【作者】 王伟；

【导师】 傅新；

【作者基本信息】 浙江大学 ， 机械电子工程， 2009， 博士

【摘要】 运动模拟器用来替代真实设备训练操作者对设备的操纵能力及研发相关设备,在科研、生产、生活中发挥了重要作用。六自由度并联运动模拟器由于其位置精度高、承载能力大、动态性能优越,从而在航空、航天、海洋等领域内得到了广泛的应用,但其并联闭环结构导致了其内在缺点:工作空间小、存在奇异位置、非线性强、耦合影响大。大型高精度、高动态响应并联运动模拟器,一般采用液压驱动,液压系统自身的非线性特性结合并联机构的强耦合性给控制带来了较大难度,使机构控制很难满足动态响应要求,现有大型六自由度运动模拟器的控制带宽均较小,严重制约了它的应用。本论文以大型高精度、高动态响应并联运动模拟器为研究对象,系统地开展了从结构参数设计到模拟器控制的研究。首先建立了系统的动力学模型,充分考虑了液压支路质量惯量的影响,分析了大型运动模拟器液压支路的动态特性;将结构参数设计与液压系统动态响应带宽相结合,提出了基于系统固有频率的结构参数优化设计方法,研究了不同构型结构参数的影响规律,并将此方法成功应用于实际运动模拟器的设计中,有效提高了其控制带宽,为大型高精度六自由度并联运动模拟器的设计提供了一种新的方法;建立了基于接口的运动模拟器机电液多领域数字样机模型,采用连续性判断及修正方法,保证了数字样机联合仿真模型的精度;基于数学模型、数字样机及实验验证,分析了并联运动模拟器耦合特性,并利用支路间的耦合规律,提出了基于耦合支路的解耦控制策略,有效减弱了支路及广义自由度间的耦合输出,为并联运动模拟器的控制策略研究提供了新的方案。论文的主要研究内容如下:第一章,在综合国内外文献的基础上,介绍了运动模拟器特别是六自由度并联运动模拟器的发展历史、结构特点及应用前景。重点从运动学、动力学、控制策略、硬件控制方案及综合优化设计等方面介绍了并联运动模拟器的研究现状及研究热点,分析了其发展趋势及有待进一步研究的问题,最后根据本课题研究的目的和意义,给出了主要研究内容。第二章,基于Lagrange法建立了液压六自由度并联运动模拟器的完整动力学模型,考虑了活塞杆及油缸的全部质量惯量,构建了系统等效质量惯量矩阵,并进行了准确性验证。通过数值计算对比分析了传统简化模型与完整模型的差异,作了等效质量惯量矩阵的分布特性研究,并引入平台加速度和质量比研究了支路对系统静力学、动力学的影响,为大型液压六自由度运动模拟器动力学研究提供了准确可靠的理论基础。第三章,将运动模拟器的结构参数设计与液压系统动态响应带宽相结合,提出了基于固有频率的结构参数优化设计方法。建立了广义固有频率数学模型,并对模型进行准确性验证。在此模型基础上,分析了不同构型动静平台直径比及铰点角度对频率的影响。重点针对6-6 SPS构型研究了不同结构参数对固有频率的影响,结合液压系统得到了液压关键参数的影响规律.经过优化设计及工作空间等验证校核,完成了大型液压六自由度运动模拟器的结构参数优化设计。第四章,针对液压六自由度运动模拟器涉及机、电、液、控制等多领域的特点,开展了基于接口的多领域建模方法研究,探讨了多领域多软件接口的控制策略,建立了液压六自由度运动模拟器的多种通用联合仿真模型,并针对多领域联合仿真模型的精度问题,开展了接口类型及处理方式对模型精度的影响研究。提出了采用连续性判断及修正方法,消除了不连续性现象,保证了联合仿真模型的精度。第五章,对运动模拟器进行了数字样机数值计算及实验研究。重点针对并联运动模拟器的内在交联耦合特性,通过数学模型、数字样机及实验验证,系统研究了两个方面的耦合特性:并联机构支路不一致带来的广义自由度耦合、支路间的交联耦合。基于支路间的耦合规律,提出了两种解耦方式,将传统基于广义自由度解耦的控制方式降阶,有效减弱了支路及广义自由度间的耦合输出,为并联运动模拟器的控制提供了新的方案。第六章,概括了全文的主要研究工作和成果,并展望了今后需进一步研究的方向和内容。更多还原

【Abstract】 Motion simulators are test equipments which can be used for developing new facilities and for the training.6-DOF parallel motion simulators possess a number of advantages such as higher rigidity,better positioning accuracy and load capacity.Therefore,they have been used in various applications.However,due to the multiple closed-loop structure and kinematic constraints,they also have disadvantages such as smaller workspace,higher nonlinearity, stronger coupling,furthermore,there are numerous singularities in workspace which make the simulators lose their stiffness,precision and load-carrying capacity.Large 6-DOF simulators are often driven by fluid power,and in general,the control of hydraulic actuators is more challenging than that of their electrical counterparts.The factors such as nonlinear flow/pressure characteristics,variations in the trapped fluid volume due to the piston motion,fluid compressibility,flow forces and their effects on the spool position,and friction,all contributing to the significant nonlinear behavior.This will influence the actual control bandwidth,which is less than half of the natural frequency in general.Currently the control bandwidths of large simulators are relatively small.This thesis deals with large hydraulic parallel simulators in applications with requirements of high precise positioning and good dynamic performance.A Lagrangian dynamic formulation which considers the whole leg inertia is developed,and the influence of legs on the dynamics is studied.Based on the accurate inertia model,an optimal design method to expand the bandwidth for the control of large hydraulic 6-DOF simulators is proposed,the influence of design parameters on the generalized natural frequency are investigated,and this optimal method has been put into application in the design of a large hydraulic simulator.In addition,a co-simulation model of the hydraulic parallel simulator is built,including hydraulic system, mechanism and control strategy.With the simulation model,mathematical model and experiments,the coupling characteristics has been studied.Based on the coupling laws among the legs,two kinds of decoupling methods are proposed.The effectiveness of the decoupling methods is validated.In Chapter 1,based on the research information home and abroad,the history,features and applications of the motion simulators especially 6-DOF parallel simulators are introduced.The related technologies are presented in detail with the latest progress of last few years,including kinematics,dynamics,control strategy,controlling hardware,optimizations and so on.Some trends and difficulties of the development for the parallel simulators are also summarized. Finally,according to the purpose and significance of the study,the major research contents of the thesis are introduced.In Chapter 2,a Lagrangian formulation which considers the whole leg inertia is developed for the dynamics of large parallel simulator,and the accurate equivalent mass matrix is obtained and verified by ADAMS model.Numerical examples are carried out to validate and confirm the efficiency of the mathematical model.Furthermore,the effect of leg inertia on the equivalent mass matrix is studied,and three parameters(acceleration of the moving platform,mass ratio of leg to upper platform,mass ratio of cylinder to piston) are used to investigate the influence of leg inertia on dynamics more detailed.In Chapter 3,an optimal design method,based on generalized natural frequency,to expand the bandwidth for the control of large hydraulic 6-DOF parallel simulators is proposed.An ADAMS model is built to validate the generalized natural frequency mathematical model.The influences of the diameter ratio and the joints angle ratio on frequencies are studied for different configurations.A detailed investigation of the influences of design parameters on natural frequencies is carded out for 6-6 SPS configuration.With workspace verification,the optimized structure parameters for one large hydraulic 6-DOF simulator are obtained.In Chapter 4,a co-simulation model of the hydraulic parallel simulator is built including hydraulic system,mechanism and control strategy.Based on the interface,the combined simulation modeling strategy for multiple research areas is studied,and the detailed models and different universal co-simulation methods are presented.The influential factors on the model’s accuracy are investigated,and a method to detect and correct the model discontinuity is developed to ensure the accuracy of the co-simulation model.In Chapter 5,combined with the co-simulation model,mathematical model and experiments,the complex coupling characteristics of the hydraulic 6-DOF parallel platform is investigated.Firstly,the dynamic coupling of the parallel simulator is studied based on the dynamic consistency of six actuators.Furthermore,the load coupling among the six actuators of the platform is investigated in detail.Finally,based on the coupling laws among the legs,two kinds of decoupling methods are proposed.The effectiveness of the decoupling methods is validated.In Chapter 6,conclusions of the thesis are summarized and the future research work is put forward.更多还原