【作者】 张志勇；

【导师】 钟志华；

【作者基本信息】 湖南大学 ， 车辆工程， 2008， 博士

【摘要】 越野车辆和工程机械经常工作于恶劣的环境中,在行驶或作业的过程中,由于路面的不平而产生强烈的振动。如果驾驶员或操作者长时间暴露于一定强度的振动中,将影响到其工作效率,严重的还会导致身体损伤。为了减小振动传递到驾驶员或操作者身上,一般通过座椅悬架系统对振动进行隔振,从而改善乘坐的舒适性。由于被动座椅悬架系统对隔振性能的改善空间有限,不能有效减小低频段振动传递的强度,因而需要半主动或主动悬架系统来进行有效衰减。磁流变液这种功能材料在近年来受到人们的极大重视,利用磁流变液特性的产品在土木工程、机械工程中的应用中显示出了优越的性能,其中以磁流变阻尼器作为减振控制的应用最为突出,例如高楼隔振和大桥悬拉索减振等。磁流变阻器减振应用的一个重要领域是悬架系统,其中包括车辆悬架系统和车辆座椅悬架系统。在磁流变阻尼器的悬架应用中,主要是为了耗散由路面激励所产生的对车辆和乘员的振动能量,改善乘座的舒适性。本文中将以基于磁流变阻尼器半主动座椅悬架为研究对象,研究和探讨控制系统的这些关键技术。研究内容主要包括如何利用磁流变阻尼器阻尼特性实验的结果,通过优化方法得到其数学模型的参数,并由此数学模型推导出结构简单、精度较高的逆模型。以及如何设计一个控制策略,不仅对参数不确定性具用鲁棒性,而且能减少传感器的使用和避免用到一些难以获取的状态量作为控制决策量,从而使控制策略容易实现,且降低其实现成本。最后通过数值仿真和实验的方法检验这些关键技术。在本文中所做的具体工作包括以下几个方面:(1)对磁流变阻尼器进行阻尼特性实验,并利用实验结果通过遗传算法辨识Bouc-Wen现象模型中的14个参数,由此建立了该磁流变阻尼器的数学模型,为座椅半主动悬架系统的数值仿真提供基础。(2)由磁流变阻尼器Bouc-Wen现象模型推导出不仅结构简单,容易实现,但又具有一定精度的磁流变阻尼器逆模型。该逆模型利用期望控制力和当前的活塞速度而得到磁流变阻尼器需要输入的电压,利用此逆模型能将目前众多的主动控制算法运用到半主动控制当中。(3)针对实际物理系统难以准确建模,以及被控对象参数随环境变化而变化的特点,运用参数不确性理论将这些因素考虑到控制器的设计过程中,推导出具有参数不确定性的H∞鲁棒输出反馈控制器,由此提高半主动控制系统的控制器对参数摄动的鲁棒性,保证控制器动态性能。(4)根据工程车辆座椅悬架系统振动实验的国家标准,利用激振加速度的功率谱密度要求,通过傅里叶逆变换的方法求得激振输入在时域的位移和速度数据,这些数据可作为半主动座椅悬架系统数值仿真和实验的激励输入。(5)应用数值仿真的方法对半主动座椅悬架系统进行仿真研究,不仅将被动悬架与半主动悬架系统的动态性能在时域中进行了对比研究,而且运用频域分析方法来进行分析比较。另外,通过在仿真中加入多种参数摄动的方法,检验控制器对参数不确定性的鲁棒性。(6)运用LabVIEW程序设计的方法来实现半主动座椅悬架的控制器,该控制器包括数据采集、信号调理、半主动约束、磁流变阻尼器逆模型、控制信号输出、H∞鲁棒输出反馈控制器等部分。(7)为了检验控制系统的可行性和鲁棒性,对基于磁流变阻尼器的座椅半主动悬架系统进行了实验设计,主要包括座椅模态实验、座椅激振的实现、座椅夹具设计、驾驶员模拟、控制器实现等方面。通过座椅悬架实验,比较被动悬架和半主动悬架系统的振动控制效果,验证控制系统的有效性。更多还原

【Abstract】 Off-road vehicles and engineering machineries often work in harsh environment, in which the road unevenness leads to the intensive vibrations in the process of driving or operating. If the drivers or operators are exposed to a certain intensity of vibration for long time, which will affects their work effectiveness, even serious bodily injury. In order to reduce the vibration energy transmitting to the drivers or operators, the seat suspension system has been equipped for vibration isolation and improvement of the riding comfort in general. Since passive seat suspension system with limited functions in improvement of vibration isolation, can not effectively reduce the strength of vibration transmitting, especially in low frequency band. Recently, semi-active or active suspension systems become popular in effective attenuation of vibrations.Magneto-Rheological (MR) fluid, such functional material has received great attentions in recent years. Many application products utilizing the MR fluid have shown superior performance in civil engineering and mechanical engineering. In these applications, the utilizations of vibration control with MR damper are the most prominent, such as vibration isolation of high buildings and vibration damping of big bride cables. In additon, suspension system is the important application field of MR damper for vibration absorption including vehicle suspension and seat suspension, and playes a role that dissipates the main vibration energy generated by road exciting. As a result, the comfort of riding is improved.This paper studies the key technologies of semi-active seat suspension based on MR damper mentioned above. The main work includes how to build the mathematical model of MR damper with the aid of experiments by optimizing method, derive MR damper inverse model with simple structure and high precision, and design a control strategy that not only takes on robust performance for parameter uncertainties, but also reduces the using of transducer, or avoids some hard-to-access state as decision-making variable. The control strategy is reqiured to be easy to apply and reduce the realizing cost accordingly. At last, numerical simulations and experiments are used to verify these key technologies. In this dissertation, the concrete work includes the following aspects.(1) In order to establish the mathematical model of a given MR damper, the fourteen parameters of the Bouc-Wen model of MR damper are identifyed by genetic algorithm using the experimental results.(2) The inverse model is derived from the Bouc-Wen model of a given MR. This model, with only structure simple and a certain precision, is easy to be implemented. The inverse model can determine the input voltage for the MR damper by using the expected force and current speed of piston, such that a number of active suspension control algorithms can apply to the semi-active suspension control.(3) Considering the properties in the controller design process that the actual physical system is difficult to be accurately modeled, and the plant parameters changes with environmental changing, an H∞robust output feedback controller with parameter uncertainty is derived, which can enhance the robustness of the semi-active controller in control system with parameter perturbation and ensure the dynamic performance.(4)According to the requirements for acceleration power spectral density (PSD) in national standard, in which vibration experiment of engineer vehicle seat suspension system is regulated, displacement and velocity signal of excitation input in time domain can obtain through the way of inverse Fourier transform, and these signal can act as excitation input in numerical simulaion and experiment of seat suspension.(5)The dynamic performance of passive seat suspension and semi-active seat suspension are compared and studied by numerical simulation not only in time domain and frequency domain. In addition, the simulation tests the robust performance of controller for parameter uncertainties, in which a variety of parameter perturbations are added in.(6) Semi-active seat suspension controller is designed by LabVIEW program, which including data acquisition, signal condition, semi-active constraint, MR damper inverse model , control signal outputing, robust H∞output feedback controller, and other parts.(7) To verify the feasibility and robustness of the control system, an experiment is performed for semi-active seat suspension based on MR damper, which including the seat modal experiments, realization exciting of seat, seat fixture designing, driver simulation, controller designing, and so on. The experiments compare the performances of passive seat suspension and semi-active seat suspension, and verify the effectiveness of the designed control system.更多还原