角与理论外轮转角差值最小以及前束角变化最小为优化目标,对断开点位置进行了优化分析。研究结果表明,断开点坐标的优化可以改善车辆转向特性,同时提高转向系统与悬架系统的运动协调性,为轮式车辆转向梯形的设计提出了较为合理的优化方案。     

某六缸机载货车转向系统优化设计

本文主要对某六缸机货汽车的转向系统进行了优化设计。提出了合理性优化设计方案,通过对转向拉杆与悬架导向机构的运动干涉量进行调整,减小由于转向拉杆机构与悬架导向机构运动不协调所造成的跳动干涉;通过转向器的合理选择,优化拉杆折弯形状,提高整车可靠性的同时降低成本。     

某suv车型行驶跑偏问题的优化分析

行驶跑偏是指车辆在行驶过程中偏离了原来直线驾驶的状态,不仅会影响车辆的操纵稳定性和转向性能,更可能会危及乘客的人身安全。某SUV车型从设计到生产导入阶段,进行小批量投产时,出现大量车辆向左行驶跑偏现象,合格率约为60%。经过鱼骨图排查法的人、机、料、法、环等几个方面分析,列举出15种可能造成车辆行驶跑偏的因素。经过逐一排查,发现该SUV车型存在前副车架的控制臂安装支架尺寸超差,白车身的前、后副车架安装点尺寸控制不合理,前后悬模块装配一致性差及测试道路不规范等主要问题,以上四种问题造成的偏差趋势与实际该SUV车辆向左行驶跑偏现象相符,因此需要对以上问题进行优化及改进。文章是在这个背景下,针对该SUV车型的向左行驶跑偏现象,通过对问题零部件进行交叉试验,三坐标尺寸测量以及生产线生产过程一致性的逐一排查,逐一分析了四种问题发生的根本原因,并由此提出了优化改进方案,通过对比方案实施前后的实测数据,验证优化改进方案是否可行。优化后实测行驶跑偏量,符合企业行驶跑偏判定标准,行驶跑偏现象消失并保证了该SUV车型的正式量产时间。     

某自卸车转向与悬架干涉的ADAMS校核和优化设计

汽车设计中通常采用平面作图法校核转向与悬架干涉量,但该方法有一定缺点。本文结合某自卸车的方案布置,探索运用ADAMS/View软件对转向与悬架干涉量进行校核和优化设计的方法。以车轮跳动引起的转向与悬架干涉量最小为优化目标,对转向垂臂的布置位置进行了优化,并对制动引起的转向与悬架干涉量进行了校核。按照优化结果进行布置,可得到理想的转向、悬架协调运动关系。     

多刚体系统动力学在汽车转向和悬架系统运动分析中的应用

多刚体系统动力学是近２０年发展起来的力学新分支。本文以该领域中的Ｒ－Ｗ方法为理论基础，编制了可自动建模半进行计算机值仿真计算的汽车转向，悬架运动分析通用程度，运用该程度对大量的实车进行了计算分析，经整车和转向悬架系统的试验结果表明，用该程序进行汽车转向，悬架运动分析，所得结果准确，计算迅速，可方便地进行转向，悬架设计方案的比较和参数的选择。     

Handling Capabilities of Vehicles in Emergencies Using Coordinated AFS and ARMC Systems

In this paper, an advanced control technique that can be implemented in hard emergency situations of vehicles is introduced. This technique suggests integration between Active Front Steering (AFS) and Active Roll Moment Control (ARMC) systems in order to enhance the vehicle controllability. For this purpose, the AFS system applies a robust sliding mode controller (SMC) that is designed to influence the steering input of the driver by adding a correction steering angle for maintaining the vehicle yaw rate under control all the time. The AFS system is then called active-correction steering control. The ARMC system is designed to differentiate the front and rear axles' vertical suspension forces in order to alter the vehicle yaw rate and to eliminate the vehicle roll motion as well. Moreover, the operation of the SMC is based on tracking the behavior of a nonlinear 2-wheel model of 2-DOF used as a reference model. The 2-wheel model incorporates real tire characteristics, which can be inferred by the use of trained neural networks. The results clearly demonstrate the enhanced characteristics of the proposed control technique. The SMC with the assistance of the ARMC provides less correction of the steering angle and accordingly reduces the possibility of occurrence of the saturation phenomenon that is likely to take place in the operation of the SMC systems.     

Handling Capabilities of Vehicles in Emergencies Using Coordinated AFS and ARMC Systems

In this paper, an advanced control technique that can be implemented in hard emergency situations of vehicles is introduced. This technique suggests integration between Active Front Steering (AFS) and Active Roll Moment Control (ARMC) systems in order to enhance the vehicle controllability. For this purpose, the AFS system applies a robust sliding mode controller (SMC) that is designed to influence the steering input of the driver by adding a correction steering angle for maintaining the vehicle yaw rate under control all the time. The AFS system is then called active-correction steering control. The ARMC system is designed to differentiate the front and rear axles' vertical suspension forces in order to alter the vehicle yaw rate and to eliminate the vehicle roll motion as well. Moreover, the operation of the SMC is based on tracking the behavior of a nonlinear 2-wheel model of 2-DOF used as a reference model. The 2-wheel model incorporates real tire characteristics, which can be inferred by the use of trained neural networks. The results clearly demonstrate the enhanced characteristics of the proposed control technique. The SMC with the assistance of the ARMC provides less correction of the steering angle and accordingly reduces the possibility of occurrence of the saturation phenomenon that is likely to take place in the operation of the SMC systems.     

Design Optimization of a Rear Independent Suspension for the Korean Light Tactical Vehicle

Steering and suspension handle the direction of a vehicle according to the driver’s intentions and control the disturbance from the road surface while supporting the vehicle body. The static and dynamic characteristics of two systems are critical factors for the ride comfort and the directional stability. In the layout stage, the hard points of steering and suspension systems are determined. In the next design stage, the detailed design of the system, including gearboxes, springs, shock absorbers, and control links, is carried out. While the optimal hard points of a suspension are determined at the precedent design, interference with other peripheral components should be carefully examined in the detailed design process. In the case of the design point change should be made to avoid the interference, subsequent position and shape changes of the link mechanism are required. Therefore, there is a need to examine the optimization of suspension compliance characteristics with chassis design changes and the durability performance of the modified design. This study proposes an integrated analysis method for the design optimization and the durability evaluation of such optimized design specifications of the rear independent suspension for a military vehicle.     

Development of an active front steering (AFS) system with QFT control

This paper investigates an active front steering control strategy based on quantitative feedback theory (QFT). By incorporating feedback from a yaw rate sensor into the active steering system, the control system improves the dynamic response of the vehicle. The steering response of a vehicle generally depends upon uncertain quantities like mass, velocity, and road conditions. Thus, QFT is used to design a controller with robust performance. A multi-degree-of-freedom nonlinear model is co-simulated here by MATLAB Simulink and ADAMS/CAR. The performance of the control system is evaluated under various emergency maneuvers and road conditions. The result shows that the designed robust control system has good control performance and can efficiently improve handing qualities and stability characteristics.     

基于凯恩方法的双横臂悬架和转向机构优化

把双横臂悬架和转向系统作为整体,利用凯恩方法建立系统的多体模型,列写系统的较低序号物体阵列,建立系统运动方程。以转向总误差为目标函数,以三维连续性函数为权重函数建立系统优化模型,用遗传算法作为解算工具,对双横臂悬架和转向系统进行优化研究,并对优化前后转向误差和运动性能进行了对比。结果表明:该方法优化效果显著,可获得较佳的悬架和转向系统参数。     

Robust yaw stability control for electric vehicles based on active front steering control through a steer-by-wire system

A robust yaw stability control design based on active front steering control is proposed for in-wheel-motored electric vehicles with a Steer-by-Wire (SbW) system. The proposed control system consists of an inner-loop controller (referred to in this paper as the steering angle-disturbance observer (SA-DOB), which rejects an input steering disturbance by feeding a compensation steering angle) and an outer-loop tracking controller (i.e., a PI-type tracking controller) to achieve control performance and stability. Because the model uncertainties, which include unmodeled high frequency dynamics and parameter variations, occur in a wide range of driving situations, a robust control design method is applied to the control system to simultaneously guarantee robust stability and robust performance of the control system. The proposed control algorithm was implemented in a CaSim model, which was designed to describe actual in-wheel-motored electric vehicles. The control performances of the proposed yaw stability control system are verified through computer simulations and experimental results using an experimental electric vehicle.     

Design and validation of a robust active trailer steering system for multi-trailer articulated heavy vehicles

ABSTRACT

Multi-trailer articulated heavy vehicles (MTAHVs) are increasingly used around the world due to their economic and environmental benefits. However, MTAHVs exhibit poor maneuverability and low lateral stability, which may lead to fatal traffic accidents. Given the safety risks, it is necessary to solve the steering and stability problems of MTAHVs before they are safely mass deployed on our roads. To this end, active trailer steering (ATS) based on the linear quadratic regulator (LQR) technique has been explored. The LQR-based ATS demonstrates improved maneuverability and enhanced lateral stability. In the ATS design, the vehicle and operating parameters are assumed constant. Thus, it is natural to question the robustness of the ATS in presence of vehicle and operating parameter uncertainties. To address the problem, this paper proposes a robust ATS system. The robust ATS controller is designed using a linear matrix inequality (LMI) based LQR method. In the design, both vehicle and steering actuator parameter uncertainties are considered; to enhance the robustness of the ATS, the weighting matrices of the proposed controller are optimized. The robust controller is applied to an A-Train Double, one type of MTAHV. The effectiveness of the robust ATS is demonstrated using numerical and hardware-in-the-loop real-time simulations.     

盘式制动器车辆的制动抖动现象

盘式制动器的制动抖动现象，会影响车辆的行驶安全性和驾驶舒适性，其产生原因是制动盘的原始几何尺寸及热膨胀作用造成几何变形的共同作用引起制动压力的波动，进而产生对制动系统及悬架和转向机构的激振作用。制动管路和悬架等传递途径的自振特性，也会对抖动的振幅产生影响。文章在结合国内外相关文献和实验分析数据的基础上，对盘式制动器特有的制动抖动现象进行了研究。主要包括制动抖动现象的成因和相关各方面的实验与分析方法，最后提出了改进建议。     

Vibration path analysis and optimal design of the suspension for brake judder reduction

Brake judder is abnormal vibration, which is mainly generated by uneven contact between the brake disc and pad. The abnormal vibration from BTV (Brake Torque Variation) is transferred to the suspension and the steering system during braking. In this paper, judder simulation is carried out using a multi-body dynamic analysis program to analyze the relationship between judder and the transfer mechanism, which consists of the suspension and the steering system. In order to verify the analytical model, test results are compared with the simulation results. A sensitivity analysis is also carried out. In addition, an optimization method is presented for judder reduction, using the design of experiments.     

Application of Analytic Hierarchy Process to Stochastic Robustness Synthesis of Integrated Vehicle Controllers

This paper deals with the robust design procedure of integrated vehicle dynamics controller based on Stochastic Robustness Synthesis with use of a rational decision making process of the controller parameters. The basic control structure that integrates four-wheel steering and four-wheel torque control is determined using a nonlinear predictive control theory. The Analytic Hierarchy Process, a basic approach to decision making, is applied to determine the weight coefficients of robustness evaluation function of the controller. The desired vehicle dynamic performance is described as four-layer hierarchy structure and the design priority is determined with respect to several design criteria. The proposed design process produced a control system with excellent stability and performance robustness to vehicle parameter variations.     

基于CAE技术的某后座椅中间安全带NVH性能设计研究

以CAE技术驱动的汽车产品性能设计,已经成为当前世界汽车设计的关键核心技术手段。以某车型出现的后座椅中间安全带拉拽噪声的性能问题以及其分析、解决过程,描述基于CAE技术驱动的性能设计的重要性。基于大型通用前、后处理软件HYPERWORKS以及其计算求解器,完成了其噪声源的分析及优化改进方案的提出及分析工作。并通过部分实验数据验证了CAE优化、改进方案的效果。     

Hierarchical optimisation of the design parameters of a vehicle suspension system

This paper presents a design methodology for the mechanical systems entitled First Design. It is based on a hierarchical organisation of the design, taking into account the notion of robustness at an early phase of the project. The aim is to improve the quality of the system in order to make it robust, less sensitive to the variability of the external parameters and design parameters. We distinguish two main stages of the design cycle: one concerning functional parameters and another concerning physical parameters. The methodology is based on simplified models, on sensitivity analysis and on robust multi-objective optimisation. As an example, the methodology will be applied to the optimisation of vehicle suspension system design parameters. For each stage of the hierarchical design, adapted simplified models, sensitivity analyses and optimisation processes will be studied and applied to our vehicle suspension system.     

Application of Analytic Hierarchy Process to Stochastic Robustness Synthesis of Integrated Vehicle Controllers

This paper deals with the robust design procedure of integrated vehicle dynamics controller based on Stochastic Robustness Synthesis with use of a rational decision making process of the controller parameters. The basic control structure that integrates four-wheel steering and four-wheel torque control is determined using a nonlinear predictive control theory. The Analytic Hierarchy Process, a basic approach to decision making, is applied to determine the weight coefficients of robustness evaluation function of the controller. The desired vehicle dynamic performance is described as four-layer hierarchy structure and the design priority is determined with respect to several design criteria. The proposed design process produced a control system with excellent stability and performance robustness to vehicle parameter variations.