A comparison of global optimization algorithms applied to a ride comfort optimization problem

This study presents a comparison of global optimization algorithms applied to an industrial engineering optimization problem. Three global stochastic optimization algorithms using continuous variables, i.e. the domain elimination method, the zooming method and controlled random search, have been applied to a previously studied ride comfort optimization problem. Each algorithm is executed three times and the total number of objective function evaluations needed to locate a global optimum is averaged and used as a measure of efficiency. The results show that the zooming method, with a proposed modification, is most efficient in terms of number of objective function evaluations and ability to locate the global optimum. Each design variable is thereafter given a set of discrete values and two optimization algorithms using discrete variables, i.e. a genetic algorithm and simulated annealing, are applied to the discrete ride comfort optimization problem. The results show that the genetic algorithm is more efficient than the simulated annealing algorithm for this particular optimization problem.     

考虑道路友好性的载货汽车悬架参数优化仿真

为了减少汽车轮胎动载荷对路面的损伤,研究兼顾行驶平顺性和道路友好性的悬架参数优化方法.建立了四自由度二分之一汽车振动模型,给出了整车振动方程、频响函数和路面输入模型,针对该汽车常用的行驶条件,以行驶平顺性指标和道路友好性指标的线性加权和作为优化目标,运用Matlab优化工具,对B级和C级路面典型工况的悬架刚度和阻尼进行仿真优化.优化结果表明,悬架参数对行驶平顺性和道路友好性有较大的影响;与原车相比,悬架参数优化后,行驶平顺性提高了5%～15%,道路友好性提高了2%～3%;针对B级和C级路面条件得到的两组优化结果为悬架参数没计提供了可行的目标范围.     

Suspension system performance optimization with discrete design variables

Suspension systems on commercial vehicles have become an important feature meeting the requirements from costumers and legislation. The performance of the suspension system is often limited by available catalogue components. Additionally the suspension performance is restricted by the travel speed which highly influences the ride comfort. In this article a suspension system for an articulated dump truck is optimized in sense of reducing elapsed time for two specified duty cycles without violating a certain comfort threshold level. The comfort threshold level is here defined as a whole-body vibration level calculated by ISO 2631-1. A three-dimensional multibody dynamics simulation model is applied to evaluate the suspension performance. A non-gradient optimization routine is used to find the best possible combination of continuous and discrete design variables including the optimum operational speed without violating a set of side constraints. The result shows that the comfort level converges to the comfort threshold level. Thus it is shown that the operational speed and hence the operator input influences the ride comfort level. Three catalogue components are identified by the optimization routine together with a set of continuous design variables and two operational speeds one for each load case. Thus the work demonstrates handling of human factors in optimization of a mechanical system with discrete and continuous design variables.     

高速铁道车辆悬挂系统参数化建模、优化与仿真分析

为了协调高速铁道车辆的运动稳定性与曲线通过性能之间的矛盾,本文采用多目标优化方法对一种高速铁道车辆的关键悬挂参数进行了优化处理.采用多体动力学技术建立了某型高速铁道车辆62个自由度的动力学模型,模型考虑了轮轨接触几何非线性、轮轨蠕滑非线性和阻尼非线性等.采用ADAMS-Matlab联合仿真对车辆悬挂系统进行参数化改造,使弹簧刚度和阻尼系数均可调.采用基于遗传算法的多目标优化方法对悬挂参数进行优化,使车辆模型能同时满足3种动力学指标.对比优化前后模型的动力学性能可以发现:模型的运动稳定性和曲线通过性能得到显著提高,虽然运行平稳性有小幅降低,但仍能保持在优良的工作状态.     

Passenger body vibration control in active quarter car model using ANFIS based super twisting sliding mode controller

This paper presents passenger body vibration control using an Adaptive Neuro Fuzzy Inference System (ANFIS) based super twisting sliding mode controller (ASTSMC) in active quarter car system. The proposed quarter car model is having three degrees of freedom composed of passenger body, sprung mass and unsprung mass. The random road profile is generated using ISO 8608 standard. The ride comfort of passenger body is calculated as per ISO 2631-1 standard. The simulation response is studied in time and frequency domain for passenger body acceleration and displacement in quarter car model. The response generated by ASTSMC controller for passenger body vibration suppression is compared with super twisting sliding mode controller and passive suspension system. The graphical and mathematical results proved the superiority of proposed ASTSMC controller in providing best ride comfort and safety to travelling passenger.     

主被动一体悬架构型的多目标粒子群最优控制

为了解决轮毂电机电动汽车中轮毂电机导致的振动负效应问题,提出了将动态减振与主动悬架结合的悬架新构型方案.针对新构型中结构及控制参数复杂的特点,建立了能够表征平顺性、操稳性以及悬架作动效率的11自由度整车动力学模型.设计基于新构型的多目标粒子群线性二次最优(MOPSO–LQR)控制器.对模型进行仿真分析,仿真结果表明,新构型方案能够实现车辆平顺性、操稳性以及悬架效率的全局最优,对比传统轮毂电机悬架构型方案,在解决轮毂电机振动负效应问题上有良好的效果.     

Definition and determination of the bus oscillatory comfort zones

The paper defines “equal oscillatory comfort zones” as a novel concept in the sphere of the bus vertical dynamics. Oscillatory zones are determined using the original and validated oscillatory model of the intercity bus and comfort criteria according to the international ISO 2631/1997 standard requirements. The bus spatial oscillatory model with 65 degrees of freedom (DOF) was built in the ADAMS/View module of the multibody software package MSC.ADAMS. The model was excited by two different real road surfaces: poor asphalt-concrete and good asphalt-concrete pavements, registered at the speed of 64 km/h and 90 km/h respectively. It was found by simulation that oscillatory zones with different comfort assessments exist in the bus. The most comfortable oscillatory zone is in the middle part of the bus (between the front and the rear axle), whereas the least comfortable oscillatory zone is on the rear bus overhang. For the purpose of the ride comfort harmonization, using Design of Experiments (DOE) analysis, new oscillatory parameters are proposed for passenger seats which do not ensure satisfactory oscillatory comfort level. It is concluded that harmonization of oscillatory comfort for all bus passengers could be achieved for good asphalt-concrete excitation. For the poor road excitation it is possible to achieve significant improvement of comfort, especially for the assistant driver and passengers in the bus rear overhang. On a poor asphalt-concrete pavement, by using the proposed seat oscillatory parameters, the allowed exposure time for vertical whole body vibration would be considerably extended.Relevance to industryOscillatory comfort has a particular importance for users of intercity buses traveling longer distances. Comfort assessment of each bus user and mapping of comfort zones can indicate the individual seat and group of the seats on which the oscillatory comfort is reduced. Proper selection of seat oscillatory parameters can improve users comfort. Results of such an analysis can significantly help bus designers and manufacturers in order to improve and harmonize oscillatory comfort on the whole vehicle platform.     

随机路面激励下整车NVH有限元分析

针对应用刚体动力学方法不能得到驾驶员可以直接感知的振动加速度的缺陷,提出应用整车柔性体模型进行汽车随机路面平顺性分析的方法.对一种典型路面不平度数据进行处理并将得到的功率谱密度(Power Spectral Density,PSD)作为激励,建立整车有限元模型,通过试验模态验证该模型后进行传递函数分析;根据所得的激励和传递函数的结果计算得出汽车方向盘处的速度响应.该速度响应与随机路面平顺性试验一致性较好。     

Multidisciplinary hybrid hierarchical collaborative optimization of electric wheel vehicle chassis integrated system based on driver’s feel

The optimization design of chassis integrated system mainly involves steering, suspension and brake subsystems, which is essentially a multidisciplinary design optimization. This paper mainly researches the multidisciplinary optimization of the chassis integrated system for the electric wheel vehicle, from the view of ensuring a favorable feel for the driver. The dynamic models of differential steering system, brake system, active suspension system and vehicle are established. Then, taking the coupling relationship of the chassis subsystems into account, this paper proposes an evaluating index of driver’s ride comfort (Drc), which is composed of the steering road feel, brake feel and suspension ride comfort. In order to determine the weight coefficient in the quantization formula of Drc, the technique for order preference by similarity to ideal solution (TOPSIS) method is used to overcome the subjectivity in the selection. Based on these, a multidisciplinary hybrid hierarchical collaborative optimization (HHCO) method is proposed on the basis of the collaborative optimization (CO), which consists of a system level coordinator and a coupling analyzer to solve the problem of poor convergence and the low efficiency of CO method. The optimization results show that the proposed HHCO method has excellent computational efficiency and better convergence compared with the CO method, which can further improve the steering road feel and the drive ride comfort, on the premise of ensuring the brake feel and suspension ride comfort.     

Multi-objective optimization for bus body with strength and rollover safety constraints based on surrogate models

It is important to consider the performances of lightweight, stiffness, strength and rollover safety when designing a bus body. In this paper, the finite element (FE) analysis models including strength, stiffness and rollover crashworthiness of a bus body are first built and then validated by physical tests. Based on the FE models, the design of experiment is implemented and multiple surrogate models are created with response surface method and hybrid radial basis function according to the experimental data. After that, a multi-objective optimization problem (MOP) of the bus body is formulated in which the objective is to minimize the weight and maximize the torsional stiffness of the bus body under the constraints of strength and rollover safety. The MOP is solved by employing multi-objective evolutionary algorithms to obtain the Pareto optimal set. Finally, an optimal solution of the set is chosen as the final design and compared with the original design.     

针对多个动力学性能的整车多目标优化

针对难以用传统单目标方法开发综合性能好的汽车的问题,建立整车刚柔耦合多体动力学模型,用车身垂向加速度、前后轮荷标准差和横摆角速度超调量等3个参数表征乘坐舒适性、行驶安全性和操纵稳定性等3方面性能,并采用多目标遗传算法进行优化.从优化得到的一组Pareto解集中选取一个最优解,有效提高汽车的若干性能,证明该方法能有效优化整车动力学性能.     

Applications of hybrid optimization techniques for model updating of rotor shafts

This paper presents an approach by combining the genetic algorithm (GA) with simulated annealing (SA) algorithm for enhancing finite element (FE) model updating. The proposed algorithm has been applied to two typical rotor shafts to test the superiority of the technique. It also gives a detailed comparison of the natural frequencies and frequency response functions (FRFs) obtained from experimental modal testing, the initial FE model and FE models updated by GA, SA, and combination of GA and SA (GA–SA). The results concluded that the GA, SA, and GA–SA are powerful optimization techniques which can be successfully applied to FE model updating, but the appropriate choice of the updating parameters and objective function is of great importance in the iterative process. Generally, the natural frequencies and FRFs obtained from FE model updated by GA–SA show the best agreement with experiments than those obtained from the initial FE model and FE models updated by GA and SA independently.     

Optimization of the new Saab 9-3 exposed to impact load using a space mapping technique

The aim of this work is to illustrate how a space mapping technique using surrogate models together with response surfaces can be used for structural optimization of crashworthiness problems. To determine the response surfaces, several functional evaluations must be performed and each evaluation can be computationally demanding. The space mapping technique uses surrogate models, i.e. less costly models, to determine these surfaces and their associated gradients. The full model is used to correct the gradients from the surrogate model for the next iteration. Thus, the space mapping technique makes it possible to reduce the total computing time needed to find the optimal solution. First, two analytical functions and one analytical structural optimization problem are presented to exemplify the idea of space mapping and to compare the efficiency of space mapping to traditional response surface optimization. Secondly, a sub-model of a complete vehicle finite element (FE) model is used to study different objective functions in vehicle crashworthiness optimization. Finally, the space mapping technique is applied to a structural optimization problem of a large industrial FE vehicle model, consisting of 350.000 shell elements and a computing time of 100 h. In this problem the intrusion in the passenger compartment area was reduced by 32% without compromising other crashworthiness parameters.     

汽车脉冲输入平顺性的仿真分析

该文讨论了运用虚拟样机技术 ,进行汽车脉冲输入平顺性仿真分析的方法 ,针对本校研制的电动牵引车建立了包括悬架、车体和人 -椅系统在内的多体系统模型 ,并通过建立轮胎的UA解析模型和三维路面模型来计算轮胎与地面的相互作用。通过仿真试验 ,对该车的平顺性能进行了评价 ,分析了悬架和座椅参数对该车平顺性的影响 ,从而实现了在该车的设计阶段 ,对其平顺性进行预测及分析的目的。     

基于自适应遗传算法的半主动悬架模糊控制研究

模糊规则的正确选择是半主动悬架模糊控制器设计的关键和难点,本文提出一种自适应地选择交叉概率和变异概率的遗传算法,以车身垂直加速度均方根值为优化目标,对汽车半主动悬架模糊控制规则进行优化,以达到提高半主动悬架模糊控制器的控制效果,改善汽车行驶平顺性的目的。为了证明该优化方法的可行性,将该自适应遗传算法优化的模糊控制器对汽车半主动悬架进行控制,并建立Matlab文本与Simulink相结合的仿真模型。仿真结果表明：优化后的半主动悬架车身垂直加速度均方根值减小,汽车行驶的平顺性得到了提高。     

应用模型预测控制的混合动力汽车模式切换动态协调控制

利用传统协调控制策略或模型预测控制(MPC)方法能够解决离合器模式切换的平顺性,但其改善效果不显著,且缺乏深入的细化研究.因此,为了改进混合动力汽车有离合器结合的模式切换过程中的平顺性,本文基于MPC制定有离合器模式切换过程的动态协调控制策略.在对混合动力系统有离合器模式切换模型进行简化的基础上,开展MPC在模式切换动态协调控制过程的原理描述,以减小有离合器模式间切换的冲击度进行基于MPC动态协调控制策略设计,并对不同权重下的冲击度进行了详细的对比.通过实验验证,其结果表明采用MPC的模式切换协调控制最大冲击度从26.3 m/s^3下降至9.26 m/s^3,降低了64.8%,明显的抑制了模式切换过程中的冲击度,有效的改善了模式切换的平顺性.     

Sensitivity analysis and optimization of vehicle–bridge systems based on combined PEM–PIM strategy

This paper presents a new optimization method for coupled vehicle–bridge systems subjected to uneven road surface excitation. The vehicle system is simplified as a multiple rigid-body model and the single-span bridge is modeled as a simply supported Bernoulli–Euler beam. The pseudo-excitation method transforms the random surface roughness into the superposition of a series of deterministic pseudo-harmonic excitations, which enables convenient and accurate computation of first and second order sensitivity information. The precise integration method is used to compute the vertical random vibrations for both the vehicle and the bridge. The sensitivities are used to find the optimal solution, with vehicle ride comfort taken as the objective function. Optimization efficiency and computational accuracy are demonstrated numerically.     

Developing artificial neural networks to estimate real-time onboard bus ride comfort

Neural Computing and Applications - The ride comfort of bus passengers is a critical factor that is recognised to attract greater ridership towards a sustainable public transport system. However,...     

橡胶衬套刚度对悬架运动学的影响

橡胶衬套在现代汽车上的广泛应用对整车操纵稳定性和平顺性造成了很大的影响。为减少由于橡胶衬套引起的悬架运动学特性的变化,论文在ADAMS/View中建立了包含有橡胶衬套的麦弗逊悬架。通过ADAMS/Insight对各个衬套的刚度进行灵敏度分析,选取刚度变化对车轮定位参数影响较大的衬套刚度作为优化变量,以车轮前束角、外倾角和轮距作为优化目标。在Matlab中运用遗传算法调用ADAMS中的脚本文件,对橡胶衬套进行优化得到最优刚度值。经比较分析,优化后悬架定位参数变化范围减小。由此通过优化橡胶衬套刚度改善了悬架运动学特性。