An Algorithm for Scheduling a No-Wait Robotic Production System with Multi-Type Parts

An exact algorithm is proposed to solve a scheduling problem of a robotic production system in which multi-type parts are processed and parts are not allowed to wait on the machines. Finding an optimal schedule in such a production system is equivalent to finding two types of correlative sequences: parts input sequence and robot moves sequence. We show that the entering times of parts are the decision variables of the problem. We formulate our problem using the notion of prohibited intervals and solve it by enumerating intervals for linear functions of the decision variables, which is accomplished with a branch and bound procedure. Computational results on randomly generated test instances indicate that the algorithm is effective.