外文翻譯--關(guān)于自動(dòng)化立體倉庫使用雙貨叉問題的探討

1、<p><b>　　附錄一 外文翻譯</b></p><p>　　An Analysis Of Dual Shuttle Automated Storage/Retrieval Systems</p><p>　　Brett A. Peters August 1, 1994</p><p><b>　　Abstract

2、</b></p><p>　　This paper addresses the throughput improvement possible with the use of a dual shuttle automated storage and retrieval system. With the use of such a system, travel between time in a dua

3、l command cycle is virtually eliminated resulting in a large throughput improvement. The dual shuttle system is then extended to perform an equivalent of two dual commands in one cycle in a quadruple command mode (QC). A

4、 heuristic that sequences retrievals to minimize travel time in QC mode is developed. Monte C</p><p><b>　　Keywords:</b></p><p>　　Automated Storage/Retrieval Systems Design; Automated

5、 Storage/Retrieval Systems Operation; Material Handling Systems; Performance Modeling and Analysis </p><p>　　Introduction</p><p>　　Automated storage/retrieval systems (AS/RS) are widely used in

6、warehousing and manufacturing applications. A typical unit load AS/RS consists of storage racks, S/R machines, link conveyors, and input/output (I/O) stations. An important system performance measure is the throughput ca

7、pacity of the system. The throughput capacity for a single aisle is the inverse of the mean transaction time, which is the expected amount of time required for the S/R machine to store and/or retrieve a unit load. The<

8、;/p><p>　　Han et al. [2] improved the throughput capacity of the AS/RS through sequencing retrievals. Intelligently sequencing the retrievals can reduce unproductive travel between time when the S/R machine is

9、traveling empty and thereby increase the throughput. They develop an expression for the maximum possible improvement in throughput if travel between is eliminated for an AS/RS that is throughput bound and operates in dua

10、l command mode. In essence, this means that if the S/R machine travels in a sing</p><p>　　In this paper, we analyze an alternative design of the S/R machine that has two shuttles instead of one as in a regul

11、ar AS/RS. The new design eliminates the travel between the storage and retrieval points and performs both a storage and a retrieval at the point of retrieval, thereby achieving the maximum throughput increase calculated

12、by Han et al. [3]. </p><p>　　The dual shuttle AS/RS is a new design aimed at improving S/R machine performance. most studies on AS/RS systems have been based on a single shuttle design. In our analysis of th

13、e dual shuttle AS/RS performance, we build upon these previous research results. </p><p>　　Alternative S/R Machine Design</p><p>　　A typical unit-load AS/RS has an S/R machine operating in each

14、aisle of the system. The S/R machine has a mast which is supported at the floor and the ceiling and travels horizontally within the aisle. Connected to this mast is a shuttle mechanism that carries the unit load and move

15、s vertically up and down the mast. The shuttle mechanism also transfers loads in and out of storage locations in the rack. Figure 1 provides an illustration of the single shuttle S/R machine. </p><p>　　Figur

16、e 1. Single Shuttle S/R Machine Design </p><p>　　A typical single shuttle AS/RS can perform a single command cycle or a dual command cycle. A single command cycle consists of either a storage or a retrieval.

17、 For a storage, the time consists of the time to pickup the load at the I/O point, travel to the storage point, deposit the load at that point, and return to the I/O point. The time for a retrieval is developed similarly

18、. </p><p>　　A dual command cycle involves both a storage and a retrieval in the same cycle. The cycle time involves the time to pickup the load at the I/O point, travel to the storage location, place the loa

19、d in the rack, travel empty to the retrieval location, retrieve a load, return to the I/O point, and deposit the load at the I/O point. </p><p>　　If we critically analyze the dual command cycle of the S/R ma

20、chine (shown by the solid line in Figure 2), a potential open location for a future storage is created when a retrieval is performed. Furthermore, if both a retrieval and a storage are performed at the same point, the tr

21、avel between time (TB) is eliminated, and the travel time will be equal to the single command travel time. With the existing AS/RS design, this mode of operation is not possible; therefore, an alternative to the S/R mac&

22、lt;/p><p>　　Figure 2. Dual Command Travel Paths of S/R and R/S Machines </p><p>　　R/S Machine Operation</p><p>　　Consider an S/R machine with two shuttle mechanisms instead of one. Thi

23、s new S/R machine could now carry two loads simultaneously. Each shuttle mechanism could operate independently of the other, so that individual loads can still be stored and retrieved. An illustration of the dual shuttle

24、 S/R machine is shown in Figure 3. This new S/R machine would operate as described below. </p><p>　　Figure 3. Dual Shuttle S/R Machine Design </p><p>　　The S/R machine picks up the item to be st

25、ored from the I/O point, loads it into the first shuttle, and moves to the retrieval location. After reaching the retrieval location, the second shuttle is positioned to pickup the item to be retrieved. After retrieval,

26、the S/R machine positions the first shuttle and deposits the load. The S/R machine then returns to the I/O point. The operation can easily be seen as a single command operation plus a small travel time for repositioning

27、the S/R machine be</p><p>　　Since the R/S machine has two shuttles, the position of the shuttles has a role in the operation of the system. With two shuttles, the R/S machine is able to perform a dual comman

28、d cycle at one location in the rack. This operation is accomplished by first retrieving the load onto the empty shuttle, transferring the second shuttle into position, and storing the load into the empty location in the

29、rack. However, the choice of shuttle configuration does not impact the analysis in this paper. </p><p>　　To perform these operations, the R/S machine must move the second shuttle into position after the firs

30、t shuttle has completed the retrieval. Due to the small distance involved, the R/S machine will use a slower creep speed for positioning, but this travel time is generally small. Furthermore, an amount of creep time is u

31、sually included in the pickup and deposit time to account for this required positioning. A second design characteristic is that additional clearance beyond the first and last row</p><p>　　Throughput Improvem

32、ent</p><p>　　To estimate the throughput improvement by the dual shuttle system over existing designs, we use the expressions for single command and dual command cycle times developed by Bozer and White [1] a

33、nd the tabulated values for the nearest neighbor heuristic from Han et al. [4]. In developing the expressions, the authors in [1] and [4] made several assumptions. The same assumptions hold for the new design and include

34、 the following. </p><p>　　1. The rack is considered to be a continuous rectangular pick face where the I/O point is located at the lower left-hand corner of the rack. </p><p>　　2. The rack lengt

35、h and height, as well as the S/R machine velocity in the horizontal and vertical directions, are known. </p><p>　　3. The S/R machine travels simultaneously in the horizontal and vertical directions. In calcu

36、lating the travel time, constant velocities are used for horizontal and vertical travel. Acceleration and deceleration effects are implicitly accounted for in either a reduced top speed or an increased pickup and deposit

37、 time. A creep speed is used for repositioning the dual shuttle. </p><p>　　4. Pickup and deposit times associated with load handling are assumed constant and, therefore, these could be easily added into the

38、cycle time expressions. </p><p>　　5.The S/R machine operates either on a single or dual command basis, i.e., multiple stops in the aisle are not allowed. (This assumption is later relaxed for the new R/S mac

39、hine to perform a quadruple command cycle.) </p><p>　　6. For the nearest neighbor heuristic, a block of n retrievals is available for sequencing and there are m initial open locations in the rack face. <

40、/p><p>　　Dual Shuttle S/R Systems</p><p>　　The new design of the S/R machine has two shuttles and therefore could be operated as a dual shuttle system: carrying two loads and depositing them, retri

41、eving two loads, and returning to the I/O point to deliver them as shown in Figure 4. The above operation can be performed by storing and retrieving the loads at four different locations. Therefore, the travel time would

42、 consist of the time for a single command travel plus three travel between times. To more efficiently perform the 4 operations</p><p>　　Figure 4. S/R Machine Path Performing Four Operations At Four Locations

43、. </p><p>　　Figure 5. S/R Machine Path Performing Four Operations At Three Locations. </p><p>　　Conclusions</p><p>　　This paper performs an analysis of dual shuttle automated storag

44、e and retrieval systems. Several contributions have been made including the following. </p><p>　　1.Throughput improvements in the range of 40-45% can be obtained using the quadruple command cycle relative to

45、 dual command cycles with a single shuttle system. </p><p>　　2.With the dual shuttle design, travel between is virtually eliminated for a dual command cycle. </p><p>　　The dual shuttle system s

46、hows promise for situations requiring high throughput. The main disadvantage with the new design is the extra cost of the S/R machine. An economic evaluation is needed to determine if it is appropriate for a particular s

47、ituation. However, based on throughput performance, the dual shuttle design appears promising. </p><p>　　The concept of dual shuttle systems can also be extended to other material handling systems. Furthermo

48、re, research is needed to consider other storage strategies, such as class based storage policies, to examine their impact on throughput in conjunction with the dual shuttle design. This paper provides a framework for an

49、alyzing dual shuttle AS/RS, and it provides a foundation for other material handling research related to this concept. </p><p>　　關(guān)于自動(dòng)化立體倉庫使用雙貨叉問題的探討</p><p>　　布雷特·彼得斯 August 1, 1994</

50、p><p><b>　　摘要</b></p><p>　　本文通過在自動(dòng)化立體倉庫中運(yùn)用雙貨叉設(shè)計(jì)，來提高立體倉庫的吞吐量。由于這種系統(tǒng)運(yùn)用，雙指令系統(tǒng)的運(yùn)行間的時(shí)間實(shí)際上被消除了，并且吞吐量得到了很大的提高。雙貨叉系統(tǒng)后來被延伸到執(zhí)行一個(gè)相等的一個(gè)周期內(nèi)執(zhí)行雙指令在四倍指令模式中。一個(gè)啟發(fā)式的檢索排序減少了運(yùn)行時(shí)間，使得QC模式得到了發(fā)展。蒙特卡羅仿真的結(jié)果被用來評(píng)價(jià)啟

51、發(fā)式算法的性能，并且顯示它表現(xiàn)出色，吞吐量得到了很大的提高相比于雙指令周期下最近鄰的檢索序列啟發(fā)。</p><p>　　關(guān)鍵字：自動(dòng)化立體倉庫，物料運(yùn)輸系統(tǒng)</p><p><b>　　1.引言</b></p><p>　　自動(dòng)化立體倉庫被廣泛地應(yīng)用于倉儲(chǔ)及生產(chǎn)應(yīng)用中，自動(dòng)化立體倉庫中一個(gè)典型的貨物裝載系統(tǒng)是由堆垛機(jī)、連接輸送帶，輸入/輸出部分

52、組成。系統(tǒng)一個(gè)重要的指標(biāo)是系統(tǒng)的吞吐能力。對(duì)于單通道系統(tǒng)的貨物吞吐能力值得是堆垛機(jī)往返的平均時(shí)間，在這個(gè)所預(yù)期的時(shí)間里要求堆垛機(jī)儲(chǔ)存一個(gè)或取出一個(gè)貨物。整個(gè)服務(wù)的時(shí)間包括堆垛機(jī)行進(jìn)的時(shí)間和貨物存放的時(shí)間。這個(gè)時(shí)間通常決定于貨架的結(jié)構(gòu)和堆垛機(jī)的規(guī)格。</p><p>　　一些人通過對(duì)檢索進(jìn)行排序來提高立體倉庫的吞吐能力，對(duì)檢索進(jìn)行明智的而排序可以減少因堆垛機(jī)執(zhí)行空運(yùn)行而消耗的時(shí)間，從而提高吞吐能力。他們制定了一個(gè)表

53、達(dá)式，為了最大限度的提高系統(tǒng)的吞吐量，通過減少系統(tǒng)的運(yùn)行時(shí)間，如果吞吐量和操作都執(zhí)行雙命令模式。本質(zhì)上，這意味著堆垛機(jī)在一個(gè)命令的指揮下可以同時(shí)完成一個(gè)存儲(chǔ)和一個(gè)取貨任務(wù)，這樣吞吐量的提高就可以實(shí)現(xiàn)了。</p><p>　　在這篇論文里，我們?cè)O(shè)計(jì)了一個(gè)有兩個(gè)貨叉的堆垛機(jī)，而不是通常立體倉庫中的一個(gè)。這種新的設(shè)計(jì)可以減少存儲(chǔ)和取貨的運(yùn)行時(shí)間，在一個(gè)運(yùn)行過程中可以執(zhí)行一個(gè)存儲(chǔ)和一個(gè)取貨任務(wù)，從而最大限度的提高了吞吐量

54、。</p><p>　　在立體倉庫中使用的雙貨叉技術(shù)是為了提高堆垛機(jī)的性能而設(shè)計(jì)的一個(gè)新技術(shù)。大多數(shù)對(duì)自動(dòng)化立體倉庫的研究還是基于單貨叉技術(shù)。我們也是基于以前的研究成果來設(shè)計(jì)雙貨叉的性能。</p><p><b>　　2.替代堆垛機(jī)設(shè)計(jì)</b></p><p>　　典型的立體倉庫貨物裝載系統(tǒng)是由每一個(gè)通道上的堆垛機(jī)進(jìn)行操作，這種堆垛機(jī)有一個(gè)大的

55、柱子支撐在地面和天花板之間，在水平過道上行進(jìn)。連接在這個(gè)柱子上的是一副貨叉可以沿著柱子上下的搬運(yùn)貨物，貨叉也可以搬運(yùn)貨物進(jìn)出貨架上的儲(chǔ)存位置。</p><p>　　一個(gè)典型的單貨叉系統(tǒng)可以執(zhí)行一個(gè)或兩個(gè)指令周期，一個(gè)指令周期包括一個(gè)存儲(chǔ)過程或者一個(gè)取貨過程。對(duì)于一個(gè)存儲(chǔ)過程的時(shí)間包括從出入貨臺(tái)拾取貨物，再將貨物運(yùn)到存儲(chǔ)位置，將貨物存放到存儲(chǔ)位置，再返回到出入貨臺(tái)。取貨過程的時(shí)間與上面類似。</p>

56、<p>　　一個(gè)雙指令周期包括存儲(chǔ)和取貨兩個(gè)任務(wù)在一個(gè)周期內(nèi)，這個(gè)周期的時(shí)間包括堆垛機(jī)在出入貨臺(tái)拾起貨物，運(yùn)行至貨位，將貨物存入貨位，再運(yùn)行至一個(gè)取貨的貨位，將貨物取出，返回出入貨臺(tái)，將貨物放在出入貨臺(tái)上。</p><p>　　如果我們準(zhǔn)確的分析雙指令周期的堆垛機(jī)，當(dāng)一個(gè)取貨的任務(wù)被執(zhí)行后，一個(gè)潛在的空位置可以用于將來的存儲(chǔ)，如果一個(gè)存貨和一個(gè)取貨任務(wù)同時(shí)都被執(zhí)行，堆垛機(jī)的運(yùn)行時(shí)間就被減少了，運(yùn)行時(shí)間相

57、當(dāng)于單指令運(yùn)行時(shí)間?；谀壳暗牧Ⅲw倉庫設(shè)計(jì)，這種操作模式是不可能的。因此，一個(gè)可共選擇的方案，雙貨叉堆垛機(jī)方案被提出來了。</p><p>　　3.取存堆垛機(jī)的操作</p><p>　　由于這種堆垛機(jī)采用雙貨叉而不是單貨叉，這種新的堆垛機(jī)可以同時(shí)攜帶兩個(gè)貨物。每一個(gè)貨叉可以獨(dú)立與另一個(gè)來進(jìn)行操作，所以單一的貨物可以被存放也可以被取出。新的堆垛機(jī)系統(tǒng)將在下面進(jìn)行描述。</p>

58、<p>　　堆垛機(jī)從出入貨臺(tái)拾起一個(gè)要被存放的貨物，將它放在第一個(gè)貨叉上，然后移動(dòng)到取貨位置，當(dāng)堆垛機(jī)到達(dá)取貨位置，堆垛機(jī)的第二個(gè)貨叉到位開始取貨，當(dāng)取貨完畢，堆垛機(jī)的第一個(gè)貨叉到貨位將要存儲(chǔ)的貨物存如貨位。堆垛機(jī)然后返回出入貨臺(tái)。這種操作可以簡單的看為單指令操作，加上一段轉(zhuǎn)換貨叉的很短的一段時(shí)間。因此，這種堆垛機(jī)就是原來的堆垛機(jī)在兩個(gè)指令周期內(nèi)先完成一個(gè)取貨任務(wù)，再完成一個(gè)存貨任務(wù)。</p><p>

59、　　這種堆垛機(jī)有兩個(gè)貨叉，所以在這種操作系統(tǒng)中兩個(gè)貨叉的定位就應(yīng)該有一個(gè)規(guī)則。堆垛機(jī)可以在一個(gè)貨位前完成兩個(gè)指令周期。這種操作是由先將貨物存入空貨位，轉(zhuǎn)移第二個(gè)貨叉到位置，再將要存的貨物存入貨位。但是貨叉結(jié)構(gòu)的選擇不會(huì)影響這篇文章的設(shè)計(jì)。要完成這個(gè)操作，堆垛機(jī)必須將第二個(gè)貨叉移動(dòng)到位當(dāng)?shù)谝粋€(gè)貨叉已經(jīng)完成了取貨任務(wù)?？紤]到這個(gè)距離很短，堆垛機(jī)必須以一種蠕動(dòng)的速度移動(dòng)到位，移動(dòng)時(shí)間總體上講是很小的。此外，貨叉存貨取貨時(shí)也應(yīng)像移動(dòng)貨叉一樣以蠕

60、動(dòng)的速度。第二個(gè)設(shè)計(jì)特點(diǎn)是第一行和最后一行以外要留有一定的間隙，貨架的每一列必須滿足堆垛機(jī)的超程以適應(yīng)雙貨叉的機(jī)械結(jié)構(gòu)。</p><p><b>　　4.吞吐量的提高</b></p><p>　　為了估計(jì)雙貨叉系統(tǒng)比單貨叉系統(tǒng)的吞吐量提高了多少，我們采用了由Bozer和White發(fā)明的單操作指令和雙操作指令周期時(shí)間的公式。為了發(fā)展這個(gè)公式，作者做了幾個(gè)設(shè)想，對(duì)于新的設(shè)

61、計(jì)的設(shè)想主要有一下幾方面。</p><p>　　1. 被看做一個(gè)連續(xù)的矩形接面，出入貨臺(tái)位于貨架的左下角。</p><p>　　2. 貨架的長度和高度，還有堆垛機(jī)在垂直和水平方向上的速度，是已知的。</p><p>　　3. 堆垛機(jī)可以在水平和垂直方向上同時(shí)的運(yùn)行，在計(jì)算時(shí)間時(shí)，水平和垂直行進(jìn)采用勻速，加速和減速效果運(yùn)用與高速的降低或者存取貨速度的提高。貨叉的定位采

62、用蠕動(dòng)的速度。</p><p>　　4. 存取貨物的時(shí)間與貨物的處理時(shí)間有關(guān)，被認(rèn)為是一個(gè)常數(shù)。因此，這將可以輕易的加進(jìn)了周期時(shí)間表達(dá)式。</p><p>　　5. 堆垛機(jī)的運(yùn)行是以單指令或者雙指令為基礎(chǔ)的，這也就是說在通道中多樣的停止方式是不被允許的。</p><p>　　6. 對(duì)于最近鄰的啟發(fā)，一大塊n個(gè)檢索對(duì)排序有效，而貨架上最初有m個(gè)空位置。</p&g

63、t;<p>　　5.雙貨叉堆垛機(jī)系統(tǒng)</p><p>　　堆垛機(jī)新的設(shè)計(jì)有兩個(gè)貨叉，所以可以按照雙貨叉系統(tǒng)進(jìn)行操作：攜帶兩個(gè)貨物并存儲(chǔ)它們，取出兩個(gè)貨物返回出入貨臺(tái)。上面的操作可以在四個(gè)不同的位置存儲(chǔ)和取出貨物。因此，整個(gè)運(yùn)行時(shí)間由一個(gè)指令運(yùn)行時(shí)間加上三個(gè)運(yùn)行間的時(shí)間。為了更有效的執(zhí)行這四個(gè)操作，存儲(chǔ)和取貨在一個(gè)位置上穿插著雙重命令操作，這種操作模式，被成為四指令周期。消除了一個(gè)運(yùn)行間時(shí)間，比以往的

64、方式更有效。四指令周期模式可以在隨機(jī)位置進(jìn)行存貨，而取貨則按照先到先取的模式。但是，通過智能檢索列表排序,，四個(gè)操作時(shí)間將會(huì)大大的減少。這種方式被Han等人用來單一貨載的立體倉庫的吞吐量。在本文中我們是以他們的研究為基礎(chǔ)。</p><p><b>　　5.結(jié)論</b></p><p>　　本文對(duì)雙貨叉存儲(chǔ)系統(tǒng)進(jìn)行了分析，主要有以下幾個(gè)貢獻(xiàn)。</p>&l

65、t;p>　　（1） 對(duì)于采用單貨叉系統(tǒng)使用兩倍指令周期，采用四指令周期可以提高吞吐量40%-45%.</p><p>　?。?） 用雙貨叉設(shè)計(jì)，行進(jìn)間的時(shí)間實(shí)際上減少到一個(gè)雙指令周期。雙貨叉系統(tǒng)可以保證所要求的高吞吐量。主要的缺點(diǎn)是新的設(shè)計(jì)會(huì)使堆垛機(jī)的成本上升。一個(gè)經(jīng)濟(jì)評(píng)估是必要的,以決定是否適合某一特定的情況。但是就吞吐量的性能指標(biāo)而言，雙貨叉設(shè)計(jì)是滿足要求的。</p><p>