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冲压 机床 自动 控制 实现

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冲压机床自动送料控制实现,冲压,机床,自动,控制,实现

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本科毕业论文（设计）题目冲压机床自动送料控制实现毕业论文（设计）诚信责任书本人郑重声明：所呈交的毕业论文（设计），是本人在导师的指导 下独立进行研究所取得的成果。毕业论文（设计）中凡引用他人已经发 表或未发表的成果、数据、观点等，均已明确注明出处。尽我所知，除 文中已经注明引用的内容外，本论文不包含任何其他个人或集体已经公 开发表或撰 写 过 的 研 究 成 果 。对本文的研究做出重要贡献的个人和集 体，均已在文中以明确方式标明。本人毕业论文（设计）与资料若有不实，愿意承担一切相关的法律 责任。论 文 作 者 签 名 : 年月日冲压机床自动送料控制实现摘要：随着社会的发展，科技水平不断提高，现代工业的自动化程度越来 越高。冲压机床在制造业中起着至关重要的作用。然而现在还有很多冲压机床使 用手动送料和机械方式送料，这些方式存在着很多缺点，比如生产效率低、成本 较高，存在着安全隐患等等。本文通过对现有的普通冲压机床的运动规律进行了解与分析，设计一种通过 PLC 控制的自动送料系统，首先设计出自动送料装置的机械结构，然后使用 PLC 控制自动送料装置，从而实现冲压机床的自动送料。这种自动送料方式可以适用 于不同的机床，方便调节送料长度，跟随时代的进步，提高冲压的自动化程度、 冲压精度以及冲压效率。关键词：冲压机床；自动送料；PLC 控制IRealization of automatic feeding control for stamping machineAbstract: With the development of society, punching machine plays an important role in manufacturing industry. But now there are a lot of stamping machine manual feed and feeding mechanical way, which has many shortcomings, such as low efficiency, high cost, and a potential safety hazard.In this paper, we understand and analyze the motion law of the existing ordinary stamping machine.A kind of automatic feeding system using PLC is designed. First of all, design the mechanical structure of the automatic feeding device is designed, then using the PLC control automatic feeding device to realize the automatic feeding of stamping machine. This automatic feeding mode can be applied to different machine tools, so as to adjust the feeding length, follow the progress of The Times, improve the automatic degree of punching, punching precision and punching efficiency.Keywords：Punching machine；mechanical feed；Programmable Logic Controller目 录III摘要IAbstractII1 绪论11.1 研究目的及意义11.1.1 研究的目的11.1.2 研究的意义11.2 国内外发展现状21.3 研究内容21.4 本章小结22 冲压机床结构分析32.1 冲压机床的原理32.1.1 简介32.1.2 工作原理32.2 冲压机床的分类32.2.1 滑块驱动力42.2.2 滑块运动方式42.2.3 滑块驱动机构42.2.4 本章小结53 控制方案设计63.1 冲压机床自动送料的功能要求63.2 送料方式的选择63.2.1 机械方式自动送料介绍63.2.2 冲床自动送料控制方法73.3 控制方案设计83.3.1 送料结构83.3.2 工作流程103.4 主要装置113.4.1 液压传动系统113.4.2 限位开关133.4.3 编码器153.4.4 本章小结154 控制系统164.1 方案选择164.2 电气原理174.2.1 I/O 分配174.2.2 电气原理图184.3 PLC 程序的编写194.4 本章小结215 总结22参考文献23致谢24附录 A 外文文献翻译25附录 B 接线图56附录 C 程序57附录 D 自动送料装置结构三维图581 绪论1.1 研究目的及意义1.1.1 研究的目的在当今世界，科技的力量越来越强，各种琳琅满目的电子产品出现在我们的 生活和学习中，衣食住行处处可见智能化的发展，但是，基础的机械制造业仍然 在世界上有很高的地位，非但没有被逐渐淘汰，而且有了更好的发展。在机械制 造领域，各式各样的机床有着不可或缺的作用，大多数的机械零件、机械产品的 加工生产都用到了机床。冲压机床更是在机械加工工厂随处可见，小到手表的金 属后盖，大到汽车的外壳都用到了冲压技术。冲压机床通过对物料如金属板料进 行冲压使其变成所需要的产品形状，在现今这个讲究效率、低成本的社会，提高 冲压机床的自动化是大势所趋，冲压机床送料的方式性能对于其提高自动化有很 关键的作用。以前的一些手动送料的方式已经不能满足现在大规模生产制造要求， 因此，冲压机床的自动送料的方法和装置渐渐出现并得到充分的利用。现如今，很多冲压式机床都是通过机械的方式实现自动送料，从而导致安装 时不方便，精度不易掌控，送料长度固定，要想改变送料长度，必须要通过重新 计算设计才能实现，极其的不便。因此，设计一种通过控制方法实现自动送料的 意义很大，它可以消除或者明显改善这些缺点、不足。本次设计采用控制方式实现其自动送料，适用于多种冲床，易调节送料间隔， 拆装简单方便，自动化程度提高，进一步提高生产效率以及生产质量。1.1.2 研究的意义冲压机床自动送料的控制实现具有以下意义;（1）提高冲压的自动化 可以适用于不同的机床，在安装时简单方便，操作起来较为简便，自动化程度高，容易调节送料的长度。（2）节省成本，生产效率高 操作时简单方便，对工人的技术水平要求不高，一人可以同时管理多台冲压机床。（3）操作安全 相对于手动送料的方式，控制方式实现自动送料不需要当每次冲压完成时，9人工将物料放入冲压机床冲头下边，在发生意外情况时，防止了工人受到伤害。1.2 国内外发展现状随着社会的不断进步，工业进展迅速，在机械制造业领域，冲压工艺的出现 简化了很多传统的机械加工，因此，冲压机床有着非常重要的地位。近几年，国内技术虽然没有国外技术更加成熟先进，但其差距已经越来越小。 大型的多工位压力机在过去只有工业发达的国家，比如德国才拥有，我国只能从 外国进口，没有自己的技术。但在 20 世纪末，经过相关行业的技术人员不断摸索 和努力开发，我国终于也研制成功。在当今机械制造业，比如汽车，航天，电器 等领域，需要很多的各种各样的板料零件，特别是在汽车生产制造方面的行业， 随着人们对潮流的追逐，汽车的样式变得越来越丰富多样，以满足人们的不同品 味要求，在制造过程中也越来越自动化、规模化。随着 21 世纪的到来，人们的生 活越来越好，人们渐渐富裕起来，对美好的生活越来越向往，这使得汽车的需求 量大大加多，这使得机械制造领域对金属板料加工有了更大需求和要求，因此， 我国的冲压机床得到了快速发展。冲压机床为了满足要求逐渐升级换代，运用到 了很多诸如信息技术、自动化技术之类的技术方法，然而，在冲压机床的自动送 料方面的技术并没有得到相对应的发展。1.3 研究内容本次设计的研究内容主要有以下几个方面:（1）对现有的冲压机床进行分析，了解其工作原理，分析冲压机床的运动规 律；（2）了解现有的冲压机床自动送料装置、分析其结构和工作原理；（3）采用控制方式实现冲压机床的自动送料。1.4 本章小结在本章中，主要介绍了冲压机床自动送料控制实现这个课题的研究目的，阐 明了冲压机床及其送料装置近几年的世界发展情况，并对本课题的研究方向及内 容进行了说明。2 冲压机床结构分析2.1 冲压机床的原理2.1.1 简介冲压机床，一种对物料进行冲压从而改变物料形状，使其变为所需要的形状 简称冲床。当今，很多工厂、生产车间都在使用冲压机床，冲压机床使得很多机 械加工变得更为简便，大大的提高了工厂的生产力。冲压机床主要针对于板料， 可以进行冲孔、拉伸、成型等等，冲压机床运用于很多领域，在当今制造业有着 不可或缺的作用。比如汽车、摩托车，电脑、家用电器、导弹、飞机等等都用到 了冲压机床。2.1.2 工作原理冲压机床将电机的转动转换为冲床冲头的上下运动，从而实现对工件进行连 续冲压，使得板料成型。连杆的旋转到冲压机床冲头上的滑块上下动作通过一种球型机构或是圆柱型 机构连接起来，这种机构通过转化这两种运动使得冲压机床正常工作。图 2.1 冲压机床2.2 冲压机床的分类现有的冲压机床可以从滑块的三个方面进行分类。2.2.1 滑块驱动力冲压机床是通过冲头的上下运动来对材料进行冲压的，冲头连接着冲床滑块， 因此，冲压机床的工作过程是通过带动滑块来完成的，不同的冲压机床有着不同 方式的驱动力，有的冲压机床是通过机械的方式驱动滑块，而有的冲压机床是通 过液压的方式驱动滑块。一般情况下，加工普通的金属板料时，大部分使用的都是机械式冲压机床。 液压式冲压机床使用的范围也较为广泛。2.2.2 滑块运动方式很多冲床为了适应不同的加工领域，其滑块设计出了不同的运动方式，以此 可分为三类：单动冲压机床、复动冲压机床、三动冲压机床。复动冲压机床和三动冲压机床更多的用在需要加工较大材料的的地方，没有 单动式冲压机床运用的多。2.2.3 滑块驱动机构不同的冲压机床在滑块的驱动上使用的机构可能也不同，现如今，冲压机床 根据滑块的驱动机构可以分为八种，分类情况见表 2.1。表 2.1 机械式冲床种类冲详解 床种类滑块驱动机构主要用途特点性能应用范围曲轴式冲压机 床曲轴机构冲切、拉伸、 锻造、弯曲功能多，适用 范围广几乎所有的冲 床加工无曲轴式冲压 机床偏心齿轮冲切、拉伸、 锻造、弯曲轴刚性好、润 滑性能好行程较长的情 况锻压、压溃、多用性、造价摩擦式冲压机摩擦传动与螺弯曲、成形、低、但加工精已经逐渐被淘床旋机构拉伸度低、生产速汰度慢肘节式冲压机压印加工、精滑块运动曲线冷间锻造床肘节机构整、压缩加工好主要用于耐火结构简单，制螺旋式冲压机螺旋机构材料的成型造容易，但效应用范围较广床率低齿条式冲压机齿条与小齿轮挤压、榨油、结构简单、制已经被液床机构压入造容易压式冲床取代连杆式冲压机连杆机构较大零件的加加工周期短、汽车主体面板床工床台面宽加工需要较小压力滑块的活动曲凸轮式冲压机凸轮机构的地方线好，但压力适用范围较小床较低2.2.4 本章小结本章中，对现存的冲压机床的原理进行了阐述，并对其结构进行了深入的研 究与分析。然后对世界上的各种冲压机床进行分类分析，了解其、冲压机床的各 种用途、结构、特点性能以及适用范围。通过以上方面开始对冲压机床自动送料 的控制实现开始设计。3 控制方案设计3.1 冲压机床自动送料的功能要求在开始设计冲压机床自动送料系统时，首先需要明确它的作用和功能，再进 行具体设计。通过第一章对冲压机床的分析了解，冲压机床自动送料的功能作用 主要有以下几点：（1）当冲床还未开始冲压时，将板料送入冲床工作台面上；（2）当冲床向下运动准备进行冲压时，送料结束；（3）可以不断循环（1）（2）过程完成自动送料动作；（4）可以按照所需要的送料长度对冲床进行送料。 具体功能为：当冲床冲头提起时，根据多需要的送料长度进行送料，在冲头下压进行冲压之前送料结束完成一次冲压。当下一次冲床的冲头提起时，自动送 料装置继续根据所需送料长度进行送料，依次循环。以上便是本次设计的冲床自 动送料装置的主要功能。3.2 送料方式的选择3.2.1 机械方式自动送料介绍图 3.1 单边辊轴送料装置原理图现今有一部分冲压机床送料方式是采用机械方式。机械方式的自动送料是将自动送料设备与冲压机床通过连杆机构连接起来，通过送料设备与冲压机床冲头 的配合进行自动送料。如上图所示，当冲压机床的冲头随滑块提起时，连杆带动大齿轮，然后大齿 轮带动辊轴使板料向前送进进行送料，当冲头下压快对板料进行冲压时，一次送 料结束。依次循环，完成冲压机床的自动送料。图 3.2 机械方式送料实物图3.2.2 冲床自动送料控制方法用控制方法实现自动送料是将送料机构与冲压机床分开，安装便捷，可控性 高。对此，通过第二章对冲压机床结构及原理进行分析选出了以下几个方案来实 现冲压机床的自动送料。方案一：设计一种机械手，通过机械手来给冲压机床进行送料。通过机械手 将物料抓住然后送到冲压机床冲头下边然后松开回到最初位置完成一次送料，之 后按此循环即可实现冲床的自动送料。这种方式自动化程度高，方便更改送料长 度，但这种方式的自动送料对控制方面的要求较高，对机械手的设计难度也必较 高，并且其造价也较为昂贵。方案二：使用液压或者气压传动的方式与冲床配合进行自动送料。通过液压 或者气压的方式先将板料夹紧，然后向前送进所需的送料长度，所需的长度送进完成后，与板料分离并回到原始位置，完成一次送料。依次循环完成冲压机床的 自动送料。整个过程基本为：夹紧板料送进板料分离板料退回复位。需要两个双 作用液压缸或者气压缸，其中一个双作用缸负责夹紧和分离板料，另一个双作用 缸负责送进和退回，两个双作用缸相互配合完成冲压机床的自动送料。对于液压传动，它是通过加装油液进行工作的，油液的温度较大时不易保持 传动速度的稳定性，油液污染对传动的性能也有较大的影响；对于气压传动，它是通过吸取空气进行工作的，因此在使用时比较方，而且 其对环境没有污染，反应也较为迅速。但气压传动运动的润滑性能不高，在工厂 车间，空气质量较差，不利于气压传动。这两种传动方式的精度都不高，不容易控制，造价也较为昂贵。 方案三：使用电机带动滚轮，通过滚轮的滚动将板料送进冲压机床。如图 3.3所示，板料上方的滚轮通过连接一个电机来带动其旋转，与板料下的滚轮配合夹紧板料使得板料向前送进。这种自动送料方式比较容易控制，工作效率高。3.3 电机带动滚轮进行送料综上分析，本此设计选择方案三，使用电机带动滚轮，通过滚轮的滚动将板 料送进冲压机床。3.3 控制方案设计3.3.1 送料结构根据冲床自动送料控制方法中的方案三设计出送料结构。对于开始送料与一 次送料结束的控制方法有两种方案可供选择。以下是这两种方案的对比分析：方案一：如图 3.3 所示，两个滚轮始终夹紧板料，上滚轮连接电机。当开始送料时启动电机，电机带动滚轮使板料向前输送，当送料长度达到以后，电机停 止转动，从而使板料停止输送完成一次冲压，依次循环。送料的一次循环基本过 程为：电机启动开始送料电机停止送料结束。这种方式控制起来比较简单， 但冲床在冲压频率较高的情况下，电机不断的开始和停止转动，很容易损坏电机。方案二：与方案一一样，上滚轮同样连接电机，但开始送料之前上滚轮与板 料分开，先启动电机，当开始送料时，将上滚轮下压但板料上与下滚轮夹紧板料 使板料向前输送，当送料长度达到以后，将上滚轮提起，从而使板料停止输送完 成一次冲压动作，依次循环。送料的一次循环的基本过程为：滚轮下压开始送 料滚轮上提送料结束。这种方案电机一直处于启动状态，连续转动，容易控 制送料长度。综上分析，选择方案二作为本次设计的自动送料装置结构方案。图 3.4 冲压机床自动送料结构具体的结构设计如图 3.5 所示，其中滚轮 1 上安装有电机和液压系统装置。电机负责带动滚轮转动，液压装置负责将滚轮 1 下压到板料上和从板料上提起，滚轮 1 的初始位置为如图所示的提起状态。滚轮 2 上安装有正交编码器，板料在向前输送时，会带动滚轮 2 转动，通过滚轮 2 的转动从而计算出将板料的送进长 度。为了防止当滚轮 1 松开时，板料由于惯性会继续向前送进，因此设计滚轮 3和滚轮 4 来夹紧板料从而增加与板料之间的摩擦力，防止板料因惯性前移影响到 冲床冲压。3.3.2 工作流程冲压机床的自动送料工作流程如图 3.5 所示。图 3.5 自动送料工作流程冲床自动送料控制系统具体工作流程如下：（1）先手动将板料放入自动送料机；（2）启动自动送料装置，电机开始转动并带动滚轮 1 转动；（3）启动冲床，冲床冲头对板料冲压，并带动连杆，冲压完成时，冲头带19动连接杆触碰到限位开关从而给安装在滚轮 1 上的液压装置一个信号；（4）液压系统接收到该信号后，此时冲床冲压刚抬起，然后液压装置通过 液压缸将滚轮 1 下压到板料上，使其与滚轮 2 配合夹紧板料，使得板料向前送料；（5）当编码器测得所需要的送料长度之后，液压装置通过液压缸将滚轮 1提起复位，一次送料结束。（6）依次循环,实现冲床的自动送料。3.4 主要装置3.4.1 液压传动系统为了更好的配合冲床冲压，通过分析对比，在用机械方式来控制滚轮 1 的上提与下压和用液压传动控制滚轮 1 的上提与下压之间两种方案里，选择了液压传 动的方式。在滚轮 1 上装有液压传动系统，用液压传动的方式来提升和下压滚轮 1 实现 开始送料与停止送料。图 3.6 滚轮 1 液压传动系统工作原理图1-溢流阀；2-油管；3-换向阀；4-液压缸；5-油箱；6-液压泵；7-单向阀 如图 3.6 所示，为冲床自动送料装置中安装在滚轮 1 上的液压传动系统工作原理。其回路为：液压泵单向阀电磁换向阀液压缸油箱。当电磁阀 3 通电，液压缸活塞向下运动，使得其带动滚轮 1 下压与滚轮 2 配合夹紧板料并将板料向前输送；当电磁阀断电，液压缸活塞向上运动，使得其带 动滚轮 1 提起与板料分开，从而停止送料。溢流阀：当液压系统的压力超过了调定的压力时，阀口将会打开，保障了液 压系统的正常工作，也可称之为安全阀。溢流阀主要分为直动式溢流阀和先导式 溢流阀，经过分析，根据送料需求，如图 3.7 所示，本次液压传动系统的设计采 用先导式溢流阀。图 3.7 先导式溢流阀工作原理图及实物图油管：输送液压油的管道。换向阀：如表 3.1 所示，为现有的各种换向阀。换向阀的作用非常大，它可 以调节油液运动的方向。表 3.1 换向阀的分类液分类 压阀阀芯运动方式操作方式阀芯位置通口数目换向阀转阀手动换向阀二位阀二通阀滑阀机动换向阀三位阀三通阀夜动换向阀四通阀电液换向阀五通阀电磁换向阀本次设计使用的是二位四通电磁换向阀，它是利用电磁铁的吸引力来推动阀 芯换向，从而改变液压系统中油液的运动方向。图 3.8 双作用液压缸原理图液压缸：液压缸有很多不同的类型。根据送料装置结构和工作要求，本次设 计使用的液压缸为双作用单杆缸，其原理图如图 3.8 所示。液压泵：现今在液压系统中使用的液压泵的工作原理基本都是一样的。它是靠液压密封的工作腔体积的变化来实现压油和吸油的液压泵根据一定时间内输出 的油液体积是否可以改变可以分为变量泵和定量泵，顾名思义，变量泵在一定时 间内输出的油液体积可以变化，而定量泵不可以。单向阀：本次设计中使用的是普通单向阀，如图 3.9 所示。其作用是避免油 液回流，使得油液只能流到一个方向。图 3.9 单向阀1-阀体；2-阀芯；3-弹簧3.4.2 限位开关在本次设计中，限位开关主要用于控制是否开始送料，当冲床冲头对板料冲 压后，连接在冲头上的连杆碰压到行程开关，此时液压系统启动将滚轮 1 下压， 实现送料。图 3.10 限位开关它的原理是当机械部件触压到开关时，使得开关改变控制电路（闭合或断开）。 这种开关是一种很常见的小电流主令电器元件。表 3.1 位现有的各种限位开关结 构和主要功用。表 3.2 限位开关结构及作用结构作用限位开关外壳定位控制操作头顺序控制触点位置状态接触式限位开关在当开关的触头触碰到挡块时，切断或改变控制电路，设备 便会根据控制要求做出下一步动作，比如停止运行、向与之前运动方向相反的方 向运动等。非接触式限位开关顾名思义，就是不需要物理接触就可以实现电路的 控制。表 3.3 为现有的各种限位开关的型式分类。表 3.3 限位开关的分类分类限位开关型式结构接触式限位开关直动式行程开关滚轮式行程开关非接触式限位开关微动式行程关组合式行程开关直动式行程开关的原理很简单，就像常见的电灯开关原理一样，当机械设备 触压到行程开关时，行程开关的触头便会动作，当机械设备与行程开关分开后，行程开关的触头在弹簧的作用下回到原始的位置。单轮的滚轮式行程开关是当运 动部件触压到滚轮时，使得开关动作，运动部件离开滚轮后，开关上的滚轮通过 弹簧回到最初的位置。但双轮旋转式行程开关只能当运动部件向与之前运动方向 相反的方向运动然后触压到另一个滚轮时才会回到原始位置。3.4.3 编码器本次设计根据自动送料装置的功能要求，使用的编码器为正交编码器。本设 计中，在自动送料装置上的滚轮 2 上装有正交编码器，使用正交编码器来测量板料送进的长度，当滚轮 1 下压开始送料后，板料带动滚轮 2 转动，这时装在滚轮2 上的编码器就会测出滚轮转动的圈数。正交编码器是把位移转换为周期性电信 号，然后把电信号转化为脉冲，位移的大小通过脉冲数来表示。计算出一个毫米 所对应的脉冲数就可以确定设定长度的脉冲数，从而可以改变所需的送料长度。图 3.11 编码器3.4.4 本章小结本章对冲压机床自动送料的功能要求进行了详细说明，根据所需的功能要求 设计了几种可以实现该功能的方案，通过对这几种方案的优缺点的仔细分析，选 出了最适用于本设计的设计方案。并对其结构进行了设计。最后，对所设计的自 动送料装置的主要元件进行了分析介绍，选出所需要的相关电气元件。4 控制系统4.1 方案选择现如今，有很多的控制方法，在大学的几年学习中，PLC（可编程控制器）和 单片机原理等控制系统都有学到。但在实际设计中需要根据所处环境、可靠性、 成本、体积等等一些不同情况下选择出最适合冲压机床自动送料系统的控制系统。 目前，此次设计有三种控制方法：继电器控制、单片机控制和 PLC 控制，通过对 继电器控制、单片机控制以及 PLC 控制三种控制方法的工作原理进行分析，选择 出最试用于本次设计的控制方法。（1）继电器控制 继电器控制系统主要利用硬件接线从而实现控制，一般是由导线、主令电器、继电器以及接触器等部件组成。线路较多，在接线时容易接错，设备的体积也较 大、系统灵活性太低、功能单一，难以满足一些控制要求多变的情况，在继电器 控制系统中有很多的触点，其寿命较短，因此继电器控制的可靠性也不高。（2）单片机控制 单片机的造价也相对较低，可以实现很多功能。但由于单片机制作工艺、部件质量、布局结构等各种因素，可能会导致其故障率高、靠干扰能力差、扩展不 方便等。单片机所处的环境对其影响较大，而且开发的周长较长。在冲床工作的 车间，环境较为恶劣，对单片机的影响和干扰较大。（3）PLC 控制图 4.1 单片机PLC可编程控制器，可编程控制器是通过设计多个模块组成的，当其出现问 题时，只用找到出现问题的的模块，然后更换就可以使系统继续正常运行，这种 模式对于查找故障也很方便，大大提高了生产工作效率。同时，可编程控制器有 很强的保护能力和自检功能，维护方便，出现故障率很低。可编程控制器可以轻松应对各种场合，很适用于在冲压车间这种环境较差的地方。它有很多不同的硬 件设备，可以根据不同的控制需要组成不同的控制系统，很容易实现不同的要求。 很多的可编程控制器使用了梯形图编程，这种编程方法逻辑简单，比较容易读懂。根据以上分析，三种控制系统的性能如表 4.1 所示。表 4.1 控制系统性能对比性控能使用环可靠性成本功能简易性扩展性维护性制方境要求继电器一般较差低一般较差较差较差单片机较高一般低较强一般一般一般PLC一般较高较高较强较好好好通过以上各个控制系统性能的对比分析，最适合本次设计所需的控制方式为PLC 控制。当今可编程控制器市场上，有着很多可编程控制器种类，比如西门子公司的 可编程控制器和三菱公司的可编程控制器，可以满足不同的工业层次所需的控制 要求。通过查阅相关资料，对三菱 PLC 与西门子 PLC 的性能功用进行对比分析， 如表 4.2 所示，选出最适用于本次设计的可编程控制器。综合分析后采用三菱 FX-2N-48MR-001 作为自动送料控制使用的控制器。表 4.2 三菱 PLC 与西门子 PLC 优缺点分析难度程序指令主要特点三菱 PLC较小简单、理解容易较多复杂动作控制西门子 PLC大较为抽象少通信和过程控制4.2 电气原理4.2.1 I/O 分配通过分析冲压机床自动送料的控制流程，对 PLC 的输入/输出地址进行合理的 分配。具体的 I/O 分配如表 4.2 所示。表 4.3 I/O 分配表输入输出端口功能端口功能X0编码器 AY0输送电机运转X1编码器 BY1输送电机高速X2手动Y2输送电机低速X3自动Y3电磁阀X4自动启动X5停止X6手动启动输送电机X7手动输送X10冲压完成信号4.2.2 电气原理图图 4.2 部分接线图根据冲床自动送料系统工作要求，通过对电气方面的知识的学习和了解设计 出冲压机床自动送料控制系统的各硬件接线原理图，如图 4.2 所示为部分接线图， 其中，各输入输出端口地址连线对应 I/O 分配表。完整的硬件接线图见附录 A。4.3 PLC 程序的编写在本次冲床自动送料控制设计中，编写 PLC 控制程序的软件使用的是 GX Works2 编程软件。该编程软件与传统三菱的 GX Developer 编程软件相比，操作性 能和其功能有了很大的提高，使用户更加容易使用和操作。图 4.3GX Works2 初始界面在用 GX Works2 编程软件时，首先打开 GX Works2，如图 4.3 所示，创建一个 新工程。点击工程，然后在工程选项的菜单栏里点击新建。图 4.4 新建工程如图 4.4 所示，设置 PLC 系列、机型、工程类型以及程序语言。根据本次设 计要求，PLC 系列为 FXCPU，机型为 FX2N,工程类型为简单工程，程序语言为梯形 图。设置完成确定以后，开始编写程序，如图 4.5 所示。图 4.5 开始编写程序界面根据自动送料装置的功能要求编写控制程序，完整控制程序见附录 B，部分 程序如图 4.6 所示。软元件注释如图 4.7 所示。图 4.6 部分控制程序29图 4.7 软元件注释最后对程序进行检查，达到所有所需的控制目的，完成冲床自动送料机的送 料过程，用 PLC 控制的方法实现冲压机床的自动送料，提高冲压机床的自动化程 度。4.4 本章小结在本章中，根据自动送料装置的控制要求，设计出了三种控制方案，通过对 这三种方案各个方面进行了综合分析，得到了最适用于本设计的控制方案（PLC 控制）。根据功能要求绘制出硬件接线图，得出 I/O 分配表，最后编写出 PLC 程 序并对其检查、调试，达到控制目的，完成冲压机床自动送料控制实现的最后部 分。5 总结在毕业设计的选题、开题、到现在的几个月里，经过指导老师的悉心指导和 支持，最终完成了这次的毕业设计。在本次设计中，通过查阅资料和网上学习运用到了液压传动、可编程控制（PLC）和相关电气控制等一些方面的知识。在液压传动系统中，分析它的结构性 能及其优缺点，了解液压系统的工作方式和回路，并通过对各种液压元件的研究 分析设计出最简便、易控制、操作简单的液压传动系统。在电气控制方面，了解 各电器元件的组成结构以及其工作原理、选择最适用的电器元件，并绘制出硬件 接线图。在可编程控制系统方面，选择合适的可编程控制器和编程软件非常重要， 确定编程所使用的软件后，设计出实现控制要求和功能的控制系统。在设计过程 中，首先对冲压机床的发展进行研究，并分析其结构和工作原理，然后对冲压机床的送料方面进行研究，了解送料方面的历史发展和现有的一些送料方式比如手 动送料和纯机械式送料，对其结构、理念进行分析，从中吸取优点及缺点，从自 动化程度、生产效率、劳动强度、安全程度、生产成本、等方面考虑，设计出一 种通过控制实现的冲压机床自动送料系统。综上，本次毕业设计主要完成了以下几个内容：（1）查阅相关资料，对英文文献进行翻译；（2）对各种冲压机床的结构进行分析，了解其运动规律；（3）对现有的各种冲压机床的送料方式和一些自动送料方式的原理进行研 究分析；（4） 采用控制方式实现冲压机床的自动送料；（5）确定控制方案，设计自动送料的结构原理；（6）绘制出电气接线图；（7）选择控制系统，编写出控制程序。（8）对控制程序进行调试检查，并加以改进。 此次的毕业设计，途中有很多很多的困难，锻炼了我解决问题的能力。学习不能只学不用，要将书本上的知识合理的运用到现实问题上。这次设计让我学会 怎么将的知识运用到设计中。参考文献1 陆国庆. 冲压自动化生产线工序间过渡系统优化设计D. 上海交通大学, 2008. 2 唐惠. 端拾器 CAD 辅助设计的研究与实现D. 上海交通大学, 2007.3 南雷英，戚春晓，孙友松.冲压生产自动送料技术的现状与发展概况J.锻压装备与制造 技术，2006（2）：18-20.2 焦连岷.冲床的数控改造及全自动送料装置的研制D.南京：南京理工大学，2007. 3 王振宁，张学良.冲压机自动送料机构气动系统及 PLC 控制J.液压与气动，2003（10）:49-50.4 徐刚，鲁洁，黄才元.金属板材冲压成形技术与装备的现状与发展J.锻压装备与制造技 术，2004（4）：16-22.5 张新华，俞震初.冲床自动送料机的原理与设计J.锻压技术，1993,18（5）：46-49. 6 张新华，鲁志康，赵建跃.冲床自动送料机的 PLC 控制与设计J.锻压技术，2000，25（2）：44-46.7 鲁世红，金龙，杜超.卷板机自动送料技术的现状及发展趋势J.锻压技术，2017,42(7):1-5.致谢光阴荏苒，四年的大学生活即将画上句号，在大学的学习生活使我受益匪浅。 在这四年的学习期间，我得到了很多老师、同学和朋友的关怀和帮忙。在毕业设 计论文即将完成之际，我要向所有期间给予我支持、帮忙和鼓励的人表示我最诚 挚的谢意。首先，我要深深感谢我的指导导师张艳丽老师。张老师为人谦和，平易近人。 在论文的选题、搜集资料和写作阶段，张老师都倾注了极大的关怀和鼓励。在论 文的写作过程中，提出许多中肯的指导意见，使我在研究和写作过程中不致迷失 方向。借此机会，我谨向张老师致以深深地谢意。其次，我还要感谢四年来教导过我的老师们，正是因为有了他们严格、无私、 高质量的教导，我才能在这几年的学习过程中汲取专业知识和迅速提升潜力;同时 也感谢这三年来与我互勉互励的诸位同学，在各位同学的共同努力之下，我们始 终拥有一个良好的生活环境和一个用心向上的学习氛围，能在这样一个团队中度 过，是我极大的荣幸.同时也感谢四年以来和我朝夕相处的五位室友，四年，我们共同学习，共同成长。我还要感谢我的家人，他们给我极大的鼓励与朴素的帮忙。附录 A 外文文献翻译Design and control of a heavy material handling manipulator for agricultural robotsSatoru Sakai Michihisa Iida Koichi Osuka Mikio UmedaAbstract In this paper, we propose a manipulation system for agricultural robots that handle heavy materials. The structural systems of a mobile platform and a manipulator are selected and designed after proposing new knowledge about agricultural robots.Also, the control systems for these structural systems are designed in the presence of parametric perturbation and uncertainty while avoiding conservative results. The validity of both the structural and control systems is confirmed by conducting watermelon harvesting experiments in an open field. Furthermore, an explicit design procedure is confirmed for both the structural and control systems and three key design tools are clarified.Keywords Agricultural robots Manipulator Robust control Evaluation index1IntroductionIn the field of agriculture, various operations for handling heavy materials must be performed. For example, in veg-etable cropping, workers handle heavy vegetables during the harvest season. Additionally, in organic farming, which is rapidly gaining popularity, workers handle heavy compost bags during the fertilizing season. These operations are dull, repetitive, and require strength and skill on the part of the workers.A great deal of research on and development of agricultural robots took place in the 1980s. Kawamura et al. (1984) developed a fruit-harvesting robot for orchards. Grand et al. (1987) developed an apple-harvesting robot. Their stud-ies were followed by others (e.g., Kondo and Ting 1998; Hwang and Kim 2003; Mario and Reina 2007; Tokunaga et al. 1999; Henten et al. 2003) including Edans study (Edan et al. 2000) and our studies (Sakai et al. 2002, 2003, 2004, 2005, 2007). Many of these studiesspecifically examine the structural system design (e.g., machine or circuit design, camera configuration) of robots and report the realization of basic actions in actual open fields. Recently, Martinet and co-workers (Lenain et al. 2006; Fang et al. 2005) rea-sonably discussed the control system design of agricultural vehicles in sliding conditions. Taken together, these studies specifically address only one structural system or one control system of agricultural robots. Few papers have discussed explicit design procedures for both structural systems and control systems. However, many agricultural robots are currently not in the commercialization or diffusion stages.In-stead, they remain in the research and development stages. It is thus important to support further research and development to improve the performance and reduce the initial cost of these robots.Apart from some developing components such as advanced vision, it remains unclear how much the existing (and implicit) design procedures can be improved. This situation is serious because it is also unclear whether there are design tools that evaluate the possible improvements to the performance and initial cost. In order to clarify the status of these design tools, we need to confirm an explicit design procedure for both the structural and control systems.In this paper, we report the realization of a heavy material handling manipulator for agricultural robots in Fig. 1. More precisely, the structural systems of a mobile platform and a manipulator with a hand are selected and designed after proposing new knowledge about agricultural robots. Also, the control systems are designed in the presence of para-metric perturbation and uncertainty while avoiding conservative results. The validity of both systems is confirmed by performing field experiments in an open field. These experimental results are the most important contribution of this paper. Our field results demonstrate that the total operation time and success rate are comparable to those of skilled workers.Furthermore, an explicit design procedure is confirmed to clarify the status of the design tools that evaluate the pos-sible improvements of agricultural robots, which is another important contribution of this paper.Fig. 1 A heavy material handling agricultural robotFig. 2 A working environmental model for agricultural robots2Global performance indexIn this section, we discusses evaluation indexes for the global performance of agricultural robots. In general, we cannot start any reasonable design without using performance indexes. Many performance indexes have been proposed for general robots. For example, manipulabilityis a well-known index for structural systems. There are, however, some indexes that have been proposed specifically for agricultural robots. For example, space for obstacle avoidanceis used for collision avoidance between agricultural robots and plants (not including the target plants). Degree of dangeris used for collision avoidance be-tween agricultural robots and humans.Nevertheless, these indexes evaluate only local performances in both space and time. From the viewpoint of holistic study of agricultural robots, there is a potentially useful global index, called the “theoretical field capacity” (TFC), which has been applied to existing agricultural vehicles, such as tractors, transplanters, and harvesters . TFC is defined as follows,where wm is the machine working width and Vm is the ma-chine straight running velocity. Actually, wm is the width of the end-effector and Vm is defined as the maximum velocity with sufficient working performance. In this section, the subscript m implies a dependence on only working machine, the subscript e implies a dependence on only working environment, and the subscript c implies a dependence on both.TFC does have two problems. First, TFC cannot be used for high-degree-of-freedom mechanisms such as manipulators because it is based on the endeffectors of existing agricultural vehicles, that is, low-degree-of-freedom mechanisms. Second, TFC does not consider turning and (un)loading nor any interactions between agricultural robots and their working environments.In order to solve these problems, we introduce a global performance index for agricultural robots. First, we start with a working environmental model. In the field of agriculture, working environments are classified into two sub-environments, namely, fields and roads. These imply that locomotion is also classifiable into “locomotion within a field” and “locomotion between fields (locomotion on roads).” Figure 2 showsa working environmental model for agricultural robots. The field consists of growing regions where plants (lattice points) grow and moving regions where robots move, and where Be : width of the growing region, we : width of the moving region, Le : length of both the growing and moving regions, me : column number of the lattice points, ne : row number of the lattice points, be : interval between lattice points in the width direction, le : interval between lattice points and the distance from the upper (or lower) sides of the growing region to the closest lattice point in the length direction.This model has the following properties:and the plant density is defined and approximated as follows:This approximation is linked to the economy of time and effort of ne measurements.Let Se be the field area and constant, then the number of growing regions is given bywhich is a global working space equation.On the other hand, let Mc be the number of growing regions where the robot simultaneously perceives and manipulates, that is, the number of growing regions in the intersection of the workspace and the field of view. For conventional agricultural vehicles, wm = Mc Be holds. By considering a normative task plan (see the Appendix or Sakai et al. 2004 for details), then the robots working time of straight running in Mc growing regions is as followsThe working time of turning for Mc growing regions iswhere Tm is the 180-degree rotation time. In all, the total working time iswhich is a global working time equation.From (5) and (8), a new evaluation index is proposed aswhich is a working frequency that is well-defined for high-degree-of-freedom mechanisms in the first problem of TFC (i.e., TFC cannot be used forhigh-degree-of-freedom mechanisms). In the case of existing agricultural vehicles, if we = 0,as Tmm + Tmp , Tct 0 and nc . This corresponds to the second problem of TFC (i.e., TFC does not take turning and (un)loading into account and does not consider interactions between agricultural robots and the working environment). In (10), Cet is an extension of Ct (an extended theoretical field capacity).3Structural systemsIn this section, we discuss the selection and design of structural systems for the mobile platform and manipulator with a hand.3.1 Design strategy of agricultural robotsThe design strategies of agricultural robots with locomotion and manipulation are classified as follows:(AR1)Selection of the mobile platform and the existing stationary manipulator, and then the superposition of them(AR2)Simultaneous design of the mobile mechanism and the manipulator(AR3)Selection of the mobile platform, and then the design of only the manipulator (AR4)Selection of the stationary manipulator, and then the design of only the mobile mechanism(AR1) is the initial cost-emphasized case, (AR2) is the performance-emphasizedcase, (AR3) and (AR4) are the intermediate cases. We select (AR3) because both the initial cost and performance cannot be neglected in the field of agriculture and because there are many mobile platforms for existing agricultural vehicles. According to (AR3), first, we select a mobile platform from existing ones and, second, we design a manipulator that is suitable to not only the intended task but also to the selected mobile platform.Table 1 Parameters of the working environmental model (watermelon field)PlaceDateYamagata Obanazawa 2000.8Chiba Tomisato 2000.6Nagano Matsumoto 1999.8Fukui Sakai 2000.5Tottori Fukube 2000.8Kumamoto Kamoto 2000.5Be m5.01.83.610.03.32.5we mle mme1122113.2 TaskHere, the task of the heavy material handling agricultural robot is to harvest watermelons. Edan et al. (2000) developed a melon-harvesting robot. Hwang and Kim (2003) developed a watermelon-harvesting robot with a teleoperation system.Tokunaga et al. (1999) developed a digital circuit vision system for awatermelon-harvesting robot. These studies mainly address only the structural system or control system. In this present paper, we discuss both simultaneously.Table 1 shows the environmental parameters investigated at some of the main product districts in Japan. The conventional operating procedure for watermelon harvesting was also investigated and divided into the following four steps.STEP 1: Select targeted watermelons and cut the vines STEP 2: Pick them and place them on a delivery vehicle STEP 3: Drive the vehicle and reload them onto a truck STEP 4: Drive the truck and unload them at a factorySTEP 1 does not require hard labor. For STEP 3 and STEP 4, working machines (e.g., vehicles with lifter) have already been developed since these operations require hard labor.For STEP 2, however, working machines have not yet been developed, even though STEP 2 requires hard labor. Picking watermelons requires the workers to have a high endpoint force. Various obstacles such as leaves, vines and unselected watermelons constrain the workers orientation. More precisely, the workers are required to handle39612 kg watermelons while standing on tiptoe. This implies that STEP 2 requires the workers to generate a high joint torque. To summarize, STEP 2 is a challenging task. Our ultimate goal is the robotization of STEP 2. The task of robotic STEP 2 operations is as follows.TASK 2A: Perceive the watermelons from a far distance TASK 2B: Locomote to their neighborhoodTASK 2C: Perceive them from a close distance TASK 2D: Manipulate (pick and place) themAfter completing TASK 2D, TASK 2A or TASK 2C follows. In this study, TASK 2D is realized and evaluated. See Sakai et al. (2005) regarding the realization of TASK 2C. It should be noted that skilled workers persistently complete the operation of pickingone watermelon in about 10 s on average.Table 2 Classification of agricultural mobile mechanismA-type:Y-type:supported by multiplesupported by single moving regionsmoving regionWheel typeCrawler typeSelectedLeg typeSnake-like type3.3 Mobile platform selectionLand mobile platforms are classified as shown in the rows of Table 2. Although the leg type and the snake-like type are still in the research and development stage, the wheel type and the crawler type are in the commercialization stage. As mentioned in Sect. 3.1, numerous mobile platforms exist for agricultural vehicles. The crawler type presents advantages in locomotion “within a field,” because the bearing capacity of soil within a field is lower than that “between fields.” The wheel type presents advantages in locomotion between fields in terms of speed.We selected the crawler type, since the heavy material handling robot must locomote within a field even when it is raining or immediately after raining, that is, even when the bearing capacity becomes too low. For locomotion between fields, transportation by another wheel-type platform, such as a truck, is assumed and this is discussed later in this sub-section.Agricultural mobile platforms are classified as shown in the columns of Table 2. The A-type “strides over” growing regions while forming an A-like figure. The Y-type does“not stride over” any growing region (and may have a coun-terweight) while forming a Y-like figure. See the Appendix for examples.The A-type has one advantage, namely, falling stability since the A-type satisfies wm Be . Nevertheless, we selected the Y-type because the A-type is not suitable to transportation by another wheel-type platform, especially in the case oflarge Be , such as the watermelon cases shown in Table 1.Table 3 Link length and link length ratiol0l1l2l3d1maxd2maxd3max1-rl :rlParallel0.50.5(2.0)0.0(5.0)3max 2PolarArticulated0.50.5(3.0)(2.0)l2:l3Cylindrical0.5(2.0)d:dCartesian(2.0)2.0(2.0)1max 3maxSCARA0.50.5(2.75)(2.75)1.0l2:l3d:l(3.0)2maxd3max:dNow we select a commercial self-propelled crawler vehicle (145 kg) with an engine (3.2 kW) for TASK 2B, as one candidate for the Y-type crawler platform.From (5), Ne decreases as we increases. This becomes a more serious problem when Se is large. The vehicle width is 490 mm, which is sufficiently small to pass through the narrow width we and can keep the existing we in Table 1. While Ct does not depend on we , we can see that a small value of we can increase the numerator of Cet , which can be considered as an index of the expected sales.3.4 Manipulator design (kinematics)Many well-known kinematic models exist, such as the po-lar coordinate type, articulated type, cylindrical coordinate type, Cartesian coordinate type, and SCARA type which was proposed from a practical viewpoint for assembly operations in industrial settings.The design guidelines of a kinematic model of the heavy material handling manipulator are summarized below:G1 High normalized endpoint force in the vertical direction G2 High normalized workspace volumeG3 High suitability to a mobile platform G4 High performance of contact safety G5 Low initial costwhere G3 is introduced because (AR3) is selected.In this study, from a practical viewpoint similar to that for SCARA type, the candidate proposed for heavy material handling in agriculture is shown in Fig. 3(a). This candidate has four degrees of freedom (4 DOF) and is termed the “par-allel type.”This type is generalized from the original design (Umeda et al. 1997), but it can achieve a higher falling stability by removing the triangular geometry constraint. Other well-known types are also shown in Fig. 3.First, we determine that the endpoint position configuration (the three joints configuration) is designed to satisfy G1G2G3 by performing a kinematics analysis for the numerical example given in Table 3. Second, we deter-mine that the endpoint orientation configuration (an additional joint configuration) is designed to satisfy G4G5. This process is discussed later in this section.The direct kinematics of the rigid manipulator is given bywhere x is the endpoint position and q is the joint displacement. For the parallel type, the kinematics are as follows:where q = 1 2 d3T . Details about the other types are not described here since they are well known.3.4.1 Endpoint forceManipulability ellipsoids are represented by the following equationwhere Im() is the image space and J (q ) = r/ q R33 is a Jacobian.Figure 4 shows the manipulability ellipsoids that are normalized by the summation L of each link length in Table 3. Note that the endpoint force is large in the direction where the manipulability is small because the endpoint force is the dual of the manipulability (Yoshikawa 1985). The vertical endpoint force of the polar coordinate type and that of the articulated type tend to be smaller than that of the parallel type.Especially when targets exist on ground level, such as in heavy vegetable harvesting,the vertical endpoint force on the ground of the polar coordinate type and the articulated type decrease as the endpoint position leaves the base. These imply that the polar coordinate type and the articulated type do not satisfy G1.Fig. 3Kinematic models3.4.2 Workspace volumeNormalized workspace volume (Yang and Lee 1984) is ex-pressed aswhere the integral sign denotes a volume integral.Figure 5 shows the relationship between the link length ratio rl and the normalized workspace volume. Each link length ratio rl is defined as in Table 3. The respective normalized workspace volumes of the cylindrical coordinate type, the Cartesian coordinate type and the SCARA type are smaller than that of the parallel type, irrespective of their link length ratio. This fact implies that the cylindrical coordinate type, the Cartesian coordinate type and the SCARA type do not satisfy G2.Fig. 4NormalizedmanipulabilityFig. 5Normalized workspace volume3.4.3 Suitability to a mobile platformIn general, as the normalized workspace volume increases, the required moving distance decreases. Figure 5 shows that the suitabilities to a mobile platform of the cylindrical coordinate type, the Cartesian coordinate type and the SCARA type are lower than that of the parallel type.Also, in general, as the manipulability becomes more in-dependent of the endpoint position, the required control of the mobile platform becomes simpler. This is all themore important in the case of the crawler type because the crawler type has no omnidirectional characteristic. Note that we do not discuss the other types, such as the wheel type, at this time, because we already selected the crawler type as our mobile platform in Sect. 3.3 under the guideline (AR3) given in Sect. 3.1. The manipulability (and the vertical endpoint force) of the parallel type is completely constant on ground level where the targets are located in the case of heavy vegetable harvesting. Figure 4 implies that the suitabilities to a mobile platform of the polar coordinate type and the articulated type is lower than that of the parallel type.Now, we can conclude that the parallel type best satisfies G1G2G3. In the analysis in the remainder of this section, we check whether the parallel type satisfies G4 and G5 or not.3.4.4 Performance of contact safety and initial costIn the fields of welfare and human care, safety strategies for collisions between robots and humans are classified into control strategies and machine design strategies, according to the situations and actions before and after a collision (Ikuta and Notaka 1999). From the viewpoint of G4, we apply this classification to a safety strategy for the collision between a robot and an agricultural target (e.g., fruit, eggs and cow udders). We select a control strategy for before a collision and a machine design strategy for after a collision.More precisely, a control system is designed to achieve small positional errors to avoid undesirable collisions and an additional joint (Joint 4) is designed to be passive to reduce the contact force immediately after a collision. This machine design strategy has an additional advantage from the viewpoint of G5. The passive joint results not only in an actuator reduction but also in an inclination sensor reduction because the steady state of the Joint 4 displacement is always equal to the inclination angle, as a result of the kinematics shown in Fig. 3(a). If we select a control strategy after a collision, we might require force sensors, and have more difficulty in satisfying G5.3.5 Manipulator design (structure)Figure 6 shows a schematic diagram of the manipulator. From (9), Cet decreases as Mc increases, and this is more effective when Tm and Le are large or Vm is small. The maximum horizontal reach of the manipulator is 2.8 m, which is sufficiently longto make Mc large, especially for small Be , and to keep the existing Be in Table 1. While Ct is ill-defined for robot manipulators, we can see that large Mc by long manipulators increases the global performance of Cet .Fig. 6Schematic diagram of the manipulator3.5.1 Transducer & power source selection and transmission & circuit designThree joints (Joint 1, Joint 2 and Joint 3) are active joints. A hydraulic motoractuates Joint 1. The torque of the motor is transferred to the harmonic drive gear (1/50) through a toothed belt and two pulleys. Two hydraulic cylinders actuate Joint 2. The force of the cylinders is converted through a mechanical linkage, and the maximum vertical endpoint force is 150 N. The hydraulic actuators have direct-type servo valve drivers.The power source of the hydraulic actuators is the crawler vehicle engine. From the viewpoint of G3, the hydraulic system is advantageous since only a pulley and a belt are required for conversion from an engine (3.2 kW, 2000 rpm) to a pump (0.2 l/s).A DC motor (110 W) with a reduction gear (1/15) actuates Joint 3. The rotary motion of the motor is converted to translational motion through a toothed belt, two toothed pulleys, and a slider. The slider has four small bearings as wheels so that it can move on the rail. The DC motor has a current driver. The power source is a battery (24V) and a vehicular generator. Unlike hydraulic cables, electrical power cables can be easily disconnected. Therefore, this long manipulator also can be disconnected for transportation by a truck.Joint 4 consists of a bearing attached to the slider with-out dampers. From the viewpoint of high-speed operation, viscous friction is preferable for reduction of the remaining oscillation of Joint 4. However, from the viewpoint of G4 (the safety strategy after collision), viscous friction is not preferable. That is, viscous friction increases the contact force on the target and the environment. This trade-off problem cannot be solved by using only machine design, such as a damper attachment. As described later, switching and scheduling of controllers can be used to solve this trade-off problem.Figure 7 shows the drive (hydraulic and electric) circuits. The controller consists of a D/A converter (12-bit), a digital computer (25 MHz) and a counter board (24-bit).Optical rotary encoders (1024, 1024, 1000, 200 24 P/R) measure the displacement of all joints. All inputs (v1, v2, v3) are constrained by 5 V and all outputs (1, 2, d3, 4) are con-strained as shown in Table 4. The manipulator is a 3-input 4-output system.3.5.2 End-effector selection and redesignWe select a hand and redesign it for picking and placing watermelons. From the viewpoint of G5, we select an original type of hand (Iida et al. 1995) consisting of four 1-DOF fingers with no actuators. It performs picking using passive force closure within a 40-mm allowable positional error. However, this hand cannot perform placing without a hydraulic actuator.Table 4 Robot specificationsVehicleMass Width145 kg490 mmManipulatorMass90 kgOperating range115 1 +115 deg25 2 +25 deg0 d3 1890 mmMaximal reach30 4 +30 deg2800 mmFig. 7Drive circuitFig. 8 Motion plan for placing using reaction forcesWe focus on the fact that reaction forces are transmit-ted from the platform to the finger during placing. We design a wire mechanism to realize placing using less power, as shown in Fig. 8. First, the wires suspend the fingers and gravity keeps the finger closed (Fig. 8(a). Second, after the hand contacts the platform by the Joint 2 motion, the wire tension can be zero because of the reaction forces (Fig. 8(b). Third, alow-power DC motor reels the wires and keeps the fingers open (Fig. 8(c). Finally, the hand rises without re-contacting the objects (Fig. 8(d).4Control systemsThis section discusses a control system designed in an analytical way. We design controllers experimentally without considering robustness and then demonstrate the robust stability of the closed-loop system in the presence of parametric perturbation and uncertainty.4.1 Motion planning and controller design guidelineThe targeted watermelon is manipulated as follows.M2D-1: The hand is moved above the watermelon by all active joints. M2D-2: The hand picks the watermelon up with Joints 2 and 3.M2D-3: The hand is moved above the platform with Joints 1 and 3. M2D-4: The hand places the watermelon with Joints 2 and 3.Immediately after M2D-4, either TASK 2A or TASK 2C fol-lows.In this paper, we select PTP control to realize this motion plan and design the controllers in the next section. Here, the following uncertainty is expected in the manipulator.Parameter perturbationsThe watermelon mass is 612.0 kg. This mass can cause additional perturbations, such as changes in joint friction or in the moment of inertia, in addition to the original perturbations, which exist in the torque constant value and the joint friction.Unmodeled dynamicsIn general, unmodeled dynamics exist for hydraulic systems because physical modeling of hydraulic systems is difficult.However, some types of robust controllers (e.g., H controller) give conservativeresults even though they are gen-erated by reasonable design procedures. To avoid this problem, we design robust controllers in an analytical way. First, we design controllers experimentally without considering robustness. Next, we demonstrate the robust stability of the closed-loop system in the presence of parametric perturbation and uncertainty.Furthermore, we separate the entire 3-input 4-output system into three subsystems: Joint 1 system, Joint 2 system, and Joint 3Joint 4 system. Their mutual interferences are sufficiently weak, or at least do not influence the closed-loop stability at all (Sakai et al. 2007). First, we design the Joint 3Joint 4 controller in the presence of parametric perturbation. Second, we design the Joint 1 controller and the Joint 2 controller in the presence of unmodeled dynamics.4.2 Controller designFor the Joint 3Joint 4 system, we design a switched controller consisting of one PD controller K1 and two LQ controllers K2 and K3, where K1 controls only the Joint 3 dis-placement, K2 and K3 controls both the Joint 3 and Joint 4 displacement. We could find no single controller with sufficient performance because of the parametric perturbations. These three controllers are switched according to the end-point position of the manipulator.Integral action was not applied instead of switching due to the large input saturation at large initial values, which is an important problem associated with long and translational robotic arms in general. This is the reason why nonlinear friction (such as Coulomb and Stribeck) was not modeled explicitly in (15).The two LQ controllers are designed for the linearized model and the following evaluation criteria are used:The respective controllers are49where the gains of K1 and their switching conditions are tuned experimentally.For the Joint 1 and Joint 2 systems, joint-independent PID controllers are implemented as4.4 Control system analysisThe perturbed parameters of the Joint 3Joint 4 system are described asIn the motion plan just mentioned, M is regarded as a static system. The robust stability of the closed loop is analyzed in the presence of the perturbation of m and cm under arbitrary fixed M .However, (16) clarifies that the elements of the coefficient matrices A and B are nonlinear with respect to the physical parameters. This nonlinearity implies that the analyzed result can be very conservative when the uncertainty is ex-pressed as affine perturbations with respect to the coefficient matrices, or as affine perturbations with respect to the coefficient of the characteristic equation for Kharitonovs theorem.Actually, these approaches cannot demonstrate closed-loop stability for the case of Table 5.Therefore, once we notice that the physical parameters are written in rational polynomial form in A and B , (16) can be rewritten in a descriptor form, as follows:In these equations, the elements of the coefficient matrices are polynomial in form. In this case, the following relation holds (Kawanishi and Sugie 1995).5 ConclusionIn this paper, we described the realization of a heavy material handling manipulator system for agricultural robots.More precisely, structural systems of the mobile platform and manipulator were selected and designed based on newly gained knowledge for agricultural robots and the kinematics indexes. The control systems were designed in the presence of parametric perturbation and uncertainty, while avoiding conservative results. In the most important phase of this study, the validity of both systems was confirmed byper-forming field experiments in an actual open field. The total operation time and the success rate were confirmed to be comparable to those of skilled workers harvesting watermelons.Furthermore, an explicit design procedure clarified the design tools required to evaluate the possible improvements of agricultural robots, which was the another important goal of the current study. From the viewpoint of both performance and initial cost, the first design tool is “evaluation indexes,” such as Cet (extended TFC). Even if no design optimization methods exist with respect to the index, this index can provide qualitative results that is useful for investigating the levels of the possible improvements. From the viewpoint of initial cost only, the second design tool is “classification tables,” such as Table 2. The structural system design actually consisted not only of the design, but also of the selection based on the classification tables. These classification tables are required except in the (AR2) case. These table size (the number of columns and rows) are the number of candidates in the selection and shows the levels of the possible improvements. From the viewpoint of performance only, the third design tool is “closed-loop analysis methods,” such as the -analysis. The control system design was actually ad hoc and the stability margin was guaranteed by analysis, not by synthesis (e.g., H design). Needless to say, the mar-gin of stability and control performance directly evaluates the levels of possible improvements in stability and control performance.译文农业机器人重物料搬运机械手的设计与控制摘要：本文提出了一种用于农业机器人搬运重物的操作系统。提出了农业机器人 的新知识，对移动平台和机械手的结构系统进行了选择和设计。同时，在参数摄 动和不确定性的情况下，设计了这些结构系统的控制系统。通过西瓜露地收获试 验，验证了结构和控制系统的有效性。在此基础上，确定了结构和控制系统的明 确设计步骤，并阐明了三种关键设计工具。关键字：农业机器人；操作者 ；鲁棒控制 ；评价指标1介绍在农业领域，必须进行各种处理重材料的操作。例如，在蔬菜种植中，工人 在收获季节处理沉重蔬菜。此外，在迅速普及的有机耕作中，工作人员在施肥季 节处理沉重的堆肥袋。这些操作枯燥、重复，需要工人的力量和技能20 世纪 80 年代，人们对农业机器人进行了大量的研究和开发。这些研究中 的许多专门研究机器人的结构系统设计(例如，机器或电路设计)，并报告实际开 放领域中基本动作的实现。最近，马丁内斯和同事们对滑动工况下农用运输车控 制系统的设计进行了合理的探讨。总之，这些研究仅针对农业机器人的一个结构 系统或一个控制系统。很少有论文讨论结构系统和控制系统的明确设计程序。然 而，许多农业机器人目前尚未进入商业化或推广阶段。相反，它们仍处于研究和 发展阶段。因此，有必要支持进一步的研究和开发，以提高这些机器人的性能和 降低其初始成本。除了一些发展中的组成部分，如先进的视觉，仍然不清楚现有的(和隐含的) 设计程序可以改进多少。这种情况很严重，因为还不清楚是否有设计工具来评估 性能和初始成本的可能改进。为了澄清这些设计工具的现状，我们需要确定结构 和控制系统的明确设计程序。本文报道了一种用于农业机器人的重型物料搬运机械手的实现。更准确地 说，在提出了农业机器人的新知识后，选择并设计了移动平台和机械手的结构系 统。此外，控制系统的设计是在参数摄动和不确定性的情况下进行的，避免了保守性的结果。通过野外实验验证了两种系统的有效性。这些实验结果是本文最重 要的贡献。现场运行结果表明，总的运行时间和成功率与熟练工人相当。此外，还确定了一个明确的设计过程，以阐明评价农业机器人可能改进之处 的设计工具的现状，这也是本文的另一个重要贡献。图 1 重型物料搬运农业机器人图 2 农业机器人的工作环境模型2 全球性能指标在本节中，我们讨论了农业机器人整体性能的评价指标。一般来说，如果不 使用性能指标，就无法开始任何合理的设计。对一般机器人提出了许多性能指标。 例如，可操作性是一个众所周知的结构系统指数。然而，有一些专门针对农业机 器人提出的指标。例如，避障空间用于农业机器人与植物(不包括目标植物)之间 的避碰。危险程度用于农业机器人与人之间的避碰。然而，这些指标仅在空间和 时间上评估局部性能。从农业机器人整体研究的角度来看，有一个潜在有用的全 球指标，称为“理论田间能力”( TFC )，它已应用于现有的农用车辆，如拖拉机、 插秧机和收割机。TFC 定义如下:其中 WM 是机器工作宽度，Vm 是机器直线运行速度。实际上，WM 是末端执行 器的宽度，Vm 定义为具有足够工作性能的最大速度。在本节中，下标 m 表示只依 赖于工作机器，下标 e 表示只依赖于工作环境，下标 c 表示两者都依赖。有两个问题。首先，TFC 不能用于机械手等高自由度机构，因为它基于现有 农用车辆的末端执行器，即低自由度机构。其次，TFC 不考虑转弯和(不)装载， 也不考虑农业机器人与其工作环境之间的任何交互作用。为了解决这些问题，我们引入了农业机器人的全局性能指标。首先，我们从 工作环境模型开始。在农业领域，工作环境分为两个子环境，即田地和道路。这 意味着运动也可分为“场内运动”和“场间运动”(道路上的运动)。图 2 显示了 农业机器人的工作环境模型。该场由植物(格点)生长的生长区域和机器人移动的移动区域组成，并且其中 Be :生长区域的宽度，we :移动区域的宽度，Le :生长 区域和移动区域的长度，me :格点的列数，ne :格点的行数，Be :格点之间在宽 度方向上的间隔，Le :格点之间的间隔以及从生长区域的上(或下)侧到长度方向 上的最近格点的距离。此模型具有以下属性:植物密度定义和近似如下:这种近似与 ne 测量的时间和精力的经济性有关。设 Se 为场面积和常数，则生长区域的数量由下式给出这是一个全局工作空间方程。另一方面，假设 Mc 是机器人同时感知和操纵的增长区域的数量，即，工作空间 和视场之间的增长区域的数量。对于常规农用车辆，WM = Mc 被保持。通过考虑 一个规范的任务计划，则机器人在 Mc 生长区直线运行的工作时间如下 Mc 生长区的车削加工时间为其中 Tm是 180 度旋转时间。总的来说，总的工作时间是这是一个全局工作时间方程。从( 5 )和( 8 )中，提出了一个新的评价指标这是在 TFC 的第一个问题中为高自由度机构明确定义的工作频率(即，TFC 不 能用于高自由度机构)。在现有农用车辆的情况下，如果我们 we = 0,Tmmm + T p, Tct 0 and nc . 这对应于 TFC 的第二个问题(即，TFC 不考虑转弯和( 不)装载，并且不考虑农业机器人与工作环境之间的相互作用)。在 ( 10 )中，Cet 是 Ct (扩展的理论场容量)的扩展。3 结构系统在本部分中，我们讨论了手动移动平台和机械手结构系统的选择和设计。3.1 农业机器人的设计策略具有运动和操纵功能的农业机器人的设计策略分为以下几类: ( AR1 )选择移动平台和现有的固定机械手，然后对它们进行叠加 ( AR2 )移动机构与机械手的同步设计( AR3 )选择移动平台，然后只设计机械手( AR4 )选择固定机械手，然后只设计移动机构( AR1 )是初始成本强调情况，( AR2 )是性能强调情况，( AR3 )和( AR4 )是中间情况。 我们选择( AR3 )是因为在农业领域，初始成本和性能都不可忽视，而且现有农用 车辆有许多移动平台。根据( AR3 )，首先，我们从现有的移动平台中选择一个移 动平台，其次，我们设计了一个不仅适用于预期任务而且适用于所选移动平台的 机械手。表 1 工作环境模型参数(西瓜田)PlaceDateYamagata Obanazawa 2000.8Chiba Tomisato 2000.6Nagano Matsumoto 1999.8Fukui Sakai 2000.5Tottori Fukube 2000.8Kumamoto Kamoto 2000.5Be m5.01.83.610.03.32.5we mle mme1122113.2 任务在这里，重型物料搬运农业机器人的任务是收获西瓜。有人研制了一种瓜收 获机器人。有人开发了一种带有遥操作系统的西瓜收获机器人和了西瓜收获机器 人的数字电路视觉系统。这些研究主要针对结构系统或控制系统。在本文中，我 们同时讨论了这两个问题。表 1 显示了在日本一些主要产品区调查的环境参数。对西瓜采收的常规操作 程序进行了研究，分为以下四个步骤。第一步:选择目标西瓜，剪下藤蔓 第二步:把它们拣起来放在送货车上 第三步:驾驶车辆并重新装载到卡车上 开卡车到工厂卸货步骤 1 不需要艰苦的劳动。对于步骤 3 和步骤 4，已经开发了工作机器(例如， 具有升降机的车辆)，因为这些操作需要艰苦的劳动。然而，对于步骤 2，尽管步骤 2 需要艰苦的劳动，但还没有开发出工作机器。 摘西瓜需要工人有一个高的终点力。各种各样的障碍，如叶子、藤蔓和未选择的 西瓜，限制了工人的方向。更准确地说，工人们需要踮起脚尖处理 6 - 12 公斤西瓜。这意味着步骤 2 要求工人产生高接头扭矩。总之，步骤 2 是一项具有挑战性 的任务。我们的最终目标是第二步的自动化。机器人步骤 2 操作的任务如下。 任务 2A :从远处观察西瓜任务 2B :移动到他们附近 任务 2C :近距离感知它们任务 2D :操纵(拾取和放置)它们在完成任务 2D 之后，接着是任务 2A 或任务 2C。在本研究中，任务 2D 被实现和 评估。应该注意的是，熟练工人平均在大约 10 秒钟内持续完成采摘一个西瓜的操 作。表 2 农业移动机构分类A-type:Y-type:supported by multiplesupported by single moving regionsmoving regionWheel typeCrawler typeSelectedLeg typeSnake-like type3.3 移动平台选择陆地移动平台分类如表 2 的行所示。腿型和蛇型仍处于研发阶段，轮式和履 带式尚处于商业化阶段。如第三节所述。3.1 农用车辆有许多移动平台。履带式 在“田内”移动方面具有优