【作者】 罗金良；

【导师】 黄茂林；

【作者基本信息】 重庆大学 ， 机械设计及理论， 2008， 博士

【摘要】 随着现代生产及科学技术的发展,为提高机械系统的运动学、动力学性能与智能化水平,使机械自身对各种内部和外部不确定因素变化具有自调与自适应功能的机械结构,正日益成为机构学研究的热点。机械自适应结构,是指无需通过测控,仅仅依靠机械本身可以自动适应外部工作条件、对象、工作参数变化的一种机械结构,具有这种自适应结构的机械就称为了自适应机械。自适应机械一般都具有多自由度、变结构、变自由度的结构特征,且原始驱动件的数量都小于机械的自由度数量,一般为欠驱动机械系统。机械自适应结构,是一种基于可变约束的机械结构。是利用可变约束的可施加、可释放、可调、可控等结构特征,使机构自身具有自动调整和适应外部变化的功能的。具有自适应功能的机械已在工程实际中得到了广泛的应用。但对其共性的工作机理及其综合设计的理论与方法还缺乏系统的研究,对自适应机械尚缺乏较明确的定义与分类,制约了它的发展和应用创新。正是基于此需要,本论文对可变约束和机械自适应结构进行了较深入,系统的分析与研究。本论文的主要工作有:①在详细分析机械中的可动联接与约束性质的基础上,基于广义约束及设计应用的观点,提出了运动约束和动力约束、内部约束和外部约束、基本约束和过约束以及常约束和可变约束的机械约束分类方法,分析了各类约束的基本性质和特征。并首次将机械中的可变约束分为可变运动约束、可变几何约束、力封闭约束和动力约束,列出了各种可变约束的特征表达式,指出了其可变、可调及可控因素,及可变约束的作用及应用范围。为自适应机械结构的分析与设计奠定了基础。②在机械自调结构研究的基础上,通过对已有自适应功能的机械的深入分析,定义了:自适应机械,是指对其外部工作对象、环境、条件的不确定性和变化,无需通过测控,且不包含专门的控制机构,而是依靠机械本身的结构自动调整来实现对变化的自动适应,从而可靠地完成预期工作要求的机械装置。深入研究了自适应机械的工作机理,指出其“自适应”,实质上就是对机械的约束和自由度变化的自动适应。其自适应功能,根本上是基于可变约束结构的力、能特性及其参数的可变与可调控性,是通过对自由度的约束和释放,调整机械自身的结构特征来实现的。③提出了按自适应机械的功能结构特征及其自动适应的对象来划分的两种自适应机械分类方法。重点针对变结构自适应机械、变自由度自适应机械和内力封闭自适应机械,阐明了其主要结构特征及自适应机理。并根据它们的共性特征,较系统地提出了自适应机械综合的要点,给出了自适应机械综合设计的一些基本原则和通用方法。④针对内力封闭自适应机械多方案设计的需要,系统地完善了一种新的型综合方法—胚图支链法。以此为基础,研究并创新了一种基于全回路拓扑特性矩阵的运动链同构辨识法,综合出了自由度为0或-1的十杆(包括十杆)以下的运动链的全部独立构型。深入分析和研究内力封闭自适应机械设计的内容、方法和原则,提出了其方案设计及功能结构设计的程序以及一般原则和方法。并通过实例详细论述了其结构及尺寸设计的过程与方法。⑤提出了一种以单自由度关节连动式仿人手指为基础的条件自适应手指设计方案。首先仿照人手指从伸直到握拳过程中三关节的相对位姿,综合其单自由度机构,再通过在原机构中增加一个条件自由度来提高和完善其自适应功能。对欠驱动3自由度手指机构的构型设计、关节可变约束的结构方案及获得条件自由度的方法进行了较深入的探讨。建立了欠驱动手指具有可变力(力矩)约束的准静力学模型;提出了按连动手指优化的参数,选定三个指节的尺寸,并以传动角最佳及握紧的中间状态为基本构型,以三个接触力相等为优化目标的综合方法。建立了优化目标函数,确定了优化参数,采用粒子群法进行优化,得到了多组可供优选的可行解。通过对虚拟样机仿真实验,论证了手指机构较强的自适应功能。⑥在分析重钢高炉折叠式堵渣机功能结构特征的基础上,根据其自适应结构存在的主要问题,提出了采用两组槽销副加弹簧力封闭约束的可变自适应结构来代替原有的重锤—滚子—摆杆式力封闭高副结构,有效的提高了工作的稳定性和可靠性,完善了自适应功能。通过虚拟样机仿真试验结果表明本文设计方法是正确的、有效和可靠的。以上研究成果,对丰富和拓展现代机构学结构设计理论与方法,开拓自适应机械的创新设计方法及应用领域,提高我国自适应机械结构分析与设计的水平,具有重要的理论意义和工程实际价值。更多还原

【Abstract】 As long as the development of modern manufacture and technology, to improve the kinematics, kinetics capability and level of intelligentization of mechanical system; the mechanical structure has self-adjustment and self-adaptability according to various interior and exterior uncertainty are becoming hotspots of mechanism scholars’investigation.Self-adaptive structure of mechanism is a mechanical structure that mechanism can automatically adapt to exterior working conditions, objects, and parameters but need not test or control. The mechanism with such structure is called self-adaptive mechanism. The self-adaptive mechanism usually has structure characteristics of multi-degree of freedom, variable structure and variable freedom. Because the quantity of the original driving member is smaller than that of the mechanical freedom, it is usually a typical underactuation mechanism system. And, the self-adaptive structure is a mechanism structure based on variable constraints. It utilize the characteristics of the variable constraint which is able to be enforced, released, adapted and controlled, and makes the structure can be self-adapted to the exterior varieties.The self-adaptive mechanism is recently widely applied in practice. However, the lack of systematic research on its commonness working mechanism and theories and methods of integrative design, the lack of a specific definition and classification are badly restricting its application, development and innovation. Based on such demand, this thesis has deeply and systematic analysis and research on variable constraint and self-adaptive mechanism structure.The major tasks of this thesis are as follows:①Based on the particular analysis of the relationship between movable join and constraint character, according to the general constraint and view of design and application, the thesis here advances the classifications of: the motion constraint and dynamical constraint; interior constraint and exterior constraint; basic constraint and extra-constraint; ordinary constraint and variable constraint. And characteristics of different constraints are analyzed. And for the first time, the variable constraint is classified to variable motion constraint; variable geometry constraint; Force closed constraint and dynamical constraint. Diversified constraint equations of variable constraint are listed; factors of variable, adjustable and controllable of the variable constraint structure are indicated; and functions and scopes of appliance of the variable constraint are specified. A foundation to analysis and design of self-adaptive mechanism structure settled.②Based on the research about the self-adjustable mechanism structure, according to deep analysis of foregone self-adaptive mechanism, a concept is advanced here: the self-adaptive mechanism is that device which can automatically adapt to the change of exterior working conditions, objects, and parameters depends on the self-adjustment and realize the adapt to varieties, and dependably achieve the expected working requirements, without any testing and controlling and special control structure either. By research on the self-adaptive mechanism working mechanism, here indicates that the“self-adaptive”in fact means its self-adaptability for varieties of the mechanism constraint and freedom. Its self-adaptive functions are realized based on variability and adaptability of varieties parameters of variable constraint power and energy, via constraint or release for degree of freedom to adjust the mechanism structure for realization.③According to the characteristics of function structure and objects to be adapted, two class methods of self-adaptive machines are advanced here. Mainly aimed at variable structure self-adaptive mechanism, variable freedom self-adaptive mechanism and internal-force-closed self-adaptive mechanism, the main structure characters and self-adaptive mechanism are set forth. According to their common characteristics, the main points of self-adaptive mechanism synthesis are particular discussed in the thesis and some basic principles and current methods of the synthesis designs of self-adaptive mechanism are brought forward also.④To the question of the demand in different structure of internal-force-closed self-adaptive mechanism, a new method of type synthesis of kinematical chains is finished systematically, that is Contracted Graph and Subchain Method. Based on which, a method to detect isomorphism of kinematical chains based on the All-Loop-Link-Join-Matrix is researched and innovated, and all possible independence structures of less than 10 links (10 links included) with 0 or–1 DOF are brought forward .Here in-depth analysis and research for the design, methods and principles of internal-force-closed self-adaptive structure is done, and the design process and general principles and methods is are brought forward. And by instances the process and methods of its function and structure design is discussed also.⑤In the thesis a conditional self-adaptive finger design method based on the apery finger of the single-degree of freedom arthrosis is forwarded. Firstly imitated the gesture of human fingers from unbend to make a fist, its single-degree mechanism is synthesised, and then add a conditional freedom in the original mechanism to advance and complete its self-adaptability. In the thesis, the method of structure synthesis; the variable constraint structure scheme of arthrosis; and how to obtain the conditional degree of freedom of 3-DOF underactuation finger mechanism are deeply discussed. And the kinetostatic analysis model having variable moment of underactuation finger is build up; the synthesis method according to parameter of optimization of fingers, and select three dimensions of the knuckle, take the best and medium condition of grasp of transmission angle to be the basic structure, take the three contact force to be equal as target of optimization is indicated. Fixed the parameter of optimization, the functions of optimization target is built up, and several conclusions for choice, throughing the Particle Swarm Optimization (PSO), are achieved. Via the simulation experiments of the dummy sample machine, the strong self-adaptive function of the finger mechanism is demonstrated.⑥Based on the analysis of the function structure of stopper from ChongQing Steel Co., Ltd., according to the main problems of its self-adaptive structure, the variable adaptive structure of two slotting-pin pair with spring force closed constraint to replace the original force closed Higher-pair structure of hammer—roller—wobbly pole are designed in the thesis. Tthe working stability and dependability of stopper are improved, and completes the self-adaptive function is completed also. The testing result from experiments of the dummy sample machine indicates that the design method of this thesis is correct, effective and dependable.The research achievements upon have very important theory significance and project actual value in enriching and developing the design theories and methods of modern mechanism structure; developing innovative design methods and field of self-adaptive machine; advancing the analysis and design level of self-adaptive machine structure of our country.更多还原