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چکیده
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This paper recognizes thirty-six, potentially optimal robot movement policies, to schedule the movements of a robot in a three-machine flexible cell. The robotic cell produces multi-type parts, in which the robot is used as a material handling system. In this manufacturing cell, the machines have operational flexibility and can be set up for different operations; all parts have three operations. Finding the robot movement policy and sequence of parts to minimize the cycle time (i.e., maximize the throughput) is the aim of this work. It was proved that cycle time calculation, in twelve out of thirty-six policies, are unary NP-complete, and a polynomial time algorithm is introduced that can solve the twenty four left policies. This paper develops the cycle times of all these thirty six robot movements policies, considering waiting times in a flexible three-machine robotic cell with multi-type parts, and introduces a parts sequence under a special condition, in which one of the policies minimizes the cycle time (i.e., maximize throughput). This kind of flexibility differs from other research into robotic cells, wherein 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, was provided for one of the robot movement policies. Furthermore, this mathematical model is also developed for the multi-type part problem.
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