Solving Two-sided Assembly Line Balancing Problem With Multiple Constraints

Two-sided assembly lines are widely applied to produce large-sized products,such as cars,trucks,loading machinery.Compared to traditional one-sided assembly line,the two-sided assembly lines can provide the following advantages: shorter line length,higher tools and fixtures utilization,less material handling and space costs,higher labor productivity.The elementary constraints of two-sided assembly line balancing problem(TALBP)include operating direction constraints,precedence constraints,cycle time constraints and occurrence constraints.This paper studies multiply constraints including the positional constraints,the zoning constraints and the synchronism constraints which must be imposed on the practical two-sided assembly lines.The main work is listed as follows:First,a mathematical model is built to describe the assembly line balancing problem according to the characteristics of two-sided assembly line balancing.A novel hybrid gravitational search algorithm(HGSA)is also proposed to solve the TALBP with zoning constraints effectively.In the HGSA,variable neighborhood search(VNS)is integrated into GSA so as to enhance the local search ability of the standard gravitational search algorithm(GSA).What's more,a new decoding scheme based on task selection rule and side selection rule is proposed to avoid the sequence-dependent finish time of tasks and balance the workload between workstations.The performance of the proposed decoding scheme is demonstrated by comparison with other four decoding schemes through analysis of variance.The experiment results compared with the ones computed by other literature validate the effectiveness of the proposed algorithm.Secondly,the HGSA is applied to solve the two-sided assembly line balancing problem with multiply constraints(TALBP-MC)including positional constraints,zoning constraints and synchronism constraints.A new decoding scheme is designed to satisfy the multiply constraints.Considering that one task may be involved in more than one constraint,the directions and constraints of all tasks are adjusted uniformly and hence the decoding process is largely simplified.The computational results demonstrate that the HGSA can solve the TALBP-MC effectively.At last,the HGSA is applied to solve two-sided assembly line balancing problem with multiply constraints with sequence-dependent setup times.A mathematical model is firstly built.And a decoding process is proposed to solve the problem.The results computed by HGSA are compared with GSA and the current best results without sequence-dependent setup times,the comparison results shows that the HGSA can solve the problem effectively.