某SUV行驶平顺性仿真与优化设计

研究某SUV (Sport Utility Vehicle)的行驶平顺性优化问题,根据车轮—悬架系统动力学原理,得出悬架刚度、阻尼参数合理匹配与整车平顺性有直接关系.针对如何协调相互矛盾的性能指标,以达到悬架系统最优设计的目的,提出了一种虚拟样机技术与试验设计相结合的优化方法.利用Adams/Car建立整车模型,进行仿真分析,并与标杆车平顺性试验结果对比,模型的正确性和准确性得到验证.参照平顺性评价方法,以优化垂向的加权加速度均方根值为目标,采用D—最优试验设计确定了悬架刚度和阻尼参数的最佳匹配方案.优化结果表明,整车的平顺性能得到明显地改善,利用本文方法对悬架参数优化具有工程可行性,可减少开发的周期和成本.     

Complex Flexible Multibody Systems with Application to Vehicle Dynamics

A formulation to describe the linear elastodynamics offlexible multibody systems is presented in this paper. By using a lumpedmass formulation the flexible body mass is represented by a collectionof point masses with rotational inertia. Furthermore, the bodydeformations are described with respect to a body-fixed coordinateframe. The coupling between the flexible body deformation and its rigidbody motion is completely preserved independently of the methods used todescribe the body flexibility. In particular, if the finite elementmethod is chosen for this purpose only the standard finite elementparameters obtained from any commercial finite element code are used inthe methodology. In this manner, not only the analyst can use any typeof finite elements in the multibody model but the same finite elementmodel can be used to evaluate the structural integrity of any systemcomponent also. To deal with complex-shaped structural models offlexible bodies it is necessary to reduce the number of generalizedcoordinates to a reasonable dimension. This is achieved with thecomponent mode synthesis at the cost of specializing the formulation toflexible multibody models experiencing linear elastic deformations only.Structural damping is introduced to achieve better numerical performancewithout compromising the quality of the results. The motions of therigid body and flexible body reference frames are described usingCartesian coordinates. The kinematic constraints between the differentsystem components are evaluated in terms of this set of generalizedcoordinates. The equations of motion of the flexible multibody systemare solved by using the augmented Lagrangean method and a sparse matrixsolver. Finally, the methodology is applied to model a vehicle with acomplex flexible chassis, simulated in typical handling scenarios. Theresults of the simulations are discussed in terms of their numericalprecision and efficiency.     

多轴越野车辆的行驶平顺性

以多轴越野车为研究对象,应用机械系统动力学仿真分析软件MSC Adams建立一、二、三桥悬架,轮胎及整车的多体系统模型. 进行整车脉冲输入及随机输入平顺性仿真分析,实现了在车辆设计阶段对其进行平顺性预测与分析的目标.     

基于改进粒子群算法的再入飞行器轨迹优化

采用基于距离量度和自适应惩罚相结合的约束处理技术的改进粒子群优化算法(PSO)应用于再入飞行器轨迹优化,避免适应值函数中复杂的罚函数及罚因子的设计,提高优化算法的通用性.以高超声速飞行器最小控制量再入轨迹优化为例,并对飞行器运动模型进行简化及控制量参数化.对两种不同的高超声速飞行器模型进行优化,仿真结果验证算法的有效性...     

A Subsystem Synthesis Method for Efficient Vehicle Multibody Dynamics

A subsystem synthesis method has been proposed for dynamicanalysis of a vehicle multibody system that consists of severalsubsystems. In this method, each subsystem can be independently analyzedwith a virtual reference body. For overall vehicle system analysis,subsystems can be synthesized to the chassis with effective inertiamatrix and force vector from the virtual reference body of eachsubsystem. Using this matrix and vector, a fixed size (6 × 6) of equationsof motion for a chassis can be formed and independently solved. There after, equations of motion for each subsystem are solved, subsystem bysubsystem. Computational efficiency of the proposed method has been alsoinvestigated theoretically through the operational counting method. Inorder to show the effectiveness of the method, a Short Long Arm (SLA)vehicle suspension subsystem has been analyzed.     

汽车操纵稳定性的自适应控制策略研究

针对汽车系统的非线性和参数不确定性,设计了一种“前馈+反馈”自适应神经模糊控制器,通过ESP和AFS的协调控制来提高汽车操纵稳定性.ESP反馈控制器采用模糊控制策略,以横摆角速度和质心侧偏角为控制目标;AFS前馈控制器采用径向基神经网络控制,以反馈控制器的输出作为误差进行学习,从而实现自适应控制.仿真结果表明,上述控制策略是可行和有效的,能显著改善汽车在高速或湿滑路面上的操纵稳定性.     

ADAMS／Car在汽车操纵稳定性仿真中的应用

在研究汽车动力学特性中,针对车辆响和操纵稳定性,利用ADAMS/Car软件建立了某轿车的操纵动力学多体仿真模型,考虑前后悬架系统、转向系统、轮胎、衬套和载重等的影响,较为真实地仿真了汽车在方向盘转角阶跃输入条件下的转向情况,为汽车的操纵稳定性分析奠定了基础,并较为详细地分析了汽车在转向盘转角的转向特性。通过对不同车速、不同载荷下的仿真研究,得出汽车在这些不同条件下的响应,研究汽车的转向特性与车速、载荷的关系。为以后汽车的操纵稳定性等此类问题的设计研究提供了参考依据。     

基于VP的油气悬挂车辆脉冲输入平顺性仿真分析

该文以某型型矿用自卸车为研究对象,建立其油气悬挂缸的数学模型,并对悬挂缸的输出力特性进行了试验研究。通过将仿真结果与实验结果对比可以看出,该文建立的模型准确可靠。在其基础上,该文建立了该型油气悬挂车辆的虚拟样机模型,利用该模型对油气悬挂车辆的脉冲输入平顺性进行了仿真研究,得出了悬挂缸初始充气压力、阻尼孔直径和环形腔横截面积变化对油气悬挂车辆脉冲输入平顺性的影响规律,从而为车辆设计时合理确定悬挂缸的各种参数提供了理论依据。     

Combining MBS with FEM for Rail Vehicle Dynamics Analysis

In this paper a non-linearmultibody model of a rail vehicle is combined with afinite element model of its carbody. The finiteelement model is reduced by eigenmode representation.Simulation, i.e. numerical solution of the equationsof motion, is carried out using the combined flexiblemultibody model. Track data measured on a real trackis used as input. Simulation results are compared withon-track measurements carried out on the real vehicleand track. The paper presents four criteria to selectimportant eigenmodes, including both general dynamicsand comfort aspects, and applies them to the abovementioned case.     

履带车多刚体建模与仿真分析

首先以车辆地面力学理论为基础,分析了典型的履带与地面相互作用关系及其在RecurDyn/Track(LM)程序中的处理,分别定义了两种典型地面土力学参数,从而建立了基于Bekker理论与Janosi & Hanamoto理论的循环动载荷作用下履带与地面相互作用力学模型;同时分析了履带系统各部件之间的接触力学模型,定义各接触参数及约束关系,从而准确合理地建立了履带车多刚体模型,通过施加运动函数,实现模型在典型地面参数下的行走特性仿真分析,仿真结果与理论分析及实际情况相符合,互为验证,从而为进一步深入研究提供了理论依据与有效分析手段.     

基于遗传算法的某微型纯电动汽车平顺性优化

针对某微型纯电动汽车在C级路面行驶时座椅处振动较大、乘员有不舒适感等平顺性问题,建立了整车多体动力学模型,在C级路面下对车辆平顺性进行了仿真,结果与实车行驶时驾驶员的主观感觉基本一致,验证了所建模型的准确性,以质心总加权加速度均方根值最小为优化目标,悬架刚度和阻尼为设计变量,最后利用遗传算法联合ADAMS和MATLAB进行了优化仿真。联合仿真结果表明,优化后的整车平顺性有明显改善,为实际优化改进提供依据。     

Friction Models and Stress Recovery Methods in Vehicle Dynamics Modelling

This paper presents two examples of calculations for vehicles with flexible bodies by using mixed multibody and finite element methods. The first example deals with dynamics computations for a bimodal train with a flexible cistern, whereas the second example concerns the dynamics calculations for the PW-6 glider. In the first example, the influence of the chosen friction model on the train dynamics calculations results was discussed. The second example presents several methods of stress calculations and a comparison of results. The achieved conclusions may be used as suggestions towards a modelling method choice for a given problem.Both issues being discussed are of great importance in dynamics of flexible multibody systems modelling practice and durability assessment. In both examples, the kinematics of the system was presented in absolute coordinates, the motion equations in the DAE form, and the reduction of the number of degrees of freedom was achieved by means of the Craig–Bampton (CB) method.     

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。     

Optimization of the Rigid Body Mechanism in a Wobble Plate Compressor

A complex mechanical system is optimized with respect to its performance. The mechanism is a compressor, which is modeled as a multibody system. The optimization is first performed on a simplified 2D model, where it is possible to find analytical sensitivities, and the results indicate that the mechanism can be optimized. Optimization is finally performed with numerical sensitivities, from a full 3D mechanism simulation with 20 bodies, and the results show that the desired change of performance is obtained. For the optimization procedure the SLP method (sequential linear programming) is used with good results, and although the paper deals with optimization of a specific mechanism, the procedure can be modified to treat also other mechanical systems.     

柔性机械臂动力学建模研究进展

刚性机械臂由于其较高的工作精度和重复性、较强的承载能力,已广泛应用于危险或相对单一、重复性高工作场景.但刚性机械臂的结构及运作方式不够灵活,无法适用于不定型、非标准、狭窄空间等生产场景.最近几年,柔性机械臂因其结构柔性、作业空间大、人机交互安全等优点而受到广泛关注,有希望应用于医疗、服务和智能制造等领域.但柔性机械臂结构柔软,运动比较自由,在作业过程中柔性效应不可忽略,这对其高精度控制提出了重大挑战.柔性机械臂控制的核心科学问题之一是建立包含结构柔性特征和动态特性的高精度动力学模型.为此,本文对柔性机械臂运动学建模和动力学建模研究进行了综述.作为动力学建模的基础,本文首先综述了柔性机械臂的运动学建模方法,主要介绍了曲率法、伪刚体运动学(PRB)方法、基于Cosserat杆的运动学建模方法、结构几何分析方法、Denavit Hartenberg(D H)法及坐标法、数据驱动和机器学习方法等.随后,本文详细综述了柔性机械臂的动力学建模方法,主要包括集中参数系统法、假设模态法、有限元法.最后,本文简述了目前柔性机械臂动力学研究的主要内容,并对未来研究做出展望.     

新型轮边驱动电动车平顺性仿真分析

为解决非簧载质量增加导致轮边驱动电动汽车平顺性下降问题,提出了一种包含磁流变半主动悬架的新型轮边驱动系统,并将其与四轮独立驱动电动车相耦合,建立了整车振动系统动力学模型,应用单一输入规则群模糊推理模型构建半主动悬架内环模糊控制器,使建立的车身运动外环控制器,通过变量转换器实现了内外环控制的有效连接,从而构建了整车平顺性双环模糊控制器。以某型四轮独立驱动电动车为例在随机路面激励下进行仿真,结果表明相对于被动悬架,双环模糊控制器结构简单,能够显著抑制车身振动,削弱了轮边驱动系统对电动车带来的垂向振动负效应,提高了行驶平顺性。     

基于ADAMS的脉冲路面输入平顺性仿真分析

以某皮卡车为研究对象。利用ADAMS／VIEW软件建立了包括前后悬架、轮胎、车身、转向系和人-椅系统等在内的整车多刚体动力学模型,并对建模中的若干关键问题进行了详细的论述。运用ADAMS软件对建立的整车多体动力学模型成功地实现了脉冲路面输入下的平顺性仿真分析。将仿真所得结果与该车试验所得结果进行了对比,结果表明数据吻合较好,从而认为整车模型建立准确。并为进一步对该车做设计分析打下了良好的基础。     

车辆平顺性的虚拟现实仿真技术

探讨了基于虚拟现实的车辆平顺性振动仿真原理,利用软件编程的方法实现了汽车在虚拟道路上的行驶运动。汽车行驶时,能够表现车箱(包括驾驶员)的垂向运动、横向运动和俯仰运动,驾驶员的垂向运动、横向运动和俯仰运动,汽车轮胎的旋转运动。其运动规律皆由车辆平顺性动力学分析数据来确定。从而实现了车辆平顺性振动运动在计算机屏幕上的虚拟显示,以图形图像运动来直观的表现车辆的平顺性。     

基于多体力学的车辆动力学控制系统仿真及优化

利用多体分析软件ADAMS建立了多自由度汽车整车多体动力学仿真模型,并进一步简化为15自由度非线性模型,结合2自由度线性模型建立PID控制策略,进行了冰面单周正弦工况下的汽车操纵稳定性仿真试验研究,采用自适应模拟退火算法与非线性序列二次规划法相结合的组合优化方法对控制系统的控制参数进行了分析和优化.结果表明,该控制方法能够大幅度提高车辆的操纵稳定性和安全性,能够适应复杂的路面和行驶工况,取得了良好的效果.