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本科生毕业设计 论文 外 文 翻 译 原 文 标 题ANovel Linear Folding Mechanism Configuration and Position Precision Analysis 译 文 标 题一种新型线性折叠机构 配置和定位机构分析 作者所在系别机电工程学院 作者所在专业机械设计制造及其自动化 作者所在班级B13113 作 者 姓 名张琳怡 作 者 学 号20134011302 指导教师姓名刘卫 指导教师职称副教授 完 成时 间2017年3月13 北华航天工业学院教务处制 第 1 页 译文标题译文标题一种新型线性折叠机构 配置和定位机构分析 原文标题原文标题 ANovel Linear Folding Mechanism Confi guration and Position Precision Analysis 作作者者LeiyuZhang YangYang译译名名张磊宇 杨阳国国 籍籍中国 原文出处原文出处Advances in Reconfigurable Mechanisms and Robots 一种新型线性折叠机构 配置和定位机构分析一种新型线性折叠机构 配置和定位机构分析 摘要摘要 线性折叠机构用于将末端执行器移动到所需位置 可以提高安全性 减少 多关节机器人占用的空间 设计了一种矩形块作为折叠机构的通用元件 以刚性 方式连接一系列块以形成折叠臂 四个相邻块之间的连接方法 基于连接方法 几 个配置的远距观测仪的机制提出了 此外 折叠臂的定位精度进行了分析 由折叠 距离和其他因素的影响 分析结果表明 提出的折叠臂配置具有高定位精度和长折 叠距离 这种类型的线性折叠机制可以应用到服务机器人与人类合作 关键词关键词折叠机制 矩形块 同步带 精密分析配置 1 1介绍介绍 折叠机制通常连接基础部分和末端执行器 以确保远程终端执行器的运动 有 几种类型的机制用于移动远程处理设备 剪刀高空作业平台是典型的类型的望远 镜设备 广泛用于高海拔的运转和维护 Enders 等人开发的折叠机制延伸通过引进 流体和缩进排气液体 Lee 等人公开了一种用于桥梁运输系统的折叠管组 其包括多个 圆筒形管和延伸 收缩线 Lee等人 设计了一种由钢丝和钢丝组成的钢丝驱动双向折叠 机构 然而 在这些类型的折叠机制之上 基础部分的体积相当大为了达到足够的刚度 此外 终端执行器需要一个相当大的扩展长度的差异 以确保一个适当的移动空间 此外 终端执行器需要一个相当大的扩展长度的差异 以确保一个适当的移动空间 因此 折叠 机制上面提到的体积收缩状态将会十分笨重 孔等人已经开发了一个可折叠的样品罐捕获机制 TSCCM 为翻滚的样品容器 在轨道上检索 另一个直线折叠机构由川渊等人发明的 包括多个块 折叠臂以 刚性连接的方式实现 黎平和叶浓描述一个往复推送链可扩展在它自身的重力下 以直线水平方向 推动链通常用于将对象从一个位置到另一个地方 一些作者提 出使用折叠机制以紧凑的体积为机械臂的发展方向 然而 上述研究缺乏足够的配 置和相对精度分析 线性折叠机制提出了一种新型折叠机制 这种类型的折叠机制可以提高安全通 过消除这种风险 不可避免的对于一个典型的机器人手臂肘关节 物体在机器人手 臂肘关节时手臂部分之间被关闭 此外 折叠臂组成的块可以存储在一个紧凑的情 况下 因此 这种机制可以减少空间来容纳传统的关节 本文几个配置这种机制的 支持 相对位置精度分析的数值模拟是通过折叠臂的数学模型 2 2折叠机构的结构折叠机构的结构 有各种各样新型折叠机构的配置 一般来说 这种折叠机构包括多个块 存储 第 2 页 箱 驱动单元和终端执行器 自由连接的块被存储在存储盒中 驱动单元驱动的 块可以在任意方向上伸出 并以刚性方式对齐以形成刚性对准 因此 折叠臂可以 由刚性的块对齐 如图 1 所示 端部执行器安装在折叠臂前端 这种折叠机构与 传统的多关节机器人相比 收缩状态占用更少的空间 a b 图 1 折叠机构的两种状态 a 收缩状态 b 扩张状态 2 12 1折叠机构的配置折叠机构的配置 为了保持扩展块以刚性的方式 本节提出了几种连接方法 第一次连接方法具 有最高的铰链连接的可靠性 为 在图 2a 所示 在自由连接方式的块可以在相对 于下一块铰链销转动 钢丝绳是另一种连接方法 如图 2b 所示 对钢丝绳的两端 分别固定在头块和最后一个 所有的块都使连接在一起 第三种连接方式是两个相邻的块由同步带连接 如图 2 所示 同步带 齿形带 与上表面网格波纹每一块结构使块固定以一个刚性的方式 如图 3a 所示 有一个 锁紧机构和凹进部分的上表面 当锁机构与相邻块的相应凹入部分接合时 相邻 块连接 因此 可以连续扩展块固定的最后方法 a b 图 2 两个折叠机制的配置 第 3 页 a b 图 3 另两个配置折叠机制 基于结构和连接方法 提出了若干折叠机制的配置 为了确保扩展块相互固 定 所有的上表面和正下方相邻块的连接形成一个可折叠的手臂 因此 这个线性 折叠手臂可以沿任意方向扩展 有一个终端执行器安装在前端的手臂 折叠臂也 能承受在任何方向上施加在末端执行器上的力 因为有四个连接方法 创建 16 个 组合 这意味着有十六个折叠臂理论上的配置 根据加载条件和连接的可靠性 四 种典型的配置如图 2 和 3 所示 折叠臂的安排并不局限于上述配置的描述 新组 合可一满足一些特定的目的 如最小空间需求和方便的存储 此外 此外 自由结 合方式可能存储在一个螺旋面情况下或其他情况下合适的形状 在传动方式的选择上 可采用链轮传动和蜗杆传动 将挡块推离 链轮传动可 实现快速延伸和回缩 每一块在底槽 然后链轮与凹槽接合 如图 3 所示 由于 多边形效应和啮合冲击 末端执行器可能产生剧烈振动 链轮驱动的折叠机构适 用于高速 低精度场合 与蜗杆传动折叠臂可以稳步扩展 如图 4 所示 此外 延伸和回缩的速度是连续的和光滑的 带蜗杆传动的折叠机构可代替穆蒂关节臂 在维修机器人中使用 因此 这种折叠臂应该具有很高的定位精度 在 2 2 章 对折叠机构的位置精度进行了详细的建模和分析 O M f i Oi 1 O G i G 图 4 直线折叠机构 第 4 页 2 22 2直线折叠机构的设计直线折叠机构的设计 本节重点研究了带蜗轮传动的折叠机构 同步带的结合和铰链采用折叠臂的配 置 如图 4 所示 它的齿形带前端与第一块粘合 它的齿啮合的上表面波纹结构确 保相邻两块面之间的紧密联系 与钢丝绳相比 同步带通常拥有足够的强度和刚 度 在该机制中 一个中国标准的带 指标选择 10 吨 压力辊用于压缩带紧 然后 折叠臂由刚性块的方式支持两个支撑轮 折叠距离 延长长度 是扩展块的长度的 总和 折叠臂缩回时 同步带通过刮刀与波纹结构分离 块是分开的 从刚性排列 到离散排列 然而 离散块仍以铰链连接 可在任何方向弯曲 因此 离散的可安 置在一个合适的形状 这种线性折叠机制 图 4 是由蜗轮传动驱动的 手臂的移动方向相同的方向 转动蜗杆的轴 此外 这种机制包括基架可以旋转中心 O 改变仰角 的折叠臂相 对于水平方向 3 3折叠臂位置精度分析折叠臂位置精度分析 终端执行器的位置精度对实现抓取任务非常重要 在块的重力与物体 同步带 张紧 然后 将弯曲折叠臂 然后终端执行器将偏离目标的位置 为了确定偏差 定位精度的数学模型 为简化复杂性 符合降低假设在力学模型的推导过程 1 铰链中的间隙被忽略 2 每个块的变形被忽略 4 4模拟结果和讨论模拟结果和讨论 对上述数学模型的计算方法与 MATLAB 编程 对于这种线性折叠机构 最大折 叠距离为 1500 mm 折叠臂由 O 形折叠臂组成 30 块 计算程序中使用的主要参数 见表 1 通过数值模拟 得到了折叠臂末端 30 的偏差 如图 5 所示 横向偏差 dh 上涨增加的扩展长度 与此同时 整个偏差在一定长度的增加上升 dh 和 dv 的 分布是相似的 折叠臂无负荷的最大偏差是 0 104 毫米和 0 06 毫米在水平和垂直 方向 i 30 分别 那么这两个偏差达到最大值 i 30 mt 2 5 公斤 表 1 直线折叠机构主要参数 第 5 页 图 5在 30 的偏差 水平偏差dh垂直偏差dv 图 6 显示了仰角 对偏差的影响某些质量 mt 2 5 kg 但是 仰角 由 于折叠臂的限制和基础框架只能改变 70 到 70 在一定长度的偏差度达到最大 时 仰角 等于零 如图 6a 所示的 两侧 整个偏差 dh 为折叠臂绕中心旋转向上 或向下逐渐降低从水平位置的 dh 几乎为零的偏差时 角 等于 70 或 70 然而 垂直偏差 dv 几乎是零角度时 等于 70 0 70 如图 6B 所示 dv 出现 偏差的最大值 在上部和下部的旋转范围内 可以发现偏差 dh 和 dv 有相对的角 双 边对称 这是因为两个偏差是 主要受 Mi 这是对称的角度 由于调频的限制力 F 我总是要满足式 4 然后最大值 FN 最大的力 FN 我 可以计算其中 Fn max 432 38 根据 T 的影响 他 和 mt 参数以上 力 FN 我通 过在 0 和 MT 2 5 公斤的数值模拟获得的 如图 7 所示 可以看出 折叠机构 的安全负荷 从 2 5 公斤的有效折叠长度为 1500 mm 图 6在 mt 2 5 kg 的偏差 水平偏差dh垂直偏差dv 第 6 页 图 7 力FN i 5 5结论结论 1 该块采用的折叠机构的主要组成部分 四相邻两块之间的连接方法 根据 各连接方式的优点提出了机构 提供了四个切实可行的折叠配置 2 建立了位置精度的数学模型 得到了扩展长度 质量 mt 和仰角 3 一个精确的模型进行数值模拟 利用 MATLAB 随着延伸长度或质量太增加 DH 和 DV 兴起的偏差 因此 这种体积小巧的折叠机构具有优良的定位精度和较长的折叠长度 第 7 页 ANovel Linear Folding Mechanism Confi guration and Position PrecisionAnalysis Abstract The linear folding mechanism which is used to move the end effector to a desired position can enhance the safety and reduce the space to be occupied by the multi joint robot A rectangle shaped block is designed as the general element of the folding mechanism A series of blocks are connected in a rigid manner to form a folding arm Four connection methods between the adjacent blocks are presented Based on the connection methods several confi gurations of the tele scopic mechanism are proposed Besides the position precision of the folding arm is analyzed which is influenced by the folding distance and other factors The analysis results show that the folding arm with the proposed confi guration possesses high position precision and a long folding distance This type oflinear folding mechanism can be applied to service robots which cooperate with humans Keywordsfolding mechanismRectangle shaped block Confi guration Precision analysis Synchronous belt 1Introduction The folding mechanism usually connects the base portion and the end effector to ensure the long distance movement of the end effector There are several types of this mechanisms used to move a remote handling equipment The scissors aerial work platform is a typical type of folding equipment that is widely used for high altitude operationandmaintenance A folding mechanismdeveloped by Enders et al extends by rapidly introducing a fluid and retracts by venting the fluid Lee et al disclosed a folding tube set for a bridge transport system which includes several cylindrical tubes and extension retraction lines Lee et al designed a wire driven bidirectional folding mechanism consisting of stages and steel wires However in these types of folding mechanisms above the volume of the base portion is quite large in order to achieve suffi cient stiffness In addition the end effector needs a considerable difference in extension lengths so as to ensure an adequate moving space As a result the volume of folding mechanisms men tioned above in the contraction state will be quite bulky Kong et al have developed a telescoping sample canister capture mechanism TSCCM for retrieval of tumbling sample containers on orbit Another linear motion folding mechanism invented by Kawabuchi et al includes a plurality of blocks A folding arm is achieved in a manner that blocks are rigidly connected with each other 第 8 页 Liping and Yenong escribe a reciprocating pushing chain which can be extended horizontally in a straight line under its own gravity The pushing chain is usually used to push objects from one position to another Several authors have proposed the use of folding mechanisms with the compact volume as the development direction of the robot arm However the researches above lack of enough confi gurations and the relative precisionanalysis The linear folding mechanism presented in this paper is a novel folding mechanism This type of folding mechanism can enhance safety by eliminating such a risk inevitable for a typical robot arm having an elbow joint that an object around the robot arm gets caught between arm sections when the elbow joint is closed Besides the folding arm consisting of blocks can be stored in a compact case Hence this mechanism can reduce the space to be occupied by the traditional multi joint robot In this paper several confi gurations of this mechanism are pro posed The relative position precision analysis is achieved through the numerical simulation of the mathematical model of the folding arm 2Structure of the Folding Mechanism There are a variety of confi gurations of this novel folding mechanism Generally this folding mechanism includes a plurality of blocks a storage case drive units and an end effector The freely jointed blocks are stored in the storage case The blocks driven by drive units are possible to be extended out in an arbitrary direction and aligned in a rigid manner to form a rigid alignment Hence a folding arm can be composed of the blocks in the rigid alignment as shown in Fig 1 The end effector is installed at the front end of the folding arm This type of folding mechanism in a retraction state occupies less space compared with the traditional multi joint robot a b Fig 1Two states of the folding mechanism a Retraction state b Extension state 2 1 Confi gurations of the Folding Mechanism In order to keep the extended block in a rigid manner several connection methods are 第 9 页 proposed in this section The fi rst connection method is the hinge which has the highest connection reliability as shown in Fig 2a The block in the freely jointed manner can rotate around a hinge pin relative to the next block The wirerope is another connection method as shown in Fig 2b Both ends of the wirerope are fi xed on the head block and the end one respectively All the blocks are stringed together The third connection method is that two adjacent blocks are connected by the synchronous belt as shown in Fig 2 The synchronous belt toothed belt meshes with the upper surface corrugated structures of each block to make the blocks fi xed to each other in a rigid manner As shown in Fig 3a there is a latch mechanism and a recessed portion in the upper surface When the latch mechanism engages with the corresponding recessed portion of the adjacent block the adjacent block is connected Hence the extended blocks can be serially fi xed by the last method a b Fig 2 Two confi guration of the folding mechanism a b Fig 3 The other two confi guration of the foldingmechanism Based on the structures and the connection methods several confi gurations of the folding mechanism are presented In order to ensure the extended blocks fi xed to each other fi rmly all the upper surface and the underface are connected to these of the adjacent block forming a folding arm Hence this linear folding arm can be extended along an arbitrary direction There is a end effector installed at the front end of the arm The folding arm also can bear the forces imposed on the end effector in any direction Since there are four connection methods sixteen combinations are created 第 10 页 That means that there are sixteen confi gurations of the folding arm theoretically According to loading conditions and the reliability of connections four typical confi gurations are illustrated in Figs 2 and 3 The arrangement of the folding arm is not limited to the description of confi gurations above yet A new combination can be proposed for some certain purposes such as minimum space requirements and the convenience of storage Furthermore the blocks in free jointed manner may be stores in a helicoids case or other cases with suitable shape On the selection of the drive modes both the sprocket drive and the worm drive can be adopted to push the blocks out of the storage case The sprocket drive can accomplish the rapid extension and retraction Each block has agroove in the undersurface Then the sprocket engages with the groove as shown in Fig 3 Adrastic vibration of end effector may generate owing to thepolygon effect and meshing impact The folding mechanism driven by the sprocket is suitable for high speed and low precision occasions The folding arm with the worm drive can be extended steadily as shown in Fig 4 Besides the velocity of the extension and retraction is continuous and smooth The folding mechanism with the worm drive can be used in the service robots instead of muti jointed arms Hence this type of folding arm should have high position precision In the Sect 2 2 the position precision of the folding mechanism is modelled and analyzed in detail O M f i Oi 1 O G i G Fig 4The linear folding mechanism 2 2Design of the Linear Folding Mechanism The research focused on the folding mechanism with the worm gear drive is presented in this section The combination of the synchronous belt and the hinge is adopted as the confi guration of the folding arm as shown in Fig 4 The front end of the toothed belt 第 11 页 and the fi rst block are bonded The teeth mesh with the upper surface corrugated structures to ensure the close contact between the upsides of two adjacent blocks Compared with wireropes the synchronous belt generally owns suffi cient strength and rigidity In this mechanism a Chinese standard belt Metric T Pd T10 ischosen The pinch rollers are used to compress the belt tightly on the block Then the folding arm composed of the blocks in rigid manner is supported by two return roller The folding distance extended length is the sum of the lengths of the extended blocks When the folding arm is retracted the synchronous belt is separated from the corrugated structures by a scraper The blocks are separated from the rigid arrangement to the discrete arrangement However the discrete blocks are still connected by hinges and can be flexed in any direction Therefore the discrete ones can be housed inside a case with suitable shape This linear folding mechanism Fig 4 is driven by the worm gear drive The moving direction of the arm is the same as the direction of a rotational axis of the worm Besides this mechanism including the base frame can rotate around the center O to change the elevation angle of the folding arm relative to the horizontal direction 3Position PrecisionAnalysis of the FoldingArm The position precision of the end effector is very important to achieve the task of grasping Under the gravity of the blocks and the objects the synchronous belt is tensioned Then the folding arm will be bent The end effector will deviate from the target location In order to determine the deviations the mathematical model of the position precision should be established For simplifying complexity the fol lowing assumptions are made in the derivation of the mechanical model 1 The clearances in the hinges are neglected 2 The deformation of each block is neglected 4Simulations and Discussions The calculation algorithm for the mathematical model above is programmed with MATLAB For this linear folding mechanism the maximum folding distance is 1500 mm and the folding arm consists of 30 blocks The main parameters used in the calculation program are listed in Table 1 Through the numerical simulation the deviations of the end of the folding arm at 30 are obtained as shown in Fig 5 The horizontal deviation dh rises with the increasing of the extended length Meanwhile the whole deviations at the certain length rise along with the increasing of mt The distribution of dh and dv are similar The maximal deviations of the folding arm with no loads are 0 104 mm 第 12 页 Table 1 Main parameters of the linear folding mechanism Fig 5The deviations at 30 a The horizontal deviation dh b The vertical deviation dv and 0 06 mm in the horizontal and vertical directions at i 30 respectively Then the two deviations reach a maximum at i 30 and mt 2 5 kg Figure 6 shows the influences of the elevation angle on the deviations at the certain mass mt 2 5 kg However the elevation angle can only change form 70 to 70 due to the restrictions of the folding arm and the base frame The deviations dh at a certain length reach a maximum when the elevation angle is equal to zero as shown in Fig 6a Besides the whole deviations dh are reduced gradually as the folding arm is