Research Trends and Outlooks in Assembly Line Balancing Problems

This paper presents the findings from the survey of articles published on the assembly line balancing problems (ALBPs) during 2014-2018. Before proceeding a comprehensive literature review, the ineffectiveness of the previous ALBP classification structures is discussed and a new classification scheme based on the layout configurations of assembly lines is subsequently proposed. The research trend in each layout of assembly lines is highlighted through the graphical presentations. The challenges in the ALBPs are also pinpointed as a technical guideline for future research works

Multi-objective discrete particle swarm optimisation algorithm for integrated assembly sequence planning and assembly line balancing

In assembly optimisation, assembly sequence planning and assembly line balancing have been extensively studied because both activities are directly linked with assembly efficiency that influences the final assembly costs. Both activities are categorised as NP-hard and usually performed separately. Assembly sequence planning and assembly line balancing optimisation presents a good opportunity to be integrated, considering the benefits such as larger search space that leads to better solution quality, reduces error rate in planning and speeds up time-to-market for a product. In order to optimise an integrated assembly sequence planning and assembly line balancing, this work proposes a multi-objective discrete particle swarm optimisation algorithm that used discrete procedures to update its position and velocity in finding Pareto optimal solution. A computational experiment with 51 test problems at different difficulty levels was used to test the multi-objective discrete particle swarm optimisation performance compared with the existing algorithms. A statistical test of the algorithm performance indicates that the proposed multi-objective discrete particle swarm optimisation algorithm presents significant improvement in terms of the quality of the solution set towards the Pareto optimal set

Multi-Objective Discrete Particle Swarm Optimisation Algorithm for Integrated Assembly Sequence Planning and Assembly Line Balancing

In assembly optimisation, assembly sequence planning and assembly line balancing have been extensively studied because both activities are directly linked with assembly efficiency that influences the final assembly costs. Both activities are categorised as NP-hard and usually performed separately. Assembly sequence planning and assembly line balancing optimisation presents a good opportunity to be integrated, considering the benefits such as larger search space that leads to better solution quality, reduces error rate in planning and speeds up time-to-market for a product. In order to optimise an integrated assembly sequence planning and assembly line balancing, this work proposes a multi-objective discrete particle swarm optimisation algorithm that used discrete procedures to update its position and velocity in finding Pareto optimal solution. A computational experiment with 51 test problems at different difficulty levels was used to test the multi-objective discrete particle swarm optimisation performance compared with the existing algorithms. A statistical test of the algorithm performance indicates that the proposed multi-objective discrete particle swarm optimisation algorithm presents significant improvement in terms of the quality of the solution set towards the Pareto optimal set

Assembly line balancing with cobots: An extensive review and critiques

Industry 4.0 encourages industries to digitise the manufacturing system to facilitate human-robot collaboration (HRC) to foster efficiency, agility and resilience. This cutting-edge technology strikes a balance between fully automated and manual operations to maximise the benefits of both humans and assistant robots (known as cobots) working together on complicated and prone-to-hazardous tasks in a collaborative manner in an assembly system. However, the introduction of HRC poses a significant challenge for assembly line balancing since, besides typical assigning tasks to workstations, the other two important decisions must also be made regarding equipping workstations with appropriate cobots as well as scheduling collaborative tasks for workers and cobots. In this article, the cobot assembly line balancing problem (CoALBP), which just initially emerged a few years ago, is thoroughly reviewed. The 4M1E (i.e., man, machine, material, method and environment) framework is applied for categorising the problem to make the review process more effective. All of the articles reviewed are compared, and their key distinct features are summarised. Finally, guidelines for additional studies on the CoALBP are offered

การจัดสมดุลที่มีหลายวัตถุประสงค์บนสายการประกอบแบบขนานผลิตภัณฑ์ผสมด้วยการหาค่าที่เหมาะสมที่สุดแบบการกระจายตัวของสิ่งมีชีวิตตามภูมิศาสตร์

บทคัดย่อการหาค่าที่เหมาะสมที่สุดแบบการกระจายตัวของสิ่งมีชีวิตตามภูมิศาสตร์ (Biogeography-based Optimization:BBO) เป็นเมตาฮิวริสติกเชิงวิวัฒนาการที่ได้รับแนวคิดมาจากพฤติกรรมการอพยพของสิ่งมีชีวิตบนเกาะต่างๆบทความนี้นำเสนออัลกอริทึม BBO เพื่อใช้สำหรับแก้ปัญหาการจัดสมดุลที่มีหลายวัตถุประสงค์บนสายการประกอบแบบขนานผลิตภัณฑ์ผสม โดยมีวัตถุประสงค์จำนวนทั้งสิ้น 4 วัตถุประสงค์ที่จะถูกทำให้เหมาะสมที่สุดไปพร้อมๆ กัน ได้แก่จำนวนสถานีงานน้อยที่สุด จำนวนสถานีน้อยที่สุด ความสมดุลของภาระงานระหว่างสถานีงานสูงที่สุด และความสัมพันธ์ของงานสูงที่สุด ผลจากการทดลองแสดงให้เห็นอย่างชัดเจนว่า BBO มีสมรรถนะในการแก้ปัญหาที่สูงกว่าอัลกอริทึมเชิงพันธุกรรมแบบการจัดลำดับที่ไม่ถูกครอบงำ II (Non-dominated Sorting Genetic Algorithm II: NSGA-II) ซึ่งเป็นอีกอัลกอริทึมหนึ่งที่เป็นที่นิยม ทั้งในด้านการลู่เข้าสู่กลุ่มคำตอบที่เหมาะสมที่สุดแบบพาเรโต การกระจายตัวของกลุ่มคำตอบ อัตราส่วนของคำตอบที่ไม่ถูกครอบงำและเวลาที่ใช้ในการคำนวณหาคำตอบคำสำคัญ: สายการประกอบแบบขนานผลิตภัณฑ์ผสม การจัดสมดุลหลายวัตถุประสงค์การหาค่าที่เหมาะสมที่สุด แบบการกระจายตัวของสิ่งมีชีวิตตามภูมิศาสตร์AbstractBiogeography-based Optimization (BBO) is an evolutionary metaheuristic inspired by migratory behavior of species among islands. This article presents a BBO algorithm for solving multi-objective mixed-model parallel assembly line balancing problem where four objectives are optimized simultaneously; i.e. to minimize the number of workstations, to minimize the number of stations, a maximization of workload balancing between workstations, and placing an emphasis on maximizing work relatedness. The results from experiments clearly show that BBO promises better performance than does Non-dominated Sorting Genetic Algorithm II (NSGA-II), which indicates another well-known algorithm, in terms of convergence to the Pareto-optimal set, spread of solutions, ratio of non-dominated solutions, and computation time to solution.Keywords: Mixed-model Parallel Assembly Lines, Multi-objective Line Balancing, Biogeography-based Optimizatio

การจัดลำดับการผลิตรถยนต์แบบหลายวัตถุประสงค์บนสายการประกอบผลิตภัณฑ์ผสมแบบสองด้าน

การจัดลำดับการผลิตรถยนต์บนสายการประกอบแบบสองด้านมีความสำคัญอย่างยิ่งสำหรับใช้ในการแก้ปัญหาสายการประกอบที่มีหลายผลิตภัณฑ์ให้เกิดประสิทธิภาพสูงสุด ซึ่งปัญหาชนิดนี้มีความยุ่งยากและสลับซับซ้อน เนื่องจากเป็นปัญหาแบบ Non-deterministic Polynomial Hard: NP-Hard โดยปัญหาการจัดลำดับการผลิตรถยนต์แบบผลิตภัณฑ์ผสมบนสายการประกอบแบบสองด้านนี้ ได้พิจารณาฟังก์ชันวัตถุประสงค์ 3 ฟังก์ชันในงานวิจัยคือ ปริมาณงานที่ทำไม่เสร็จน้อยที่สุดจำนวนรถยนต์ที่ละเมิดรวมน้อยที่สุด และจำนวนครั้งการเปลี่ยนแปลงสีน้อยที่สุด และนำเสนออัลกอริทึมการบรรจวบแบบขยาย (Combinatorial Optimization with Coincidence Expand: COIN-E) ซึ่งเป็นอัลกอริทึมที่ประยุกต์มาจาก COIN มาใช้ในการแก้ปัญหา โดยทำการเปรียบเทียบกับอัลกอริทึมที่ยอมรับในการแก้ปัญหาการจัดลำดับการผลิต ได้แก่ NSGA-II, DPSO, BBO และ COIN ผลจากการเปรียบเทียบพบว่า COIN-E มีประสิทธิภาพด้านการลู่เข้าสู่กลุ่มคำตอบ ด้านการกระจายกลุ่มคำตอบและด้านอัตราส่วนของจำนวนกลุ่มคำตอบที่ค้นพบเทียบกับกลุ่มคำตอบที่แท้จริงเท่ากับ 91.85, 51.08 และ 57.48 ตามลำดับ ซึ่งจากตัวชี้วัดสมรรถนะของทั้ง 3 ชนิดจะพบว่า COIN-E มีประสิทธิภาพในการใช้การแก้ปัญหาได้ดีกว่า NSGAII, DPSO, BBO และ COINคำสำคัญ: อัลกอริทึมการบรรจวบแบบขยาย การจัดลำดับการผลิตรถยนต์บนสายการประกอบ ผลิตภัณฑ์ผสมแบบสองด้านCar Sequencing on two-sided assembly line is an important problem in an automotive industry. Researchers and practitioners have attempted several approaches to solve this problem aiming at maximum production efficiency. The problem is considered as an “NP-Hard problem”. In this paper, three objective functions are considered including 1) minimizing utility work, 2) reducing the number of violation and 3) decreasing the number of color changes. The expansion of Combinatorial Optimization with Coincidence (COIN-E) algorithm is developed from its original version (i.e. COIN). Several well-known algorithms are compared in solving this problem including Non-dominated Sorting Genetic Algorithms (NSGA-II), Discrete Particle Swarm Optimization (DPSO), Biogeography-based Optimization (BBO) and (COIN). The experimental results indicate that COIN-E is efficient and it obtains the values of convergence = 91.85%, spread = 51.08% and ratio = 57.48%, which are significantly superior to NSGA-II, DPSO, BBO and COIN.Keywords: Expanded Combinatorial Optimization with Coincidence, Car Sequencing, Mixed-model Two-sided Assembly Line

Energy Efficient Policies, Scheduling, and Design for Sustainable Manufacturing Systems

Climate mitigation, more stringent regulations, rising energy costs, and sustainable manufacturing are pushing researchers to focus on energy efficiency, energy flexibility, and implementation of renewable energy sources in manufacturing systems. This thesis aims to analyze the main works proposed regarding these hot topics, and to fill the gaps in the literature. First, a detailed literature review is proposed. Works regarding energy efficiency in different manufacturing levels, in the assembly line, energy saving policies, and the implementation of renewable energy sources are analyzed. Then, trying to fill the gaps in the literature, different topics are analyzed more in depth. In the single machine context, a mathematical model aiming to align the manufacturing power required to a renewable energy supply in order to obtain the maximum profit is developed. The model is applied to a single work center powered by the electric grid and by a photovoltaic system; afterwards, energy storage is also added to the power system. Analyzing the job shop context, switch off policies implementing workload approach and scheduling considering variable speed of the machines and power constraints are proposed. The direct and indirect workloads of the machines are considered to support the switch on/off decisions. A simulation model is developed to test the proposed policies compared to others presented in the literature. Regarding the job shop scheduling, a fixed and variable power constraints are considered, assuming the minimization of the makespan as the objective function. Studying the factory level, a mathematical model to design a flow line considering the possibility of using switch-off policies is developed. The design model for production lines includes a targeted imbalance among the workstations to allow for defined idle time. Finally, the main findings, results, and the future directions and challenges are presented

Solving no-wait two-stage flexible flow shop scheduling problem with unrelated parallel machines and rework time by the adjusted discrete Multi Objective Invasive Weed Optimization and fuzzy dominance approach

Purpose: Adjusted discrete Multi-Objective Invasive Weed Optimization (DMOIWO) algorithm, which uses fuzzy dominant approach for ordering, has been proposed to solve No-wait two-stage flexible flow shop scheduling problem. Design/methodology/approach: No-wait two-stage flexible flow shop scheduling problem by considering sequence-dependent setup times and probable rework in both stations, different ready times for all jobs and rework times for both stations as well as unrelated parallel machines with regards to the simultaneous minimization of maximum job completion time and average latency functions have been investigated in a multi-objective manner. In this study, the parameter setting has been carried out using Taguchi Method based on the quality indicator for beater performance of the algorithm. Findings: The results of this algorithm have been compared with those of conventional, multi-objective algorithms to show the better performance of the proposed algorithm. The results clearly indicated the greater performance of the proposed algorithm. Originality/value: This study provides an efficient method for solving multi objective no-wait two-stage flexible flow shop scheduling problem by considering sequence-dependent setup times, probable rework in both stations, different ready times for all jobs, rework times for both stations and unrelated parallel machines which are the real constraints.Peer Reviewe

Optimised configuration of sensing elements for control and fault tolerance applied to an electro-magnetic suspension system

New technological advances and the requirements to increasingly abide by new safety laws in engineering design projects highly affects industrial products in areas such as automotive, aerospace and railway industries. The necessity arises to design reduced-cost hi-tech products with minimal complexity, optimal performance, effective parameter robustness properties, and high reliability with fault tolerance. In this context the control system design plays an important role and the impact is crucial relative to the level of cost efficiency of a product. Measurement of required information for the operation of the design control system in any product is a vital issue, and in such cases a number of sensors can be available to select from in order to achieve the desired system properties. However, for a complex engineering system a manual procedure to select the best sensor set subject to the desired system properties can be very complicated, time consuming or even impossible to achieve. This is more evident in the case of large number of sensors and the requirement to comply with optimum performance. The thesis describes a comprehensive study of sensor selection for control and fault tolerance with the particular application of an ElectroMagnetic Levitation system (being an unstable, nonlinear, safety-critical system with non-trivial control performance requirements). The particular aim of the presented work is to identify effective sensor selection frameworks subject to given system properties for controlling (with a level of fault tolerance) the MagLev suspension system. A particular objective of the work is to identify the minimum possible sensors that can be used to cover multiple sensor faults, while maintaining optimum performance with the remaining sensors. The tools employed combine modern control strategies and multiobjective constraint optimisation (for tuning purposes) methods. An important part of the work is the design and construction of a 25kg MagLev suspension to be used for experimental verification of the proposed sensor selection frameworks