Skyhook Surface Sliding Mode Control on Semi-Active Vehicle Suspension System for Ride Comfort Enhancement

A skyhook surface sliding mode control method was proposed and applied to the control on the semi-active vehicle suspension system for its ride comfort enhancement. A two degree of freedom dynamic model of a vehicle semi-active suspension system was given, which focused on the passenger’s ride comfort perform-ance. A simulation with the given initial conditions has been devised in MATLAB/SIMULINK. The simula-tion results were showing that there was an enhanced level of ride comfort for the vehicle semi-active sus-pension system with the skyhook surface sliding mode controller.

Semi-active Sliding Mode Control of Vehicle Suspension with Magneto-rheological Damper

The vehicle semi-active suspension with magneto-theological damper（MRD） has been a hot topic since this decade, in which the robust control synthesis considering load variation is a challenging task. In this paper, a new semi-active controller based upon the inverse model and sliding mode control （SMC） strategies is proposed for the quarter-vehicle suspension with the magneto-rheological （MR） damper, wherein an ideal skyhook suspension is employed as the control reference model and the vehicle sprung mass is considered as an uncertain parameter. According to the asymptotical stability of SMC, the dynamic errors between the plant and reference systems are used to derive the control damping force acquired by the MR quarter-vehicle suspension system. The proposed modified Bouc-wen hysteretic force-velocity （F-v） model and its inverse model of MR damper, as well as the proposed continuous modulation （CM） filtering algorithm without phase shift are employed to convert the control damping force into the direct drive current of the MR damper. Moreover, the proposed semi-active sliding mode controller （SSMC）-based MR quarter-vehicle suspension is systematically evaluated through comparing the time and frequency domain responses of the sprung and unsprung mass displacement accelerations, suspension travel and the tire dynamic force with those of the passive quarter-vehicle suspension, under three kinds of varied amplitude harmonic, rounded pulse and real-road measured random excitations. The evaluation results illustrate that the proposed SSMC can greatly suppress the vehicle suspension vibration due to uncertainty of the load, and thus improve the ride comfort and handling safety. The study establishes a solid theoretical foundation as the universal control scheme for the adaptive semi-active control of the MR full-vehicle suspension decoupled into four MR quarter-vehicle sub-suspension systems.

Fuzzy Sliding Mode Control for the Vehicle Height and Leveling Adjustment System of an Electronic Air Suspension

The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system.

STABILITY ANALYSIS IN SPATIAL MODE FOR CHANNEL FLOW OF FIBER SUSPENSIONS

Different from previous temporal evolution assumption, the spatially growing mode was employed to analyze the linear stability for the channel flow of fiber suspensions. The stability equation applicable to fiber suspensions was established and solutions for a wide range of Reynolds number and angular frequency were given numerically . The results show that, the flow instability is governed by a parameter H which represents a ratio between the axial stretching resistance of fiber and the inertial force of the fluid. An increase of H leads to a raise of the critical Reynolds number, a decrease of corresponding wave number, a slowdown of the decreasing of phase velocity , a growth of the spatial attenuation rate and a diminishment of the peak value of disturbance velocity. Although the unstable region is reduced on the whole, long wave disturbances are susceptible to fibers.

SLIDING MODE CONTROL FOR ACTIVE AUTOMOBILE SUSPENSIONS

Nonlinear control methods are presented based on theory of sliding mode control (SMC) or variable structure control (VSC) for application to active automobile suspensions. Requirements of reducing manufacturing cost and energy consumption of the active suspension system may be satisfied by reasonable design of the sliding surface and hydraulic servo system. Emphasis is placed on the study of the discrete sliding mode control method (DSMC) applicable for a new sort of speed on off solenoid valves of anti dust capability and low price. Robustness and effectiveness of the feedback linearized controller in typical road conditions are demonstrated by numerical results for a quarter car suspension model.

Discuss about the Driving Device Suspension Mode of Locomotive

分析了机车驱动装置悬挂方式对轮轨在垂向动作用力的影响，介绍机车驱动装置悬挂方式主要结构和技术特点，说明了不同驱动装置悬挂方式在机车的运用。

A new controller for the semi-active suspension system with magnetorheological dampers

A new sliding mode controller for semi-active suspension system with magnetorheological (MR) damper is presented in this paper. In the proposed sliding mode controller, a semi-active suspension based on the skyhook damper system is chosen as the reference model to be followed, and the control law is so determined that the asymptotically stable error dynamics occurs between the controlled state and the reference model state. Numerical simulations are carried out to study the performance of the new sliding mode controller. The results show that the proposed controller yields almost perfect tracking to the reference model and has a high robustness against model parameter uncertainties and disturbances.

Height stability control of a large sprayer body based on air suspension using the sliding mode approach

When a high clearance self-propelled sprayer sprays,the sprung mass varies with the amount of liquid in the tank,which causes a change in the height of the sprayer body.This change not only is harmful to the sprayer ride comfort,but also has a greater impact on the sprayer application quality.In this paper,a large-scale high clearance self-propelled sprayer with air suspension was taken as the research object.Based on vehicle dynamics and air thermodynamics theory,a mathematical model of air spring inflation/deflation was established,then a 3 degree of freedom(3-dof)vertical dynamics model of sprayer air suspension was built.On this basis,the height control strategy of the sprayer body was formulated.Due to the nonlinear characteristics of air suspension,two control algorithms,namely sliding mode control and the on-off control,were used to design the suspension height stability controller,respectively.A simulation experiment was carried out by using the sprayer spraying crops as an example.The simulation experiment results showed that sliding mode control and on-off control could track and stabilize the height of the sprayer body when it changed under no excitation and D-grade road random excitation.However,due to strong nonlinearity and hysteresis of the pneumatic system,on-off control precision was poor.With the on-off control method,further reduction of the sprung mass would change the internal parameters of the pneumatic system,cause the air spring over deflation,even worse,the over deflation phenomenon presented a serious trend and cause system instability under random road excitation.Compared with on-off control method,sliding mode control approach had good control ability and precision due to its robustness to change in model parameters.The research will provide a reference for the height stability adjustment of large high clearance self-propelled sprayers during spraying and dosing operations.

Test and numerical investigations on static and dynamic characteristics of extra-wide concrete self-anchored suspension bridge under vehicle loads

The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite element simulations, the static deformations of different components, stress increments and distributions of the girder, as well as the vibration characteristics and damping ratio of the Hunan Road Bridge were analyzed, which is the widest self-anchored suspension bridge in China at present. The dynamic responses were calculated using the Newmark-β integration method assisted by the simulation models of bridge and vehicles, the influences on the dynamic impact coefficient(DIC) brought by the vehicle parameters, girder width, eccentricity travel and deck flatness were also researched. The spatial effect of the girder is obvious due to the extra width, which performs as the stress increments distribute unevenly along the transverse direction, and the girder deflections and stress increments of the upper plate change as a "V" and "M" shape respectively under the symmetrical vehicle loads affected by the shear lag effect, cross slope and local effect of the wheels, the maximum of stress increments are located in the junctions with the inner webs. The obvious girder torsional deformation and the apparent unevenness of the hanger forces between the two cable planes under the eccentric vehicle loads, together with the mode shapes such as the girder transverse bending and torsion which appear relatively earlier, all reflect the weakened torsional rigidity of the extra-wide girder. The transverse displacements of towers are more obvious than the longitudinal ones. As for the influences on the DIC, the static effect of the heavier vehicles plays a major role when pass through with a higher speed and the changes of vehicle suspension stiffness generate greater impacts than the suspension damp. The values of DIC in the vehicle-running side during the eccentric travel, affected by the restricts from the static effects of the eccentric moving trucks, are significantly smaller than the vehicle-free side, the increase in the road roughness is the most sensitive one among the above influential factors. The results could provide references for the design, static and dynamic response analysis of the similar extra-wide suspension bridges.

开口断面钢-混结合梁悬索桥颤振特性及颤振形态研究

为准确评估开口断面双边箱钢-混结合梁悬索桥颤振性能和多模态参与效应,以典型的钢-混结合梁悬索桥——怀化洞庭溪沅水特大桥为背景,开展风洞模型试验及数值分析。制作加劲梁节段缩尺模型并进行风洞试验,测试原桥梁结构的颤振性能,分析调整阻尼比、采用气动措施及结构措施对结构颤振特性的影响,采用三维和二维两种颤振分析方法分析设置中央扣结构的颤振模态及多模态参与效应。结果表明:该钢-混结合梁悬索桥存在较明显的颤振起振点,且颤振是以扭转为主的弯扭耦合振动,同时其扭转和竖向振动存在较大的相位差(相差近180°);节段模型风洞试验与三维和二维颤振分析一致得到设置中央扣后,频率较高的正对称扭转模态先于反对称模态发生颤振,且三维与二维颤振分析结果相差不大。

基于深度迁移学习的车辆悬架高频异常振动故障诊断

在车辆悬架故障诊断过程中,深度学习故障诊断模型在面对少量样本数据时模型训练效果不佳,导致诊断模型的接收者操作特性曲线(receiver operating characteristic,ROC)的曲线下面积(area under curve,AUC)较小的问题,利用经验模态分解(empirical mode decomposition,EMD)方法,对采集的车辆悬架高频振动信号进行分解处理,根据每个经验模态分量(intrinsic mode functions,IMF)的能量,提取高频异常振动故障特征,构建了基于深度迁移学习的诊断模型;以深度卷积神经网络算法为基础,对小样本特征矢量信息进行故障知识迁移处理,通过参数微调更新权值,优化故障诊断模型。实验结果表明:优化后模型的AUC值为0.89,模型故障诊断结果具有较高准确性。

基于超螺旋二阶滑膜的汽车主动悬架控制方法研究

汽车悬架的控制效果直接影响汽车的稳定性和舒适性,针对一阶滑模控制在主动悬架控制中存在的抖振和控制精度问题,基于汽车二自由度1/4主动悬架模型,提出了一种基于超螺旋二阶滑模控制的汽车主动悬架控制方法。在控制器前端串联一个负加速度反馈回路来调节悬架性能,并使用扩展的超螺旋观测器实时补偿系统的未知内部动态。为了验证控制方法的可行性,通过仿真进行对比分析。仿真结果表明,相比于一阶滑膜控制,该方法解决了悬架未知非线性动态的多目标控制问题,能更有效地改善汽车稳定性和舒适性。

基于路面激励预瞄范围切换的主动悬架滑模控制

针对不同行驶工况下悬架控制力与实际路面激励反馈的不匹配问题,提出一种切换路面激励预瞄范围的主动悬架滑模控制方法。搭建由激光雷达、惯性测量单元和GPS(Global Positioning System)组成的路面预瞄系统,采集原始路面信息并完成数据坐标转换;建立车轮运动轨迹数学模型,根据该数学模型设计了预瞄范围切换的路面激励识别方法;以理想天棚模型为参考模型,设计主动悬架滑模控制器;仿真分析了直线工况和转向工况下的悬架动态性能。仿真结果表明,直线工况下,预瞄范围切换的主动悬架与预瞄范围固定的主动悬架系统动态性能一致;转向工况下,相比于预瞄范围固定的悬架,预瞄范围切换的悬架系统在簧载质量加速度均方根值和轮胎动载荷均方根值分别降低了8.42%和8.76%,验证了所提出控制方法对悬架动态性能提升的有效性。

基于扰动观测器的主动悬架切换控制算法研究

悬架控制需要实现乘坐舒适性和操纵稳定性之间的良好折中,此外还需要考虑系统的不确定性,是一项复杂的任务。本文以兼顾悬架的动力学性能指标、算法鲁棒性与成本因素为出发点,提出了一种基于扰动观测器的次优-非奇异终端滑模切换控制算法(DOB-SNTSM)。首先,以簧载质量加速度信息为输入,通过卡尔曼滤波器设计,实现了悬架动挠度和簧载质量速度的有效估计。然后,针对悬架系统中的不确定项估计,设计了一种扰动观测器,并将扰动估计值作为前馈补偿。接下来,以滑模面函数为依据,提出了一种次优-非奇异终端滑模切换控制算法,并与扰动观测器的前馈补偿相结合,共同构成一种新的主动悬架控制策略。最后,分别进行了凸包路面和平稳随机路面下的仿真和台架试验验证,结果表明,扰动观测器的引入能显著提升悬架的乘坐舒适性指标,相比经典的天棚控制、理想状态LQR方法、不带有扰动观测器的SNTSM算法,新算法不仅很好地实现各项悬架性能指标的均衡,而且能够仅利用簧载质量加速度信息就可以达到接近理想状态LQR的控制效果,同时,控制器切换方案可以显著提升算法鲁棒性。

车辆主动空气悬架控制系统开发与研究

以主动空气悬架为研究对象,建立1/4动力学模型。针对悬架系统非线性特性强、易受外界干扰等缺点,选用模糊滑模控制算法对主动悬架控制系统进行设计与开发。使用Simulink软件建立悬架控制系统模型,并设计控制系统硬件。通过硬件在环仿真验证所设计的控制算法的有效性,结果表明:所设计主动悬架控制系统相较于被动悬架在车身加速度、悬架动挠度和轮胎动位移性能上分别提高了24.52%、29.40%和9.72%,有效地提高车辆行驶的操纵稳定性,同时也改善整车乘坐的舒适性。

清江某特大桥隧道锚承载特性数值模拟研究

以清江某特大桥左岸隧道锚为例,在工程地质分析的基础上建立三维地质概化模型,利用不同软件实现对复杂岩体和隧道锚结构的近似网格化离散划分。采用FLAC^(3D)软件进行不同工况模拟,获得隧道锚的变形特征和承载能力,明确该隧道锚的潜在破坏模式为锚碇连同锚碇上部受结构面切割的岩体,在主缆拉力作用下发生沿锚碇底部岩/混凝土胶结面的整体滑移。该文采用的研究思路及相关研究成果,一方面能够为清江某特大桥隧道锚工程实践提供技术支撑,同时还有助于构建系统的隧道锚分析研究方法和评价指标体系,对后续隧道锚工程建设具有较强借鉴意义。

基于模态驱动分析方法的桥梁颤振模态影响机理

通过定量描述各阶模态及其分布特性在颤振演化过程中的影响,研究了多阶模态耦合导致的桥梁颤振三维效应。首先,根据系统模态中固有模态间的激励-反馈机制推导出能够反应各阶模态参与贡献的系统阻尼和刚度解析解,建立了适用于三维颤振机理分析的模态驱动分析方法。其次,对桥梁整体系统阻尼沿着跨向进行泰勒展开,建立了跨向节段与气动性能间的定量关系,使得该方法能够量化各阶模态跨向分布特性的影响。然后,以主跨径为500~1500m的悬索桥为例,系统地研究了模态的参与及其分布特性对颤振性能的影响。最后,通过比对二维和三维分析结果,揭示了三维效应的影响及其产生原因。研究结果表明:由于基础竖弯和扭转振型不可能完全相似,三维两模态结果必然大于二维分析结果;随着风速提升二阶正对称竖弯模态先提供负向阻尼后提供正向阻尼,其对颤振性能的影响取决于自身频率与系统颤振频率的比值;约70%的梁段贡献了绝大多数的气动阻尼。

基于模式切换的互联空气悬架性能研究

为进一步提高互联空气悬架性能,设计了一种互联模式切换策略,该策略首先建立互联空气悬架整车动力学模型;然后基于平顺性和操稳性性能指标函数设计综合评价指标,利用不同连通模式下综合指标的变化规律,设计互联模式切换控制策略;最后进行数值仿真,仿真结果表明,该控制策略可明显地改善互联空气悬架性能,提高乘车舒适性。

基于多工况模式的复合型悬架平顺性研究

悬架系统作为调控车辆平顺性的核心组件,其性能直接决定了车辆行驶的优劣。针对目前车辆在复杂路面行驶过程中平顺性较差的问题,本文构建了不同于传统悬架的复合型悬架结构,并搭建该悬架的整体系统构架。首先为了探究整车复合型悬架的振动机理,构建整车复合型悬架动力学模型;其次结合驾驶员复杂的行驶需求,构建基于多工况的复合悬架系统控制策略,通过车辆行驶中不同的加权加速度均方根值验证其优化效果,并结合反空气弹簧模型证明了该系统可以减少空气弹簧的磨损;最后,在VI-Grade紧凑型驾驶模拟器中根据所构建的复杂工况进行试验验证,对比有无控制时的车身垂向加速度、侧倾角加速度和俯仰角加速度试验结果。试验结果表明,通过复杂工况中的车辆性能测试,所提出的复合型悬架系统在直线、弯道和制动3种工况下改善性能分别达到了32.26%、23.77%和7.38%,可以有效改善车辆行驶时的平顺性性能,解决了正常行驶下空气弹簧的损耗问题。