【作者】 侯志利；

【导师】 武文革； 李瑞琴；

【作者基本信息】 中北大学 ， 机械设计及理论， 2017， 博士

【摘要】 机构创新决定机械装备产品的创新性。结构可重构、运动柔性可控的可重构并联机构,可快速响应现代机械产品及制造工艺定制化的需求,适应不同工作环境和不同任务的柔性要求,是机构及机器人领域的研究热点。平面并联机构构型简单、易控制、成本低、应用广泛。二自由度平面五杆并联机构是平面并联机构的典型代表,可完成平面内任意轨迹,但缺乏较为完善的可重构结构设计方法。鉴于此,本文研究基于五杆机构的少自由度平面并联机构的可重构结构设计方法,并进行运动分析与实验验证。主要开展以下几方面的研究工作:(1)基于机构的变拓扑结构设计、模块化设计方法及李群理论,提出可重构并联机构的结构创新设计方法。以机构的一类构型作为结构设计主模型,对具有重构特性的运动支链模块进行综合,兼顾结构尺度约束和运动约束间存在的关联关系,构造新运动支链,通过变驱动布局、变参数配置、变运动支链等多种结构变换方式,生成具有拓扑关联关系的新构型族,实现全数据相关的尺寸驱动设计,奠定可重构机构的结构设计理论基础。变驱动布局的结构设计方法,既能有效避开奇异位形,又能扩大机构的工作空间,提高机构的刚度。(2)建立包含运动信息的杆副全信息主构型模型,进行可重构并联机构的结构衍生设计及变驱动布局设计,衍生重构出系列新构型,并分析其不同运动模式的运动特性。以5R机构作为设计主构型,通过多种结构变换方式进行构型重构,建立五杆机构的十三种基本构型、含5R变胞闭环子链的衍生并联机构的模型。运用李群理论描述了5R变胞构型、3R2P变胞构型、2R3P变胞构型及其混联运动支链的不同运动模式的运动特性。以3-RRR机构作为设计主构型,建立平面三自由度并联机构八种构型及其衍生新构型模型;基于3-RRR+P混联平台,变换衍生出八种实现不同运动模式的新构型。基于机架同轴心布局,设计一类新型少自由度平面并联机构,用于扩大并联机构的运动空间,为构型对比与优选提供设计方案参考。(3)进行可重构平面并联机构的运动学分析,提出运动轨迹搜索机构可达工作空间的CAD几何分析法。对比分析5R机构的三种运动学解析方法的求解特性,基于几何法研究5R机构、变驱动布局5R机构的运动轨迹图谱、工作空间等运动特性,并进行运动可控的实验验证;建立平面三自由并联机构的运动学统一方程,研究其工作空间的运动特性;研究含5R机构的衍生并联机构的运动轨迹输出特性。在运动轨迹研究的基础上,提出运动轨迹搜索机构可达工作空间的CAD几何分析法,简化数值计算过程。(4)基于机械产品三维CAD平台SolidWorks,开发了两自由度、三自由度并联机构的构型设计、尺寸综合、运动学特性分析一体化计算机辅助分析系统。以结构尺度、运动约束为主结构设计参数,开发了包含五杆机构的十三种构型、三自由度平面并联机构八种构型的计算机辅助设计与分析一体化系统,有助于设计人员可便捷地完成两自由度、三自由度平面并联机构的结构变型设计、尺寸综合、运动学特性分析,研究并联机构的运动学特性规律,实现新构型的快速设计。(5)利用运动轴卡控制系统,搭建了平面两自由度五杆机构实验平台,开展5R机构的可重构机构运动特性实验及工程应用研究。实验验证了基于运动轨迹正解与逆解控制方法的正确性,通过驱动电机控制的编程及增益调节实现了运动轨迹的可控稳定输出。针对不同规格尺寸纸箱/纸盒定制封装的需求,基于多组可控变驱动布局的5R机构,研制了可控可重构手指式纸箱封装机、可重构蛋挞包装盒包装机,可实现不同规格纸箱、纸盒的封装工艺动作,可降低劳动强度,提高工作效率,拓展了五杆机构构型的工程应用范围。上述研究工作得到了国家自然科学基金项目“多自由度混合驱动型可控机构设计理论与应用研究(51275486)”的资助。通过上述设计方法和实验研究,确立了基于一类主构型模型衍生重构系列新构型的设计方法,变驱动布局的设计方法拓展了并联机构的工作空间。开发可重构并联机构的计算机辅助设计与运动分析系统,有助于提高构型设计效率。结合包装行业的应用需求开展实验研究,为新构型设计及工程应用提供参考。论文的研究工作可完善可重构并联机构的设计理论体系,快速响应产品及制造工艺定制化的需求。更多还原

【Abstract】 The innovation of mechanical equipment depends on the novelty of the mechanism structure.Nowadays,product and manufacturing process customization demand is getting higher and higher.Reconfigurable parallel mechanism has the characteristics of reconfigurable structure and flexible motion,which can respond to the requirements of modern mechanical products and manufacturing process customization.It can adapt to different working environment and flexible requirements for different tasks.It has become a research hotspot in the field of robotics and robotics.The planar parallel mechanism(PPM)has the merits of simple configuration,easy control,low cost and wide application.Two degree-of-freedom(DOF)five-bar PPM is a typical representative of PPM,and it can realize arbitrary trajectory motion in the plane.But there is a lack of a perfect reconfigurable design method.Therefore,the reconfigurable design method of PPM based on five bar mechanism is studied in this paper.The five sections of this dissertation are organized as follows:(1)Based on variable-topology design for mechanism structure,modular design and Lie group theory,a novel structural design method for reconfigurable parallel mechanisms is proposed.A class of mechanism configurations is the master model for structural design.Taking into account the relationship between structural scale constraints and motion constraints,the new kinematic limbs are constructed.Series of novel configuration families with topology association are generated through various configuration changes,including variable actuated layout,variable parameters,and variable kinematic limbs.Parameter-driving design with all-data association is carried out,providing a theoretical basis for structural design of reconfigurable mechanisms.Variable actuated layout may lead to less singular configurations,larger workspace and higher mechanism stiffness.(2)The main configuration model with full-information of bars and pairs are established.Series derived structures are designed for reconfigurable PPM,and kinematic characteristics of different kinematic patterns are analyzed.Thirteen basic configurations of the five bar mechanism are established based on 5R mechanism,and 5R metamorphic closed-loop limbs are derived.Kinematic characteristic of 5R,3R2 P,2R3P metamorphic configuration and their hybrid kinematic chains are described through Lie group.Taking 3-RRR mechanisms as the main configuration,seven configurations and their novel derived configurations are invented.Eight novel configurations with different motion patterns are derived on the 3-RRR+P hybrid platform.Novel planar lower-mobility parallel mechanisms with coaxial revolute joints on fixed base are designed.The novel mechanisms have larger workspace.These provide reference for design and optimization of configuration.(3)In this paper,the kinematic analysis of reconfigurable PPM is presented,and the CAD geometric analysis method is proposed to search mechanism reachable workspace.The three kinematic analytical methods of 5R mechanism are analyzed and compared.Based on the geometric method,the motion locus and motion characteristics of 5R mechanism and 5R mechanism with variable actuated layout are studied.Meanwhile,Experimental verification of kinematic controllability is attained.The unified kinematic equations of 3-OOF PPM are established.The kinematic characteristics of derivative 5R mechanism are researched.The CAD geometric analysis method is used to attain reachable workspace and simplify the numerical calculation process.(4)Based on the three dimensional CAD platform SolidWorks,the CAD rapid design system of 2-DOF and 3-DOF PPM is developed.Configuration design,dimension synthesis and kinematics analysis are integrated into the system.The system contains thirteen configurations of five bar mechanism and eight configurations of 3DOF PPM.It is helpful for the designers to accomplish the structural design,dimensional synthesis and kinematic analysis of 2-DOF and 3-DOF PPM.(5)An experimental platform of five bar mechanisms is set up with the DMCNET(Delta Motion Control Network).Experimental study on the kinematic characteristics of 5R mechanism and its application in Engineering are developed.The experimental results verify the correctness of the control method based on the forward and inverse solution of motion trajectory.The output trajectory is controllable and stable.Considering the packaging requirements of different sizes of customized cartons,reconfigurable carton packaging machine and egg tart packing machine are developed,which are made up of variable actuated layout five bar mechanisms.The folding processes for different sizes of the cartons are accomplished.It will be helpful for the delivery staff to improve the working efficiency and reduce the workload.The dissertation was supported by the National Natural Science Foundation of China(Grant No.51275486).Based on the above design method and experimental study,the design method of new configuration is derived.The development of computer aided design and motion analysis system for reconfigurable parallel mechanism is helpful to improve the design efficiency.The application of packaging and experimental research provides reference for the design and engineering application of new configuration.The research of this paper can improve the design theory of reconfigurable parallel mechanism,and quickly respond to the requirements of product and manufacturing process customization.更多还原