Feedback control for suppression of crane payload oscillation using on-off commands

When cranes move objects in a workspace, the payload frequently swings with large amplitude motion. Open loop methods have addressed this problem, but are not effective for disturbances. Closed loop methods have also been used, but require variable speed driving motors. This paper develops a feedback based method for controlling single speed motors to cancel the measured payload oscillations by intelligently timing the ensuing on and off motor commands. The oscillation suppression scheme is experimentally verified on a bridge crane