Stewart平台电液驱动机构设计(六自由度运动平台)全套含cad图纸
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毕业设计(论文)任务书学生姓名: 学号: 学 院:机械动力工程学院 专业:机械设计制造及其自动化任务起止时间: 毕业设计(论文)题目:Stewart平台电液驱动机构设计毕业设计工作内容:1. 查阅相关资料,了解Stewart平台电液驱动机构的组成、结构特点和国内外研究现状,并完成开题报告,准备开题。 13周2. 完成Stewart平台电液驱动机构整体结构设计,绘制总装配图零号图纸一张,并接受中期检查。 48周3. 完成Stewart平台电液驱动机构零件图折合零号图纸两张和毕业设计说明书初稿。 913周4. 对所有相关设计图纸和毕业设计说明书进行修改。 1415周5. 准备毕业设计答辩稿、电子演示稿,并进行答辩。 1517周资料:1 李洪人. 液压控制系统. 国防工业出版社. 1990.2 张尚盈. 液压驱动并联机器人力控制研究.哈尔滨工业大学博士学位论文, 2005.3 黄真,孔令富,方跃法. 并联机器人机构学理论及控制. 北京:机械工业出版社,1997.4 雷天觉. 液压工程手册. 北京:机械工业出版社,1990.5 蔡春源. 机电液设计手册. 北京:机械工业出版社,1997.指导教师意见:签名:年 月 日系主任意见:签名:年 月 日教务处制表附录美国国家标准和技术研究所(NIST)对并联运动机床过去、现在、未来的研究摘要并联运动机床在突破了控制器局限性的限制后,其在制造业方面的应用开始产业化。并联机床由于其投放市场后的商业价值,在1994年芝加哥国际制造业展览会上出现了新发明的数控并联机床。与传统机床相比,并联驱动技术在加工制造方面具有许多优点,比如:较高的刚度体积比、较高的速度、较高的精度、安装次数少,夹具简单。在美国,一些机床制造者正在研发并联驱动技术,同时并联驱动技术的潜在用户加工制造商正企划这种新型的多轴加工技术在操作领域的用途。NAMT、NIST的研究员及来自各行业、大学的合作者正在研究这个新型工具的独特性能。其工作包括对1995年五月搭建的八面体、六驱动器机床的大范围的实验。研究领域包括机床测量、性能测试方法及标准、性能拓展方法、仿真试验工具和开放式体系结构控制界面。本论文给出了美国国家标准和技术研究所(NIST)对并联运动机床的研究现状及历史的综述。并联运动的优点、所面临的挑战、将来的研发方向也被提到。1简介提高产品质量、降低产品成本、缩短产品开发周期是企业保持竞争力的迫切需要。这些决定竞争力的关键因素要求机床的加工精度、速度、多功能性不断发展、提高。这就对机床研究领域提出了挑战。鞭策机床研发单位为设计新机床而演化基本的机构。因此,基于并联运动机构的机床模型并联运动机床研发成功。六自由度杰出代表Stewart平台是并联运动机床的机构模型,最近许多新机床的设计都是基于Stewart平台机构模型。基于Stewart平台机构模型的并联机床的经典结构组成:动平台与固定的基础平台之间由六个同样的能活动的可伸缩杆联接。高的力容积比、高的结构刚性、低动量是Stewart平台机构的优点。从加工应用的角度考虑,Stewart平台的缺点在于工作空间复杂、运动方向受到限制、对于五自由度工作(磨、钻、简单操作)需要六个驱动器驱动。一些基于Stewart平台的机床机构模型通常叫做并联机械机构。这些并联机床与传统机床相比具有许多优点。它们还提出了一些重要的问题。这些机床的性能如何描述?计算工作空间的最好方法是什么?机床可以达到的加工精确程度?实际应用时什么是最好的控制算法?在成本方面是否具有竞争力?这些机床最适合于何种加工方式?这些机床的模块化程序设计如何最优化?何种结构在低成本的前提下又具有较多的功能?这些都是从并联机床方面提出的重要问题,自从1990年美国国家标准和技术研究所(NIST)在并联机床的许多领域进入了研究。这一论文概述了美国国家标准与技术研究对于并联运动机床的过去、现在、未来的研究,提出了一些依然具有挑战性的课题。本论文的讨论围绕着六自由度的Stewart平台机械机构、并联运动机床的机构模型。然而,还有一些并联机构的排列方式也许更适合于作为机床的机构模型(可能优于Stewart平台机构本身)。工业机器人问世以来, 采用串联机构的操作器一直占主导地位,它结构简单,工作空间大,因而获得广泛应用。与之相比,并联机器人活动空间小,活动上平台远不如串联机器人手部灵活。但是,并联机器人也有其独特的优点:并联式结构其末端件上平台同时经由6 根杆支撑,与串联的悬臂梁相比,刚度大,而且结构稳定;由于刚度大,并联式较串联式在相同的自重或体积下,有高得多的承载能力;串联式末端件上的误差是各个关节误差的积累和放大,因而误差大、精度低,并联式则没有那样的误差积累和放大关系,误差小、精度高;串联式机器人的驱动电机及传动系统大都放在运动着的大小臂上,增加了系统的惯量,恶化了动力性能,而并联式则很容易将电机置于机座上,减小了运动负荷;位置求解上,串联机构正解容易, 但反解十分困难, 而并联机构正解困难,反解却非常容易。由于机器人的在线实时计算是要计算反解的,这对串联式十分不利,而并联式却容易实现。并联机构的出现,扩大了机器人的应用范围。随着对并联机器人研究的不断深入,其应用领域也越来越广阔。并联机器人的应用大体分为六大类:运动模拟器、并联机床、工业机器人、动机构、医用机器人和操作器。运动模拟器 作为运动模拟器,其最广泛的应用是飞行模拟器。训练用飞行模拟器具有节能、经济、全、不受场地和气象条件限制、训练周期短、效率高等突出优点,目前已成为各类飞行员训练的必备工具。同时,这种运动模拟器也是研究和开发各种运载设备的重要工具。通过模拟器可以在早期发现问题、减少风险、进行综合系统验证,解决各系统间的动态匹配关系、加速系统实验过程,缩短研制周期,降低开发费用。并联机床 用作并联机床是并联机构最具吸引力的应用。并联机床结构简单,传动链短,刚度大、质量轻、成本低,容易实现“6轴联动”,能加工更加复微杂的三维曲面。还具有环境适应性强的特点,便于重组和模块化设计,可构成形式多样的布局和自由度组合。德国Micromat 公司生产的6X 并联机床,这种机床采用伸缩杆的长度变化驱动主轴部件,实现加工轨迹所需的运动,工件固定在工作台上不动。工业机器人 随着工业现代化发展的高速进程,以及加工业工艺的不断完善,技术的不断进步,工业机器人的应用被越来越多的企业认识和接受。工业机器人既保证了产品质量,又减少了特殊环境工作的危险和实现对人员的劳动强度的降低和人员劳动保护意识的提高。微动机构 作为微动机构是并联机器人的一个重要应用方面。这种微动机构发挥了并联机构的特点,工作空间不很大但精度和分辨率都非常高。医用机器人 医疗机器人已经成为医学外科学会和机器人学会共同关注的新兴技术领域。近年来,医疗机器人技术引起美、法、德、意、日等国家学术界的极大关注,研究工作蓬勃兴起。医疗机器人具备选位准确、动作精细、避免病人感染等特点。操作器 作为操作器, 并联机器人可以用作飞船和空间对接器的对接机构,上下平台中间都有通孔作为对接后的通道,上下平台作为对接环,由6 个直线驱动器驱动以帮助飞船对正;对接机构还能完成吸收能量和减振,以及主动抓取、对正拉紧、柔性结合、最后锁住卡紧等工作。对于困难的地下工程,如土方挖掘、煤矿开采,也可以采用这种强力的并联机构。Arai 等1991 年提出将并联机构装于履带式或步行式可移动的小车上,挖掘头装于并联机构的上平台,强有力的并联机构可以承受巨大的挖掘力。其他方面应用 此外,Stewart 平台还在其他方面应用,如力或位移传感器,造船起重机,主动式振动控制器,体感模拟娱乐机械等。并联机器人具有很多传统串联机器人不具备的优点,并联机器人还有很多理论问题需要进一步的研究和完善,适用于不同工作要求的新型的并联机构有待于进一步开发。目前,并联机器人研究所要解决的问题应包含以下内容: 不同自由度的新型并联机构的研究。研究新型的并联机构,并研究相应的运动学、动力学等理论,必将会进一步丰富并联机构领域的研究成果,并进一步扩大并联机构的应用范围。并联机器人运动学正解数值算法的研究。主要是提高位置正解的计算速度,这项工作是并联机器人轨迹规划的基础。并联机器人动力学模型研究。建立通用的适用于控制系统设计的并联机器人动力学数学模型,这项工作是计开发出具有优良动力学性能的并联机构,对不同类型并联机构进行动力学分析的基础。并联机机器人工作空间研究。研究各种奇异性对工作空间的影响,可以提高我们对并联机构运动机理的认识,是进行并联机构无奇异路径规划和实现运动的可控性的基础。并联机器人误差分析。建立实用的、完整的并联机构误差数学模型,分析并联机构输入误差因子对动平台位资误差的影响,从而通过控制敏感输入误差因子,提高并联机器人精度。少自由度并联机构的研究由于少自由度并联机构具有结构简单、造价低廉等特点,有着广阔的应用前景。但少自由度并联机构在某些时候的运动、动力分析反而变得更复杂。2美国国家标准和技术研究所(NIST)制造工程实验室对于并联运动机床的研究历史美国国家标准和技术研究所(NIST)制造工程实验室对Stewart平台机械机构的创新应用的研究兴趣要追溯到19世纪80年代中期,当时詹姆士和他的从事机器人系统(现在的智能系统)研究的同事研制了一个新项目绳索机器人吊车,这台机械采用的是Stewart平台的机械结构模型。用六个绞车控制的电缆的方式来控制平台,这台绳索机器人吊车最初研发的目的像传统的吊车那样是用来稳定的起重货物的。在制造业和建筑业领域,为了稳地过地搬运货物、直升机的救援工作、有害废物的再利用,许多不同型号的这种绳索机器人吊车被研发出来应用。这种绳索机器人吊车在控制负载的位置和姿态方面明显的优于传统的起重机。美国国家标准和技术研究所(NIST)对Stewart平台的深入研究生产了这种创新的机械结构绳索机器人吊车。这种八面体结构包括三个用来悬挂工作平台的上支点,采用三个上支点是为了本身是较轻的结构却能提供足够的结构刚度。詹姆士和克莱顿认为这种Stewart平台结构和八面体空间结构的结合在机床应用方面具有潜在的优点。基于这一思想,他们在1991 年提出了“新型机床”,并且建造了样机。模型结构表明该机床是由三个可运动的Stewart平台串连嵌套,第四个Stewart平台固定的结构组合而成。与传统的设计相比,这种机构的优点在于提高了刚度和精度。在建立这种新型机床设计的机构模型启动计划的过程中,美国国家标准和技术研究所(NIST)的研究员意识到:形成一种商业性的并联机床的过程也就是利用相似原理搭建成一样机的过程。美国国家标准和技术研究所(NIST)认为商业性的并联机床样机为将来的研究提供一个好的起点,并且获得了一个试验样机,该机床样机原型来自 Ingersoll 铣床公司。这种八面体机构,被公司改进后的二代产品,于1995年5月在美国国家标准和技术研究所(NIST)安装。该机床大约高5米,六个同样的绞杆,每个绞杆功率11千瓦、绞的转速范围0转/分钟6000转/分钟,机床上还配备有一个同样的备用绞杆。3美国的六条腿机床(Hexapod)用户群在美国,随着对并联运动机床研究兴趣的上升,桑蒂亚国家实验室、麻省理工学院、美国国家标准和技术研究所(NIST)等各大组织形成一个强大的六条腿机床(Hexapod)用户群,这一用户群包括机床制造商、机床用户、对并联机床的研发感兴趣的研究机构,大约34个企业,大学和政府组织的代表已经参与了第一个六条腿机床(Hexapod)用户会议,该会议在于1996 年八月在麻省理工学院举行。第二次会议于1997年3月在美国国家标准和技术研究所(NIST)举行,后来还有一些非正式会议在召开,美国机械工程师交流(ASME) 暨美国机械工程技术研讨和展览会 (IMECE) 在 1997年十一月、1998年六月、1998年九月举行, 这些非正式的会议为共享并联运动机床的试验结果、研发方向的想法和计划、确定行业需求提供了宝贵的机会。当然,在六条腿机床(Hexapod)用户群这一组织成立以前,并联机床的研发还吸引了许多院校及其他组织对并联运动机械装置(大多为机器人应用领域)的研究。4美国国家标准和技术研究所对并联运动机床现在研究领域的研究美国国家标准和技术研究所(NIST)对并联运动机床现状的研究突出在以下几点:对并联运动机床特性的更深层次的理解;评价并联运动机床性能的测试方法及检测手段的标准;冷却液走向的排布问题;与应用、研发、测试并联运动机床相关的建模和仿真问题;完成同一工作过程中的协同工作、远程控制能力的提高;控制检测的综合问题。因此,并联运动机床的研发问题围绕着达到以下设计目标而进行: 精确测量、性能拓展、及对并联机床协同研发、测量学的应用、远程控制、仿真工具的探讨、论证。这一工作的完成要依赖于各个学科的有机综合及政府、企业、大学各个合作部门的共同努力。美国国家标准和技术研究所(NIST)的并联运动机床研究项目被美国制造工程实验室引进为先进制造基础项目(NAMT)。以下部分是美国国家标准和技术研究所(NIST)对并联运动机床项目的最新研究成果。4.1并联运动机床的工作性能描述及测量4.2并联运动机床的校准4.3并联运动机床中伸缩杆的测量4.4并联运动机床的机构刚度及测量4.5并联运动机床的建模和仿真4.6在并联运动机床上零件编程和加工的应用4.7控制器的发展5结论、挑战及并联运动机床的研发方向致谢附录First European-American Forum on Parallel Kinematic MachinesTheoretical Aspects and Industrial Requirements31 August 1 September, 1998Milan, ItalyParallel Kinematic Machine Research at NIST:Past, Present, and FutureAlbert J. WaveringIntelligent Systems DivisionNational Institute of Standards and Technology (NIST)Gaithersburg, MD 20899, U.S.A.AbstractUnchained from the confines of controller limitations, the industrial application of parallel kinematic machines in manufacturing is beginning to emerge. The launch of commercially available hexapod machine tools at the 1994 International Manufacturing Technology Show in Chicago represented the first radical departure in machine tool design since the introduction of numerical controls. The parallel actuator technology promises to offer manufacturers a number of advantages relative to conventional machine tools, such as a higher stiffness-to-mass ratio, higher speeds, higher accuracy, reduced installation requirements, and mechanical simplicity.Several machine tool makers in the U.S. and around the world are pursuing parallel actuator technology, while their prospective customersmanufacturersare beginning to contemplate what the novel multi-axis machining technology might mean for their operations.As part of the Manufacturing Engineering Laboratorys National Advanced Manufacturing Testbed (NAMT), NIST researchers and collaborators from industry and universities are studying the new tools unique capabilities. The work includes extensive tests on an octahedral hexapod machine tool that was installed at NIST in May 1995. Research areas include machine metrology, performance characterization test methods and standards, performance enhancement methods, simulation and remote experimentation tools, and open architecture controller interfaces. This paper will give an overview of history and current status of research in parallel kinematic machines at NIST. The merits and key challenges of parallel kinematic machine tools will also be addressed, and directions for future research will be identified.1 IntroductionImproving product quality, reducing product cost, and shortening the product development cycle have always been critical for companies to stay competitive. These competitive drivers result in a continuing need to achieve improvements in accuracy, speed, and versatility in machining operations. These pressing needs pose challenges to the machine tool research community, and have driven several machine tool companies to revisit some of their basic assumptions about machine tool design. As a result, prototypes of a new class of machine tools based on parallel kinematic structures, known as parallel kinematic machines (PKMs), have been introduced.The six degree-of-freedom Stewart platform 1 is one PKM configuration that has been used recently in a number of new machine tool designs. A Stewart platform machine tool typically consists of a moveable spindle platform connected to a rigid base through six identically jointed and extensible struts. The Stewart platform mechanism is characterized by high force capacity,high structural rigidity, and low moving mass 2. For machining applications, disadvantages of the Stewart platform include a complex work volume, limited orientation range of motion, and a requirement of six actuators for a five degree-of-freedom task (milling, drilling, and similar operations). Several prototypes of Stewart-platform-based machine tools, commonly called hexapods, have been produced in the U.S. by companies such as Giddings & Lewis1, Hexel Corporation, and the Ingersoll Milling Machine Company.These machine tools promise some key advantages over conventional machine tools, but they raise important questions as well. How should the performance of these machines be characterized? What is the best way to describe the work volume? What degree of accuracy is achievable? What are the best control algorithms to employ? Can they be cost-competitive? What types of machining applications are best suited to these machines? How can part programs be optimized for them? What configurations provide the most versatility for the least cost? These are just a few of the important issues raised by hexapod machine tools. Since the early 1990s, NIST has conducted research in a number of these areas. This paper summarizes the past, current, and future work at NIST in parallel kinematic machines, and examines some of the remaining challenges. In this paper, the discussion is focused on the six degree-offreedom Stewart platform mechanism, reflecting the configuration of the prototype machine at NIST. However, there are certainly other parallel kinematic arrangements that may be well suited for use as machine tools (perhaps even more so than the Stewart platform).Since the development of industrial robots, using tandem with the operation has been dominated by its simple structure, work space, which was widely used. By comparison, parallel robot small space activities, activities on the platform are far less flexible series robot hand. However, the parallel robot has its unique advantages: Parallel structure of its terminal on the platform at the same time through the six-support, compared with the series of cantilever, stiffness, and structural stability; because of stiffness, a series of parallel with the same dignity or volume, there is high And more carrying capacity; Series at the end of the error is the accumulation of error in all joints and enlarge, thus error, precision low, there is no parallel as the accumulation of errors and to enlarge relations, small error and high precision; Series Robot The drive motor and transmission system mostly on the size of the campaign arm, to increase the systems inertia, the deterioration of the dynamic performance, and the parallel is very easy to put motor-seat, reducing the exercise load; location for , The series of institutions is easy, but the anti-solution is very difficult, and parallel institutions are of the difficulties, the anti-solution is very easy. As the robot on-line real-time calculation is to calculate the anti-solution, which is very unfavorable Series, and the parallel is easy to achieve. The emergence of parallel institutions, expanded the scope of application of robots. As the parallel robot in-depth research of its increasingly broad applications. The application of parallel robot can be divided into six major categories: Motion Simulator, parallel machine tools, industrial robots, moving bodies, and medical robot for operations. Motion Simulator as a sports simulator, the most widely used is the flight simulator. Flight simulator training with energy, economy, all from the venue and weather conditions, short training period, the outstanding merits of high efficiency, all kinds of pilot training has become an indispensable tool. At the same time, this movement simulator is also research and develop an important tool for carrying equipment. Through the simulator can be found in the early problems, reduce risk, comprehensive verification system to solve all the dynamic matching system, speed up the process of experimental systems, shorten the development cycle and reduce development costs. PMT for PMT parallel mechanism is the most attractive application. PMT structure is simple, short transmission chain, stiffness, light weight, low cost, easy to implement six-axis, to processing more complex three-dimensional surface of the micro-hybrid. Adaptability also has the characteristics of the environment, facilitate restructuring and modular design, can constitute a variety of layout and composition of freedom. Germany Micromat companys 6 X parallel machine tools, such a telescopic machine-driven changes in the length of spindle components, to achieve the required processing track the movement of the workpiece fixed at the stage fixed. With the modernization of industrial robots industrial development of high-speed process and increase the continuous improvement of industrial technology and technology advances in the application of industrial robots are more and more enterprises understand and accept. Industrial robots not only ensure the quality of products, and reduce the risk of the work of the special environment and realize the strength of the labor and personnel to reduce labor protection awareness raising. Fretting institutions as a micro-robot body is an important parallel applications. Such fretting agencies played a parallel mechanism to the characteristics of the work space but not great precision and resolution are very high. Robot has become a medical robot Institute of Medicine and Surgery Robot Institute of common concern emerging technology. In recent years, the medical robot technology from the United States, France, Germany, Italy, Japan and other countries of great concern to the academic, research have mushroomed. Medical robot with the election of accurate, precise movements, to avoid the characteristics of the patient. Operators as the operation, parallel robot can be used for spacecraft and space docking with the docking mechanism, from top to bottom among all platforms through holes as the channel after docking, and docking ring as a platform from top to bottom, from six straight drive to help drive the spacecraft Is; can complete the docking mechanism of energy absorption and vibration, and take the initiative to crawl, the tension is, flexible integration, the last card locked tight, and so on. The difficulties of underground works, such as the Turkish side mining, coal mining, can also use this powerful parallel institutions. Arai, such as in 1991 proposed a parallel mechanism installed in or walk-tracked to a small mobile vehicles, in parallel with the first excavation of the bodies on the platform, a powerful parallel institutions can withstand the excavation of huge. Other applications In addition, Stewart also other aspects of application platforms, such as force or displacement sensors, shipbuilding cranes, active vibration control, the sense of mechanical simulation, and other entertainment. Parallel series robot has many traditional robots do not have the advantage of parallel robot there are many theoretical issues need further study and improve, apply to different job requirements of the new parallel mechanism to be further developed. At present, the Institute for parallel robot to solve the problem should include the following: Different degrees of freedom parallel mechanism of the new study. New Study on the parallel institutions, and to study the corresponding kinematics, dynamics, and other theories, will be further enriched the field of parallel institutions research results and further expand the application of parallel institutions. Parallel kinematics robot is the study of the numerical algorithm. Location is the main solution is to increase the computing speed, which is parallel robot trajectory planning base. Parallel robot dynamics model. The establishment of a common control system applicable to the design of the parallel robot dynamics model, the development of this work is to have excellent dynamic performance of parallel institutions, the different types of parallel institutions based on the analysis of the dynamics. And on-line robot work space research. The study of the various singularity of the impact of the work space, we can improve on the parallel mechanism of awareness campaigns, a parallel mechanism is not singular path planning and realization of the controlled movement of the foundation. Parallel Robot error analysis. The establishment of practical, complete parallel mechanism error mathematical model of parallel institutions enter error factor on moving platforms in the error-effects, thereby through control of sensitive input error factor, increased parallel robot accuracy. Parallel institutions less freedom because of fewer degrees of freedom parallel mechanism is simple in structure, low cost, and other characteristics, have broad application prospects. But less freedom parallel mechanism at certain times of movement, dynamic analysis it has become more complex.2 History of PKM Research at the NIST Manufacturing Engineering LaboratoryInterest within the NIST Manufacturing Engineering Laboratory (MEL) in innovative applications of Stewart platform mechanisms dates back to the mid 1980s, when James Albus and his colleagues in the Robot Systems (now Intelligent Systems) Division developed a concept for a robot crane (Figure 1). The machine, now called the RoboCrane 3,4, is a Stewart platform configuration where six winch-actuated cables are used to suspend and control the platform. The RoboCrane was developed originally under a Defense Advanced Research Project Agency (DARPA) contract to stabilize loads on conventional cranes. Many different RoboCrane configurations have been developed for applications ranging from large-scale manufacturing and construction, to stabilized cargo handling, helicopter rescue, and hazardous waste remediation. The principal advantage of the RoboCrane over conventional crane systems is improved control of the position and orientation of the load.NIST research into Stewart platforms also produced an innovative structure from which tosuspend the RoboCrane work platform. An octahedral structure containing the three upper support points necessary to suspend the work platform provides exceptional structural stiffness in a lightweight frame. This combination of a Stewart platform and an octahedral space frame was also recognized by NIST researchers James Albus and Clayton Teague to have potential advantages for machine tool applications. In 1991 they proposed a “New Class of Machine Tools” based on this concept, and built the model shown in Figure 2. The model configuration shown actually can be considered to be three Stewart platforms in series (lower motion platform, “virtual” Stewart platform for laser metrology, and upper fixed platform) nested within a fourth fixed Stewart platform that forms the structural frame. The benefits expected to result from this configuration included greatly improved stiffness and accuracy haracteristics compared with conventional designs.During the course of pursuing a start-up project to build a prototype of this new machine tool design, NIST researchers became aware that a commercial machine tool builder was in the process of building a prototype machine with a very similar configuration. NIST decided that a commercial prototype would provide a good starting point for investigations, and procured an experimental prototype Octahedral Hexapod machine tool from the Ingersoll
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