平衡臂機械手的設(shè)計之平衡臂及機械手爪

平衡臂機械手的設(shè)計之平衡臂及機械手爪,平衡臂機械手的設(shè)計之平衡臂及機械手爪,平衡,機械手,設(shè)計,機械,手爪 目 錄摘要、關(guān)鍵詞1第1章 緒 論.41.1國內(nèi)外機械手綜述41.1.1簡史41.1.2應(yīng)用簡況51.1.3國內(nèi)外機械人發(fā)展趨勢51.2機械手的組成和分類61.2.1機械手的組成61.2.2機械手的分類71.3本課題研究的主要內(nèi)容及意義81.3.1 課題 七桿二自由度機械手設(shè)計內(nèi)容及基本要求81.3.2重點研究的問題：91.3.3 本次設(shè)計的意義9第2章 機械手基本參數(shù)的確定102.1抓重102.2 轉(zhuǎn)角102.3工作速度102.4定位精度11第3章 機械手機械結(jié)構(gòu)的設(shè)計計算123.1 機械手機構(gòu)的分析與設(shè)計123.1.1機械手的自由度123.1.2坐標形式133.1.3機械手的機構(gòu)簡圖以及部件尺寸133.1.4機械手總體方案的比較143.2 機構(gòu)桿件的受力校核分析153.2.1支撐桿的受力校核153.2.2導軌滑桿的強度檢驗153.2.3立柱支撐軸的強度校核1633機械手手指結(jié)構(gòu)的設(shè)計與計算173.3.1概述173.3.2手指的驅(qū)動力計算183.3.3手部伸縮的驅(qū)動裝置203.3.4 手指定位誤差的分析203.4機械手手腕結(jié)構(gòu)的設(shè)計與計算203.4.1手腕自由度和結(jié)構(gòu)203.4.2手腕的結(jié)構(gòu)213.4.3 手腕驅(qū)動力矩的計算213.4.4回轉(zhuǎn)缸的驅(qū)動力矩計算233.5手臂結(jié)構(gòu)分析243.5.1大手臂的結(jié)構(gòu)及其工作原理243.5.2大手臂做升降運動時所需的驅(qū)動力263.5.3驅(qū)動油缸的計算273.5.4缸蓋的強度計算283.5.5活塞桿的穩(wěn)定行驗算293.5.6大手臂系統(tǒng)溫升的驗算293.5.7 設(shè)計手臂時注意的問題30總結(jié)31參考文獻32附錄一 英文文獻翻譯33附錄二 英文翻譯原文.4031平衡臂機械手的設(shè)計之平衡臂及機械手爪摘 要 ：論文模仿機械手的基本功能和設(shè)計思路，根據(jù)給定的規(guī)定動作順序，綜合運用所學的基本理論、基本知識和相關(guān)的機械設(shè)計專業(yè)知識，完成了機械手的設(shè)計，并繪制必要的零部件圖和裝配圖，其中包括機器裝置的原理方案構(gòu)思和擬定；原理方案的實現(xiàn)、傳動方案的設(shè)計；主要結(jié)構(gòu)的設(shè)計簡圖；設(shè)計計算與說明；控制油路系統(tǒng)的設(shè)計。工業(yè)機械手設(shè)計的主要技術(shù)關(guān)鍵問題為：夾持機構(gòu)的夾緊與翻轉(zhuǎn)；行程機構(gòu)的轉(zhuǎn)向與伸縮；提升機構(gòu)的提升；控制油路系統(tǒng)的設(shè)計。關(guān)鍵詞：工業(yè)機械手；手爪；伸縮油缸；轉(zhuǎn)動油缸Manipulator arm of a balanced design and mechanical gripper arm balanceSummary：The thesis deploys the basic function and the way of design of the automatic hand , according to the given provision of action in proper order, comprehensively using the basic theories, basic knowledge and the related professional knowledge of mechanical design, completing the design of mechanical hand, and drying the diagrams of the necessary spare parts and the assemble diagram, including the consideration and the establishment of the principle;The realization of the principle, powertrains of the project; sketch plan of the structure;calculation of design and the elucidation; design of the the liquid press system.The mainly key problem of design a mechanical hand is :Clipping the object and revolving;The route of travel organization;the promotion of the organization;the design of the liquid press system.Keyword:Industrial mechanical hand Hand claw Flexible oil urn recolcing oil urn第1章 緒 論工業(yè)機械手是近代自動控制領(lǐng)域中出現(xiàn)的一項新技術(shù)，并已經(jīng)成為現(xiàn)代機械制造生產(chǎn)系統(tǒng)中的一個重要組成部分。這種新技術(shù)發(fā)展很快，逐漸成為一門新興的學科機械手工程。機械手的迅速發(fā)展是由于它的積極作用正日益為人們認識：其一，它能部分地代替人工操作；其二，它能操作必要的機具進行焊接和裝配。從而大大得改善人工的勞動條件，顯著得提高勞動生產(chǎn)效率，加快實現(xiàn)工業(yè)生產(chǎn)機械化和自動化的步伐。因而，受到各先進工業(yè)國家的重視，投入大量的人力物力加以研究和應(yīng)用。尤其在高溫，高壓，粉塵，噪音以及帶有放射性和污染的場合，應(yīng)用得更為廣泛。在我國，近幾年來也有較快的發(fā)展，并取得一定的效果，受到機械工業(yè)和鐵路工業(yè)部門的重視。機械手一般分為三類。第一類是不需要人工操作的通用機械手。它是一種獨立的不附屬于某一主機的裝置。它可以根據(jù)任務(wù)的需要編制程序，以完成各項規(guī)定操作。它的特點是具備普通機械的物理性能外，還具備通用機械，記憶智能的三元機械。第二類是需要人工操作的，稱為操作機。它起源于原子，軍事工業(yè)，先是通過操作機來完成特頂?shù)淖鳂I(yè)，后來發(fā)展到用無線電尋好操作機械手來進行月球的探測等。工業(yè)中采用的鍛造操作機也屬于這一范疇。第三類是專用機械手，主要負數(shù)于自動機床或自動線上，用以解決機床上下料和工件傳送。這種機械手在國外稱為Mechanical Hand，它是為主機服務(wù)的，有主機驅(qū)動；除少數(shù)外，工作程序一般是固定的，因此是專用的。1.1國內(nèi)外機械手綜述1.1.1簡史機械手首先是從美國開始研制的。1958年美國聯(lián)合控制公司研制出第一臺機械手。她的結(jié)構(gòu)是：機體上安裝一回轉(zhuǎn)長臂，端部裝有電磁鐵的工件抓放機構(gòu)，控制系統(tǒng)是示教型的。1962年，美國聯(lián)合控制公司在上述方案的基礎(chǔ)上又試制一臺數(shù)控示教再現(xiàn)型機械手。商名為Unimate（即萬能自動）。同年，美國機械鑄造公司也實驗成功一種叫Versatrap機械手，原意是靈活搬運。1978年美國Unimate公司和斯坦福大學，麻省理工大學聯(lián)合研制一種叫Unnimation-Viearm型工業(yè)機械手，裝有小型電子計算機進行控制，用于裝配作業(yè)。到目前為止，日本是工業(yè)機械手發(fā)展最快，應(yīng)用最多的國家。但是，目前的機械手大部分還屬于第一代，主要依靠人工進行控制；控制方式為開環(huán)式，沒有識別能力；改進的方向主要是減低成本和提高精度。第二代機械手設(shè)有微型電子計算機控制系統(tǒng)，具有視覺，觸覺能力，甚至聽、想的能力。研究安裝各種傳感器，把感覺到的信息反饋，使機械手具有感覺機能。第三代機械手（機器人）則能獨立地完成工作過程中的任務(wù)。它與電子計算機和電視設(shè)備保持聯(lián)系。并逐步發(fā)展成為柔性制造系統(tǒng)FMS（Flexible Manufacturing System）和柔性制造單元FMC(Flexible Manufacturing Cell)中重要的一環(huán)。1.1.2應(yīng)用簡況就國內(nèi)機械工業(yè)，鐵路 部門應(yīng)用機械手的簡況，介紹如下：（一） 熱加工方面的應(yīng)用熱加工是高溫、危險的笨重體力勞動，很久以來就要求實現(xiàn)自動化。為了實現(xiàn)高效率和工作安全，尤其對于大件、少量、低速和人力所不能勝任的作業(yè)就更加需要采用機械手操作（二） 冷加工方面 冷加工方面機械手主要采用于柴油機配件以及軸類、盤類和箱體類等零件單機加工時的上下料和刀具安裝等。進而在程序控制、數(shù)字控制等機床上應(yīng)用，成為設(shè)備的一個組成部分。更在加工生產(chǎn)線、自動線上應(yīng)用，成為機床、設(shè)備上下工序聯(lián)結(jié)和重要手段。（三） 拆修裝方面 拆修裝是鐵路工業(yè)系統(tǒng)繁重體力勞動較多的部門之一，促進了機械手的發(fā)展。目前國內(nèi)鐵路工廠、機務(wù)段等部門，已采用機械手拆裝三通閥、鉤舌、分解制動缸、裝卸軸箱、組裝輪對、清除石棉等，減輕了勞動強度，提高了拆修裝的效率。 采用機械手進行裝配更是目前研制的重點，國外已研究采用攝象機和里的傳感裝置和微型計算機聯(lián)系在一起，能確定零件的方位，達到鑲裝的目的。1.1.3國內(nèi)外機械人發(fā)展趨勢在普及第一代工業(yè)機器人的基礎(chǔ)上，第二代工業(yè)機器人已經(jīng)推廣，成為主流安裝機型，第三代智能機器人也占有一定比重(占日本1998年安裝臺數(shù)的10%，銷售額的36% )。 機械結(jié)構(gòu) 以關(guān)節(jié)型為主流，80年代發(fā)明的適用于裝配作業(yè)的平面關(guān)節(jié)型機器人約占總量的1/3。應(yīng)3K和汽車、建筑、橋梁等行業(yè)的需求，超大型機器人應(yīng)運而生。CAD , CAM等技術(shù)己普遍用于設(shè)計、仿真和制造中?？刂萍夹g(shù) 大多采用32位CPU，控制軸數(shù)多達27軸，NC技術(shù)、離線編程技術(shù)大量采用。協(xié)調(diào)控制技術(shù)日趨成熟，實現(xiàn)了多手與變位機、多機器人的協(xié)調(diào)控制。采用基于PC的開放結(jié)構(gòu)的控制系統(tǒng)已成為一股潮流。驅(qū)動技術(shù) 80年代發(fā)展起來的AC伺服驅(qū)動已成為主流驅(qū)動技術(shù)應(yīng)用于工業(yè)機器人中。新一代的伺服電機與基于微處理器的智能伺服控制器相結(jié)合已由FANUC等公司開發(fā)并用于工業(yè)機器人中;在遠程控制中已采用了分布式智能驅(qū)動新技術(shù)。應(yīng)用智能化的傳感器 裝有視覺傳感器的機器人數(shù)量呈上升趨勢，不少機器人裝有兩種以上傳感器，有些機器人留了多種機器人接口。通用機器人編程語言 在ABB公司的20多個型號產(chǎn)品中，采用了通用模塊化語言RAPID。最近美國機器人空間技術(shù)公司開發(fā)了Robot Script V.10通用語言，運行于該公司的通用機器人控制器URC的Win NT/95環(huán)境下。該語言易學易用，可用于各種開發(fā)環(huán)境，與大多數(shù)WINDOWS軟件產(chǎn)品兼容。網(wǎng)絡(luò)通訊方式 大部分機器人采用了Ether網(wǎng)絡(luò)通訊方式，占總量的41.3%，其他采用RS-232, RA-422, RS-485等通訊接口。高速、高精度、多功能化 目前，最快的裝配機器人最大合成速度為16. 5m/s，有一種大直角坐標搬運機器人，其最大合成速度竟達80m/ s;而另一種并聯(lián)結(jié)構(gòu)的NC機器人，其位置重復精度達limo 90年代末的機器人一般都具有兩、三種功能，向多功能化方向發(fā)展。集成化與系統(tǒng)化 當今機器人技術(shù)的另一特點是機器人的應(yīng)用從單機、單元向系統(tǒng)發(fā)展。百臺以上的機器人群與微機及周邊設(shè)備和操作人員形成一個大群體?？鐕蠹瘓F的壟斷和全球化的生產(chǎn)將世界眾多廠家的產(chǎn)品聯(lián)接在一起，實現(xiàn)了標準化、開放化、網(wǎng)絡(luò)化的“虛擬制造”，為工業(yè)機器人系統(tǒng)化的發(fā)展推波助瀾。隨著計算機技術(shù)的不斷向智能化方向發(fā)展，機器人應(yīng)用領(lǐng)域的不斷擴展和深化以及機器人在FMS, CIMS系統(tǒng)中的群體應(yīng)用，工業(yè)機器人也在不斷向智能化方向發(fā)展，以適應(yīng)“敏捷制造”(Agile Manufacturing)，滿足多樣化、個性化的需求，并適應(yīng)多變的非結(jié)構(gòu)環(huán)境作業(yè)，向非制造領(lǐng)域進軍。我國的工業(yè)機器人從80年代“七五”科技攻關(guān)開始起步，在國家的支持下，通過“七五”、“八五”科技攻關(guān)，目前己基本掌握了機器人操作機的設(shè)計制造技術(shù)、控制系統(tǒng)硬件和軟件設(shè)計技術(shù)、運動學和軌跡規(guī)劃技術(shù)，生產(chǎn)了部分機器人關(guān)鍵元器件，開發(fā)出噴漆、弧焊、點焊、裝配、搬運等機器人:其中有130多臺套噴漆機器人在二十余家企業(yè)的近30條自動噴漆生產(chǎn)線(站)上獲得規(guī)模應(yīng)用，弧焊機器人己應(yīng)用在汽車制造廠的焊裝線上。但總的來看，我國的工業(yè)機器人技術(shù)及其工程應(yīng)用的水平和國外比還有一定的距離，如:可靠性低于國外產(chǎn)品:機器人應(yīng)用工程起步較晚，應(yīng)用領(lǐng)域窄，生產(chǎn)線系統(tǒng)技術(shù)與國外比有差距:在應(yīng)用規(guī)模上，我國己安裝的國產(chǎn)工業(yè)機器人約200臺，約占全球己安裝臺數(shù)的萬分之四。以上原因主要是沒有形成機器人產(chǎn)業(yè)，當前我國的機器人生產(chǎn)都是應(yīng)用戶的要求，“一位客戶，一次重新設(shè)計”，品種規(guī)格多、批量小、零部件通用化程度低、供貨周期長、成本也不低，而目質(zhì)量、可靠性不穩(wěn)定。因此迫切需要解決產(chǎn)業(yè)化前期的關(guān)鍵技術(shù)，對產(chǎn)品進行全面規(guī)劃，搞好系列化、通用化、?；O(shè)計，積極推進產(chǎn)業(yè)化進程。 我國的智能機器人和特種機器人在“86“計劃的支持下，也取得了不少成果。其中最為突出的是水下機器人技術(shù)居世界領(lǐng)先水平，還開發(fā)出直接遙控機器人、雙臂協(xié)調(diào)控制機器人、爬壁機器人、管道機器人等機種:在機器人視覺、力覺、觸覺、聲覺等基礎(chǔ)技術(shù)的開發(fā)應(yīng)用上開展了不少工作，有了一定的發(fā)展基礎(chǔ)。但是在多傳感器信息融合控制技術(shù)、遙控加局部自主系統(tǒng)遙控機器人、智能裝配機器人、機器人化機械等的開發(fā)應(yīng)用方面則剛剛起步，與國外先進水平差距較大，需要在原有成績的基礎(chǔ)上，有重點地系統(tǒng)攻關(guān)，才能形成系統(tǒng)配套可供實用的技術(shù)和產(chǎn)品，以期在“十五”后期立于世界先進行列之中。國內(nèi)主要是逐步擴大應(yīng)用范圍，重點發(fā)展鑄鍛，熱處理方面的機械手，以減輕勞動強度，改善作業(yè)條件。在應(yīng)用專用機械手的同時，相應(yīng)地發(fā)展通用機械手，有條件的還要研制示教型機械手、計算機控制機械手和組合式機械手等。將機械手各運動構(gòu)件，如伸縮、擺動、升降、俯仰等機構(gòu)，以及適于不同類型的夾緊機構(gòu)，設(shè)計成典型的通用機構(gòu)，以便根據(jù)不同的作業(yè)要求，選用不同的典型部件，即可組成各種不同用途的機械手。既便于設(shè)計制造，又便于改換工作，擴大了應(yīng)用的范圍。同時要提高速度，減少沖擊，正確定位，以更好地發(fā)揮機械手的作用。更為主要的是將機械手和柔性制造系統(tǒng)和柔性制造單元相結(jié)合，從而根本改變目前機械制造系統(tǒng)的人工操作狀態(tài)。1.2機械手的組成和分類1.2.1機械手的組成 機械手主要由執(zhí)行機構(gòu)、驅(qū)動機構(gòu)和控制系統(tǒng)三大部分組成。一、 執(zhí) 行 機 構(gòu)（1） 手部 手部安裝在手臂的前端，手臂的內(nèi)孔裝有傳動軸，可把動作傳給手腕，以轉(zhuǎn)動、伸屈手腕、開閉手指。 機械手手部的構(gòu)造系模仿人的手指，分為無關(guān)節(jié)、固定關(guān)節(jié)和自由關(guān)節(jié)三種。手指的數(shù)量又分為二指、三指、四指等，其中以二指用的最多。（2） 手臂 手臂有無關(guān)節(jié)臂和有關(guān)節(jié)臂之分。目前采用的手臂幾乎都是無關(guān)節(jié)臂。 手臂的作用是引導手指準確得抓住工件，并運送到所需要的位置上。為了使機械手能夠正確的工作，手臂的三個自由讀都需要精確的定位。（3） 軀干 軀干是安裝手臂、動力源和各種執(zhí)行機構(gòu)的支架。二、 驅(qū) 動 系 統(tǒng) 驅(qū)動機構(gòu)主要有四種：液壓驅(qū)動、氣體驅(qū)動、電氣驅(qū)動和機械驅(qū)動。其中以液壓、氣動用的最多，占90%以上；電動、機械驅(qū)動用的較少。液壓驅(qū)動主要是通過油缸、閥、油泵和油箱實現(xiàn)傳動。它的優(yōu)點是壓力高、體積小，出力大，動作平緩，可無級變速，自鎖方便，并能在中間位置停止。缺點是需配備壓力源，系統(tǒng)復雜，成本較高。氣動驅(qū)動所采用的元件為氣壓缸、氣馬達、氣閥等。它的優(yōu)點是氣源方便，維護簡單，成本低。缺點是出力小，體積大。尤其空氣的可壓縮性大，很難實現(xiàn)中間位置的停止，只能用于點位控制，而且潤滑性較差，氣壓系統(tǒng)容易生銹。為了減少停機時產(chǎn)生的沖擊，氣壓系統(tǒng)的裝有速度控制機構(gòu)或緩沖減震機構(gòu)。電器驅(qū)動都采用三相感應(yīng)電機作為動力，用大減速比減速器來驅(qū)動執(zhí)行機構(gòu)；直線運動則用電機帶動絲杠螺母機構(gòu)；有的采用直線電動機。電氣驅(qū)動的優(yōu)點是動力源簡單；維護、使用方便。一般只用于動作固定的場合。一般用凸輪連桿機構(gòu)實現(xiàn)規(guī)定的動作。它的優(yōu)點是動作確實可開，工作速度高，成本低；缺點是不易于調(diào)整。 三、 控 制 系 統(tǒng)機械手控制的要素，包括工作順序、到達位置、動作時間、運動速度和加減速度等。機械手的控制分為點位控制和連續(xù)詭計控制兩種?？刂葡到y(tǒng)可根據(jù)動作的要求，設(shè)計采用數(shù)字順序控制。它首先要編制程序加以存儲，然后再根據(jù)規(guī)定的程序，控制機械手進行工作。程序的存儲方式分為分離存儲和集中存儲兩種。對于動作復雜的機械手（機械人），采用示教再現(xiàn)型控制系統(tǒng)。更復雜的機械手（機械人）則采用數(shù)字控制系統(tǒng)、小型計算器或微處理機控制的系統(tǒng)。1.2.2機械手的分類 一、按 用 途 分 類 1. 專用機械手 專用機械手是專為一定設(shè)備服務(wù)的，簡單、使用，目前在生產(chǎn)中運用的比較廣泛。它一般只能完成一、二種特定的作業(yè)。如用來抓取和傳送工件。它的工作程序是固定的，也可根據(jù)需要編制程序控制，以獲得多種工作程序，適應(yīng)多種作業(yè)的需要。 2. 通用機械手 通用機械手是在專用機械手的基礎(chǔ)上發(fā)展起來的。它能對不同物件完成多種動作，具有相當?shù)耐ㄓ眯?。它是一種能獨立工作的自動話裝置。它的動作程序可以按照工作需要來改變，大概是采用順序控制系統(tǒng)。通用機械手又分簡易型、示教再現(xiàn)型和只能機械手、草中式機械手等幾種。三、 按控制型式分類 1.點位控制型機械手點位控制型機械手的運動詭計是空間二個點之間的連接?？刂泣c書越多，性能越好。它基本能滿足于各種要求，結(jié)構(gòu)簡單。絕大部分機械手是點位控制型。2.連續(xù)軌跡控制型機械手這種機械手的運動軌跡是空間的任意連續(xù)曲線，它能在三維空間中作極其復雜的動作。工作性能完善，但控制部分比較復雜?？刂品绞椒譃殚_關(guān)式和伺服式兩種。1.3本課題研究的主要內(nèi)容及意義 1.3.1 課題 七桿二自由度機械手設(shè)計內(nèi)容及基本要求設(shè)計一個機械手，用于工廠機床邊抓取圓棒料和餅類零件，實現(xiàn)從地面到機床卡盤和從機床卡盤到地面的運動。 抓取重量；40千克。在總體的設(shè)計過程中，該抓取物重量可以減小。 機械臂活動范圍：活動半徑2 m 夾持物最大直徑100mm（軸類）、最大直徑300(餅類) 活動高度 2.0m 動力：盡可能采用機械傳動、電磁力或氣動。必要時可以采用液壓，但不宜使用高壓液壓設(shè)備。 工作量要求：1平衡臂部件圖紙，油缸裝配圖，活塞零件圖，零部件一覽表，標準間匯總表。 2設(shè)計說明書 3英文翻譯成漢文（5000字）第二章 機械手基本參數(shù)的確定 一個機械手系統(tǒng)所包含的基本參數(shù)有抓重（即臂力）、自由度、工作行程（包括轉(zhuǎn)角），行程速度，工作節(jié)拍和定位精度等。 2.1抓重 抓重就是指機械手所能搬運物件的重量。考慮到這個機械手的結(jié)構(gòu)強度等因素，且抓重要求是40公斤，所以安全系數(shù)K選擇在23范圍內(nèi)。2.2 轉(zhuǎn)角 結(jié)合工廠實地參觀的工件擺放和機床設(shè)備的擺放位置，做出如下簡圖： （虛線所示為手臂抓取工件的位置）所以我們設(shè)計機械手的回轉(zhuǎn)角度為90度。2.3工作速度 機械手的動作節(jié)拍是指機械手完成一個動作循環(huán)所需要的時間。它的運動節(jié)拍只占到生產(chǎn)節(jié)拍的一部分。我們假設(shè)機械手夾持的軸形工件是需要在車床上完成車的工序，當工件在機床加工時是不動作的，當這一工序加工結(jié)束時機械手才再開始動作，所以這時機械手的動作節(jié)拍需要加上工件加工的那段時間。機械手在上料的過程中，需要完成夾緊工件，手臂上升、手腕回轉(zhuǎn)、手臂 伸出、下降、放松工件、手臂縮回、反轉(zhuǎn)、手腕反轉(zhuǎn)等動作?？紤]到以下一些問題，機械手的動作節(jié)拍還需要加上以下這些時間：1.由于繼電器、電磁滑閥以及執(zhí)行機構(gòu)都有一定的慣性，從動作指令發(fā)出到考試動作需要一段時間，因此單個動作時間不宜少于0.2秒（直流電磁閥打開響應(yīng)時間為0.10.5秒，交流電磁閥的打開響應(yīng)時間為0.010.07秒）2.夾緊或放松動作時間一般定為0.20.3秒。3.手臂伸縮、水平回轉(zhuǎn)和升降運動的時間，是機械手動作節(jié)拍的主要部分，應(yīng)考慮抓重和形成的大小、驅(qū)動方式、緩沖方式和定位方式而加以確定。2.4定位精度機械手的定位精度是由加工工藝要、機械手本身的結(jié)構(gòu)特點（如制造精度、結(jié)構(gòu)剛性）、抓重、工作行程、工作速度以及驅(qū)動、控制方式和緩沖定位方式諸因素所決定。其中加工工藝要求是主要的因素。切削機床上下料機械手的定位精度一般為毫米第三章 機械手機械結(jié)構(gòu)的設(shè)計計算3.1 機械手機構(gòu)的分析與設(shè)計3.1.1機械手的自由度 機械手要像人的手一樣完成各種動作是比較困難的。因為人的手指、手長、手腕、手臂由十九個關(guān)節(jié)所組成，并具有27個自由度，而生產(chǎn)實踐中機械手不需要這么多自由度。下面按機械手所具有的主運動和輔助運動來分析其自由度。手臂和立柱的運動成為主運動，因為它們能改變抓取工件在空間的位置。手腕和手指的運動成為輔助運動，因為手腕的運動只能改變被抓取工件的方位，而手指的夾放運動不能改變工件的位置和方位，故它不計為自由度數(shù)，其他運動都算作自由度數(shù)。 這次參考了江麓機械廠的機械手，在確定了被抓取工件所在的空間位置，及將工件搬運到規(guī)定的位置時所需要的運動。得知我們改造的機械手包括了大臂的回轉(zhuǎn)和升降兩個運動，而將要設(shè)計的手腕的自由度僅僅是為了配合手臂完成工件的預(yù)定裝卸方位要求加以增設(shè)的，故只算成兩個自由度。 圖一 由圖可知，此機械手在XY平面內(nèi)有回轉(zhuǎn)運動，且在Z方向和X方向有直線運動，故做出它的運動軌跡圖，如下： 圖二 自由度數(shù)多少是衡量機械手技術(shù)水平的指標之一，自由數(shù)越多，可以完成的動作越復雜，通用性越強，應(yīng)用范圍也越廣，但是響應(yīng)的帶來了技術(shù)難度大，控制系統(tǒng)和機械結(jié)構(gòu)復雜，機械手本身的體積和重量增加，成本高和維修困難。自由度少，通用性越差，但是技術(shù)上容易達到，結(jié)構(gòu)簡單，使用和維修方便。所以在此次設(shè)計中，二自由度已經(jīng)足夠，沒有必要盲目的加入自由度。3.1.2坐標形式如一圖所示的機械手，其手臂的運動由兩個直線運動和一個回轉(zhuǎn)所組成，即沿X軸的伸縮，沿Z軸的升降和繞Z軸的回轉(zhuǎn)。這種坐標型式的機械手成為圓柱坐標式機械手。它與指教坐標式相比較，占地面積大而活動范圍大，結(jié)構(gòu)較為簡單，并能達到較高的定位精度，因此得到廣泛的應(yīng)用。3.1.3機械手的機構(gòu)簡圖以及部件尺寸 圖三由受力分析和平衡方程可得：Fx=0 Fbx=0 fy=0 Fna+Fby-P=0 Mx=0 PDB-FnaAB=0由幾何關(guān)系得：Fna=6P Fbx=0 Fby=-5P 由A得：Fx=0 Faecos a -Fakcos =0 fy=0 Fna-Faesin a Faksin =0Fae=Ph。cos hsin(a + )Fak= Ph。cos a hsin(a + ) 由C得：Fx=0 Fcx-Feacos a =0fy=0 Fcy+Feasin a P =0Fcx=Ph。cos acos hsin(a + )Fcy=P1- h。sin a cos hsin(a + ) 在江麓機械廠的實地測繪，要進行改造的機械手機構(gòu)簡圖如上圖所示 。為一個七桿二自由度機械手。其各部件的尺寸如下：桿件一250mm桿件二1250mm桿件三250mm桿件四1250mm桿件五1500mm 此機械手的尺寸恰能滿足回轉(zhuǎn)半徑1m3m和提升工件高度2.5m的要求，所以在這次設(shè)計過程中不做改動。由圖一計算其他尺寸：圖中虛線所示位置就是當機械手將工件舉到最高時候的位置，實線所示的位置就是機械手在地面高度抓取工件的位置。設(shè)計手臂在這兩個位置時，桿件與水平所成的角度都為30。則Ae長度等于250=125mm，bf長度也為125mm，bC長度等于BC=250=125mm，cc產(chǎn)度等于bc-bC=250-125=125mm，Bb長度等于BC=250=213mm，所以確定Aa等于Ae+bf+Bb=125+125+213=463mm。即為大臂升降油缸的行程取l=500mm.3.1.4機械手總體方案的比較除了上圖所看到的方案，還有一種設(shè)計的方案，即將伸縮油缸和回轉(zhuǎn)油缸放置在同一個立柱中，但是如果這樣放置，一個是裝配時十分不方便，二個是在機械手夾持工件進行回轉(zhuǎn)時，回轉(zhuǎn)中心將更加遠離回轉(zhuǎn)油缸的中心，那樣對支撐軸的扭矩將增大，且對立柱的彎曲應(yīng)力更大，機械手的壽命將縮短。所以，我們設(shè)計的是將伸縮油缸和液壓站用支撐板固定在遠離工件的立柱的另側(cè)，這樣，當機械手回轉(zhuǎn)時，回轉(zhuǎn)中心將比較靠近回轉(zhuǎn)油缸的回轉(zhuǎn)中心，這樣，即減少了支撐軸的彎曲應(yīng)力，又可以使的機械手在裝配和設(shè)置油管路線時更加方便。 橫向擴展一下，本人聯(lián)想到資料中海港的集裝箱的起吊手臂，它在空間運行的時候，保證了集裝箱的水平放置，那樣手臂的設(shè)計將更加復雜。本人設(shè)計的機械手，在空間的運動位置是不定的，如果要改進，則需要在橫向伸縮的導桿中加入一個伸縮油缸，用來精確控制工件被夾取后在空間中的運動位置。3.2 機構(gòu)桿件的受力校核分析3.2.1支撐桿的受力校核當機械手將工件抬舉到最大高度的時候，支撐桿的受彎曲力矩最大。此時的受力分析如圖：機械手的構(gòu)件部分都設(shè)計成為空心圓鋼桿，其外徑為115mm，內(nèi)徑為75mm,查表得到它的=60MPa,E=200GPa.此時受到的壓力P為工件和前端桿件的重量，約為50KN。（1）此時1桿和2桿的軸力NN分別為 N=2P=100KN N=P=86.6KN（壓）（2）強度校核 A=5.86m所以1桿2桿的應(yīng)力分別為： =17.06MPa 由此可見手臂的桿件都滿足強度要求，整個結(jié)構(gòu)強度都是滿足要求的。3.2.2導軌滑桿的強度檢驗導軌滑桿是放置在大臂頂部的構(gòu)件，它承受了各機構(gòu)桿件和工件對其的壓力，其受力狀況如下：其中AB長度等于CD長度等于40mm。BC長度等于120mm。P=7kN，它的為100MPa.（1） 計算支反力并做梁的彎矩圖根據(jù)梁的平衡條件，求得梁的支撐反力為： R=7 kN作出梁的彎矩圖如圖所示：由圖可見，梁上最大的彎矩為： M=M=0.28 kNm（2） 強度校核梁的B截面和C截面為危險截面。因此對B截面進行校核： 57.07MPa15。進行壓桿穩(wěn)定性驗算?；钊麠U由45#鋼制成，=350MPa，=28MPa，E=210GPa，長度=1200mm，直徑d=60mm，最大壓力=15.1KN，規(guī)定穩(wěn)定安全系數(shù)為=810。校核穩(wěn)定性： 活塞桿簡化成兩端鉸支桿，截面為圓形，i=，柔度為 柔度。 所以不能用歐拉公式計算臨界壓力。若用直線公式，由表查的優(yōu)質(zhì)鋼的a和b分別為：a=461MPa，b=2.568MPa。 。 可見活塞桿的柔度介于和之間，是中等柔度壓桿。由直線公式求出臨界壓力為：MPa。 活塞桿的安全系數(shù)為：n=。 所以滿足穩(wěn)定性要求。3.5.6大手臂系統(tǒng)溫升的驗算在整個機械手的工作循環(huán)中，上升階段所占的時間最長，為了簡化計算，主要考慮上升時的發(fā)熱量。一般情況下，上升時發(fā)熱量最大，因為液壓系統(tǒng)提供的能量很大一部分用來化為機械手的構(gòu)件的勢能，由于限壓試變量泵在流量不同時，下率相差極大，所以分別計算最大，最小時的發(fā)熱量，然后加以比較，取數(shù)值大者進行分析。當V=1500cm/min時 Q=m/min=25.9L/min 此時泵的效率為0.7，泵的出口壓力為3.2MPa，則有 =1.38Kw =Fv=13600=4.005Kw此時的功率損失為： 1.3533kW當v=125cm/min時，q=9042L/min,總效率=0.7 則=0.718Kw =Fv=136001253.5.7 設(shè)計手臂時注意的問題一、手臂應(yīng)該剛度大，重量輕我們設(shè)計的機械手懸伸長度比較長，若手臂的剛度不夠，則會導致手臂彎曲變形過大，就會引起手臂的定位不竟準，而且也直接影響活塞桿（大手臂）運動的靈活性。另外，手臂在起動或制動的過程中受到慣性力或者慣性力矩的作用，手臂將會發(fā)生顫動，由于手臂的顫動，也回影響手臂的定位精度，除了采用可靠的定位裝置外，應(yīng)對手臂結(jié)構(gòu)有一定的剛度要求，才能保證手臂的準確工作和一定的定位精度。手臂懸伸的彎曲變形主要與手臂的抓取重量、手臂結(jié)構(gòu)本身的材料、截面形狀以及幾何尺寸等有關(guān)。在相同的條件下，工字形截面梁的彎曲剛度比圓截面要大1020倍；空心管的彎曲剛度為實心軸的45倍。而且，工字形梁和空心梁的重量比能承受同樣彎曲剛度的實心軸要輕的多，所以，在本次設(shè)計中，我們采用的是工字形的梁臂結(jié)構(gòu)。它承受垂直方向的載荷能力大，而且手臂結(jié)構(gòu)簡單輕巧。二.應(yīng)使手臂運動速度快、慣性大手臂的運動速度是由形成大小、生產(chǎn)節(jié)拍的時間和運動平穩(wěn)性及抓重大小來決定的。一般情況下，我們設(shè)計的好艘比的移動和回轉(zhuǎn)速度均為等速運動（即V和為常數(shù)），但是在手臂啟動和制動的過程中，它的運動為加速和減速運動。理想狀態(tài)下，機械手在運動到形成終點的時候，加速度為零，所以停止的瞬間沒有慣性沖擊，這是最理想的狀態(tài)。但是因為加速度是變化的，手臂非等速運動，設(shè)計時就復雜的多。其運動曲線如圖所示：由于制造設(shè)計的復雜性，我們放棄了理想中機械手的最佳運動方案。而采取了一般的設(shè)計。為了減少慣性沖擊，我們采取了以下的措施：（1） 手臂架選用鋁合金這種輕質(zhì)材料來制造，以減輕手臂運動件的重量。（2） 盡量縮短了手臂懸伸部分的長的，使手臂未伸出時的總重量的重心盡量靠近立柱，以減小回轉(zhuǎn)半徑，此外對編制程序時，應(yīng)該盡量先縮回后再回轉(zhuǎn)或在較小的前伸位置下進行回轉(zhuǎn)，以減小慣性力矩。（3） 減小手臂運動件的輪廓尺寸，使其結(jié)構(gòu)緊湊。（4） 在驅(qū)動系統(tǒng)中增設(shè)緩沖裝置，使運動減速緩沖。 四、 應(yīng)使手臂傳動準確、導向性好 為了能準確的傳遞工件和保證傳動的平穩(wěn)，我們設(shè)計了導向和支承裝置，以保證手指的正確方向，并增強手臂的剛性。五、 輸油管道的布置應(yīng)合理機械手的各工作油缸彼此在空間作相對的直線運動或回轉(zhuǎn)運動，要求結(jié)構(gòu)緊湊、外觀整齊、動作靈活，因此對各工作油缸的輸油管道不止應(yīng)給予足夠的重視，尤其是接近工作對象的手腕和手指夾緊缸，在外部用很多的軟管向油缸輸入壓力油，雖然軟管安裝和維修比較方便，但是它會影響機械手的運動，并且容易損傷，而且對外觀的整齊有影響。所以，我們對機械手的輸油管道的布置，采用了從液壓操縱板引出油管，通到油路分配板處集中輸入，然后根據(jù)結(jié)構(gòu)特點在缸壁或活塞桿等內(nèi)部鉆孔形成管道，并采用回轉(zhuǎn)接頭和伸縮油管，將壓力油輸往運動部分的油缸，從而保證手臂的外形結(jié)構(gòu)簡單整齊美觀，但是工藝性方面就受到了一定的影響。總 結(jié) 參考文獻：1 羅迎社主編. 材料力學. 武漢理工大學出版社，2000.2 唐增寶，何永然，劉安俊主編.機械設(shè)計課程設(shè)計.華中理工大學出版社，1998.3 成大先主編.機械設(shè)計手冊聯(lián)接與緊固.北京化學工業(yè)出版社，2004.4 曹玉平，閻祥安主編.液壓傳動與控制.天津大學出版社，2003.5 毛謙德，李振清主編.袖珍機械設(shè)COMBINATION OF ROBOT CONTROL AND ASSEMBLY PLANNING FOR A PRECISION MANIPULATOORAbstractThis paper researches how to realize the automatic assembly operation on a two-finger precision manipulator. A multi-layer assembly support system is proposed. At the task-planning layer, based on the computer-aided design (CAD) model, the assembly sequence is first generated, and the information necessary for skill decomposition is also derived. Then, the assembly sequence is decomposed into robot skills at the skill-decomposition layer. These generated skills are managed and executed at the robot control layer. Experimental resulte show the feasibility and efficiency of the proposed system.Keywords ：Manipulator Assembly planning Skill decomposition Automated assembly1IntroductionOwing to the micro-electro-mechanical systems (MEMS) techniques, many products are becoming very small and complex, such as microphones, micro-optical components, and microfluidic biomedical devices, which creates increasing needs for technologies and systems for the automated assembly have been focused on microassembly technologies. However, microassembly techniques of high flexibility, efficiency, and reliability skill open to further research. This paper researches to how to realize the automatic assembly operation on a two-finger micromanipulator. A muli-layer assembly support system is proposed.Automatic assembly is a complex problem which may involve many different issues, such as task planning, assembly sequences generation, execution, and control, etc. It can be simply divided into two phases, the assembly planning and the robot control. At the assembly-planning phase, the information necessary for assembly operation, such as the assembly sequence, is generated. At the robot control phase, the robot is driven based on the information generated at the assembly-planning phase, and the assembly operations are conducted. Skill primitives can work as the interface of assembly planning to robot control. Several robot systems based on skill primitives have been reported. The basic idea behind these systems is the robot programming. .Robot movements are specified as skill primitives, based on which the assembly task is manually coded into programs. With the programs, the robot is control to assembly tasks automatically. A skill-based micromanipulation system has been developed in the authors lab, and it can realize many micromanipulation operations. In the system, the assembly task is manually discomposed into skill sequences and complied into a file. After importing the file into the system, the system can automatically execute the assembly task. This paper attempts to explore a user-friendly, and at the same time easy, sequence-generation method, to relieve the burden of manually programming the skill sequence.It is an effective method to determine the assembly sequence from geometric computer-aided design (CAD) models. Many approaches have been proposed. This paper applies a simple approach to generate the assembly sequence. It is not involved with the low-level data structure of the CAD model, and can be realized with the application programming interface (API) functions graph among different components is first constructed by analyzing the assembly model, and then, possible sequences are searched, based on the graph. According to certain criterion, the optimal sequence is finally obtained.To decompose the assembly sequence into robot skill sequences, some works have been reported. In Nnaji et al.work, the assembly task commands are expanded to more detailed commands, which can be as robot skills, according to a predefined format. The decomposition approach of Mosemann and wahl is based on the analysis of hyperarcs of AND/OR graphs representing the automatically generated assembly plans. This paper proposes a method to guide the skill decomposition .The assembly processes of parts are grouped into different start atate and target of the workflow, the skill generator creates a series of skills that can promote the part to its target state. The hierarchy of the system proposed here, the assembly information on how to assemble a product is transferred to the robot through multiple layers. Te top layer is for the assembly-task planning. The information needed for the task planning and skill generation are extracted from the CAD model and are saved in the database. Base on the CAD model, the assembly task squences are generated. At the skill-decomposition layer, tasks are decomposed into skill sequences. The generated skills are managed and executed at the robot control layer.2 Task planningSkills are not used directly at the assembly-planning phase, the concept of a task is used. A task can fulfill a series of assembly operations, for example, from locating a part, through moving the part, to fixing it with another part. In other words, one task includes many functions that may be fulfilled by several different skills. A task is defined as:T = (Base Part; Assembly Part; Operation)Based-part and Assembly-Part are two parts that are assembled together. Base-part is fixed on the worktable, while Assembly-Part is handled by robots end- effector and assembled onto the Base-Part. Operation describes how the Assembly-Part is assembled with the Base-Part; Operation=Intertion-T,serew-T,align-T,.The structure of microparts is usually uncomplicated, and they can be modeled by the constructive solid geometry (CAG) method. Currently, many commercial CAD software packages can support 3D CSG modeling. The assembly model is represented as an object that consists of two parts with certain assembly relations that define how the parts are to be assembled. In the CAD model, the relations are defined by geometric constraints. The geometric information cannot be used directly to guide the assembly operation-we have to derive the information necessary for assembly operations from the CAD model.Through searching the assembly tree and geometric relations (mates relations) defined in the assemblys CAD model, we can generate a relation graph among parts, for example, In the graph, the nodes represent the parts. If nodes are connected, it means that there are assembly relations among these connected nodes (parts).2.1 Mating directionIn CSG, the relations of two parts, geometric constraints, are finally represented as relations between planes and lines, such as collinear, coplanar, tangential, perpendicular, etc. For example, a shaft is assembled in a hole. The assembly relations between the two parts may consist of such two constraints as collinear between the centerline of shaft Lc-shaft and the centerline of hole Lc-hole and coplanar between the P-Shaft and the plane P-Hole. The mating direction is a key issue, for an assembly operation. This paper applies the following approach to compute the possible mating direction based on the geometric constraints (the shaft-in-hole operation of Fig. 3 is taken as an example):For a part in the relation graph, calculate its remaining degrees of freedom, also called degrees of separation, of each geometric constraint.For the conplanar constraint, the remaining degrees of freedom are R1= x,y,Rotz . For the collinear constraint, the remaining degrees of freedom are R2= z,Rotz. R1 and R2 can also be represented as R1= 1,1,0,0,0,1 and R20,0,1,0,0,1. Here, 1 means that there is a degree of separation between the two parts. R1R2= 0,0,0,0,1,and so, the degree of freedom around the z axis will be ignored in the following steps.In the ease that there is loop in the relation graph, such as parts Part5,Part6, and Part 7 in Fig. 2,the loop has to be broken before the mating direction is calculated. Under the assumption that all parts in the CAD model are fully constrained and not over-constrained, the following simple approach is adopted. For the part t in the loop, calculate the number of is in Nin=Ri1Ri2.Rin; where R is the remaining degrees of freedom of constraint k by part i. For example, in Fig. 2, given that the number of 1s in U is larger than U, then it can be regarded that the position of part 7 is determined by constraints between part 5 and part 6,while Part5 and Part6 can be fully constrained by constraints between Part 5 and Part 6. we can unite Part 5 and Part 6 as one node will be regarded as a single, but it is obvious that the composite node implies an assembly sequence.Calculate mating directions for all nodes in the relation graph. Again, beginning at the state that the shaft and the hole are assembled, separate the part in one degree of separation by a certain distance (larger than the maximum tolerance), and than check if interference occurs. Separation in both x axis and y axis of R1 causes the interference between the shaft and the hole. Separation in the +z direction raises on interference. Then, select the +z direction as the mating direction, which is represented as a vector M measured in the coordinate system of the assembly. It should be noted that , in some case, there may be several possible mating directions for a part. The condition for assembly operation in the mating direction at the assembled state, which can be checked simply with geometric constraints, the end condition is measured by force sensory information, whereas position information is used as an end condition.Calculate the grasping position. In this paper, parts are handled and manipulated with two separate probes, which will be discussed in the Sect.4, and planes or edges are considered for grasping. In the case that there are several mating directions, the grasping plans are selected as G1G2Gi, where Gi is possible grasping plane/edge set for the ith mating direction when the part is at its free state. For example, in Fig. 4, the pair planes P1/P1, P2/P2, and P3/P3 can serve as possible grasping planes, and then the grasping planes are P1/P1, P2/P2, P3/P3/P1/P1, P3/P3/P1/P1,P2/P2=P1/P1The approaching direction of the end-effector is selected as the normal vector of the grasping planes. It is obvious that not all points on the grasping plane can be grsped. The following method is used to determine the grasping area. The end-effector, which is modeled as a cuboid, is first added in the CAD model, with the constraint of coplanar or tangential with the grasping plane. Beginning at the edge that is far away from the Bae-Part in the mating direction, move the end-effector in the mating direction along the grasping plane until the end-effector is fully in contact with the part, the grasping plane is fully in contact with the end-effector, or a collision occurs. Record the edge and the distance, both of which are measured in the parts coordinate system.Separate gradually the two parts along the mating direction, which checking interference in the other degrees of separation, until no interference occurs in all of the other degrees of separation. There is obviously a separation distance that assures interference not to occur in every degree of separation. It is called the safe length in that direction. This length is used for the collision-free path calculation, which will be discussed in the following section.2.2 Assembly sequenceSome criteria can be used to search the optimal assembly sequence, such as the mechanical stability of subassemblies, the degree of parallel execution, types of fixtures, etc. But for microassembly, we should pay more attention to one of its most important features, the limited workspace, when selecting the assembly sequence. Microassembly operations are usually conducted and monitored under microscopy, and the workspace for microassembly is very small. The assembly sequence brings much influence on the assembly efficiency. For example, a simple assembly with three parts. In sequence a, part A is first fixed onto part B. In the case that part C cannot be mounted in the workspace at the same time with component AB because of the small workspace, in order to assemble part C with AB, component AB has to unmounted from the workspace. Then, component C is transported and fixed into the workspace. After that, component AB is transported back into the workspace again. In sequence b, there is no need to unmount pay part. Sequence a is obviously inefficient and may cause much uncertainty by an assembly sequence , the more inefficient the assembly sequence. In this paper, due to the small-workspace feature of microassembly, the number of times necessary for mounting of parts is selected as the search criteria to find the assembly sequence that has a few a number of times for the mounting of parts as possible. This paper proposes the following approach to search the assembly sequence. The relation graph of the assembly is used to search the optimal assembly sequence. Heuristic approaches are adopted in order to reduce the search times: Check nodes connected with more than two nodes. If the mating directions of its connected nodes are different, mark them as inactive nodes, whereas mark the same mating directions as active mating direction.Select a node that is not an inactive node. Mark the current node as the base node (part). The first base part is fixed on the workspace with the mating direction upside (this is done in the CAD model).Compare the size (e.g., weight or volume) of the base part with its connected parts, which can be done easily by reading the bill of materials (BOM) of the assembly. If the base part is much smaller, then mark it as an inactive node.Select a node connected with the base node as an assembly node (part). Check the mating direction if the base node needs to be unmounted from the workspace. If needed, update a variable In the CAD model, move the assembly part to the base part in the possiblemting direction, which checking if interference (collision) occurs. If interference occurs, mark the base node as an inactive node and go to step 2, whereas select the Operation type according to parts geometric features. In this step, an Obstacle Box is also computed. The box, which is modeled as a cuboid , includes all parts in the workspace. It is used to calculate the collicion-free path to move the assembly part, which will be introduced in the following section. The Obstacle Box is described by a position vector and its width, height, and length.Record the assembly sequence with Operation type, the mating direction, and the grasping position.If all nodes have been searched, then mark the first base node as an inactive node and go to step 2. If not, select a node connected with the assembly node. Mark it as an assembly node, and the assembly node that is same as the mating direction of the former assembly node. If there is, use the former mating direction in the following steps. Go to step 3. After searching the entire graph , we may have search assembly sequence s. Comparing the values of mount , the more efficient one can be selected. If there are N nodes in the relation graph of Fig. 2b , all of which are not classed as inactive node, and each node may have M mating directions, then it needs M computations to find all assembly sequences. But because, usually, one part only has one mating direction, and there are some inactive nodes, the computation should be less than Mn.It should be noted that, in the above computation, several coordinate systems are involved, such as the coordinates of the assembly sequences, the coordinates of the base part, and the coordinates, of the assembly. The relations among the coordinates are represented by a 4*4 transformation matrix , which is calculated based on the assembly CAD model when creating the relations graph. These matrixes are stored with all o the related parts in the database. They are also used in skill decomposition.3 Skill decomposition and execution3.1 Definition of skill primitiveSkill primitives are the interface between the assembly planning and robot control. There have been some definitions on skill primitives. The basic difference among these definitions is the skills complexity and functions that one skill can fulfill. From the point of view of assembly planning, it is obviously better that one skill can fulfill more functions. However, the control of a skill with many functions may become complicated. In the paper, two separate probes, rather than a single probe or process is not easy. In addition, for example, moving a part may involve not only the manipulator but also the worktable. Therefore, to simplify the control process, sills defined in the paper do not include many functions.More importantly, the skills should be easily applied to various assembly tasks, that is, the set of skill should have generality to express specific tasks. There should not be overlap among skill. In the paper, a skill primitive for robot control is defined as: Attribute -I, Action -i(Attribute -i), Si= Start -i(Attribute -i), End -i(Attribute -i) Condition -i(Attribute -i).Attribute I Information necessary for Si to be executed. They can be classified as required attributes and option attributes, or sensory attributes and CAD-model-driven attributes. The attributes are represented by global variables used in different layers.Action_I Robots action, which is the basic sensormotion. Many actions are defined in the system, such as Move_Worktable, Move_Probes, Rotation_Worktable, Rotation_Probes, Touch, Insert, Screw, Grasp, ect. For one skill, there is only one Action. Due to the limited space, the details of actions will not be discussed in the paper.Start_i The start state of Action_i, which is measured by sensor values.End_i The end state of Action_i, which is measured by sensor values.Condition_i The condition under which Action_i is executed.From the above definitions, we may find that skill primitives in the paper bobot motions with start state and end state, and that they are executed under specific conditions. Assembly planning in the paper is to generate a sequence of robot actions and to assign values to attributes pf thede actions.3.2 Skill decompositionSome approaches have been proposed for skill decomposition. This paper presents a novel approach to guide the skill decomposition. As discussed above, in the present paper, a task is to assemble the Assembly_Part with the Base_part. We define the process from the state that Assembly_Part is at a free state to the state it is fixed with Bese_Part as the assembly lifestyle of the Assembly_Part. In its assembly lifecycle, the Assembly_Part may be at different assembly states. Here shows a shafts sates show as blocks and associated workflows of an insertion task. A workflow consisting of group of skills pushes forward the Assembly_Part from one state to another state. A workflow is associated with a specific skill generator that is in charge of generating skills. For different assembly tasks, the same workflows may be uded, though specific skills generated for different tasks may be different.The system provides default task templates, in which default states are defined. These templates are imported into the system and instantiated after they are associated with the corresponding Assembly_Part. In some cases, some states defined by the default template may be not needed. For example, determined by the fixture, then the Free and In_WS states can be removed from the shafts assembly lifecycle. The system provides a tool for users to modify thede templates or generate their own templates. The tools user interface is displayed in.For a workflow, the start state is measured by sensory values, which the target state is calculated based on the CAD model and sensory attributes. According to the start state and target state, the generator generates a series of skills. Here, we use the Move workflow in as an example to show how skills are gener