Small ship-mounted telescopic cranes are used to load and unload cargo of limited size and weight. The wave-induced motions of the host ship can cause large pendulations of the hoisted payload, thereby bringing the transfer operations to a complete stop. The small size of such a crane, combined with its limited maneuverability, compared to the relatively larger motion of the host ship, poses a serious control challenge. In this work, a nonlinear control system is introduced, which reduces pendulations on these cranes to the point where the transfer operations do not pose a safety hazard. The delayed position-feedback technique is used to reduce payload pendulations. The presented control system uses the slewing, luffing, and telescopic degrees of freedom of the crane to drive the horizontal position of the boom tip. Saturation problems arising from the limited speed and motion of the crane actuators are another issue addressed by this control technique. To demonstrate the performance of the developed control system, numerical simulations are performed on a nonlinear three-dimensional mathematical model of the telescopic crane mounted on the USNS WATERS. The crane has four degrees of freedom: hoisting, slewing, luffing, and extension of the telescopic boom. In addition to its limited maneuverability, nonlinear hydraulic actuators are used for the luffing and extension degrees of freedom. The actions of the actuators are dependent on the direction of the motion.
Pendulation reduction on small ship-mounted telescopic cranes
2003
6 Seiten, 15 Quellen
Conference paper
English
Pendulation Reduction on Small Ship-Mounted Telescopic Cranes
British Library Conference Proceedings | 2003
|Cargo Pendulation Reduction on Ship-Mounted Cranes via Boom-Luff and Slew Angles Actuation
British Library Conference Proceedings | 2000
|