Simultaneous scheduling of machines and automated guided vehicles utilizing heuristic search algorithm

Abstract

Proper scheduling of flexible manufacturing systems is considered a key success for industry. Automated guided vehicles are parts of flexible manufacturing systems and are easy to utilize in production systems. Time is directly related to the production costs of all kind. It is necessary to minimize production costs. Improper scheduling of machines and automated guided vehicles may increase the production time. Simultaneous scheduling of machines and material handling systems has many benefits though they are not challenges free. Scheduling of machines and automated guided vehicles, if considered separately, are NP-Hard problems regardless of being considered together or separately. There are two types of scheduling problems according to the literature. Review of literature show that although offline scheduling of machines and vehicles has been studied in a great detail, lack of studies related to dynamic scheduling of machines and automated guided vehicles is very visible. Therefore, the main focus of this study is simultaneous scheduling of machines and automated guided vehicles. First, a heuristic scheduler is designed, in MATLAB software, to propose solutions for simultaneous scheduling of machines and automated guided vehicles in flexible manufacturing systems. Then, a time frame is applied to the offline test problems from the literature to produce dynamic scheduling problem. The methodology in this study is applied on a sample test problem from previous studies for validation purpose. Furthermore, the new dynamic scheduling was performed by producing time tables for pre-defined time frames. The sample test problems are then mathematically modeled to represent the limitations and constraints of the offline and dynamic scheduling problem.