This paper addresses the trade-off between time- and energy-efficiency for
the problem of loading and unloading a ship. Container height constraints and
energy consumption and regeneration are dealt with. We build upon a previous
work that introduced a coordinate system suitable to deal with container
avoidance constraints and incorporate the energy related modeling. In addition
to changing the coordinate system, standard epigraph reformulations result in
an optimal control problem with improved numerical properties. The trade-off is
dealt with through the use of weighting of the total time and energy
consumption in the cost function. An illustrative example is provided,
demonstrating that the energy consumption can be substantially reduced while
retaining approximately the same loading time.Comment: Paper accepted for presentation at 22nd IFAC World Congres