New data generation and solution techniques for the Sequential Ordering Problem with Time Windows

The motivation for this thesis resulted from a study of semi-automated rail mounted gantry cranes at an Australian seaport container terminal. The Sequential Ordering Problem with Time Windows (SOP-TW) can arise as a subproblem of these crane operations. The SOP-TW corresponds to the task of scheduling a single crane to move a set of containers, where each container has: a fixed pick-up location; a fixed drop-off location; a time window during which the container must be picked up and moved to its destination; and some container movements must be performed before other container movements. A crane schedule is a list showing the pick-up time of each container. If time permits, a crane is allowed to sit idle between moving containers; however, once a container is collected from its pick-up location it must be delivered to its drop-off location. Consequently, the order of the container movements and a path for the crane can be determined from the schedule. For this application the aim is to minimise the total time the crane spends moving while not carrying a container, that is, the total time moving from the drop-off location of one container movement to the pick-up location of the next container movement. The SOP-TW can be viewed in more general terms as the problem of scheduling n jobs on a single machine with sequence-dependent setup times, generalised precedence constraints between some pairs of jobs and start time windows, where the objective is to minimise the sum of all setup times; the jobs are container moves and the setup time is the time needed for a crane to move from the drop-off location for one job to the pick-up location for the next.