【作者】 潘宇晨；

【导师】 蔡敢为；

【作者基本信息】 广西大学 ， 结构工程， 2013， 博士

【摘要】 工程机械是我国装备工业的重要组成部分,在农田、水利、交通、市政建设维护和各类综合性机械化施工方面发挥了重要的作用。但是,现有工程机械产品存在一些不足之处。以挖掘机为例,传统单自由度机械式挖掘机坚固耐用,但输出不够灵活；液压式挖掘机可实现柔性化的输出,但又存在液压系统零部件加工装配要求高、寿命不长、漏油等缺陷。这是工程机械领域一个长期未能取得突破的棘手难题。多自由度可控机构是机械技术与电子技术有机结合的产物,具有输出柔性化、刚度高、惯量低、承载能力强、动力学性能好等特点。国内外学者对可控机构开展了较多研究工作,但总体说来,有关成果还比较-零散、孤立,多是针对某种可控机构(如平面两自由度五杆机构)的研究,可供工程实际应用的机构构型依然很少。而且所讨论的多为平面机构,对空间可控机构的研究鲜见报道,尤其结合工程实际应用的研究还较少。针对上述问题,本文将多自由度可控机构应用于工程机械产品,研究这类机构面向任务创新设计相关的理论和方法,主要工作及创新点如下：1.提出了基于功能分析的面向任务机构型综合方法,并将其应用于工程机械产品的创新设计当中：在对现有工程机械输出动作要求、机构拓扑结构要求等全面分析的基础上,运用功能分析方法,通过功能求解模型求解得到其输出运动的规律和特性。通过机构构型演化和基于螺旋理论的约束综合,发明了一系列平面可控机构式、空间可控机构式、变胞可控机构式工程机械产品的执行机构。2.提出了新型可控机构式工程机械的结构学分析理论和方法：针对平面和空间可控机构各自的结构特点,在运动副运动自由度旋量描述的基础上,求解了机构各运动链运动螺旋系的基。基于互易螺旋理论,研究了运动链终端约束及其在约束下的自由运动,进而得到了这类机构末端执行器受到的约束以及在此约束下的自由度数和运动输出规律；针对具有变胞功能可控机构的特点,综合运用构态邻接矩阵、拓扑图、变胞机构的基因建模与构态进化的拓扑结构分析方法等,分析其工作原理和构态转化特点,得到了机构构态演变过程的生物学进化特性,发展了自由度为0的两种有向阿苏尔杆组作为新的变胞元并给出其表达方式,获得了变胞进化生长过程中构型的转化方式和蜕化方法,最后通过进化计算,得到了变胞源装载机构的基因模型表达式。3.提出了新型可控机构式工程机械的运动学分析理论和方法：针对平面可控机构式挖掘机的特点,以一种正铲式平面三自由度可控挖掘机构为例,运用闭环矢量法和约束方程建立了机构运动学模型,分析了机构的速度和加速度特性,求解得到了一阶和二阶运动影响系数。根据隐函数存在定理,求解了机构处于理论工作空间边界的条件,得到了机构的理论可达工作空间；针对空间可控机构式装载机的特点,运用D-H参数法建立了铲斗可实现两维转动输出的可控装载机构的运动学模型,进而通过位移群的平移计算,求解得到了铲斗运动学输出参数与各个输入变量之间的映射关系。4.提出了新型可控机构式工程机械的动态性能分析理论和方法：以正铲式平面三自由度可控挖掘机构为例,考虑到驱动电机转子偏心旋转引起不均匀磁场的机电耦合关系,运用有限元建模方法建立了此类可控挖掘机构整个系统的耦合动力学模型,利用多尺度法,研究了系统在驱动电机电磁参数激励下的主共振问题,得到其在此情况下的一阶近似定常解,分析了系统主共振机理。在上述理论分析的基础上,建立了多自由度可控机构式新型工程机械的虚拟样机模型,并进行了仿真分析。依据仿真结果,结合挖掘机和装载机完成典型挖掘、装载动作的要求,选取了各自驱动电机的型号以及相应的运动控制卡,设计了电气控制柜并开发了相关控制软件,完成了控制系统的搭建。制造了物理样机模型两台并进行相关实验,对本文所提出设计理论和方法予以验证,为后续实物样机的试制提供了参考。更多还原

【Abstract】 Construction machinery is an important part of the equipment industry in China, which has played a significant role in the areas such as farmland, water conservancy, transportation, municipal building and maintenance, and all kinds of comprehensive mechanized constructions. However, there are some shortcomings in traditional construction machinery products. Excavator, for example, which is one of the most important construction machinery divided into two categories:mechanical excavator (also called Electric Shovel or Cable Shovel) and hydraulic excavator. Former is the excavator of choice in oil sands digging and surface mining for its durability, high productivity and low ownership costs resulting from long economic operating life, but lacks flexibility due to the structural limitations. The latter has almost replaced the mechanical excavator because of its flexibility and mobility. But there still exists some problems such as hydraulic leaks and high costs of manufacturing and maintaining. This is a long-term unsolved problem in construction machinery field.Multi-DOF (Degree of Freedom) controllable mechanism was developed by the combination of mechanics and electronics, which is provided with the characteristics such as flexible output, low inertia, high stiffness and carrying ability, etc. Researches on this type of mechanism have been conducted widely. But generally speaking, results are isolated and separated, mostly focusing on some specific type controllable mechanism such as the planar2-DOF five-bar mechanism. Configurations including planar and spatial type of the mechanism are still not enough for engineering applications.This paper introduces the application oriented design theories and methodologies applying controllable mechanism to the innovative design of engineering machinery, including:1. Application oriented type synthesis methods based on functional analysisBased on the analysis on output characteristics of traditional engineering machinery, functional analysis applying the solving model in the form of Function-Effect-Technical Action Process-Executive Action-Mechanism (F-E-P-A-M) is carried out. By configuration evolution and screw theory based type synthesis, a series of novel planar and spatial controllable mechanism type loaders and excavators are proposed, as well as an electric loader with metamorphic functions.2. Structure analysis theory and methodA basis of the kinematic chain screw system is obtained according to the characteristics of the proposed planar and spatial controllable mechanisms respectively, based on the screw description of the kinematic pairs. Terminal constraints on the kinematic chains and the free movements under the constraints are analyzed based on the reciprocal screw theory. Then, the constraints as well as the numbers of DOF and the laws of output motions of the end effectors of these mechanisms are revealed.The source-metamorphic mechanism of the loading mechanism is introduced first, as well as its metamorphic ways to achieve variable topology. The adjacency matrix and topological graphs are applied to describe topological change of each working phase, based on which the principles and characteristics of configuration changing are analyzed. Two0-DOF directional Assur groups are developed to be the new metamorphic cells as well as their representations. Configuration transformation and its degeneration ways during the genetic growth are studied. Biological modeling for working-phase mechanisms is then proposed. The evolutionary synthesis process for generating the source-metamorphic loading mechanism and its representation is introduced by evolutionary operations.3. Kinematics analysis theory and methodAccording to the features of planar controllable mechanism type excavators, the kinematic model of a face shovel type planar3-DOF controllable excavating mechanism is established applying the closed-loop vector method and constraint equations. The first-order and second-order kinematic influence coefficients are deduced by analyzing the velocity and acceleration characteristics. Based on the implicit function theorem, the conditions are obtained when the mechanism is in its workspace boundary as well as the theoretical reachable workspace.According to the characteristics of spatial controllable mechanism type loaders, the kinematic model of a controllable loading mechanism whose bucket can achieve two-dimensional rotating output is established using D-H parameter method. The mapping relationships between the output parameters and each input variable are obtained by the translational calculations of displacement groups.4. Dynamic characteristics analysis methodsTaking a shovel type planar3-DOF controllable excavating mechanism as an example, the coupling dynamic model of the system is established using finite element method which contains the non-uniform magnetic field electromechanical coupling relationship caused by rotor eccentric rotation of the driven motors. The first order stationary solution is obtained by calculation applying the method of multiple scales, based on which, the primary resonance of the system aroused by electromagnetic parameters of the motors is analyzedOn the basis of the above theoretical studies, a simulation analysis is carried out based on the virtual prototype model of the proposed multi-DOF controllable mechanism type novel engineering machinery. According to the simulation results, the control system satisfying the typical digging and loading demands of traditional hydraulic excavators and loaders is built, which contains the selection of the motor types, the motion control cards and the development of the electric control cabinet and relevant control software. Two physical prototypes are manufactured. Excavating and loading experiments are conducted, whose results verified the proposed design theories and methodologies, which can also provide some useful references for the subsequent trial of the physical prototypes.更多还原