hoist scheduling problem-HSP

• Main Authors: Yu-kuo Chien, 簡煜國
• Other Authors: Y-C Ho
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/60981008007326608225

碩士 === 國立中央大學 === 工業管理研究所 === 91 === There are a lot of researches which consider scheduling and control of automated material handling systems, including robotic cell scheduling、scheduling of automated guided vehicle and so on. Among these problems, the hoist scheduling problem-HSP or crane scheduling problem is the most restricted one (Crama 1999). And it was proved to be NP-hardness in the class of this problem by Lei and Wang (1989). Most of the systems installed are designed by experienced experts using trail-and-error based techniques. The fixed schedule derived by trial-and error must be validated with an actual system and usually it takes several days to correct some unexpected errors in the original design. The previous study about the HSP in automated surface treatment lines mainly focus on single hoist、single product type environment. A fixed hoist schedule for maximum through-put was considered before the operation. The difference between previous case studied and actual systems is: real systems are usually composed by several hoists, and it will encounter three difficulties with a fixed schedule design: (1)the system could only operate with one product type at one time (2)it will not work if one of the hoist fails. Therefore there will be lots of scrap products if only one hoists fails(3)a previous study (Mak 2002) suggest that adding overlapping zones between hoists movement could be beneficial to material handling efficiency but no further conclusion. The purpose of this study is to develop an efficient hoist dispatching rule that deal with above scenarios in a automated electroplating line. To analyze the performance of different approaches, some of the single hoist cases are discussed extensively by many researchers. For example, the cases provided by Phillips and Unger(1976)、Shapiro and Nuttle(1988). And these cases already become benchmark problems in this field. But it is rare to study a multi-hoist system. We will use the multi-hoist case provided by Mak(2002) to study the performance of our rule.