【作者】 李强；

【导师】 王宣银；

【作者基本信息】 浙江大学 ， 机械电子工程， 2008， 博士

【摘要】 并联电液伺服六自由度平台广泛应用于对飞行、航海及车载驾驶运动的模拟。因其承载能力强、刚度大和精度高的优点,正在被不断地拓广于各种应用领域之中。随着应用的需要,对其低速平稳运行的性能和良好的动态轨迹跟踪精度的要求越来越高。不同于一般的伺服系统,由于并联电液伺服六自由度平台为多输入、多输出强耦合的非线性系统,因此平台整体低速平稳运行的影响因素更为多样化,其系统低速特性更为复杂。本文首次系统地对平台低速运动进行全面的研究,以揭示其特性规律,并提出相应有效的解决措施。研究思路为对含运动副低速摩擦的平台系统进行完整建模,利用基于数学模型的理论分析与仿真手段,按照由部分到整体的过程,分析系统的支链部分和平台整体的低速特性。根据其特性规律,得到改善平台低速性能的理论着眼点。针对各种特性,分别从平台的空间结构参数设计和控制策略两个方面出发,进行理论与实验研究,以求获取能够提高该类平台低速性能的普遍有效途径。论文分八章进行阐述,主要内容如下:第一章综述了本课题相关方面的研究背景。介绍了机械、电气、液压伺服系统的低速理论发展历程和摩擦补偿研究的现状,对并联电液伺服六自由度平台低速运动相关的各方面研究现状和发展趋势进行综述,结合课题来源与意义,给出本文的主要工作和研究内容。第二章对实验平台进行数学建模。在实验平台建模推导中,特别考虑了低速运动时各运动副之间的摩擦因素,以及系统支链惯量因素,以得出系统完整的非线性模型,为全文提供理论基础。第三章基于数学模型,对支链及平台进行低速特性分析与仿真研究。对各支链摩擦进行建模和辨识实验。在此基础上,利用AMESim对支链液压系统进行建模和仿真,研究各种因素对支链低速平稳运行的影响,得出支链的低速特性。通过分析平台输入输出之间的空间广义传动关系,得出平台各自由度运动的空间特性。利用AMESim与MATLAB/Simulink联合仿真的手段,对整体系统平台低速的各种特性进行仿真研究,同时通过实验验证了模型的正确性。第四章针对平台各自由度低速运动的空间分布特性,从平台空间结构参数设计角度出发,提出表达平台各自由度运动在设计空间内的全局性能指标,依据该指标,得出平台各自由度运动独立优化的目标函数,为满足各种不同自由度运动低速应用需求的平台,提供了平台各自由度低速运动性能独立优化的方法。同时,提出一种基于广义力平衡原理的结构参数标定方法,从力学角度对平台进行标定,丰富了平台参数标定的方法。第五章针对平台支链低速运动的摩擦特性和系统输入输出之间的空间广义传动特性,提出基于摩擦模型的支链摩擦补偿和平台整体空间闭环变增益调节,进行系统低速实验研究。第六章针对系统所存在的各种干扰(包括摩擦)特性,对各类干扰的作用进行分析和分类,依据干扰作用的类型设计由基于系统模型的自适应滑模补偿器和结构不变原理的干扰抑制器组成的综合补偿器,对系统低速运动进行综合干扰补偿的仿真及实验研究。第七章针对系统支链间的耦合,以及在跟踪过程中彼此之间性能差异所引起的不协同运动特性,提出描述各支链之间互相干扰作用所产生的广义同步偏差和平台各自由度运动之间的干扰偏差,依据自身偏差与相互间的扰动偏差所组成的综合跟踪偏差量,利用Backstepping方法推导鲁棒控制器,对系统惯性参数的不确定因素进行自适应补偿研究,以提高系统的低速运动性能。在此基础上,对实验室平台进行低速空间性能测试,验证了平台本身的低速空间特性。且对不同系统油压下的平台性能进行测试,结合第三章的理论分析,可以得出实验室平台的低速空间性能分布。第八章对全文作了总结,阐述了本课题的研究成果和结论,并对后续研究工作做出了展望。更多还原

【Abstract】 For its high load carrying capacity, good dynamic performance and precise positioning, the electro-hydraulic 6dof parallel platform is used to all kinds of fields by generating general motion in space such as motion simulator, parallel machine, parallel manipulator, and so on. With the development of its application, how to improve the trajectory tracking precision of the platform in low velocity motion becomes more important in the field. The platform is a MIMO nonlinear system. There are all kinds of influencing factors that influence the smooth running and trajectory tracking precision of the platform in low velocity such as motion asynchrony, coupling disturbance force among the linear hydraulic actuators, the frictions of each pairing element and so on. So the low velocity characteristic of the platform is more complex. Through the general research on each aspect of the low velocity motion of the platform, the dissertation discloses the low velocity characteristic and regularity of the platform to improve the trajectory tracking precision of the platform in low velocity motion from control issue and design methods two sides.The dissertation consist of eight chapters, the main content of each chapter is as follow:The first chapter of the dissertation generally discusses the correlative background of the research. The low velocity crawl of mechanical servo system, electrical servo system and hydraulic servo system and the friction compensation research are introduced. At the same time, the each aspect research about the low velocity movement of the electro-hydraulic 6dof parallel platform is respectively summarized. At the end of this chapter, the support, significance of the research and main research content of the subject is illustrated.In the second chapter, the whole dynamics of the platform is deriving to found the theoretical basis of the research. In this processing, the frictions of each pairing element and the inertia of each cylinder take into account to build the system dynamic model. The third chapter has analyzed the each influencing factor about the low velocity characteristic of the joints and the platform based on the dynamics. The input/output transmission relationship of the platform in space is shown to disclosure low velocity characteristic of each degree of freedom of the platform. The simulation results of the low velocity characteristic of the system are shown to validate the analysis and the accuracy of the model by AMESim and MATLAB/Simulink tool.In the fourth chapter, a new design method is proposed to optimize each degree motion performance in the low velocity according to the low velocity characteristic of each degree of freedom of the platform in space. According to the characteristic, the global indices of each degree motion performance and the correlate cost function are present. At the same time, a new kinematic calibration method based on generalized force principle is proposed to improve the setting accuracy.In the fifth chapter, friction compensation research of cylinders based on LuGre model and closed loop gain scheduling of the whole platform in space are present to improve the trajectory tracking performance in the low velocity motion according to the friction characteristic of cylinders and the transmission relationship characteristic of the platform in space.In the sixth chapter, according to the disturbance force characteristic include the friction during the low velocity trajectory tracking process for the electro-hydraulic 6dof parallel platform, a mix compensator of the disturbance force is proposed in the chapter. Through analyzing the source and effect of the disturbance force, an adaptive robust compensator and the classical compensator based on structure invariance principle are designed to separately deal with the influence of different disturbance force.In the seventh chapter, according to the non-synchronization and coupling disturbance force among the hydraulic cylinder of the platform in low velocity motion, the position synchronization errors is investigated by considering motion synchronization between each actuator joint and the synchronization errors of cylinders. The position disturbance errors of each degree motion are investigated too. According to the compositive tracking errors which consist of the position errors and the synchronization errors, the robust controller is proposed to guarantee asymptotic convergence to zero of both the position errors and the synchronization errors in low velocity trajectory motion by backstepping design methodology. The adaptive law is deduced to deal with the unknown parameters of the platform. Finally, the low velocity performance of the platform is measured in space with the controller. The result validated the analysis of the third chapter. At the same time, the low velocity performance is measured in different pressure condition to express the influence of the system pressure of the oil. According the results and the analysis, the low velocity performance of the platform in whole design space can be known.In the eighth chapter, main research work, conclusion and innovation points of this dissertation are summarized. At the same time, future development of the platform about the low velocity motion research is predicted in order to provide references for the further research on this project.更多还原