A priority rule-based constructive heuristic and an improvement method for balancing assembly lines with parallel multi-manned workstations

Abstract

Assembly lines of big-size products such as buses, trucks and helicopters are very different from the lines studied in the literature. These products' manufacturing processes have a lot of tasks most of which have long task times. Since traditional assembly line models including only one worker in each station (i.e. simple assembly lines) or at most two workers (two-sided assembly lines) may not be suitable for manufacturing these type of products, they need much larger shop floor for a number of stations and long product flow times. In this study, an assembly line balancing problem (ALBP) with parallel multi-manned stations is considered. Following the problem definition, a mixed integer programming formulation is developed. A detailed study of priority rules for simple ALBPs is also presented, and a new efficient constructive heuristic algorithm based on priority rules is proposed. In order to improve solutions found by the constructive heuristic, a genetic algorithm-based solution procedure is also presented. Benchmark instances in the literature are solved by using the proposed mathematical programming formulation. It has been seen that only some of the small-size instances can be solved optimally by this way. So the efficiency of the proposed heuristic method is verified in smallsize instances whose optimal solutions are found. For medium-and big-size instances, heuristics' results and CPU times are demonstrated. A comparative evaluation with a branch and bound algorithm that can be found in the literature is also carried out, and results are presented.

Balancing of assembly lines with collaborative robots

“…In this problem, tasks and workers have to be allocated among the stations and tasks are explicitly (and exclusively) assigned to the workers. The minimization of the number of workers is pursued by Roshani et al (2013) and Kellegöz and Toklu (2015). Fattahi et al (2011) minimize the number of workers as a primary objective and the number of stations as a secondary objective.…”

Balancing Lexicographic Multi-Objective Assembly Lines with Multi-Manned Stations

“…The set of Constraints (14) and (15) models the second goal. Constraint (14) assigns proper value to variable . Constraint (15) with deviational variables is the goal constraint of the total number of workers used in the line.…”

“…For building a solution based on priority values, a restricted version of the constructive heuristic proposed by Kellegöz and Toklu [14] is used. The procedure of building solution used in this study is given in Algorithm 2.…”

“…The list which includes best solution's stations which have more than one worker (multi-manned) is used in solution restriction process. This list includes stations based on minimum worker load-related strategy proposed by Kellegöz and Toklu [14]. According to this strategy, stations in are decreasingly ordered according to their minimum worker's load.…”

“…They solved several test instances to illustrate their methods' performance. For solving MALBP with minimizing the total number of workers, Kellegöz and Toklu [14] recently proposed a new MIP formulation, a constructive heuristic based on priority rules and an improvement heuristic based on genetic algorithms. By using benchmark instances, they illustrated the performance of methods they proposed.…”