电液控制的主动横向稳定杆的应用仿真研究

为了改善商用车的侧倾稳定性,设计了一种集液压控制与电机控制的优势于一体,具有较高控制精度和较大反侧倾力矩的电液控制主动横向稳定杆,并以某19座商用车为例,建立了包含转向、俯仰、侧倾,车身垂向运动在内的九自由度整车模型,对其中的主动横向稳定杆设计了一种PID+前馈的控制策略以提高控制精度,减少迟滞,并通过Simulink和Trucksim的联合仿真以验证其有效性。在附着系数为0.8的B级路面上,分别进行鱼钩、方向盘角阶跃和双移线三种不同的工况下的仿真。结果表明,与被动稳定杆相比,提出的这种主动稳定杆能够让车身侧倾角,横摆角速度,侧向加速度和质心侧偏角均有(20~45)%的降低,极大的提高了车辆的侧翻稳定性。     

软路面下矿用自卸车侧倾响应分析与优化

矿用自卸车所处路况多为松软路面,地面与轮胎作用存在变形沉陷,这对整车行驶过程中的侧倾响应有很大影响。建立了弹性轮胎-变形地面相互作用模型,并将轮胎跳动自由度与整车结合,建立了十一自由度非线性整车动力学模型。在MATLAB/Simulink环境下搭建地面-轮胎-车辆耦合系统进行仿真分析,对仿真结果与实验数据进行对比,验证了模型的正确性,同时得出,软路面下侧倾角响应较之硬路面增加1.28°,增幅达23.81%,从而验证了软路面下轮胎沉陷变形对矿用自卸车侧倾有不容忽视的影响。采用遗传算法对油气悬架参数进行联合优化,优化后侧倾值下降了16.7%,明显提高了自卸车侧倾稳定性。     

整车主动悬架解耦控制

由于车辆各个车轮受路面的激励,车辆簧上质量的振动耦合了各个车轮引起的振动。为使车辆有效减振,建立了带主动悬架的整车非线性模型并利用微分几何方法对该非线性模型进行解耦。经过解耦的悬架系统簧上质量的垂向、俯仰和侧倾振动互相独立,成为独立的线性子系统,从而可以实现对其单独控制。设计了减振控制律,对解耦的悬架系统减振。仿真结果表明,簧上质量各个方向振动大幅衰减,说明该控制方法是有效的。     

Human response of vertical and pitch motion to vertical vibration on whole body according to sitting posture

When a whole body is exposed to vertical vibration, the body??s asymmetric shape affects the response to translational and rotational motion. The degree of asymmetry of a body on a seat is affected by posture. In our study, sixteen male subjects sitting on a seat were used to obtain a response to vertical vibration over a frequency range of 3 to 40 Hz. Two kinds of magnitude of the vibration at each frequency were applied (0.224 m/s² and 0.708 m/s² RMS). Without a backrest, three kinds of sitting postures (average thigh contact P1, supported thigh contact P2, and minimum thigh contact P3) were set by adjusting the height of the footrest and by using an inclined seat pan. The vertical and rotational responses were measured using a force plate mounted on a rigid seat. The apparent eccentric mass (AEM) is defined in this study as rotational response of body to vertical whole body vibration exposure. In the result, the AEM of P2 posture was bigger than that of P1 and P3 posture, especially in a frequency range of 20 to 40 Hz where idle vibration of the passenger vehicle exists. The apparent mass (AM) was even changed by the three kinds of sitting posture, but the difference was not as much as in the case of the AEM. The bigger difference of the AEM is assumed that the sitting posture mainly affects the asymmetry of the fore-and-aft direction, which is more strongly correlated with the rotational pitch response.     

基于随机变幅动载的驱动桥道路模拟试验研究

开发了转鼓凸块式驱动桥室内道路模拟试验系统，在直径达4m的转鼓表面安装了一定数量的高程凸块，运行时能模拟车辆行驶时来自不平路面的冲击和振动，并形成作用于车桥的随机变幅动载。介绍了试验系统的总体结构，分析了系统道路模拟的工作特性，阐述了试验原理和随机变幅动载荷的形成机理，给出了两组不同车速下试验时实测的变幅动载的时间历程曲线。通过对载荷曲线和试验结果的分析，证明了该试验方法是可行的。     

Adaptive control of a vehicle-seat-human coupled model using quasi-zero-stiffness vibration isolator as seat suspension

We propose the quasi-zero-stiffness (QZS) vibration isolator as seat suspension to improve vehicle vibration isolation performance. The QZS vibration isolator is composed of vertical spring and two symmetric negative stiffness structures used as stiffness correctors. A vehicle-seat-human coupled model considering the QZS vibration isolator is established as a three degree-of-freedom (DOF) model; it is composed of a quarter car model and a simplified 1 DOF model combined vehicle seat and human body. This model considers the changing mass of the passengers and sets the total mass of the vehicle seat and human body as an uncertain parameter, which investigates the overload and unload conditions in practical engineering. To further improve the vehicle ride comfort, a constrained adaptive backstepping controller law based on the barrier Lyapunov function (BLF) is presented. The dynamic characteristic of the active vehicle-seathuman coupled model under shock excitation was analyzed using numerical method. The results show that the designed controller law can isolate the shock excitation transmitted from the road to the passengers effectively, and both the vehicle and seat suspension strokes remain in the allowed stroke range.     

自适应神经模糊推理的四轮转向车辆转向控制研究

模糊规则的建立和隶属度函数的确定是设计模糊系统的难题。基于神经网络和模糊逻辑的自适应神经模糊推理系统,能够从仿真数据中自动提取出If-Then规则。并在Matlab/Simulink软件中,建立包含侧向运动、横摆运动、侧倾运动三个自由度的四轮转向车辆三自由度动力学模型。将得到的If-Then规则读取到模糊控制器中和三自由度车辆模型进行联合仿真。其中模糊控制器以方向盘转角、方向盘转角速度和车速作为输入,后轮转角作为输出。最后与前轮转向的车辆进行转向盘角阶跃仿真对比。仿真分析结果表明:基于自适应神经模糊推理系统建立的后轮转角模糊控制器能够实现理想的质心侧偏角和车辆横摆角速度响应,提高了车辆的操纵稳定性。     

十自由度车-轨耦合仿真分析

文章以十自由度车轨耦合模型为例,探究由轨道不平顺所导致车-轨耦合垂向振动的问题,由功率谱密度计算确定了轨道不平顺并以此作为激励源,计算分析车辆与轨道之间的垂向耦合振动响应.通过MATLAB仿真结果图分析得出,轨下的高底不平顺主要影响的是构架和轮对的振动频率,对车体的影响并不大,因此要减轻车-轨系统的振动主要从一系悬挂和...     

车辆电液馈能型互联悬架特性分析

为了提高馈能悬架的能量回收效果及动力学性能,提出了一种车辆电液馈能型互联悬架结构。根据流量/压降之间的关系,建立了整车7自由度与电液馈能型互联悬架的耦合数学模型,通过正弦激励对车辆电液馈能型互联悬架进行阻尼特性和馈能特性仿真。以四轮随机路面为输入,分析悬架对车辆的平顺性、行驶稳定性的影响。结果表明：阻尼力、馈能功率与激励频率、幅值成正比,馈能功率波动与之成反比,馈能效率随幅值、频率增大而先增大后减小;随机路面下,与被动悬架相比,电液馈能型互联悬架的俯仰模式、侧倾模式均可以改善动力学性能的同时实现振动能量的回收。     

Skyhook-based semi-active control of full-vehicle suspension with magneto-rheological dampers

The control study of vehicle semi-active suspension with magneto-rheological (MR) dampers has been attracted much attention internationally. However, a simple, real time and easy implementing semi-active controller has not been proposed for the MR full-vehicle suspension system, and a systematic analysis method has not been established for evaluating the multi-objective suspension performances of MR full-vehicle vertical, pitch and roll motions. For this purpose, according to the 7-degree of freedom (DOF) fullvehicle dynamic system, a generalized 7-DOF MR and passive full-vehicle dynamic model is set up by employing the modified Boucwen hysteretic force-velocity (F-v) model of the MR damper. A semi-active controller is synthesized to realize independent control of the four MR quarter-vehicle sub-suspension systems in the full-vehicle, which is on the basis of the proposed modified skyhook damping scheme of MR quarter-vehicle sub-suspension system. The proposed controller can greatly simplify the controller design complexity of MR full-vehicle suspension and has merits of easy implementation in real application, wherein only absolute velocities of sprung and unsprung masses with reference to the road surface are required to measure in real time when the vehicle is moving. Furthermore, a systematic analysis method is established for evaluating the vertical, pitch and roll motion properties of both MR and passive full-vehicle suspensions in a more realistic road excitation manner, in which the harmonic, rounded pulse and real road measured random signals with delay time are employed as different road excitations inserted on the front and rear two wheels, by considering the distance between front and rear wheels in full-vehicle. The above excitations with different amplitudes are further employed as the road excitations inserted on left and right two wheels for evaluating the roll motion property. The multi-objective suspension performances of ride comfort and handling safety of the proposed MR full-vehicle suspensi     

基于H∞控制的车辆座椅主动悬架系统

建立了四自由度的“车-椅-人”悬架系统的力学和数学模型,运用H∞鲁棒控制理论设计了车辆座椅主动悬架系统的鲁棒控制器。并且用MATLAB软件包及Robust-Control-Toolbox对座椅悬架系统进行了仿真分析。仿真结果表明：鲁棒控制策略能很好地抑制座椅主动悬架系统的垂直振动加速度,其减振幅度在共振频率附近能达到50～60％,大大提高了乘坐舒适性。并且,该系统能够承受一定的模型参数不确定性,具有良好的鲁棒稳定性。     

地铁车辆车轮偏磨原因分析与对策研究

轮对偏磨是铁道车辆常见的车轮磨耗形式。对国内某地铁线路的车轮磨耗进行测试分析,发现该线路车辆存在严重的车轮偏磨现象,左侧车轮以轮缘磨耗为主,右侧车轮以踏面磨耗为主。该地铁线路小半径曲线多,且左、右曲线分布严重不均,以及车辆不掉头运行是造成车轮偏磨的主要原因。基于UM动力学软件建立车轮磨耗预测模型,利用地铁车轮磨耗测试结果对磨耗预测模型进行验证,根据数值仿真结果提出轮对偏磨的解决措施。仿真结果表明,车辆掉头行驶能明显减缓车轮的偏磨现象,最佳掉头运行里程数为2×104～4×104km。小半径曲线占比对车轮磨耗影响较大,左、右曲线百分比差值小于3%时可不采取掉头措施。     

液压缸非线性弹簧力下的轧机特性及控制

建立了非线性弹簧力约束作用下的轧机辊系振动模型,采用平均法求得轧机辊系的幅频响应方程。仿真分析了不同非线性弹簧力和活塞杆初始位移的幅频特性曲线,以及系统分岔响应随外激励幅值的变化规律。引入吸振器控制装置,比较了吸振器加入前后的时域曲线和幅频曲线,仿真分析了吸振器质量、弹簧力和摩擦力对幅频曲线的影响。研究结果表明：非线性弹簧力和外激励都会改变轧机辊系振动特性的规律,吸振器的控制效果与吸振器质量、弹簧力和摩擦力有关。     

履带车辆悬挂参数变化对悬挂特性影响分析

通过确定实际履带车辆的简化条件,建立了二自由度车辆悬挂系统模型,得出了车身加速度、悬挂动行程、负重轮相对动载荷对路面输入的幅频特性,分析了悬挂刚度、阻尼系数、负重轮胶圈刚度和非悬置质量等参数变化对悬挂传递特性的影响.结果表明,在进行车辆悬挂系统设计和振动控制时,必须考虑悬挂系统参数的匹配问题和参数变化对振动控制的影响.     

轻型载货汽车减振技术分析及优化设计

对某轻型载货汽车产生的低频振动现象进行了试验分析及优化设计研究.在对轻型载货汽车振动测试分析的基础上,利用有限元仿真和拓扑优化技术对样车进行了固有频率分析和优化设计.通过对样车的振动测试及有限元分析,找到了轻型载货汽车产生低频振动的主要原因:车辆系统的1阶固有频率与车轮动不平衡引起的激励频率接近,导致了车辆系统的共振.分析及试验结果表明,通过优化车架的结构和匹配驾驶室橡胶垫块的刚度能够提高车辆系统的1阶固有频率,明显改善轻型载货汽车产生的低频异常振动现象,提高了车辆的乘坐舒适性.     

人-椅8自由度车辆系统的平顺性和稳定性研究

文中在Matlab/Simulink中搭建了人-椅8自由度车辆系统仿真模型,在仿真分析时考虑汽车前、后轮之间的延迟性,以路面随机信号作为输入激励,研究了汽车平顺性的时频特性,且分别通过4个轮胎的输入激励研究了汽车的稳定性.研究结果表明:路面输入为随机信号时,车身垂直加速度,车身俯仰角加速度,人-椅垂直加速度,前、后悬架...     

多级路况下车载无人机疲劳载荷仿真

建立五自由度的车载无人机的振动系统在随机路面激励下的数学模型.由路面功率谱反推路面不平度的方法,对A、B、C和D四个等级路面不平度交替冲击的复杂情况进行时域模拟.运用MATLAB的Simulink工具,对一种典型的车载无人机的任务剖面进行仿真,获得无人机的位移加速度响应值.     

斗轮机俯仰运动受力分析与方案优化

分析了在斗轮机空载、取料、堆料的三种工况下,俯仰运动液压缸受力状况。针对斗轮机俯仰运动受力特点,提出了斗轮机俯仰液压系统的改进方案,以解决斗轮机臂架振动问题。     

汽车操纵稳定性仿真用轮胎模型的研究

介绍了四种常见的车辆操纵稳定性仿真用轮胎模型,即简单非线性轮胎模型、半经验公式轮胎模型、魔术公式轮胎模型和分析轮胎模型。通过对含上述四种轮胎模型的车辆动力学系统进行C级不平路面上转向盘角阶跃输入仿真试验,结果表明车辆系统响应总体趋势一致。以简单非线性轮胎模型为例,对比了车辆在水平路面与正弦路面上的响应,分析了不平路面的频率和幅值及车速对车辆操稳性的影响。     

汽车振动系统的分析研究

建立前轮为独立悬架,后轮为非独立悬架汽车的七自由度动力学模型,并给出该模型所需要的质量特性与运动学特性参数。由给出的运动微分方程,利用仿真分析得出车身的振动加速度图。研究结果表明,建立的汽车振动系统动力学模型是有合理的。