Abstract
The purpose of this study is to develop a spreader for loading and unloading a container in unstable environments of the open sea. In order to overcome the swing of a spreader due to waves and wind, an auto positioning spreader was proposed with three degrees of freedom (DOF). By constraining a spreader on the top of a container, DOFs for the auto positioning were reduced from six to three in three dimensional spaces and therefore the auto positioning spreader was easily implemented. Virtual force algorithm employing six proximity sensors was proposed to control the remaining three DOFs of the spreader system. A RecurDyn dynamic model and a one to twenty scale model were developed and the effectiveness of the new spreader system introduced in this paper was verified in both numerical simulation and downscale model test.
