Cyclic Scheduling Problem of a Flexible Robotic Cell with a Self-Buffered Robot

Extensive usage of automatic processing in industries has created Flexible Manufacturing Systems (FMSs). In a robotic FMS there are some Computer Numerical Control (CNC) machines for processing the parts, there is an input buffer for keeping unprocessed parts and an output buffer for finished parts, and at least one robot for transporting the parts in the system and loading/unloading the machines, and a central computer controlling the system. Such systems provide advantage in flexibility and standardization in production systems and they have been employed in recent years in order to keep up with the market competition. In order to use the system efficiently the system should be scheduled carefully. In this content, the order of the robot actions such as robot movements and loading/unloading activities should be determined for maximizing the system’s efficiency. When the system repeats a cycle in its run maximizing the efficiency is equivalent to minimizing the cycle time. This thesis considers a robotic FMS in which there is a single self-buffered robot which has the ability to carry more than one part at a time in an inline robotic cell where parts produced are identical. The system repeats a cycle in its long run. The problem is to determine the schedule of the system for minimizing the cycle time. A Mixed Integer Programming (MIP) model of the problem is developed to find the optimal solutions. Since the developed MIP model could not solve the large size problems a Simulated Annealing meta-heuristic algorithm is developed to solve those problems. Performances of the proposed methods and considered robotic FMS cells are evaluated on several numerical instances. Numerically, it has been shown that the performances of the proposed methods are satisfactory and the performance of the robotic FMS increases significantly by using a self-buffered robot up to some robot buffer capacity. After a point more robot buffer capacity becomes useless. Keywords: Flexible Manufacturing Systems, Cyclic Robotic FMS Scheduling, Self-Buffered Robot.