Currently, the speed at which constructing materials can be transferred from a transport ship to an offshore construction site is limited by sea conditions. Rough sea conditions cause the payload to sway making load transfer difficult and time-consuming. The objective of this research is to develop a real-time, command compensating control for reducing sea state induced payload sway for shipboard robotic cranes. The future use of this control strategy will be to facilitate faster 'ship-to-offshore construction site' payload transfer in rough sea conditions. In this study, only the sea-induced rotational motion of the ship is considered, since it is assumed that a station-keeping control maintains a constant position of the ship. This rotational motion is modelled using pitch-yaw-roll Euler angles. The shipboard robotic crane is modelled as a spherical pendulum attached to a three-degree-of-freedom manipulator. The three degrees-of-freedom are azimuth (rotation about an axis normal to the ship's deck), elevation (rotation about an axis parallel with the ship's deck, also referred to as luffing), and lift-line length. An inverse kinematics based approach and a sliding mode control strategy are explored. Both approaches use the azimuth and the elevation capability of the crane manipulator to maintain a horizontal position of the suspended load to reduce sea-induced payload sway.
Anti-sway control of suspended loads on shipboard robotic cranes
Anti-Schwankungssteuerung von Lasten an Roboter-Schiffskranen
2003
6 Seiten, 12 Bilder, 5 Quellen
Aufsatz (Konferenz)
Englisch
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