含分数阶Bingham模型的阻尼减振系统时滞半主动控制

针对基于磁流变液阻尼器的半主动控制系统中存在的时滞问题, 采用了一种将可控的时滞变量引入半主动控制切换条件的控制策略, 研究了考虑时滞的天棚阻尼控制切换条件对半主动阻尼减振系统的影响, 分析了含有分数阶Bingham模型的线性刚度系统在基础激励下的振动特性. 利用平均法得到了系统在含时滞半主动控制策略下主共振响应的近似解析解, 根据Lyapunov理论分析了系统的稳定性. 通过数值解验证了近似解析解的准确性, 二者具有较好的一致性. 利用近似解析解分析了固定激励频率下时滞对系统幅频响应特性的影响, 以及主共振峰值响应和共振频率随时滞变化的特性规律. 结果表明, 含时滞的半主动控制系统存在一个小时滞区间, 使得系统的振幅在主共振峰对应的频率附近低于不考虑时滞时系统的振幅, 且存在最优时滞使得系统的振幅大幅度降低; 而大时滞的引入会加剧系统的振动, 导致系统的颤振. 确定了基于分数阶Bingham模型的线性刚度系统在天棚阻尼半主动控制下的时滞选取原则, 为振动系统半主动阻尼控制中的时滞选取提供了参考.      

磁流变阻尼器半主动控制方法的实验研究

由于磁流变阻尼器是一种高度非线性的装置,因此建立与之相适应的控制系统是半主动控制问题的关键。本文采用改进的Bingham模型建立了磁流变阻尼器的动力学特性模型,根据天棚阻尼开关控制、天棚阻尼连续控制和模糊控制三种控制方法,确立了从系统速度响应到磁流变阻尼器励磁电流之间的关系,并开发了一套半主动控制系统。在一个两自由度的简化车辆试验平台上进行半主动控制试验,对比研究了三种控制方法的控制效果。实验结果表明,在1.3Hz~2.0Hz的低频段内,开关控制的最佳减振效果为15.1%,连续控制的最佳减振效果为14.9%,模糊控制的最佳减振效果为20.1%。可见,三种控制方法都能有效的减小车体的振动,模糊控制的减振效果最佳。     

一类阻尼控制半主动隔振系统的解析研究

研究了一类基于相对速度反馈的含立方刚度的单自由度非线性半主动隔振系统.通过平均法得到了系统分别在基于加速度-相对速度反馈的加速度驱动阻尼控制策略、速度-相对速度反馈的天棚阻尼控制策略和位移-相对速度反馈的地棚阻尼控制策略下主共振响应的近似解析解,并利用数值解验证了近似解析解的准确性.通过 Lyapunov 理论对不同控制策略下系统的稳定性进行了分析,讨论了系统参数对控制效果的影响.分析结果表明,对 3 种基于相对速度反馈的控制策略进行解析研究时,切换条件中的控制参数具有相同的表达式;在抑制共振响应振幅方面,基于速度-相对速度反馈的天棚阻尼控制策略在低频时的减振效果最好,而基于加速度-相对速度反馈的加速度驱动阻尼控制策略在高频时的减振效果最优;在抑制瞬态响应振幅方面,基于速度-相对速度反馈的天棚阻尼控制策略的减振效果最好.此类解析研究方法可应用到其他半主动开关控制策略中,为半主动隔振系统的控制策略研究提供了有效的方法和手段.      

DYNAMICAL ANALYSIS ON A KIND OF SEMI-ACTIVE VIBRATION ISOLATION SYSTEMS WITH DAMPING CONTROL 1)

研究了一类基于相对速度反馈的含立方刚度的单自由度非线性半主动隔振系统.通过平均法得到了系统分别在基于加速度-相对速度反馈的加速度驱动阻尼控制策略、速度-相对速度反馈的天棚阻尼控制策略和位移-相对速度反馈的地棚阻尼控制策略下主共振响应的近似解析解,并利用数值解验证了近似解析解的准确性.通过 Lyapunov 理论对不同控制策略下系统的稳定性进行了分析,讨论了系统参数对控制效果的影响.分析结果表明,对 3 种基于相对速度反馈的控制策略进行解析研究时,切换条件中的控制参数具有相同的表达式;在抑制共振响应振幅方面,基于速度-相对速度反馈的天棚阻尼控制策略在低频时的减振效果最好,而基于加速度-相对速度反馈的加速度驱动阻尼控制策略在高频时的减振效果最优;在抑制瞬态响应振幅方面,基于速度-相对速度反馈的天棚阻尼控制策略的减振效果最好.此类解析研究方法可应用到其他半主动开关控制策略中,为半主动隔振系统的控制策略研究提供了有效的方法和手段.     

DYNAMICAL ANALYSIS ON A KIND OF SEMI-ACTIVE SUSPENSION WITH TIME DELAY

对一类采用有限相对位移控制的含时滞单自由度半主动悬架系统进行了动力学分析.首先通过平均法得到了该系统的一阶近似解, 然后基于Lyapunov理论建立了系统的稳定性条件, 结果表明近似解的稳态幅值和稳定性条件都是时滞量的周期函数, 并且和外激励具有相同周期.通过对数值解和解析解的幅频曲线进行比较, 验证了一阶近似解析解的准确性, 并且解释了半主动控制中的高频颤振现象.研究了被动悬架系统并且和半主动悬架系统进行了比较, 证实了半主动悬架系统的优越性.最后, 探讨了一些关键的系统参数, 如控制间隙、时滞量、最小阻尼比等对半主动悬架系统稳态幅值的影响.     

结构振动的滑模变结构半主动控制

研究应用磁流变阻尼器(MRD)对结构振动半主动控制的算法和原理。研制并对磁流变阻尼器进行了阻尼特性实验，采用非线性滞回双粘性模型描述磁流变阻尼器的阻尼特性，模型结果与实验结果非常一致。采用滑模控制算法和趋近律方法设计了半主动控制器。利用滑模控制方法所建立的控制器，本文给出了地震激励下结构振动半主动控制算例。计算分析表明，半主动滑模控制具有控制效果明显、鲁棒性好等优点，是一种非常有发展前途的控制方法。     

高速列车磁流变半主动悬挂控制策略研究

为了提高列车运行平稳性,在经典的天棚控制和加速度控制的基础上,提出了一种新型混合控制策略,对高速列车磁流变半主动悬挂控制系统进行了仿真和实验研究.首先,对磁流变阻尼器(MRD)的力学特性测试分析,引入具有电流饱和特性的修正函数,建立了MRD的修正扩展双曲正切模型.然后,设计了面向列车平稳性的新型混合控制策略,通过分析车体加速度传递特性,比较了不同控制策略在全频域内的控制效果.此外,从相频特性的角度阐释了新型混合控制策略在全频段的控制优势.将MRD修正模型应用于悬挂控制,利用UM和Simulink软件建立了整车磁流变半主动悬挂控制系统联合仿真模型,分析不同控制策略对车辆动力学性能的影响.最后,构建了基于MRD的整车悬挂系统硬件在环实验台,通过开展硬件在环实验分析不同控制策略下的车体响应.结果表明,相比传统的控制策略,新型混合控制策略能兼顾低频段和高频段的振动控制效果,不仅可以提高列车的运行平稳性,而且不会恶化列车的运行安全性.硬件在环实验证明了新型混合控制策略的有效性,以及高速列车应用半主动控制悬挂的可行性.     

随机激励下汽车悬架磁流变阻尼半主动控制研究

本文研究了在被动控制、半主动线性控制、半主动磁流变非线性控制三种控制策略情况下，采用磁流变阻尼的1／4车体模型的运行效果，所采用的路面激励为对正弦的摄动激励和随机激励。研究结果表明磁流变阻尼应用于车辆半主动控制后具有很好的效果，证实了磁流变阻尼在汽车控制中的可行性及优越性。     

时滞对结构振动半主动控制效果的影响

应用磁流变阻尼器对结构振动进行控制，采用最优控制原理设计了控制器，给出在地震激励下结构半主动控制的仿真计算。研究了时滞对结构振动半主动控制效果的影响。数值结果表明：本文设计的半主动控制策略可有效地减小结构的振动响应，时滞对磁流变半主动控制效果随着时滞的增大而变差，但时滞不会导致该反馈控制系统的失稳。     

可调磁流变阻尼在汽车悬架的半主动控制中的应用

本文研究了采秀磁流变阻尼的汽车半主动控制悬架在确定性激励和随机激励下的运行效果,分析了可调磁流变阻尼半主动控制的控制规律及响应情况,并与采用传统阻尼的汽车被动悬架和主动悬架进行了对比,证实了磁流变阻尼应用于汽车半主动控制的可行性及优越性。     

Semi-active hydro-gas suspension system for a tracked vehicle

A semi-active hydro-gas suspension is proposed for a tracked vehicle to improve ride comfort performance, without compromising the road holding and load carrying capabilities of the passive suspension. This is achieved through an active damper used in parallel with a gas spring. The suspension damper parameters are varied by a control mechanism based on sky-hook damping theory, which alters the flow characteristics. A damper prototype has been developed, tested for its flow characteristics, after which it has been integrated into an existing hydro-gas suspension system. An analytical model has been proposed from first principles rather than developing a phenomenological model based on experimental characteristics. This model is validated with experiments carried out on a suspension test rig. In order to compare the performance with the original passive system, an in-plane vehicle model is developed and the simulations clearly show that the semi-active system performance is superior to the passive system.     

The ride comfort vs. handling compromise for off-road vehicles

When designing vehicle suspension systems, it is well-known that spring and damper characteristics required for good handling on a vehicle are not the same as those required for good ride comfort. Any choice of spring and damper characteristic is therefore necessarily a compromise between ride comfort and handling. The compromise is more pronounced on off-road vehicles, as they require good ride comfort over rough off-road terrain, as well as acceptable on-road handling. In this paper, the ride comfort vs. handling compromise for off-road vehicles is investigated by means of three case studies. All three case studies indicate that the spring and damper charcteristics required for ride comfort and handling lie on opposite extremes of the design space. Design criteria for a semi-active suspension system, that could significantly reduce, or even eliminate the ride comfort vs. handling compromise, are proposed. The system should be capable of switching safely and predictably between a stiff spring and high damping mode (for handling) as well as a soft spring and low damping mode (for ride comfort). A possible solution to the compromise, in the form of a four state, semi-active hydropneumatic spring-damper system, is proposed.     

An analytical approach to optimally design of electrorheological fluid damper for vehicle suspension system

This work develops an analytical approach to optimally design electrorheological (ER) dampers, especially for vehicle suspension system. The optimal design considers both stability and ride comfort of vehicle application. After describing the schematic configuration and operating principle of the ER damper, a quasi-static model is derived on the basis of Bingham rheological laws of ER fluid. Based on the quasi-static model, the optimization problem for the ER damper is built. The optimization problem is to find optimal value of significant geometric dimensions of the ER damper, such as the ER duct length, ER duct radius, ER duct gap and the piston shaft radius, that maximize damping force of the ER damper. The two constrained conditions for the optimization problem are: the damping ratio of the damper in the absence of the electric field is small enough for ride comfort and the buckling condition of the piston shaft is satisfied. From the proposed optimal design, the optimal solution of the ER damper constrained in a specific volume is obtained. In order to evaluate performance of the optimized ER damper, simulation result of a quarter-car suspension system installed with the optimized ER damper is presented and compared with that of the non-optimized ER damper suspension system. Finally, the optimal results of the ER damper constrained in different volumes are obtained and presented in order to figure out the effect of constrained volume on the optimal design of ER damper.     

Semi-active hydropneumatic spring and damper system

This paper is concerned with the development of a semi-active hydropneumatic spring and damper system, comprising of a two state hydropneumatic spring and a two state hydraulic damper. The system was specifically developed to improve the ride comfort and handling of large off-road vehicles. The suspension requirements for good ride comfort and handling for heavy off-road vehicles are discussed with special reference to the advantages of semi-active hydropneumatic springs and semi-active dampers. The layout and functioning of an experimental spring and damper unit used for laboratory tests are discussed. Spring and damper characteristics, as well as valve response times for both the semi-active spring and semi-active damper were determined. A single degree of freedom test rig with a sprung mass of 3 tons was used to perform first order ride comfort tests. Tests include step response and random input response. The test rig was also used to evaluate semi-active control strategies for both spring and damper as well as a control strategy for implementing ride height adjustment without using an external hydraulic pump.     

Performance evaluation of electronic control suspension featuring vehicle ER dampers

This paper presents ride comfort and driving stability performances of electronic control suspension (ECS) equipped with controllable electrorheological (ER) damper and appropriate control strategy. In order to achieve this goal, a cylindrical type ER damper which is applicable to Macpherson strut type suspension of a mid-sized passenger vehicle is designed and manufactured on the basis of the required damping force level of an existing passenger vehicle. After experimentally evaluating the field-dependent damping force and dynamic characteristics of the controllable ER damper, ECS consisting of sprung mass, spring, tire and controller is established in order to investigate the ride comfort and driving stability performances. On the basis of the governing equation of motion of the suspension system, five control strategies (soft, hard, comfort, sports and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle ECS system. Control performances such as vertical acceleration of the car body and tire deflection are evaluated in both time and frequency domains under various road conditions. In addition, a comparative work is undertaken to investigate inherent control characteristics of each control strategy.