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第1章 緒論
1.1課題的來源，目的及意義
近年來，隨著經濟的發(fā)展，我國的城市化水平加快和人民生活水平的提高，汽車的數量不斷增加。中國的汽車市場2006年新車銷量達721萬輛,與上一年相比增加了25%。轎車的增長幅度尤為明顯,同比增長37%,達到380萬輛,三年間增加了近一倍。根據權威估計,2008年中國汽車市場的銷量將達1000萬輛。但與此同時，汽車停車場地的增長卻不能與之同步，汽車泊位與汽車數量嚴重比例失調，由此帶來停車難，違章停車，停車管理困難等一系列問題。
鏈驅動雙層升降橫移式停車設備又名立體車庫，它占地空間小，并且可以最大限度的利用空間，安全方便，是解決城市用地緊張，緩解停車難的一個有效手段。國家記委已明確機械立體停車設備及城市立體停車場為國家重點支持的產業(yè)。1998年1月1日起執(zhí)行的《國家記委6號令》把機械式立體車庫和立體停車場列入“國家重點鼓勵發(fā)展的產業(yè)，產品和技術”。國家海關總署對機械式停車產品規(guī)定“國內投資項目給予免征進口稅”。上述措施為我國立體車庫產業(yè)的成長提供了良好的條件，也為我國解決城市停車問題提供了機會。可以預見：立體車庫具有廣闊的市場前景。
研究的目的就是開發(fā)一套實用，安全有效的鏈驅動雙層升降橫移式立體車庫停車設備，并進行相應的擴展研究。
本項目的研究與開發(fā)，為21世紀初期的城市交通系統(tǒng)提供實用的，具有自主知識產權，國產化城市停車技術和裝備，對緩解城市用地緊張，解決城市停車難的問題具有重要意義。
1.2立體車庫概述
車輛無處停放的問題是城市的社會、經濟、交通發(fā)展到一定程度產生的結果，立體停車設備的發(fā)展在國外，尤其在日本已有近30~40年的歷史，無論在技術上還是在經驗上均已獲得了成功。我國也于90年代初開始研究開發(fā)機械立體停車設備，距今已有十年的歷程。由于很多新建小區(qū)內住戶與車位的配比為1:1，為了解決停車位占地面積與住戶商用面積的矛盾，鏈驅動雙層升降橫移式立體車庫停車設備以其平均單車占地面積小的獨特特性，已被廣大用戶接受。
鏈驅動雙層升降橫移式車庫與傳統(tǒng)的自然地下車庫相比，在許多方面都顯示出優(yōu)越性。首先，機械車庫具有突出的節(jié)地優(yōu)勢。以往的地下車庫由于要留出足夠的行車通道，平均一輛車就要占據40平方米的面積，而如果采用雙層機械車庫，可使地面的使用率提高80％-90％，如果采用地上多層（21層）立體式車庫的話50平方米的土地面積上便可存放40輛車，這可以大大地節(jié)省有限的土地資源，并節(jié)省土建開發(fā)成本。
鏈驅動雙層升降橫移式車庫與地下車庫相比可更加有效地保證人身和車輛的安全，人在車庫內或車不停準位置，由電子控制的整個設備便不會運轉。應該說，鏈驅動雙層升降橫移式車庫從管理上可以做到徹底的人車分流。
在地下車庫中采用機械存車，還可以免除采暖通風設施，因此，運行中的耗電量比工人管理的地下車庫低得多。鏈驅動雙層升降橫移式車庫一般不做成套系統(tǒng)，而是以單臺集裝而成。這樣可以充分發(fā)揮其用地少、可化整為零的優(yōu)勢，在住宅區(qū)的每個組團中或每棟樓下都可以隨機設立機械停車樓。這對眼下車庫短缺的小區(qū)解決停車難的問題提供了方便條件。
在中華人民共和國機械行業(yè)標準 JB/T 8713-1998 ：機械式停車設備類別，形式，基本參數要目中，對機械式停車設備進行了劃分，其類別代號如下：
升降橫移類，代號為SH，是指通過設備的垂直升降和水平橫移進行移動，實現車輛存取功能的停車設備。
垂直循環(huán)類，代號為CX，是指通過搬運器在垂直平面內做連續(xù)的循環(huán)移動，來實現車輛存取功能的停車設備。
水平循環(huán)類，代號為SX，是指搬運器在水平平面內排列成2列或2列以上連續(xù)循環(huán)列尖轉換移動，實現車輛存取功能的停車設備。
多層循環(huán)類，代號為DX，是指車輛搬運器在垂直平面內排成2層或2層以上做連續(xù)移動，兩端有升降機構進行循環(huán)層間轉換移動，實現車輛存取的停車設備。
平面移動類，代號為PY，是指存車位與搬運器在同一水平面內，通過搬運器在水平面內做往復移動，實現車輛存取功能的停車設備。
巷道堆垛類，代號為XD，是指存車位在巷道一邊或兩邊多層布置，通過搬運器在巷道內做水平，垂直或水平垂直復合運動，實現車輛的存取功能的停車設備。
垂直升降類，代號為CS，是指停車位分布在井道周圍，通過升降搬運器在專用升降通道內做升降移動，時間車輛存取功能的停車設備。
簡易升降類，代號為JS，是指通過單一搬運器的升降，俯仰或二三層搬運器的整體升降，俯仰，實現車輛二三層車輛存取功能的停車設備。
汽車升降機類代號為QS;是指搬運器運載車輛(或同時運載駕駛員)垂直升降運行進行多層平層對位，從搬運器到存車位需要駕駛員駕車入位，實現車輛存取功能的停車設備。
巷道堆垛式立體車庫采用堆垛機作為存取車輛的工具，所有車輛均由堆垛機進行存取，因此對堆垛機的技術要求較高，單臺堆垛機成本較高，所以巷道堆垛式立體車庫適用于車位數需要較多的客戶使用。
巷道堆垛式立體車庫設備是20世紀60年代后歐洲根據自動化立體車庫原理設計的一種專門用于停放小型汽車的停車設備。該種車庫設備采用先進的計算機控制，是一種集機、光、電、自動控制為一體的全自動化立體全封閉車庫，存車安全等特點。該類車庫主要適應大型密集式存車。
1.3幾種機械停車設備的特點及比較
（一） 升降橫移式
升降橫移式立體車庫采用模塊化設計，每單元可設計成兩層、三層、四層、五層、半地下等多種形式，車位數從幾個到上百個。此立體車庫適用于地面及地下停車場，配置靈活，造價較低。
1. 產品特點：
1) 節(jié)省占地，配置靈活，建設周期短。
2) 價格低，消防、外裝修、土建地基等投資少。
3) 可采用自動控制，構造簡單，安全可靠。
4) 存取車迅速，等候時間短。
5) 運行平穩(wěn)，工作噪聲低。
6) 適用于商業(yè)、機關、住宅小區(qū)配套停車場的使用。
（二） 巷道堆垛式
巷道堆垛式立體車庫采用堆垛機作為存取車輛的工具，所有車輛均由堆垛機進行存取，因此對堆垛機的技術要求較高，單臺堆垛機成本較高，所以巷道堆垛式立體車庫適用于車位數需要較多的客戶使用。
（三）垂直提升式
垂直提升式立體車庫類似于電梯的工作原理，在提升機的兩側布置車位，一般地面需一個汽車旋轉臺，可省去司機調頭。垂直提升式立體車庫一般高度較高（幾十米），對設備的安全性，加工安裝精度等要求都很高，因此造價較高，但占地卻最小。
（四） 垂直循環(huán)式
產品特點：
1) 占地少，兩個泊位面積可停6~10輛車。
2) 外裝修可只加頂棚，消防可利用消防栓。
3) 價格低，地基、外裝修、消防等投資少，建設周期短。
4) 可采用自動控制，運行安全可靠。
基于上述比較，根據需要現選擇鏈驅動雙層升降橫移式車庫進行設計。
1.4 總體方案確定
由于我設計的鏈驅動雙層升降橫移式車庫，所以首先應確定用哪種方式升降，如可采用升降機式、電梯式。其次，對于傳動系統(tǒng)（包括鏈傳動的鏈與棘輪的設計、鋼絲吊動的滑輪和鋼絲繩的設計、電機型號的選用）、載車板等機械部分的繪圖設計和控制系統(tǒng)的簡單設計，要確定傳動的方式，如鋼絲繩，鏈條等；
初步擬定方案如下：
方案1：一、根據轎車尺寸確定每個車位載車板的長度寬度。設計載車板的形式，計算校核載車板的力學性能。
二、根據對傳動結構的分析和受力的分析選擇采用電梯式升降。選擇滑輪，確定其尺寸。確定鋼絲繩的材料、直徑。對上述部件進行力學計算，校核。
三、使用轉向盤，當車降下時已轉換方向。轉向盤可通過齒輪或者渦輪蝸桿實現轉向。
四、確定制動方案。選擇電磁接觸閥。
五、載荷均勻分布，機械效率高。
六、結構簡單，工作可靠，拆裝維修方便。
七、考慮安全防護設計。
八、考慮環(huán)保設計。
九、經濟性考慮。
方案2：一、根據轎車尺寸確定每個車位載車板的長度寬度。設計載車板的形式，計算校核載車板的力學性能。
二、根據傳動結構的分析和受力的分析選擇采用升降機式的升降機構。選擇鏈輪和鏈，確定其尺寸規(guī)格。然后對其校核。
三、不用轉向，故不用轉向盤。結構簡單，工作可靠，拆裝維修方便
四、確定制動方案。選擇電磁接觸閥。
五、載荷均勻分布，機械效率高。
六、考慮安全防護設計。
七、考慮環(huán)保設計。
八、經濟性方案設計。
綜合以上兩種設計方案，第二種方案比較適合本設計。整個機構的傳動機構采用鏈傳動，在上面放置兩條循環(huán)鏈，兩條鏈通過一條通軸連接，而通軸上的鏈輪由與減速器相連鏈帶動，實現轉動，從而帶動兩條循環(huán)鏈同步轉動，這樣就保證了傳動的平穩(wěn)性。而第一種方案中，如果用鋼絲繩傳動也可實現機構的傳動，但是如果要實現第一種方案一樣的功能，傳動過程顯得就要麻煩一些。因為要是實現同步轉動，必須選擇鏈與鋼絲繩同時使用才能達到同步傳動的效果。
本設計的傳動特點是：
·自動化程度高，快速處理，連續(xù)出入庫，停車效率高。
·組合式框架設計，保證了產品一致性， 安裝拆卸非常方便。
·設有多重安全防護措施，確保人車安全。
·操作簡便，既可集中管理，又可由客戶自己操作。
·電機及所用電器元件采用進口名牌產品。
·不排出汽車廢氣，清潔環(huán)保。
1.5 移動方案的比較
機械式立體停車庫有許多種類型，根據其工作原理可分為：升降橫移式；水平循環(huán)式； 平面移動式等等。采用以載車板升降或橫移存取車輛的機械式停車設備叫做升降橫移式立 體停車庫，由于升降橫移式停車庫的類型比較多，規(guī)?？纱罂尚?，對場地的適應性強，因 此采用這一類型的停車庫十分的普遍。
升降橫移式立體停車庫每個車位均有載車板，所需存取車輛的載車板通過升降橫移運
動到達地面層，駕駛員進入車庫，存取車輛，完成存取過程。停泊在這類車庫內地面的車 只作橫移，不必升降，上層車位或下層車位需要通過中間層橫移出空位，將載車板升或降 到地面層，駕駛員才可以進入車庫內將汽車開進或開出車庫。升降橫移式立體停車庫的布 置型式主要有兩種：半地下布置型式和地上布置型式
本設計是雙層六位五車的小型立體車庫，多用于居民小區(qū)，其簡圖如下所示:
4
5
6
1
2
3
圖2-1
移動方案（1）：
將1號車位作為定位，2，3 號車位可以直接提取車。 在存取 4 號車時，將 4 號位降到 1 號位上，進行存取車。
在存取 5 號車時，將 2 號位移動到 1 號為上，5 號位降到 2 號位上，進行存取車。 在存取 6 號車時，將 2 號位移動到 1 號位上，3 號位移動到 2 號位上，5 降到 3 號位
進行存取車。
移動方案（2）：
可將3號車位作為定位，其存取方式和方案（1）相同，故不再做表述。
移動方案（3）：
將號2車位作為定位，1，3 號車位可以直接進行存取車。
在存取 4 號車時，將 1 號車位移動到 2 號車位上，4 號車位降到 1 位進行存取車。 在存取 5 號車時，將 5 號車位降到 2 位上，進行存取車。
在存取 6 號車時，將 3 移動到 2 位上，6 降到 3 號車位上，進行存取車。
綜上所述，可以知道方案（3）最快捷，所以本設計采用方案（3）作為車庫整體移動的方案。
第2章 鏈驅動雙層升降橫移式車庫技術參數
2.1傳動機構的組成
本傳動機構如下圖，由循環(huán)鏈，兩條升降鏈，和14個鏈輪組成，圖中顯示的是對稱結構的一部分，兩部分由端部的一通軸連接。升降部分主要是用于第二層車輛的存放，在第一層將車存放在載車板上，通過兩條升降鏈將車升到二層，然后在經過PLC控制，由循環(huán)鏈來控制轎車放在哪個車位。
2.2 傳動機構的主要參數
技 術 性 能 參 數
名稱：鏈驅動雙層升降橫移式車庫
放車輛數：5輛
使用車尺寸：4700*1700*1550
驅動：5.5kw電動機
速度：6m/min
車重：〈1600KG
適用車型：小型轎車
控制方式：伺服定位控制
管理方式：專人管理方式
操作方式：觸摸屏操作
實現方式：上層實現鏈驅動形式升降存取車輛，下層實現橫移存取車輛
第3章 機械系統(tǒng)傳動設計
3.1傳動鏈和鏈輪的選擇
起重鏈有環(huán)行焊接鏈和片式關節(jié)鏈。焊接鏈與鋼絲繩相比，優(yōu)點是撓性大，鏈輪片齒數可以很少，因而直徑小，結構緊湊，其缺點是對沖擊的敏感性大，突然破斷的可能性大，磨損也較快。
另外，不能用于高速，通常速度小于0.1米/秒（用于星輪），速度小于1米/秒，用于光輪卷筒。片式關節(jié)鏈的優(yōu)點：撓性較焊接鏈更好，可靠性高，運動較平穩(wěn)。缺點：有方向性，橫向無撓性，比鋼絲繩重，與焊接鏈差不多，成本高，對灰塵和銹蝕膠敏感。
起重鏈用于起重量小，起升高度小，起升速度低的起重機械。為了攜帶和拆卸方便，鏈條的端部鏈節(jié)用可拆卸鏈環(huán)。
片式關節(jié)鏈是由薄剛片以銷軸鉸接而成的一種鏈條。焊接鏈與片式關節(jié)鏈選擇計算方法相同。
根據最大工作載荷及安全系數計算鏈條的破壞載荷
（N） Fmax—鏈條最大工作載荷（N）
S—安全系數（按手冊2—8.1—75選?。?
選擇片式關節(jié)鏈中的傳動用短節(jié)距精密磙子鏈
結構和特點：
由外鏈節(jié)和內鏈節(jié)鉸接而成。銷軸和外鏈板、套筒和內鏈板為靜配合；銷軸和套筒為動配合；磙子空套在套筒上，可以自由轉動，以減少嚙合時的摩擦和和磨損，并可以緩和沖擊，故選擇單排短節(jié)距磙子鏈。
3.2鏈的設計計算
3.2.1設計標準
準GB/T181500—2000〈〈滾子鏈傳動選擇指導〉〉是鏈傳動設計選擇標準。此標準等同采用ISO10823。
3.2.2傳動的計算
1. 鏈輪齒數
小鏈輪齒數 取=25，傳動比i=2.5
大鏈輪齒數 =i=2.5×25=62.5 取62
2. 實際傳動比
i===2.48
3. 鏈輪轉速
初選小鏈輪線速度=0.1m/s，
估選小鏈輪直徑d=160mm，
則大鏈輪直徑D=id=2.48×160=396mm
由大鏈輪和小鏈輪在同一軸上，故大鏈輪上的線速度=×=0.1×2.48=0.248m/s，則與電機相連的小鏈輪的線速度==0.248m/s
則其轉速為===30m/s
則大鏈輪轉速為===12r/min
4. 修正功率
小鏈輪傳遞功率為P=2.4kW
故=2.4×1.4×1=3.36kW
式中參數：
查機械設計手冊表14.2-4，工況系數=1.4，
主動鏈輪齒數系數=1，
5. 鏈條節(jié)距P
11
摘要 3
Abstract 4
第1章 緒論 5
1.1課題的來源，目的及意義 5
1.2立體車庫概述 5
1.3幾種機械停車設備的特點及比較 7
1.4 總體方案確定 8
第2章 鏈驅動雙層升降橫移式車庫技術參數 12
2.1傳動機構的組成 12
2.2 傳動機構的主要參數 12
第3章 機械系統(tǒng)傳動設計 13
3.1傳動鏈和鏈輪的選擇 13
3.2鏈的設計計算 13
3.2.1設計標準 13
3.2.2傳動的計算 14
3.3 鏈輪的設計計算 16
3.3.1 設計鏈論尺寸 16
3.4 滾子鏈的靜強度計算 22
3.5 鏈條的使用壽命計算 23
3.6 鏈條的耐磨工作能力計算 24
3.7 電動機的選擇 25
3.8減速器的選擇 26
3.9軸承的選擇 27
3.10軸的選擇 27
3.10.1 選擇材料 27
3.10.2 初步估算軸徑 27
3.10.3軸的結構設計 28
3.10.4 軸上的受力分析 28
3.10.5軸的強度校核 30
第4章 經濟分析 35
4.1 機會研究 35
4.1.1社會需求程度 35
4.1.2 開展的基本條件 35
4.2 初步可行性研究 35
4.2.1 投資機會是否有希望 35
4.2.2是否需要作詳細可行性分析 35
4.2.3 有待解決的關鍵性問題 36
4.2.4 初步經濟效益預測 36
第5章 專題 37
自動化立體車庫管理系統(tǒng) 37
結 論 44
參考文獻 45
致謝 46
附錄1：翻譯（英文） 47
附錄2：翻譯（漢文） 68
2
摘要
隨著汽車工業(yè)和建筑業(yè)兩大支柱產業(yè)的快速發(fā)展，在一些大、中城市相繼出現了停車難和亂停車的現象。在解決城市城市停車難的問題中，機械式立體停車設備以其獨特的優(yōu)點，引起了各界的重視，得到了廣泛的應用。
車輛無處停放的問題是城市的社會、經濟、交通發(fā)展到一定程度產生的結果，立體停車設備的發(fā)展在國外，尤其在日本已有近30~40年的歷史，無論在技術上還是在經驗上均已獲得了成功。我國也于90年代初開始研究開發(fā)機械立體停車設備，距今已有十年的歷程。由于很多新建小區(qū)內住戶與車位的配比為1:1，為了解決停車位占地面積與住戶商用面積的矛盾，立體機械停車設備以其平均單車占地面積小的獨特特性，已被廣大用戶接受。
機械車庫與傳統(tǒng)的自然地下車庫相比，在許多方面都顯示出優(yōu)越性。首先，機械車庫具有突出的節(jié)地優(yōu)勢。以往的地下車庫由于要留出足夠的行車通道，平均一輛車就要占據40平方米的面積，而如果采用雙層機械車庫，可使地面的使用率提高80％-90％，如果采用地上多層（21層）立體式車庫的話，50平方米的土地面積上便可存放40輛車，這可以大大地節(jié)省有限的土地資源，并節(jié)省土建開發(fā)成本。
論文以研究工作的進展順序為序，分章、節(jié)逐一論述了課題的來源，目的及意義，設計過程，在設計中遇到的問題與難點及其解決方法與措施。在設計過程部分，詳細論述了設備總體結構設計、橫移傳動系統(tǒng)設計、提升傳動系統(tǒng)設計、存取車結構設計、控制系統(tǒng)設計和安全防護設計 。
關鍵詞:立體停車設備 ； 傳動設計； 控制系統(tǒng) ； 升降機構； 安全性
Abstract
Along with the fast development of two major of pillar industry of the automobile industry and building industry, the city one after another appears to park the car the phenomenon of the difficult and disorderly parking in somely bigly,.In resolve the city city park the car difficult problem, stereoscopic parking equipments of the machine type with its special advantage, caused the value of the public, get the extensive application.
The vehicle has no a the society, economy, transportation that the problem for park is a city to develop output result to certain extent, the development of the stereoscopic parking equipments is abroad, particularly at Japan already is close to 30~40 years of history, all have already acquired the success on the technique still on the experience regardless.The our country also starts study to develop the stereoscopic parking equipments of machine at the beginning of in 90's, being apart from to already have the process of the decade now.Because a lot of set up the little inhabitant inside the area to go together with the car to compare to 1 lately:1, for solving the parking lot to cover the area and inhabitant's company to use the antinomy of the area, stereoscopic machine parking equipments with it average the bicycle covers the small special characteristic of area, have already been accept by the large customer.
The machine garage and traditional get off the database to compare naturally, in many respect display the superiority.First, the machine garage has an advantage of outstanding stanza.Before underground garage because of toing stay to go the car passage enough, average car will occupy 40 areas of the square meters, but if a layer of adoption machine garage, can make the utilization rate of the ground raise 80%-90%, if an up many type garages with stereoscopic layer(21 layers) of adoption, can deposit 40 cars then on 50 areas of the land of the square meters, this resources that can save the limited land consumedly, and save the soil to set up to develop the cost.
Currently the society contain a lot of mature and technical parking equipmentses for example:Ascend and descend horizontal move the type;Perpendicular and circulating type;Level circulation type;The flat surface moves the type;A of tunnel;The perpendicular rise and fall type;Simple rise and fall.Pass the comparison and analysises to these garages type characteristicses, I was end to choose a garage type that is the design.
Thesis with research the progress of the work is in proper order for the preface, dividing the chapter, stanza to discuss the source of the topic one by one, purpose and meaning, the design process, problem meet in the design with a little bit difficult and it resolve method and measure.At design the process part, detailed discussed the total structure of equipments design, horizontal move to spread to move the system design and promote to spread to move the system design, access the car structure design, control the system design and safe protection design.
Keyword: stereoscopic parking equipments; The structure design; Control the system; PLC; Safety
5
附錄1：翻譯（英文）
Modeling and specifcations of dynamic agents in fractal manufacturing systems
Kwangyeol Ryua, Youngjun Sonb, Mooyoung Junga,*
a Department of Industrial Engineering, Pohang University of Science and Technology, Pohang, South Korea Systems and Industrial Engineering Department, The University of Arizona, Tucson, AZ, USA
b Received 9 September 2002; accepted 16 April 2003
Abstract In order to respond to a rapidly changing manufacturing environment and market, manufacturing systems must be flexible, adaptable, and reusable. The fractal manufacturing system (FrMS) is one of the new manufacturing paradigms that address the need for these characteristics. The FrMS is comprised of a number of ‘‘basic components’’, each of which consists of five functional modules: (1) an observer, (2) an analyzer, (3) an organizer, (4) a resolver, and (5) a reporter. Each of these modules, using agent technology, autonomously cooperates and negotiates with others while processing its own jobs. The resulting architecture has a high degree of self-similarity, one of the main characteristics of a fractal. Despite the many conceptual advantages of the FrMS, it has not been successfully elaborated and implemented to date because of the difficulties involved in doing so. In this paper, the static functions and dynamic activities of each agent are modeled using the unified modeling language (UML). Then, relationships among agents, working mechanisms of each agent, and several fractal-specific characteristics (selfsimilarity, self-organization, and goal-orientation) are modeled using the UML. Then, a method for dealing with several types of information such as products, orders, and resources in the FrMS is presented. Finally, a preliminary prototype for the FrMS using AgletsTM is presented. # 2003 Elsevier B.V. All rights reserved. Keywords: Fractal manufacturing system (FrMS); Agent technology; UML; Modeling
Abbreviations: FrMS, fractal manufacturing system; BFU, basic fractal unit; DRP, dynamic restructuring process; UML, uni?ed modeling language; HMS, holonic manufacturing system; BMS, bionic/biological manufacturing system; CNP, contract net protocol; MANPro, mobile agent-based negotiation process; NMA, network monitoring agent; EMA, equipment monitoring agent; SEA, schedule evaluation agent; DRA, dispatching-rule rating agent; RSA, real-time simulation agent; SGA, schedule generation agent; GFA, goal formation agent; TGA, task governing agent; NEA, negotiation agent; KDA, knowledge database agent; DMA, decision-making agent; FSM, fractal status manager; FAM, fractal address manager; REA, restructuring agent; NCA, network command agent; ECA, equipment command agent; STA, system agent; NTA, network agent; MP, material processor; MH, material handler; MT, material transporter; BS, buffer storage; MRP, material removal processor; MFP, material forming processor; MIP, material inspection processor; PD, passive device; FMH, ?xed material handler; MMH, movable material handler; FMT, fixed material transporter; MMT, movable material transporter; ABS, active buffer storage; PBS, passive buffer storage E-mail address: myjung@postech.ac.kr (M. Jung).
* Corresponding author. Tel.: t82-54-279-2191; fax: t82-54-279-5998.
0166-3615/$ – see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0166-3615(03)00099-X
1. Introduction
Facing intensified competition in a growing global market, manufacturing enterprises have been reengineering their production systems to achieve computer integrated manufacturing (CIM). Major goals of CIM include, but are not necessarily limited to, lowering manufacturing costs, rapidly responding to changing customer demands, shortening lead times, and increasing the quality of products [1–3]. However, the development of a CIM system is an incredibly complex activity, and the evolution to CIM has been slower than expected [4,5]. This can be directly attributed to high software development and maintenance costs. Therefore, in order to achieve a competitive advantage in the turbulent global market, the manufacturing enterprise must change manufacturing processes from all angles including ordering, product design, process planning, production, sales, etc. As a control model for implementing CIM systems, hierarchical decomposition of shop floor activities has been commonly used in the shop floor control system (SFCS), the central part of a CIM system [2]. Generally, a central database provides a global view of the overall system, and controllers generate schedules and execute them. Hierarchical control is easy to understand and is less redundant than other distributed control architectures such as heterarchical control. However, it has a crucial weak point, which is that a small change in one level may significantly and adversely affect the other levels in the hierarchy. Therefore, it is normally said that hierarchical control of CIM systems is much more suitable for production in a steady environment than in a dynamically changing environment because it is so diffcult to apply control hierarchy changes immediately to the equipment. Furthermore, it is diffcult to meet dynamically changing customer requirements because the hierarchical control architecture is not flexible enough to handle the reconfiguration of the shop. Therefore, the manufacturing system of tomorrow should be flexible, highly reconfigurable, and easily adaptable to the dynamic environment. Furthermore, it should be an intelligent, autonomous, and distributed system composed of independent functional modules. To cope with these requirements, new manufacturing paradigms such as a bionic/biological manufacturing system (BMS) [6,7], a holonic manufacturing system (HMS) [8,9], and a fractal manufacturing system (FrMS) [10–13] have been proposed. Tharumarajahet al. [14] provide a comprehensive comparison among a BMS, a HMS, and an FrMS in terms of design and operational features. An FrMS is a new manufacturing concept derived from the fractal factory introduced by Warnecke [13]. It is based on the concept of autonomously cooperating multi-agents referred to as fractals. The basic component of the FrMS, referred to as a basic fractal unit (BFU), consists of five functional modules including an observer, an analyzer, a resolver, an organizer, and a reporter [10,11]. The fractal architectural model represents a hierarchical structure built from the elements of a BFU, and the design of a basic unit incorporates a set of pertinent attributes that can fully represent any level in the hierarchy [12]. In other words, the term ‘fractal’ can represent an entire manufacturing shop at the highest level or a physical machine at the bottom-level. Each BFU provides services according to an individual-level goal and acts independently while attempting to achieve the shoplevel goal. An FrMS has many advantages for a distributed and dynamic manufacturing environment. Automatic reconfiguration of a system through a dynamic restructuring process (DRP) is the most distinctive characteristic of the FrMS. In this paper, the scope of the reconfiguration does not include reconfigurable hardware [15] and external layout design. Rather, it focuses on the interior structure of software components that can be reorganized with software manipulations. The reconfiguration or restructuring in this paper considers both dynamic clustering of the agents and construction/destruction/cloning of agents, which affect the number of agents in the system. The function of a fractal is not specifically designated at the time of its first installation in the FrMS. The reconfiguration addressed in this paper also includes situations where the agents’ enrollments are changed, meaning that the agents are assigned a new goal and new jobs, but their composition does not change. This paper focuses on formal modeling of agents and fractal-specific characteristics that will provide a foundation for the development of the FrMS. Because associated difficulties have, to date, prevented a fractal-based system from being embodied, it is necessary to first explicitly define a concept, mechanisms, and characteristics.
The objective of this paper, therefore, is to clearly define and model fractal-specifc characteristics for a manufacturing system to have such characteristics. In order to develop the agents, interand intra-fractal activities are first clarified. Then, dynamic activities for each agent and relationships between agents are modeled. In order to more fully develop the FrMS, several fractal-specific characteristics are also modeled. To support embodiment of modeled characteristics, a method for dealing with information about products, orders, and resources in the FrMS is investigated. Through this research, mechanisms of agents and characteristics of the FrMS can be described with simple diagrams that make the system easier to understand. The work contained in this paper extends the FrMS from previous papers by emphasizing and detailing its characteristics. The activities of agents are specified using activity models so that the agents can use the activity models to forecast their next activities at run-time. The rest of this paper is organized as follows: Section 2 describes functions and dynamic activities of agents using functional and activity models of unified modeling language (UML). In Section 3, inter- and intra-fractal activities are specified. Several fractal-specific characteristics are described using UML models in Section 4. Section 5 describes a method for dealing with information about products and resources in the FrMS. Section 6 concludes the paper.
2. Agent-based fractal manufacturing system (FrMS) 2.1. Background of an FrMS An overview of the FrMS is depicted in Fig. 1. Every controller at every level in the system has a selfsimilar functional structure composed of functional modules. In addition, each of these modules, regardless of its hierarchical level, consists of a set of agents. After the initial setup of a system, the configuration of the system may need to be reorganized in response to unexpected events such as machine breakdown. The system will also need to be reconfigured when the set of parts to be produced in the system changes due to a change in customer needs. In these cases, fractals in the FrMS autonomously and dynamically change their structure, via the actions of agents for the appropriate working mechanisms of the fractals. Fig. 1 shows two facility layouts and the corresponding compositions of fractals before and after the restructuring process. When a machine (M) and a robot (R3) are added to the system, fractals reorganize their interior configurations with the mechanism of dynamic restructuring process in a way that the system continues to work with greatest efficiency. A fractal consists of five functional modules illustrated with their relationships in Fig. 2. The functions of each module can be defined depending upon the application domain.
Fig. 1. Reorganization of the system using a dynamic restructuring process in the FrMS.
However, when the target domain is determined, the main functions of each module will be consistent throughout the system. For example, the function of a resolver may be different depending upon whether it is defined for controlling a manufacturing system or for managing supply chains. However, the main function of a resolver in a manufacturing system is similar to other resolvers in that system regardless of their level in the hierarchy. A bottom-level fractal has similar functions to those of a conventional equipment controller in a SFCS. A fractal, which is directly connected to equipment (e.g. machine, robot, etc.), receives sensory signals of equipment and returns messages or commands. The function of an observer is to monitor the state of the unit, to receive messages and information from outer fractals, and to
Fig. 2. Functional modules and relationships of a fractal in an FrMS.
transmit composite information to correspondent fractals. The function of an analyzer is to analyze alternative job profiles with status information, to rate dispatching rules, and to simulate analyzed job profiles in real-time. The analyzer finally reports results to the resolver so that the resolver can use them to make decisions. A resolver plays the most important role in a fractal, generating job profiles, goal-formation processes, and decision-making processes. During goal-formation processes, the resolver may employ a variety of numerical optimization or heuristic techniques to optimize the fractal’s goal. If necessary, the resolver executes negotiations, cooperation, and coordination among fractals. The function of an organizer is to manage the fractal status and fractal addresses, particularly for dynamic restructuring processes. The organizer may use numerical optimization techniques to find an optimal configuration while reconfiguring fractals. The fractal status is used to select the best job profile among several alternatives, and the fractal address is used to find the physical address of the fractal (e.g. machine_name, port_number, etc.) on the network. The function of a reporter is to report results from all processes in a fractal to others. In the case of a bottom-level controller, the fractal is similar to a traditional equipment controller. Therefore, most of its messages are commands for controlling the hardware.
2.2. Agents in an FrMS
Agent technology has been widely used for various applications including information filtering and gathering [16], knowledge management [17], supply chain management [18], manufacturing architecture, system and design [19–21]. While the features and characteristics of an agent vary depending on the application, some common features found across different applications are as follows: Autonomy: capability of controlling and acting for itself in order to achieve goals. Mobility: capability of migrating its location to other places (an agent with mobility is called a mobile agent, otherwise known as a software or stationary agent). Intelligence: capability of learning and solving problems. Cooperativeness: capability of helping others if requested and accepting helps from others. Adaptability: capability of being effectively used at various domains. Reliability: capability of dealing with unknown situations (disturbances) and continuing actions if committed, etc. The mobility of agents is a useful feature in a distributed and dynamic system. A mobile agent is not bound to the system where it begins execution. It can travel freely among the controllers in a network and transport itself from one system in a network to another. The following are some advantages of the use of mobile agents in a system [22]: (1) it reduces the network load, (2) it overcomes network latency, (3) it encapsulates protocols, (4) it executes asynchronously and autonomously, (5) it adapts dynamically, (6) it is naturally heterogeneous, and (7) it is robust and faulttolerant. The types and functions of agents that implement functional modules of an FrMS have been brie?y described, and their initial development has been published in the earlier literature [11]. This paper enhances and re?nes the previously defined types and functions of agents so that they can perform functions of fractals successfully in the system. The names, types, and functions of agents in the FrMS are described as follows. The terms ‘‘-M’’ and ‘‘-S’’ written after the abbreviated name of each agent represent mobile agents and software agents, respectively.
2.2.1. Agents for an observer
Network monitoring agent (NMA-S): It monitors messages from other fractals through TCP/IP. It receives messages from the upper/same/lower-level fractals, such as requests for negotiations, negotiation replies, job orders, status information, etc. The NMA delivers those messages to the resolver or the analyzer. Equipment monitoring agent (EMA-S): It monitors messages directly coming from equipment through a serial communication protocol such as RS232/ 422. Information on the status of equipment including signals indicating the start and completion of jobs are detected by the EMA. However, the fractal need not directly control equipment if it is not included in a bottom-level.
2.2.2. Agents for an analyzer
Schedule evaluation agent (SEA-S): A SEA evaluates job profiles generated by the resolver. It helps the resolver to select the best job profile with respect to the current situation of the fractal. Dispatching-rule rating agent (DRA-S): It chooses the best dispatching rule for achieving its goals among several rules, such as shortest processing time (SPT), earliest due date (EDD), and so on. Real-time simulation agent (RSA-S): It performs real-time simulations in the on-line state with the results of the analyzed job profiles and the best dispatching rule. The RSA reports the results of simulations to the resolver.
2.2.3. Agents for a resolver
Schedule generation agent (SGA-M): It generates operational commands or alternative job profiles for achieving the fractal’s goals. After evaluation and analysis of alternatives in the analyzer, the SGA selects the best job profile. It must have mobility in order to use SEA, DRA, and RSA in the analyzer.
Goal formation agent (GFA-S): It modifies incomplete goals delivered from the upper-level fractal, and tries to make the goals complete by considering the current situation of the fractal. GFA divides the goal of the fractal into several sub-goals, and sends them to the sub-fractals. Task governing agent (TGA-S): A TGA generates tasks from the best job profile and its goals. It also performs tasks after arriving at the target fractal. When it finishes performing tasks, it sends acknowledgement to its sender. Negotiation agent (NEA-M): It moves to other fractals to deliver negotiation messages or to gather negotiation replies created by participating agents. It filters out unreasonable replies by a pre-evaluation process and brings the rest back to the resolver. Knowledge database agent (KDA-M): KDA invokes knowledge data from the knowledge database to make decisions. It accumulates new knowledge or updates the existing knowledge. Decision-making agent (DMA-S): It performs several operations during the decision-making processes. A DMA creates NEAs to negotiate with other fractals and KDAs to use the knowledge database. After making decisions, the DMA generates several TGAs. Further, the DMA provides a context to agents for negotiation.
2.2.4. Agents for an organizer
Fractal status manager (FSM-S): The FSM collects and manages the information on the status of fractals that is used for analyzing job profiles in the analyzer. It also makes negotiation replies to the status requests from other fractals. Fractal address manager (FAM-S): The FAM manages information about the addresses of fractals in lower levels and at the same level. A fractal address is the fractal’s physical address on the network, such as an IP address. The reporter uses a fractal’s address to confirm the destination of tasks and messages. Restructuring agent (REA-M): It performs several operations related to dynamic restructuring processes, such as BFU generation, BFU deletion, and the evaluation of the fractal’s performance. The performance of a fractal is its utilization, e.g. total number of processed jobs or the portion of processing time within total time, etc. If the REA decides that a fractal needs to be restructured, it gathers information about fractal and network addresses, and fractal status. It moves to the DMA and lets it generate a series of jobs for a restructuring process. The cloning mechanism is used to create a new BFU. After creation, the REA tells the FAM to update the addresses of other fractals.
2.2.5. Agents for a reporter
Network command agent (NCA-M): All tasks or messages are deliver