MULTI FACTOR JOB SHOP LAYOUT PROBLEM USING ANT COLONY OPTIMIZATION TECHNIQUE

Abstract

In the present work the facility layout problem (FLP) is being mathematically formulated and solved for a job shop type layout. In a job shop, the interdepartmental material flow is usually large enough and thereby the relative placement of the departments is a very important problem, which if solved properly might result in huge savings in material handling costs and enable greater ease in carrying out the manufacturing operations. There are several important factors that should be considered to solve plant layout problem viz, materials flow, noise, safety, etc. These factors may be categorized as qualitative and quantitative, in nature. The layout problem thus be formulated by considering both qualitative and quantitative factors simultaneously. Qualitative factors are for placing the departments that utilize common material, personnel, or utilities adjacent to one another, while separating departments for reasons of safety, noise, or cleanliness. Quantitative factors primarily involve the minimization of distance of the flow of materials between departments. Except this, other factors considered are area shape factor (ASF), shape ratio factor (SRF), area utilization factor (ALTF), and aisles consideration. In this dissertation the Ant Colony Optimization (ACO) technique is used for solving the multi factors job shop layout problem for both equal area and unequal area facilities. ACO is the most successful and widely recognized algorithm technique to solve combinatorial optimization problems by using principles of communicative behavior occurring in ant colonies. It is an evolutionary technique where several generations of artificial ants search for good solutions. Every ant of a generation builds up a solution step-by-step, thereby going through several decisions until a solution is found. Ants that found a good solution mark their paths through the decision space by putting some amount of pheromone on the edge of the path. The following ants of next generation are attracted by the pheromone to search in the solution space near good solution.