Parallel autonomous guided vehicle assembly line for a semi-continuous manufacturing system

2016 ◽  
Vol 36 (3) ◽  
pp. 262-273 ◽  
Author(s):  
Hamed Fazlollahtabar
Keyword(s):  
Manufacturing System ◽  
Assembly Line ◽  
Dynamic Scheduling ◽  
Continuous Manufacturing ◽  
Scheduling Problems ◽  
Assembly Lines ◽  
Short Term ◽  
Line System ◽  
Content Type ◽  
Multiple Products

Purpose This paper aims to propose a parallel automated assembly line system to produce multiple products in a semi-continuous system. Design/methodology/approach The control system developed in this research consists of a manufacturing system for two-level hierarchical dynamic decisions of autonomous/automated/automatic-guided vehicles (AGVs) dispatching/next station selection and machining schedules and a station control scheme for operational control of machines and components. In this proposed problem, the assignment of multiple AGVs to different assembly lines and the semi-continuous stations is a critical objective. AGVs and station scheduling decisions are made at the assembly line level. On the other hand, component and machining resource scheduling are made at the station level. Findings The proposed scheduler first decomposes the dynamic scheduling problems into a static AGV and machine assignment during each short-term rolling window. It optimizes weighted completion time of tasks for each short-term window by formulating the task and resource assignment problem as a minimum cost flow problem during each short-term scheduling window. A comprehensive decision making process and heuristics are developed for efficient implementation. A simulation study is worked out for validation. Originality/value Several assembly lines are configured to produce multiple products in which the technologies of machines are shared among the assembly lines when required. The sequence of stations is pre-specified in each assembly line and the components of a product are kept in machine magazine. The transportation between the stations in an assembly line (intra assembly line) and among stations in different assembly lines (inter assembly line) are performed using AGVs.

Adjustment mode decision based on support vector data description and evidence theory for assembly lines

2018 ◽  
Vol 118 (8) ◽  
pp. 1711-1726 ◽  
Author(s):  
Youlong Lv ◽  
Wei Qin ◽  
Jungang Yang ◽  
Jie Zhang
Keyword(s):  
Assembly Line ◽  
Historical Data ◽  
Classification Model ◽  
Support Vector ◽  
Support Vector Data Description ◽  
Vector Data ◽  
Assembly Lines ◽  
Content Type ◽  
Input Layer ◽  
Multi Classification

PurposeThree adjustment modes are alternatives for mixed-model assembly lines (MMALs) to improve their production plans according to constantly changing customer requirements. The purpose of this paper is to deal with the decision-making problem between these modes by proposing a novel multi-classification method. This method recommends appropriate adjustment modes for the assembly lines faced with different customer orders through machine learning from historical data.Design/methodology/approachThe decision-making method uses the classification model composed of an input layer, two intermediate layers and an output layer. The input layer describes the assembly line in a knowledge-intensive manner by presenting the impact degrees of production parameters on line performances. The first intermediate layer provides the support vector data description (SVDD) of each adjustment mode through historical data training. The second intermediate layer employs the Dempster–Shafer (D–S) theory to combine the posterior classification possibilities generated from different SVDDs. The output layer gives the adjustment mode with the maximum posterior possibility as the classification result according to Bayesian decision theory.FindingsThe proposed method achieves higher classification accuracies than the support vector machine methods and the traditional SVDD method in the numerical test consisting of data sets from the machine-learning repository and the case study of a diesel engine assembly line.Practical implicationsThis research recommends appropriate adjustment modes for MMALs in response to customer demand changes. According to the suggested adjustment mode, the managers can improve the line performance more effectively by using the well-designed optimization methods for a specific scope.Originality/valueThe adjustment mode decision belongs to the multi-classification problem featured with limited historical data. Although traditional SVDD methods can solve these problems by providing the posterior possibility of each classification result, they might have poor classification accuracies owing to the conflicts and uncertainties of these possibilities. This paper develops a novel classification model that integrates the SVDD method with the D–S theory. By handling the conflicts and uncertainties appropriately, this model achieves higher classification accuracies than traditional methods.

scholarly journals Integrating Queueing Theory and Scheduling for Dynamic Scheduling Problems

2014 ◽  
Vol 50 ◽  
pp. 535-572 ◽  
Author(s):  
D. Terekhov ◽  
T. T. Tran ◽  
D. G. Down ◽  
J.C. Beck
Keyword(s):  
Queueing Theory ◽  
Dynamic Scheduling ◽  
Queueing Network ◽  
Scheduling Problems ◽  
Short Term ◽  
Arrival Times ◽  
Processing Times ◽  
Long Run ◽  
Resource Requirements ◽  
First Time

Dynamic scheduling problems consist of both challenging combinatorics, as found in classical scheduling problems, and stochastics due to uncertainty about the arrival times, resource requirements, and processing times of jobs. To address these two challenges, we investigate the integration of queueing theory and scheduling. The former reasons about long-run stochastic system characteristics, whereas the latter typically deals with short-term combinatorics. We investigate two simple problems to isolate the core differences and potential synergies between the two approaches: a two-machine dynamic flowshop and a flexible queueing network. We show for the first time that stability, a fundamental characteristic in queueing theory, can be applied to approaches that periodically solve combinatorial scheduling problems. We empirically demonstrate that for a dynamic flowshop, the use of combinatorial reasoning has little impact on schedule quality beyond queueing approaches. In contrast, for the more complicated flexible queueing network, a novel algorithm that combines long-term guidance from queueing theory with short-term combinatorial decision making outperforms all other tested approaches. To our knowledge, this is the first time that such a hybrid of queueing theory and scheduling techniques has been proposed and evaluated.

scholarly journals A Mathematical Model for Tool Sharing between Workers by Exact Solution Approach

2021 ◽  
pp. 132-137
Author(s):  
Ashish Yadav ◽  
Keyword(s):  
Mathematical Model ◽  
Assembly Line ◽  
Assembly Line Balancing ◽  
Exact Algorithm ◽  
System Configuration ◽  
Assembly Lines ◽  
Line System ◽  
Solution Approach ◽  
Assembly Line Balancing Problem ◽  
Tool Cost

Multi-manned assembly lines are generally used to produce large-sized volume products such as cars and trucks. This article addresses the multi-manned two sided assembly line balancing problem with the objectives sharing tool between workstations. This paper presents a mathematical model and a Lingo -16 solvers based exact algorithm for multi-manned two-sided assembly line system configuration with tool sharing between adjacent workstations for companies that need intelligent solutions to satisfy customized demands on time with existing resources. The results obtained indicate that tool shared between parallel stations of two or more parallel lines beneficial for assembly line to minimize workstations, idle time and reduce tool cost.

An improved immune clonal selection algorithm for bi-objective robotic assemble line balancing problems considering time and space constraints

2019 ◽  
Vol 36 (6) ◽  
pp. 1868-1892 ◽  
Author(s):  
Binghai Zhou ◽  
Qiong Wu
Keyword(s):  
Assembly Line ◽  
Clonal Selection ◽  
Assembly Line Balancing ◽  
Robotic Assembly ◽  
Line Balancing ◽  
Clonal Selection Algorithm ◽  
Selection Algorithm ◽  
Assembly Lines ◽  
Content Type ◽  
Multi Objective

Purpose The extensive applications of the industrial robots have made the optimization of assembly lines more complicated. The purpose of this paper is to develop a balancing method of both workstation time and station area to improve the efficiency and productivity of the robotic assembly lines. A tradeoff was made between two conflicting objective functions, minimizing the number of workstations and minimizing the area of each workstation. Design/methodology/approach This research proposes an optimal method for balancing robotic assembly lines with space consideration and reducing robot changeover and area for tools and fixtures to further minimize assembly line area and cycle time. Due to the NP-hard nature of the considered problem, an improved multi-objective immune clonal selection algorithm is proposed to solve this constrained multi-objective optimization problem, and a special coding scheme is designed for the problem. To enhance the performance of the algorithm, several strategies including elite strategy and global search are introduced. Findings A set of instances of different problem scales are optimized and the results are compared with two other high-performing multi-objective algorithms to evaluate the efficiency and superiority of the proposed algorithm. It is found that the proposed method can efficiently solve the real-world size case of time and space robotic assembly line balancing problems. Originality/value For the first time in the robotic assembly line balancing problems, an assignment-based tool area and a sequence-based changeover time are took into consideration. Furthermore, a mathematical model with bi-objective functions of minimizing the number of workstations and area of each station was developed. To solve the proposed problem, an improved multi-objective immune clonal selection algorithm was proposed and a special coding scheme is designed.

An integrated approach for line balancing and AGV scheduling towards smart assembly systems

2020 ◽  
Vol 40 (2) ◽  
pp. 219-234 ◽  
Author(s):  
Humyun Fuad Rahman ◽  
Mukund Nilakantan Janardhanan ◽  
Peter Nielsen
Keyword(s):  
Material Handling ◽  
Assembly Line ◽  
Computational Study ◽  
Automated Guided Vehicles ◽  
Robotic Assembly ◽  
Line Balancing ◽  
Assembly Systems ◽  
Scheduling Problems ◽  
Content Type ◽  
Smart Assembly

Purpose Optimizing material handling within the factory is one of the key problems of modern assembly line systems. The purpose of this paper is to focus on simultaneously balancing a robotic assembly line and the scheduling of material handling required for the operation of such a system, a topic that has received limited attention in academia. Manufacturing industries focus on full autonomy because of the rapid advancements in different elements of Industry 4.0 such as the internet of things, big data and cloud computing. In smart assembly systems, this autonomy aims at the integration of automated material handling equipment such as automated guided vehicles (AGVs) to robotic assembly line systems to ensure a reliable and flexible production system. Design/methodology/approach This paper tackles the problem of designing a balanced robotic assembly line and the scheduling of AGVs to feed materials to these lines such that the cycle time and total tardiness of the assembly system are minimized. Because of the combination of two well-known complex problems such as line balancing and material handling and a heuristic- and metaheuristic-based integrated decision approach is proposed. Findings A detailed computational study demonstrates how an integrated decision approach can serve as an efficient managerial tool in designing/redesigning assembly line systems and support automated transportation infrastructure. Originality/value This study is beneficial for production managers in understanding the main decisional steps involved in the designing/redesigning of smart assembly systems and providing guidelines in decision-making. Moreover, this study explores the material distribution scheduling problems in assembly systems, which is not yet comprehensively explored in the literature.

Multi-manned assembly line balancing problem with balanced load density

2015 ◽  
Vol 35 (1) ◽  
pp. 137-142 ◽  
Author(s):  
Hamid Yilmaz ◽  
Mustafa Yilmaz
Keyword(s):  
Mathematical Model ◽  
Assembly Line ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Assembly Lines ◽  
Content Type ◽  
Task Load ◽  
Balance Task ◽  
Assembly Line Balancing Problem ◽  
First Time

Purpose – The purpose of this paper is balancing multi-manned assembly lines with load-balancing constraints in addition to conventional ones Most research works about the multi-manned assembly line balancing problems are focused on the conventional industrial measures that minimize total number of workers, number of multi-manned workstations or both. Design/methodology/approach – This paper provides a remedial constraint for the model to balance task load density for each worker in workstations. Findings – Comparisons between the proposed mathematical model and the existing multi-manned mathematical model show a quite promising better task load density performance for the proposed approach. Originality/value – In this paper, a mathematical model that combines the minimization of multi-manned stations, worker numbers and difference of task load density of workers is proposed for the first time.

Balancing of parallel U-shaped assembly lines with a heuristic algorithm based on bidirectional priority values

2021 ◽  
pp. 1063293X2110655
Author(s):  
Yuling Jiao ◽  
Xue Deng ◽  
Mingjuan Li ◽  
Xiaocui Xing ◽  
Binjie Xu
Keyword(s):  
Mathematical Model ◽  
Heuristic Algorithm ◽  
Assembly Line ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Assembly Lines ◽  
Line System ◽  
Assembly Line Balancing Problem ◽  
The Mathematical Model ◽  
Better Than

Aiming at improving assembly line efficiency and flexibility, a balancing method of parallel U-shaped assembly line system is proposed. Based on the improved product priority diagram, the bidirectional priority value formula is obtained. Then, assembly lines are partitioned into z-q partitions and workstations are defined. After that, the mathematical model of the parallel U-shaped assembly line balancing problem is established. A heuristic algorithm based on bidirectional priority values is used to solve explanatory examples and test examples. It can be seen from the results and the effect indicators of the assembly line balancing problem that the heuristic algorithm is suitable for large balancing problems. The proposed method has higher calculation accuracy and shorter calculation time. The balancing effect of the parallel U-shaped assembly line is better than that of single U-shaped assembly line, which verifies the superiority of the parallel U-type assembly line and effectiveness of the proposed method. It provides a theoretical and practical reference for parallel U-type assembly line balancing problem.

A novel optimal method of robotic weld assembly line balancing problems with changeover times: a case study

2018 ◽  
Vol 38 (4) ◽  
pp. 376-386 ◽  
Author(s):  
Binghai Zhou ◽  
Qiong Wu
Keyword(s):  
Local Search ◽  
Cycle Time ◽  
Assembly Line ◽  
Research Work ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Assembly Lines ◽  
Optimal Method ◽  
Content Type ◽  
Changeover Times

PurposeThe balancing of robotic weld assembly lines has a significant influence on achievable production efficiency. This paper aims to investigate the most suitable way to assign both assembly tasks and type of robots to every workstation, and present an optimal method of robotic weld assembly line balancing (ALB) problems with the additional concern of changeover times. An industrial case of a robotic weld assembly line problem is investigated with an objective of minimizing cycle time of workstations.Design/methodology/approachThis research proposes an optimal method for balancing robotic weld assembly lines. To solve the problem, a low bound of cycle time of workstations is built, and on account of the non-deterministic polynomial-time (NP)-hard nature of ALB problem (ALBP), a genetic algorithm (GA) with the mechanism of simulated annealing (SA), as well as self-adaption procedure, was proposed to overcome the inferior capability of GA in aspect of local search.FindingsTheory analysis and simulation experiments on an industrial case of a car body welding assembly line are conducted in this paper. Satisfactory results show that the performance of GA is enhanced owing to the mechanism of SA, and the proposed method can efficiently solve the real-world size case of robotic weld ALBPs with changeover times.Research limitations/implicationsThe additional consideration of tool changing has very realistic significance in manufacturing. Furthermore, this research work could be modified and applied to other ALBPs, such as worker ALBPs considering tool-changeover times.Originality/valueFor the first time in the robotic weld ALBPs, the fixtures’ (tools’) changeover times are considered. Furthermore, a mathematical model with an objective function of minimizing cycle time of workstations was developed. To solve the proposed problem, a GA with the mechanism of SA was put forth to overcome the inferior capability of GA in the aspect of local search.

Implicit memory-based technique in solving dynamic scheduling problems through Response Surface Methodology – Part II

2014 ◽  
Vol 7 (2) ◽  
pp. 143-174
Author(s):  
Manuel Blanco Abello ◽  
Zbigniew Michalewicz
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Project Scheduling ◽  
Design Methodology ◽  
Dynamic Scheduling ◽  
Variable Number ◽  
The Other ◽  
Scheduling Problems ◽  
Content Type ◽  
Dynamic Resource

Purpose – This is the second part of a two-part paper. The purpose of this paper is to report the results on the application of the methods that use the Response Surface Methodology to investigate an evolutionary algorithm (EA) and memory-based approach referred to as McBAR – the Mapping of Task IDs for Centroid-Based Adaptation with Random Immigrants. Design/methodology/approach – The methods applied in this paper are fully explained in the first part. They are utilized to investigate the performances (ability to determine solutions to problems) of techniques composed of McBAR and some EA-based techniques for solving some multi-objective dynamic resource-constrained project scheduling problems with a variable number of tasks. Findings – The main results include the following: first, some algorithmic components of McBAR are legitimate; second, the performance of McBAR is generally superior to those of the other techniques after increase in the number of tasks in each of the above-mentioned problems; and third, McBAR has the most resilient performance among the techniques against changes in the environment that set the problems. Originality/value – This paper is novel for investigating the enumerated results.

Study on Reconfiguration Approach of Mixed-Model Assembly Line Based on Petri Net Modeling of Workstations

2012 ◽  
Vol 263-266 ◽  
pp. 3265-3273
Author(s):  
Shu Xu ◽  
Fu Ming Li
Keyword(s):  
Assembly Line ◽  
Mixed Model ◽  
Equivalent Transformation ◽  
Assembly Lines ◽  
Short Term ◽  
Mixed Model Assembly Lines ◽  
Equipment Configuration ◽  
Mixed Model Assembly Line ◽  
Mixed Model Assembly ◽  
Structure Research

This thesis puts forward a reconfiguration approach of mixed-model assembly line on the basis of adding equipments against short-term and violent change of demand. This approach makes uses of equivalent transformation of task volume to judge whether the capacity of current assembly line can satisfy the demand according to delivery time, and gives equipment configuration of completing the order by adjusting assembly line structure. Research results show that the shortage and excess of assembly line capacity as well as equipment configuration is different when order changes. The approach proposed in this thesis can be directly adopted as the scheme of mixed-model assembly line and referred to other capacity adjustment schemes, such as balancing the mixed-model assembly lines and cooperative manufacture.

Sign in / Sign up

Export Citation Format

Share Document