Robot Movements in a cyclic multiple-part type Three-machine Flexible Robotic Cell problem

Abstract

Abstract This paper recognizes thirty-six potentially optimal robot movement policies to schedule, movements of a robot in a three-machine flexible cell. The robotic cell produces multi-type parts in which the robot is used as material handling system. In this manufacturing cell the machines have operational flexibility and can be set up for different operations, and all parts have three operations. Finding the robot movement policy and sequence of parts to minimize cycle time (i.e.; maximize the throughput) is the aim of this work. It was proved that cycle time calculation in twelve policies out of thirty-six policies, are unary NP-complete, and a polynomial time algorithms is introduced that can solve the twenty-four left policies. This paper develops cycle times of all these thirty six robot movements policies where considering waiting times in a flexible three machine robotic cell with multi-type parts, and introduces parts sequence in a special condition that one of the policies minimize the cycle time (i.e. maximize throughput). This kind of flexibility is differing from the other researches in robotic cells that a machine can process different operations, moreover we consider cells with multiple part types which is more realistic than other developed models. Finally a new mathematical model based on Petri nets provided, for one of robot movement policies. Further this mathematical model is developed for the multi-type part problem.