• Title/Summary/Keyword: Dispatching Algorithm

Search Result 94, Processing Time 0.033 seconds

A Study on Machine and AGV Dispatching in Flexible Manufacturing Systems (유연생산 시스템에서 기계와 무인 운반차의 할당규칙에 관한 연구)

  • 박성현;노인규
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.20 no.43
    • /
    • pp.81-89
    • /
    • 1997
  • This study is concerned with the scheduling problems in flexible manufacturing systems(FMSs). The scheduling problem in FMSs is a complex one when the number of machines and jobs are increased. Thus, a heuristic method is recommended in order to gain near-optimal solutions in a practically acceptable time. The purpose of this study is to develope a machine and AGV dispatching algorithm. The proposed dispatching algorithm is a on-line scheduling algorithm considering the due date of parts and the status of the system in the scheduling process. In the new machine and AGV dispatching algorithm, a job priority is determined by LPT/LQS rules considering job tardiness. The proposed heuristic dispatching algorithm is evaluated by comparison with the existing dispatching rules such as LPT/LQS, SPT/LQS, EDD/LQS and MOD/LQS. The new dispatching algorithm is predominant to existing dispatching rules in 100 cases out of 100 for the mean tardiness and 89 cases out of 100 for the number of tardy jobs.

  • PDF

A Study on Scheduling by Mixed Dispatching rule in Flexible Manufacturing Systems (유연생산시스템에서 혼합할당규칙에 의한 일정계획에 관한 연구)

  • 이동진;노인규
    • Journal of Korean Society of Industrial and Systems Engineering
    • /
    • v.21 no.47
    • /
    • pp.35-45
    • /
    • 1998
  • Scheduling problem in Flexible Manufacturing Systems(FMS) is complex because of various situation of Manufacturing Systems. Especially, in case of short-term scheduling demanding high efficiency, low cost at short-period, efficient scheduling is a serious problem. To solve this problem, many dispatching rules are developed. But, it leave much to be desired, because real situation in shop floor is complex and real-time scheduling is needed in real manufacturing shop floor. In this paper, search algorithm that allocate different dispatching rules to each machine is presented to complement lack of dispatching rule and develop practical real-time scheduling system. The search algorithm is described in detail. First, algorithm detect machine breakdown, evaluate each dispatching rule. dispatching rules for each machine meeting performance criteria are ranked. The algorithm selects new dispatching nile for bottleneck machine. The effectivenes and efficiency of the mixed dispatching rule and search algorithm is demonstrated.

  • PDF

A SIMULATION/OPTIMIZATION ALGORITHM FOR AN FMS DISPATCHING PRIORITY PROBLEM

  • Lee, Keun-Hyung;Morito, Susumu
    • Proceedings of the Korea Society for Simulation Conference
    • /
    • 1993.10a
    • /
    • pp.16-16
    • /
    • 1993
  • The efficient use of capital intensive FMS requires determination of effective dispatching priority with which the parts of the selected part types are to be inputed into the system. This paper presents a simulation-optimization approach to find an appropriate dispatching priority. The study is based on a detailed simulator for a module-type commercial FMS, Specifically, after presenting the basic configuration and fundamental control logic of the system together with its main characteristics as a special type of a job shop, an algorithm is presented which combines simulated annealing and simulation to explore a dispatching priority of operations that minimizes the total tardiness, Computational performance of the algorithm shows that good solutions can be obtained within a reasonable amount of computations. The paper also compares the performance of the "optimal" or near optimal dispatching priority generated by the proposed algorithm with those generated by standard dispatching rules such as SPT, EDD and SLACK.

  • PDF

A Fuzzy Dispatching Algorithm with Adaptive Control Rule for Automated Guided Vehicle System in Job Shop Environment (AGV시스템에서 적응 규칙을 갖는 퍼지 급송알고리듬에 관한 연구)

  • 김대범
    • Journal of the Korea Society for Simulation
    • /
    • v.9 no.1
    • /
    • pp.21-38
    • /
    • 2000
  • A fuzzy dispatching algorithm with adaptable control scheme is proposed for more flexible and adaptable operation of AGV system. The basic idea of the algorithm is prioritization of all move requests based on the fuzzy urgency. The fuzzy urgency is measured by the fuzzy multi-criteria decision-making method, utilizing the relevant information such as incoming and outgoing buffer status, elapsed time of move request, and AGV traveling distance. At every dispatching decision point, the algorithm prioritizes all move requests based on the fuzzy urgency. The performance of the proposed algorithm is compared with several dispatching algorithms in terms of system throughput in a hypothetical job shop environment. Simulation experiments are carried out varying the level of criticality ratio of AGVs , the numbers of AGVs, and the buffer capacities. The rule presented in this study appears to be more effective for dispatching AGVs than the other rules.

  • PDF

AN ADAPTIVE DISPATCHING ALGORITHM FOR AUTOMATED GUIDED VEHICLES BASED ON AN EVOLUTIONARY PROCESS

  • Hark Hwnag;Kim, Sang-Hwi;Park, Tae-Eun
    • Proceedings of the Korea Society for Simulation Conference
    • /
    • 1997.04a
    • /
    • pp.124-127
    • /
    • 1997
  • A key element in the control of Automated Guided Vehicle Systems (AGVS) is dispatching policy. This paper proposes a new dispatching algorithm for an efficient operation of AGVS. Based on an evolutionary operation, it has an adaptive control capability responding to changes of the system environment. The performance of the algorithm is compared with some well-known dispatching rules in terms of the system throughput through simulation. Sensitivity analysis is carried out varying the buffer capacity and the number of AGVS.

  • PDF

An Online Personal Rapid Transit Dispatching Algorithm Based on Nearest Neighbor Dispatching Rule (최근린 배차 규칙 기반 온라인 Personal Rapid Transit 배차 알고리즘)

  • Han, Chung-Kyun;Kwon, Bo Bea;Kim, Baek-Hyun;Jeong, Rag-Gyo;Lee, Hoon;Ha, Byung-Hyun
    • Journal of the Korea Society for Simulation
    • /
    • v.23 no.4
    • /
    • pp.97-109
    • /
    • 2014
  • Personal rapid transit (PRT) is a new transportation system, which is energy efficient and brings high quality of customer service. Customers arrive dynamically at stations and request transportation service. In this paper, we propose a new online PRT dispatching algorithm for pickup and delivery of customers. We adopt the nearest neighbor dispatching rule, which is known as performing well in general. We extend the rule with bipartite matching in order to deal with multiple vehicles and customers at the same time. We suggest a systematic way for selecting vehicles that will be considered to be dispatched, since the scope with which vehicles are selected may affect the system performance. We regard the empty travel distance of vehicles and the customer waiting time as the performance measures. By using simulation experiments, it has been examined that the scope of dispatching affects the system performance. The proposed algorithm has been validated by comparing with other dispatching rules for transportation services. We have shown that our algorithm is more suitable for PRT operating environment than other dispatching rules.

Scheduling Algorithm for Nonidentical Parallel Machines Problem with Rework (Rework가 존재하는 이종병렬기계에서의 일정계획 수립)

  • Kang, Yong Ha;Kim, Sung Shick;Park, Jong Hyuck;Shin, Hyun Joon
    • Journal of Korean Institute of Industrial Engineers
    • /
    • v.33 no.3
    • /
    • pp.329-338
    • /
    • 2007
  • This paper presents a dispatching algorithm for nonidentical parallel machines problem considering rework, sequence dependent setup times and release times. For each pair of a machine and a job type, rework probability of each job on a machine can be known through historical data acquisition. The heuristic scheduling scheme named by EDDR (Earliest Due Date with Rework probability) algorithm is proposed in this paper making use of the rework probability. The proposed dispatching algorithm is measured by two objective function value: 1) total tardiness and 2) the number of reworked jobs, respectively. The extensive computational results show that the proposed algorithm gives very efficient schedules superior to the existing dispatching algorithms.

A Simulation-based Genetic Algorithm for a Dispatching Rule in a Flexible Flow Shop with Rework Process (시뮬레이션 기반 유전알고리즘을 이용한 디스패칭 연구: 재작업이 존재하는 유연흐름라인을 대상으로)

  • Gwangheon Lee;Gwanguk Han;Bonggwon Kang;Seonghwan Lee;Soondo Hong
    • The Journal of Bigdata
    • /
    • v.7 no.1
    • /
    • pp.75-87
    • /
    • 2022
  • This study investigates a dynamic flexible flow shop scheduling problem under uncertain rework operations for an automobile pipe production line. We propose a weighted dispatching rule (WDR) based on the multiple dispatching rules to minimize the weighted sum of average flowtime and tardiness. The set of weights in WDR should be carefully determined because it significantly affects the performance measures. We build a discrete-event simulation model and propose a genetic algorithm to optimize the set of weights considering complex and variant operations. The simulation experiments demonstrate that WDR outperforms the baseline dispatching rules in average flowtime and tardiness.

Optimizing Automated Stacking Crane Dispatching Strategy Using an MOEA for an Automated Container Terminal

  • Wu, Jiemin;Choe, Ri;Park, Tae-Jin;Ryu, Kwang-Ryel
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • 2011.06a
    • /
    • pp.216-217
    • /
    • 2011
  • The problem of automated stacking cranes (ASC) dispatching in container terminals is addressed in this paper. We propose a heuristic-based ASC dispatching approach which adopts multi-criteria decision strategy. By aggregating different criteria the proposed strategy can consider multiple aspects of the dispatching situation and make robust decision in various situations. A multi-objective evolutionary algorithm (MOEA) is adopted to tune the weights associated to each criteria to minimize both the quay crane delay and external truck delay. The proposed approach is validated by comparison with different dispatching heuristics and simulation results obtained confirms its effectiveness.

  • PDF

An Adaptive Dispatching Architecture for Constructing a Factory Operating System of Semiconductor Fabrication : Focused on Machines with Setup Times (반도체 Fab의 생산운영시스템 구축을 위한 상황적응형 디스패칭 방법론 : 공정전환시간이 있는 장비를 중심으로)

  • Jeong, Keun-Chae
    • IE interfaces
    • /
    • v.22 no.1
    • /
    • pp.73-84
    • /
    • 2009
  • In this paper, we propose a dispatching algorithm for constructing a Factory Operating System (FOS) which can operate semiconductor fabrication factories more efficiently and effectively. We first define ten dispatching criteria and propose two methods to apply the defined dispatching criteria sequentially and simultaneously (i.e. fixed dispatching architecture). However the fixed type methods cannot apply the criteria adaptively by considering changes in the semiconductor fabrication factories. To overcome this type of weakness, an adaptive dispatching architecture is proposed for applying the dispatching criteria dynamically based on the factory status. The status can be determined by combining evaluation results from the following three status criteria; target movement, workload balance, and utilization rate. Results from the shop floor in past few periods showed that the proposed methodology gives a good performance with respect to the productivity, workload balance, and machine utilization. We can expect that the proposed adaptive dispatching architecture will be used as a useful tool for operating semiconductor fabrication factories more efficiently and effectively.