We address the problem of scheduling robots' moves in a robotic cell that is used by a Dallas-area semiconductor equipment manufacturer. The cell has parallel machines, multiple robots, and Euclidean travel times. We describe a plan of operation that allows the robots to operate concurrently, efficiently, and with no risk of colliding. We propose a set of sequences of robot moves, analytically determine this scheme's throughput, and determine problem instances for which it is optimal. Through simulation, we demonstrate that our scheme is superior to the heuristic dispatching rule currently in use by the manufacturer.
Note to Practitioners-Efficient scheduling of a robotic cell can greatly increase productivity and revenue for manufacturers in many different industries. This increase becomes more pronounced for larger cells that employ multiple robots and parallel machines at various production stages. This paper describes a schedule of robotic actions that is optimal under a common set of conditions for such large cells, in addition to many other types of cells. When this set of conditions does not hold, even though optimality could not be proven, this schedule is shown to be superior to one currently in use by some semiconductor manufacturers. We also present a scheme that allows the robots to operate concurrently, efficiently, and with no risk of colliding. Additionally, an approximation to the improvement in revenues realized by using this schedule is provided.