含四杆机构单元的重载转运机器人构型综合

针对用于轴类物料抓取及卸载的重载转运机器人机构形式单一、转运范围局限大等问题,进行了重载转运机器人新构型的研究。首先分析了重载转运机器人机构的结构特点和工作原理,发现含有四杆机构单元的重载转运机器人具有灵活性高、承载能力大等优势,为构型综合和新方案优选提供依据。其次基于图论对只含转动副的平面机构进行构型综合,得到七杆、九杆机构拓扑胚图,利用胚图插点法对拓扑胚图进行插点,建立拓扑图,进而转化成对应的运动链,得到构型图谱。然后根据重载转运机器人机构中的四杆机构单元和功能构件,对拓扑图进行特定化标记,提出重载转运机器人优选条件,分析和优选特定化标记的拓扑图,得到其最佳构型。最后,利用Adams软件对一种优选机构进行仿真分析,结果表明,该机构在平面运动过程中可以同时实现远距离抓取和大范围俯仰运动,从而验证了该机构构型设计的合理性。     

重载搬运机器人的动力学仿真及控制系统设计

关节型重载搬运机器人各运动关节动态性能和能量耗散水平直接影响机器人以及运动规划的可达性。以ABB公司生产的IRB460型重载搬运机器人为研究对象,针对其机械本体结构特性,建立重载搬运机器人三维模型。若仅考虑回转轴、大臂和小臂组成的三个自由度,重载搬运机器人系统模型可简化成空间三关节机器人系统模型;依据拉格朗日力学方程建立重载搬运机器人系统动力学模型,利用机械臂逆运动学和五次多项式插值算法完成对多关节机械臂空间轨迹规划。通过动力学仿真分析可知,重载搬运机器人各运动关节的动态性能变化稳定且能量耗散较小,且能够沿着预定轨迹完成PTP模式的运动控制。最后,搭建控制系统仿真实验平台,提出一种重载搬运机器人控制系统模型,实验结果表明,所设计的重载搬运机器人控制系统能够准确、稳定的控制各运动关节运动,验证了各运动关节驱动电动机功率参数选择的合理性,为实际的工业生产应用奠定了理论基础。     

双足机器人腿部新构型设计与试验研究

探究高动态性能双足机器人对腿部设计的要求,阐明机器人腿部设计准则、设计方案和实现措施。提出一种腿部串并联新构型方案,膝关节驱动器上移到髋关节,踝关节驱动器上移到膝关节,膝关节驱动器通过简化五连杆机构将运动传递到膝部,踝关节驱动器通过并联四连杆机构将运动传递到踝部。对踝关节并联机构和整个腿部关节进行运动学正逆解,建立新构型机器人的仿真模型。考虑运动控制算法,完成机器人动力学仿真。测试准直驱驱动器性能,并完成串并联构型腿部样机试验验证,机器人可实现0.4m/s的行走速度。结果表明,提出的腿部串并联新构型与传统串联构型比具有更高的运动性能,新构型机器人性能在真机测试中得到验证。该串并联新构型方案在双足机器人和其它服务机器人领域具有广阔的应用前景。     

基于凯恩法的大摆角混联机床并联机构的动力学分析

针对一种大摆角混联机床的并联机构,首先对其机构构型进行了描述:然后以输入端和输出端的运动映射为基础,引入凯恩方法根据运动学分析原理来分析动力学问题,分别对输入和输出端运动构件进行动力学建模。假定机床各部件为刚性构件,不存在弹性力和摩擦力,通过综合从而建立并联机构系统的动力学方程,得到并联机构输出运动与所受驱动力的关系。最后,通过算例进行了仿真验证,得到了在给定输出运动时,动平台、滑块及各个驱动支链的驱动力曲线,对进一步分析大摆角混联机床的动态性能、机构优化设计和控制模型的建立等工程应用奠定了基础。     

基于刚柔耦合建模的工业机器人瞬变动力学分析

为适应工业机器人高速、重载、高精度的要求,以工业机械臂的瞬变过程为研究对象,提出以末端执行器的振幅判断机器人在瞬变过程中的动态性能,利用多体动力学和有限元的方法建立刚柔耦合模型,对工业机器人在整个作业过程中的动态特性进行描述和分析,仿真计算工业机器人在振幅最大时刻的应力分布及危险区域节点的应力变化,为机器人的动态性能评估、疲劳强度分析和寿命预测提供了依据.     

基于ADAMS的管道机器人变径机构优化设计

为提高支撑轮式管道机器人驱动效率、改善其性能,对管道机器人变径机构进行了优化设计。通过变径原理阐述及动力学分析,建立机构优化数学模型。基于ADAMS参数化建模和优化设计功能,以高灵敏度设计参数为优化变量,考虑机构几何学、运动学及动力学约束条件,以变径过程驱动电机转矩最小为目标对其展开优化设计。优化后电机最大输出转矩较优化前减小45.2%,优化效果明显,为管道机器人设计提供了参考。     

混合驱动连杆机构优化设计和性能实验研究

本文针对混合驱动连杆机构辅助运动最大瞬时驱动功率最小为目标函数,对机构进行动力学优化设计.同时考虑到构件变速运动所产生的动载荷难以完全平衡和消除,对辅助电机控制和系统动态性能均有不利影响.故而以构件材料为目标,进行了优化设计研究,分别就碳素钢、尼龙、酚醛层压材料等材料构件机构进行了动力学计算,分析其对应驱动功率的大小;并通过对比实验,分析它们对系统动态输出性能的影响程度,结果表明复合材料构件有效的改善了系统的性能.     

六轮腿复合型移动机器人越障分析及机构设计

面向无人化复杂野外环境考察及勘探的需求,以设计具有良好的机动性、通过性的自动勘察机器人为目标。进行了六轮腿复合型移动机器人本体的抗倾翻能力分析;选取了两种典型障碍沟和坎,对六轮腿复合型移动机器人本体的越障过程进行构型分析;进行了六轮腿复合型移动机器人本体的机构设计研究,重点设计了一种可以主动转动又能被动柔顺的轮腿复合移动机构;进行了机器人性能测试试验,验证了机器人本体的可靠性和实用性。     

基于柔体动力学分析的平面并联机器人结构优化设计

针对高速高精度机器人的结构柔性问题，提出了一种基于柔体动力学分析的结构参数优化设计方法，并对一种含平行四边形结构的平面并联机器人进行了结构参数优化。采用离散梁模型来仿真机器人的柔性，轴套模型来仿真机器人关节的柔性，建立了参数化的柔体动力学模型。利用动力学仿真软件ADAMS对机器人的动态响应、驱动力矩和固有频率进行了计算，据此对机器人的结构参数进行了优化。最后通过固有频率测试和动态响应实验结果验证了优化设计的有效性和准确性。     

2-UPR-RPU并联机器人的动力学建模与性能分析

动力学建模和性能分析是并联机器人设计中的研究重点。以2-UPR-RPU三自由度并联机器人(U:虎克铰,P:移动副,R:转动副)为研究对象,采用螺旋理论对其进行动力学建模与性能分析。基于闭环矢量法建立2-UPR-RPU并联机器人的运动学逆解模型。采用螺旋理论分析2-UPR-RPU并联机器人分支中各个关节和杆件的速度和加速度,结合虚功原理计算2-UPR-RPU并联机器人运动时的驱动力,并通过ADAMS软件进行数值仿真验证。基于动力学模型分析2-UPR-RPU并联机器人的动态可操作度椭球指标,获得2-UPR-RPU并联机器人在不同操作高度下的转动和移动动态性能分布图谱,为机构的样机设计提供参考依据。2-UPR-RPU并联机器人的动力学建模和性能分析为实现机构在实际操作中的高效高精度控制提供了重要的基础保证。     

一种大型复杂构件加工新模式及新装备探讨

大型复杂构件是航空航天、能源、船舶等领域装备的核心结构件,此类构件通常具有尺寸大、形状复杂、刚性弱等特点。传统"分体离线加工-在线检测"模式存在工艺不稳定、过程复杂、柔性差、周期长等问题,以龙门式多轴数控机床加工为代表的"包容式"加工模式,难以适应大型复杂构件的高效高质量加工制造需求。提出一种基于移动式和吸附式机器人的多机协同原位加工新模式,通过多机器人系统自主寻位、精确定位加工与加工质量原位检测,实现大型复杂构件多安装面并行铣削、制孔与打磨等作业。多机器人系统包括移动式混联机器人、吸附式并联机器人、移动式串联铣削机器人、移动式双臂加工机器人和移动式打磨机器人。构建多机协同原位加工模式,需要揭示多机器人协同原位加工行为与大型弱刚性结构件质量控制的交互机理,面临着本体、测量、工艺和集成四个方面的挑战,需要设计高灵活、高刚度的移动式和吸附式加工机器人,解决移动机器人自主准确寻位和超大结构件原位高精检测难题,攻克加工变形误差在线补偿和振动抑制技术,通过集成实现多机协同高效高精加工,为大型复杂构件的高效高质量制造提供创新技术及装备,并实现此类构件制造核心技术及装备自主可控。     

Dynamic load analysis and design methodology of LCD transfer robot

The objective of the present study is to develop a design methodology for the large scale heavy duty robot to meet the design requirements of vibration and stress levels in structural components resulting from exposure of system modules to LCD (Liquid Crystal Display) processing environments. Vibrations of the component structures significantly influence the motion accuracy and fatigue damage. To analyze and design a heavy duty robot for LCD transfer, FE and multi-body dynamic simulation techniques have been used. The links of a robot are modeled as flexible bodies using modal coordinates. Nonlinear mechanical properties such as friction, compliance of reducers and bearings were considered in the flexible multi-body dynamics model. Various design proposals are investigated to improve structural design performances by using the dynamic simulation model. Design sensitivity analyses with respect to vibration and stresses are carried out to search an optimal design. An example of an 8G (8th-Generation) LTR (LCD Transfer Robot) is illustrated to demonstrate the proposed methodology. Finally, the results are verified by real experiments including vibration testing.     

基于刚度定向的工业机器人铣削姿态优化研究

针对工业机器人结构非对称引起的主刚度方向难以确定、因刚度低导致的铣削过程中容易发生模态耦合颤振的问题,提出了一种机器人加工系统主刚度定向方法,并利用机器人功能冗余特性优化姿态,以提高铣削过程的稳定性。计算工业机器人末端笛卡儿坐标系中的刚度椭球,确定切削平面内机器人的主刚度方向;通过建立加工系统的动力学模型,得到机器人铣削模态耦合颤振的稳定性判据;基于刚度定向方法,提出一种机器人铣削姿态优化算法。实验结果表明,在不改变其他参数的情况下,通过优化工业机器人姿态,可以保证机器人沿给定轨迹加工的稳定性。     

Robot machining: recent development and future research issues

Early studies on robot machining were reported in the 1990s. Even though there are continuous worldwide researches on robot machining ever since, the potential of robot applications in machining has yet to be realized. In this paper, the authors will first look into recent development of robot machining. Such development can be roughly categorized into researches on robot machining system development, robot machining path planning, vibration/chatter analysis including path tracking and compensation, dynamic, or stiffness modeling. These researches will obviously improve the accuracy and efficiency of robot machining and provide useful references for developing robot machining systems for tasks once thought to only be capable by CNC machines. In order to advance the technology of robot machining to the next level so that more practical and competitive systems could be developed, the authors suggest that future researches on robot machining should also focus on robot machining efficiency analysis, stiffness map-based path planning, robotic arm link optimization, planning, and scheduling for a line of machining robots.     

Design of a five-axis ultra-precision micro-milling machine—UltraMill. Part 2: integrated dynamic modelling, design optimisation and analysis

Using computer models to predict the dynamic performance of ultra-precision machine tools can help manufacturers to substantially reduce the lead time and cost of developing new machines. However, the use of electronic drives on such machines is becoming widespread, the machine dynamic performance depending not only on the mechanical structure and components but also on the control system and electronic drives. Bench-top ultra-precision machine tools are highly desirable for the micro-manufacturing of high-accuracy micro-mechanical components. However, the development is still at the nascent stage and hence lacks standardised guidelines. Part 2 of this two-part paper proposes an integrated approach, which permits analysis and optimisation of the entire machine dynamic performance at the early design stage. Based on the proposed approach, the modelling and simulation process of a novel five-axis bench-top ultra-precision micro-milling machine tool—UltraMill—is presented. The modelling and simulation cover the dynamics of the machine structure, the moving components, the control system and the machining process and are used to predict the entire machine performance of two typical configurations.     

Static balancing of planar articulated robots

Static balancing for a manipulator’s weight is necessary in terms of energy saving and performance improvement. This paper proposes a method to design balancing devices for articulated robots in industry, based on robotic dynamics. Full design details for the balancing system using springs are presented from two aspects: One is the optimization for the position of the balancing system; the other is the design of the spring parameters. As examples, two feasible balancing devices are proposed, based on different robotic structures: The first solution consists of linkages and springs; the other consists of pulleys, cross mechanisms and (hydro-) pneumatic springs. Then the two solutions are compared. Pneumatic, hydro-pneumatic and mechanical springs are discussed and their parameters are decided according to the requirements of torque compensation. Numerical results show that with the proper design using the methodology presented in this paper, an articulated robot can be statically balanced perfectly in all configurations. This paper therefore provides a design method of the balancing system for other similar structures.     

A mechanical structure-based design method and its implementation on a fly-cutting machine tool design

The mechanical structure has a main influence of the machining performance and the servo performance. In this study, a mechanical structure-based design method is presented to design and optimize an ultraprecision fly-cutting machine tool. This method takes full account of the influence of mechanical components on the machining performance and servo performance at the design stage. The effect of the components structure on the roughness of machined surface is discussed, and an optimized structural form of the aerostatic spindle is given. The influence of the mechanical structure on the control system and electronic drives is discussed, and an integrated dynamic design model is built and used to optimize the hydrostatic slide. Furthermore, the impact of mechanical system dynamic performance of the machine tool on the processing topography is analyzed by the finite element model of the machine tool. This method provides a theoretical basis for the design and optimization of mechanical components and machine tools stiffness loop.     

Dynamic characterization of machining robot and stability analysis

Machining robots have major advantages over cartesian machine tools because of their flexibility, their ability to reach inaccessible areas on a complex part, and their important workspace. However, their lack of rigidity and precision is still a limit for precision tasks. Innovations and design optimization of robotic structure, links, and power transmission allow robot manufacturers to propose business solutions for machining applications. Beyond accuracy problems, it is also necessary to quantify the vibration phenomena that may affect, as in machine tools, the quality of machined parts and the tools and spindle lifespan. These vibrations occurred at specific machining conditions depending on robot and spindle dynamic properties. The robot’s posture evolved significantly in its workspace and induces dynamic’s changes observed at the tool tip that in turn impact the stability of the machining process. The objective of this paper is to quantify the dynamic behavior’s variation of an ABB IRB 6660 robot equipped with a high-speed machining (HSM) spindle in its workspace and analyze the consequences in terms of machining stability. Through an experimental modal characterization, significant variability of modal parameters is observed at the tool tip and impacts the stability of machining. The results show that an adjustment of the cutting conditions must accompany the change of robot posture during machining to ensure stability.