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

The vehicle semi-active suspension with magneto-rheological 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.     

馈能磁流变半主动悬架模糊滑模控制

为优化悬架减振性能和馈能性能,提出了一种馈能磁流变减振器结构,并设计了相应的半主动悬架模糊滑模控制策略。建立了磁流变减振器力学模型和馈能模型,以及相应的二自由度半主动悬架系统数学模型。针对半主动悬架系统的不确定性,基于混合天地棚阻尼控制系统,设计了滑模变结构控制器。使用饱和函数缓解系统抖振,并运用模糊控制优化滑模控制器。用谐波叠加法生成路面激励输入,分别对被动悬架、基于混合天地棚阻尼控制的半主动悬架以及基于模糊滑模控制的半主动悬架进行对比仿真。结果表明：基于模糊滑模控制的半主动悬架减振性能更好,能耗更小,且有良好的馈能性能,验证了馈能磁流变减振器结构的可行性和模糊滑模控制策略的有效性。     

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。     

一种馈能型混合悬架的多模式协调控制

为了有效控制车辆悬架振动及回收振动能量,提出了一种基于滚珠丝杠式作动器和磁流变减振器的车辆馈能型混合悬架结构。建立了1/4车辆2自由度混合悬架动力学模型,分析了混合悬架的主动控制模式和具有电磁阻尼力反馈调节的半主动控制模式,设计了混合悬架多模式协调控制器,并利用MATLAB/Simulink软件对混合悬架多模式协调控制的动态性能、悬架系统的自供能进行了仿真分析,开展了混合悬架台架试验研究。仿真和试验结果表明：与被动悬架相比,随机路面谱输入条件下混合悬架的簧载质量加速度均方根减小了30%以上,混合悬架减振效果显著。     

半主动空气悬架的非线性特性及控制算法研究

在分析空气弹簧刚度特性的基础上,建立了阻尼可调半主动空气悬架1/4车模型.针对系统的非线性特性强的特点,同时兼顾平顺性和操纵稳定性,选取理想的混合天地棚控制器作为参考跟踪模型,设计滑模变结构控制器,以弥补传统控制理论处理非线性问题时的不足.运用广义误差方程控制滑动模态,确定切换面参数,选择趋近律削减抖振现象并推导出实时...     

GENERATION OF ASYMMETRIC F-v CHARACTERISTICS FOR SYMMETRIC MR DAMPERS

An asymmetric damping force generation algorithm is originally proposed to yield the asymmetric force-velocity characteristics for the symmetric magneto-rheological (MR) dampers. The command current is formulated in an asymmetric manner to excite the symmetric MR dampers by employing the "on-off" control law in response to the direction of velocity, and a smooth modulation function is developed without phase shift to suppress strong transients in the damping forces caused by the current-switching discontinuity. The effectiveness of the proposed algorithm is evaluated by analyzing the dynamic responses of a quarter-vehicle suspension system with a symmetric MR-damper by modulating the command current into the asymmetric manner. The simulation results show that the proposed algorithm could achieve a better compromise between the conflicting requirements of the asymmetric damping force ratio and the force-velocity curve smoothness, and the asymmetric damping MR-suspension design can ideally improve the road holding and ride performances of vehicle motion. The proposed algorithm can be generally incorporated with a controller synthesis to realize an intelligent vehicle suspension design with the symmetric MR dampers.     

两类数据的转角自由度模态综合法及应用

提出一种利用实验测试的位移自由度数据估算所需要的转角自由度数据,并以此对实验数据模型和有限元模型进行模态综合的方法。通过对一段空调配管的例子说明文中方法在MSC．NATRAN中的应用。模态综合结果显示转角自由度的应用使模态综合的频率误差和模态振型的MAC值均有显著提高。     

Design of damping valve for vehicle hydro pneumatic suspension

According to the design features of a hydro pneumatic spring, the necessity of a separate damping valve is proposed. Based on a 1/4 vehicle linear suspension model, the optimum damping coefficient is worked out and the parameters of the damping valve are determined with the equivalent linearization method. A practical structure of the damping valve is proposed having a small size, high flowrate when the valve opens, and the ability of enduring high back pressure. Based on bench tests, the damping valve has been found to properly work and be suitable. The design method and damping valve structure are useful guides for hydro pneumatic suspension, especially for the design of heavy-duty vehicles.     

Performance evaluation of a quarter-vehicle MR suspension system with different tire pressure

This paper evaluates performance of a quarter-vehicle magneto-rheological (MR) suspension system with respect to different tire pressure. In order to achieve this goal, controllable MR damper that satisfies design specifications for a midsized commercial passenger vehicle is designed and manufactured based on the optimized damping force levels and mechanical dimensions. After experimentally evaluating the field-dependent characteristics of the manufactured MR damper, the quarter-vehicle suspension system consisting of sprung mass, spring, tire and the MR damper is constructed in order to investigate the ride comfort. After deriving the equations of the motion for the proposed quarter-vehicle MR suspension system, vertical tire stiffness with respect to different tire pressure is experimentally identified. The skyhook controller is then implemented for the realization of quarter-vehicle MR suspension system. Ride comfort characteristics such as vertical acceleration RMS (root mean square) and WRMS (weighted RMS) of sprung mass are evaluated under bump and random road conditions using a quarter-vehicle test facility.     

某越野汽车磁流变半主动悬架变论域模糊控制

为了解决半主动悬架传统变论域模糊控制器过度依赖经验规则的问题,提出了一种基于模糊神经网络的变论域T-S模糊控制策略。首先,根据磁流变减振器阻尼特性的实验结果,建立基于自适应模糊神经网络的减振器阻尼力模型及1/2车辆半主动悬架动力学模型;其次,建立悬架系统T-S模糊控制器,同时为了实时调节T-S模糊控制器变量的论域,采用模糊神经网络结构描述伸缩因子的变化。仿真结果表明,笔者提出的变论域模糊控制策略能够有效提高车辆行驶平顺性和操作稳定性。     

Damping collaborative optimization of five-suspensions for driver-seat-cab coupled system

Both the seat and cab system of truck play a vital role in ride comfort. The damping matching methods of the two systems are studied separately at present. However, the driver, seat, and cab system are one inseparable whole. In order to further improve ride comfort, the seat suspension is regarded as the fifth suspension of the cab, a new idea of“Five-suspensions”is proposed. Based on this idea, a 4 degree-of-freedom driver-seat-cab coupled system model is presented. Using the tested cab suspensions excitations as inputs and seat acceleration response as compared output, the simulation model is built. Taking optimal ride comfort as target, a new method of damping collaborative optimization for Five-suspensions is proposed. With a practical example of seat and cab system, the damping parameters are optimized and validated by simulation and bench test. The results show the seat vertical frequency-weighted RMS acceleration values tested for the un-optimized and optimized Five-suspensions are 0.50 m/s2 and 0.39 m/s2, respectively, with a decrease by 22.0%, which proves the model and method proposed are correct and reliable. The idea of “Five-suspensions” and the method proposed provide a reference for achieving global optimal damping matching of seat suspension and cab suspensions.     

MR阻尼器控制与滞环特性相分离的F-v模型

提出了一种基于对称和不对称Sigmoid函数,描述半主动可控磁流变液(MR)阻尼器阻尼力—相对速度(F-v)数学模型。该模型准确地描述了MR阻尼器非线性饱和的直流电流控制和对称滞环F-v的工作特性,以及激励频率和幅度对阻尼力的强影响特性,具有精度高和电流控制增益与滞环算子相分离的特点。将该模型与车辆悬架动力学模型结合分析,仿真结果表明MR阻尼器对实现新一代智能车辆悬架系统设计有潜在的意义,所提出的模型对进一步推动车辆悬架减振控制器设计研究有重要作用。     

SEMI-ACTIVE CONTROL OF VEHICLE SUSPENSION WITH MAGNETO-RHEOLOGICAL DAMPERS PART Ⅱ——EVALUATION OF SUSPENSION PERFORMANCE

The design and analysis of an intelligent vehicle suspension with MR dampers should address hybrid semi-active control goals, such as rejection of current-switching discontinuity and MR-damper hysteresis, asymmetric damping from the symmetric MR-damper design, robustness on the vehicle operation parameter uncertainties and consideration of essential multiple suspension goals. Following the proposed skyhook-based asymmetric semi-active controller (Part Ⅰ) for achieving the above goals, herein, a set of suspension performance measures and three kinds of varying amplitude harmonic, rounded pulse and really measured random excitations are systematically defined, and the sensitivity of quarter-vehicle MR-suspension performance to variations in operating conditions is thoroughly analyzed. The results illustrate that the proposed skyhook-based semi-active MR-suspension in the asymmetric mode yields relatively superior dynamic responses to meet the multiple suspension performances of ride, rattle space, road-holding and dynamic tire force transmitted to the pavement, and has desirable robustness on variations in operating conditions of vehicle load and speed and the road roughness.     

Design of damping valve for vehicle hydro pneumatic suspension

According to the design features of a hydro pneumatic spring, the necessity of a separate damping valve is proposed. Based on a 1/4 vehicle linear suspension model, the optimum damping coefficient is worked out and the parameters of the damping valve are determined with the equivalent linearization method. A practical structure of the damping valve is proposed having a small size, high flowrate when the valve opens, and the ability of enduring high back pressure. Based on bench tests, the damping valve has been found to properly work and be suitable. The design method and damping valve structure are useful guides for hydro pneumatic suspension, especially for the design of heavy-duty vehicles. __________ Translated from Transactions of Beijing Institute of Technology, 2006, 26(4): 301–304 [译自: 北京理工大学学报]     

HYBRID FUZZY CONTROL FOR ELECTRO-HYDRAULIC ACTIVE DAMPING SUSPENSION

A new control scheme, the hybrid fuzzy control method, for active damping suspension system is presented. The scheme is the result of effective combination of the statistical optimal control method based on the statistical property of suspension system, with the bang-bang control method based on the real-time characteristics of suspension system. Computer simulations are performed to compare the effectiveness of hybrid fuzzy control scheme with that of optimal damping control, bang-bang control, and passive suspension. It takes the effects of time-variant factors into full account. The superiority of the proposed hybrid fuzzy control scheme for active damping suspension to the passive suspension is verified in the experiment study.     

Comparative study of damped FE model updating methods

Most of finite element (FE) model updating techniques do not employ damping matrices and hence, cannot be used for accurate prediction of complex frequency response functions (FRFs) and complex mode shapes. In this paper, a detailed comparison of two approaches of obtaining damped FE model updating methods are evaluated with the objective that the FRFs obtained from damped updated FE models is able to predict the measured FRFs accurately. In the first method, damped updating FE model is obtained by complex parameter-based updating procedure, which is a single-step procedure. In the second method, damped updated model is obtained by the FE model updating with damping identification, which is a two-step procedure. In the first step, mass and stiffness matrices are updated and in the second step, damping matrix is identified using updated mass and stiffness matrices, which are obtained in the previous step. The effectiveness of both methods is evaluated by numerical examples as well as by actual experimental data. Firstly, a study is performed using a numerical simulation based on fixed–fixed beam structure with non-proportional viscous damping model. The numerical study is followed by a case involving actual measured data for the case of F-shaped test structure. The updated results have shown that the complex parameter-based FE model updating procedure gives better matching of complex FRFs with the experimental data.     

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     

基于流动模式的汽车双筒式磁流变减振器设计与试验研究

提出一种基于流动模式的汽车单出杆、双筒式磁流变减振器的结构与工作原理,该减振器采用已有汽车悬架双筒式普通液压减振器的设计标准制造,对现有双筒式减振器具有很强工艺继承性。根据Bingham流体模型建立双筒式磁流变减振器阻尼力数学模型,并提出该减振器的磁路设计方法;针对磁路的非轴对称特性,建立磁路三维有限元仿真模型,结合北京现代某款汽车前悬架减振器的技术要求和磁流变液流变特性,进行三维静态磁场分析,确定活塞磁路的主要参数。制作汽车双筒式磁流变减振器,并对此进行台架特性试验;通过试验与理论计算对比,结果表明理论计算数据与试验数据较吻合,所提出的双筒式磁流变减振器设计方法是可行的,对汽车双筒式磁流变减振器的设计使用具有指导意义。     

馈能式磁流变半主动悬架协调控制研究

为了优化车辆悬架的减振控制及振动能量回收,提出了一种基于协调控制的馈能式磁流变半主动悬架。建立了1/4车二自由度悬架力学模型、磁流变减振器数学模型和馈能模型,利用MATLAB/Simulink软件对馈能特性进行了仿真分析,并进行了参数敏感性分析。分析了减振器实现自供能的条件及结构参数的影响,设计并分析了多模式协调控制下的悬架动力学特性和馈能特性。结果表明,该减振器馈能结构参数对自供能影响较大;协调控制器能够有效协调悬架系统减振与馈能关系,降低能耗,阻尼力可控性好,能够衰减车辆振动,馈能特性效果良好,验证了该结构的可行性。     

单自由度车辆悬挂系统非线性振动特性研究

对非线性弹簧与阻尼共同作用下的单自由度车辆悬挂系统进行振动特性研究.在研究中,建立单自由度非线性系统动力学模型,利用Melnikov方法分析悬挂系统发生混沌的临界条件,求出悬挂系统发生斯梅尔马蹄意义下混沌时的轨道激励幅值阈值,同时分析非线性刚度、悬挂阻尼等参数对悬挂系统混沌区域的影响.在进行单自由度车辆悬挂系统参数设计...