Magneto-rheological suspensions for improving ground vehicle’s ride comfort,stability, and handling

ABSTRACT

A state-of-the-art discussion on the applications of magneto-rheological (MR) suspensions for improving ride comfort, handling, and stability in ground vehicles is discussed for both road and rail applications. A historical perspective on the discovery and engineering development of MR fluids is presented, followed by some of the common methods for modelling their non-Newtonian behaviour. The common modes of the MR fluids are discussed, along with the application of the fluid in valve mode for ground vehicles’ dampers (or shock absorbers). The applications span across nearly all road vehicles, including automobiles, trains, semi-trucks, motorcycles, and even bicycles. For each type of vehicle, the results of some of the past studies is presented briefly, with reference to the originating study. It is discussed that Past experimental and modelling studies have indicated that MR suspensions provide clear advantages for ground vehicles that far surpasses the performance of passive suspension. For rail vehicles, the primary advantage is in terms of increasing the speed at which the onset of hunting occurs, whereas for road vehicles – mainly automobiles – the performance improvements are in terms of a better balance between vehicle ride, handling, and stability. To further elaborate on this point, a single-suspension model is used to develop an index-based approach for studying the compromise that is offered by vehicle suspensions, using the H₂ optimisation approach. Evaluating three indices based on the sprung-mass acceleration, suspension rattlespace, and tyre deflection, it is clearly demonstrated that MR suspensions significantly improve road vehicle’s ride comfort, stability, and handling in comparison with passive suspensions. For rail vehicles, the simulation results indicate that using MR suspensions with an on-off switching control can increase the speed at which the on-set of hunting occurs by as much as 50% to more than 300%.     

半主动浮筏隔振系统的模糊PID控制

对带有电流变液智能阻尼器的半主动双层浮筏隔振系统设计了一种模糊PID控制器.将半主动浮筏隔振系统中间质量的位移及其导数作为模糊控制器的输入,PID控制器的三个增益参数作为其输出,利用电流变液智能阻尼器的阻尼力可随电压变化的特性来降低中间质量的振动.仿真分析了多种激励下浮筏隔振系统的输出力响应.仿真结果表明:与最优被动阻尼和电流变液阻尼器最大阻尼系统相比,模糊PID控制下的半主动浮筏隔振系统的减振效果最好.     

基于磁流变弹性体的船舶轴系纵振动力吸振器的实验研究

磁流变弹性体是一种新型的智能材料,由微米级的羰基铁粉和聚合物合成.由于它具有弹性模量可调、无需封装、稳定性好、响应快等优点,已被广泛应用于机械振动控制等领域.文中针对船舶推进轴系纵振动力学特性,提出一种固有频率可调的磁流变弹性体动力吸振器用于轴系纵振控制.首先理论分析了安装动力吸振器的推进轴系的动力学模型,其次对动力吸振器进行了移频特性试验,并在1:4的船舶轴系缩比模型上进行了变转速工况下吸振效果试验.实验结果表明,该吸振器具有12.3 Hz的移频范围,并且在不同轴系工作转速下相比于被动式吸振器均有更好的吸振效果.     

简支箱梁桥地震反应半主动控制分析

为提高某简支梁桥的抗震能力,采取适当的减震控制措施能够有效地减小桥梁的地震反应。建立了某简支箱梁桥的有限元模型,将板式橡胶支座与磁流变阻尼器组合使用,在桥梁的支座和伸缩缝处共设置8组磁流变阻尼器,分析了不同地震动输入下的简支箱梁桥主动控制、半主动控制和被动控制的减震效果。结果表明,半主动控制对简支梁桥的减震效果非常显著,并且能够很好地接近主动控制的减震效果。半主动控制对于桥梁整体地震反应的减震效果优于始终提供最大阻尼力的被动控制。这为半主动控制阻尼器在简支梁桥抗震中的实际应用提供了理论上的指导。     

行波效应对大跨斜拉桥减震控制的影响

为了研究行波效应对斜拉桥减震控制地震反应的影响,推导了多点地震动输入下的大跨桥梁减震控制计算方法,以一座大跨飘浮体系斜拉桥为实例,在桥塔和桥墩处设置阻尼器,建立其三维有限元模型,分析了行波输入下半主动控制和被动控制对斜拉桥的减震效果。计算结果表明:半主动控制比较缓和地控制桥梁的地震反应,而被动控制则急剧地控制桥梁的地震反应,因此,要慎用被动控制;行波效应对无控制、半主动控制和被动控制斜拉桥的桥塔均具有很小的不利影响,仅使桥塔内力增大约10%,对主梁均具有显著不利影响,使主梁内力增大近8倍;行波效应对半主动控制和被动控制减震效果的不利影响很小,没有出现明显的控制效果变差的现象。     

半主动悬挂的横向和垂向阻尼系数对车辆动力学性能的影响

利用天棚控制原理和SIMPACK动力学软件建立了具有二系横向和垂向半主动悬挂车辆模型,分析在不同的半主动悬挂横向和垂向阻尼系数下,车体平稳性指标、构架加速度、轮对冲角和磨耗指数的变化情况,结果表明动力学性能之间存在多处相互矛盾的地方,在选择半主动悬挂横向和垂向阻尼系数时应合理安排,充分协调相互矛盾的动力学性能.     

Actively controlled vehicle suspension with energy regeneration capabilities

The paper presents an innovative dual purpose automotive suspension topology, combining for the first time the active damping qualities with mechanical vibrations power regeneration capabilities. The new configuration consists of a linear generator as an actuator, a power processing stage based on a gyrator operating under sliding mode control and dynamics controllers. The researched design is simple and energetically efficient, enables an accurate force–velocity suspension characteristic control as well as energy regeneration control, with no practical implementation constraints imposed over the theoretical design. Active damping is based on Skyhook suspension control scheme, which enables overcoming the passive damping tradeoff between high- and low-frequency performance, improving both body isolation and the tire's road grip. The system-level design includes configuration of three system operation modes: passive, semi–active or fully active damping, all using the same electro-mechanical infrastructure, and each focusing on different objective: dynamics improvement or power regeneration. Conclusively, the innovative hybrid suspension is theoretically researched, practically designed and analysed, and proven to be feasible as well as profitable in the aspects of power regeneration, vehicle dynamics improvement and human health risks reduction.     

高速客车垂向悬挂稳定控制双振子模型机理研究

以Adams与Matlab作为协同仿真平台，基于双振子模型LQG控制器设计，建立了稳定控制方案和技术路线．仿真结果表明：垂向悬挂具有与双振子类似的隔振效果．尽管有横向和纵向相关运动模态的非线性影响，转向架仍可以实行有源／无源控制．仿真研究可以证实，无源控制转向架的系统机制是通过阻尼控制强制(垂向)主导运动模态处于稳定状态．     

开关式横向半主动悬挂系统的研制

开关式半主动悬挂系统可以提高高速列车的运行平稳性。文章介绍了开关式横向半主动悬挂系统的研制过程。样机台架试验结果表明,开关式横向半主动悬挂系统可以根据控制指令有效地维持和断开减振器所提供的阻尼力,从而提高旅客的横向乘坐舒适性。     

半主动悬架系统对汽车侧翻稳定性的改善

为提高汽车高速弯道行驶、紧急变线行驶时的安全性,针对被动悬架系统侧翻稳定性比较差的问题,建立了半主动悬架系统模型和控制系统模型。通过控制器调整减振器阻尼力的大小,改变车身侧倾振动状态。模拟分析得到半主动悬架系统使得汽车在高速变线行驶时的侧倾角有效值下降了60．9％,侧倾角加速度有效值下降了64．6％,侧翻因子有效值下降了35．2％。结果表明利用半主动悬架系统可以有效降低汽车非直线行驶时的侧倾角与侧倾角加速度,提高了汽车的侧翻稳定性。