Stabilization of Load’s Position in Offshore Cranes

Abstract

It is often desirable to keep the load of an offshore crane in a fixed point in space despite the movement of its base. To solve the problem of stabilizing the load’s position, the authors have proposed application of the hoisting winch drum’s drive and an auxiliary system. The auxiliary system enables independent moving of a selected point of the hoisting rope in two perpendicular planes. In this paper, two methods for determining the drive functions of the auxiliary system and the hoisting winch’s drum ensuring stabilization of an offshore crane’s load are presented. Both methods are based on a simplified model of a crane and allow compensation for a pseudo-harmonic base motion. In order to take into account the deviations of base motion from the assumed and avoid over simplifications, the second, more sophisticated model is developed. This model is proposed to be applied in closed-loop control systems with a PID controller. Results of sample numerical simulations are included that proved useful information about the developed methods and models for stabilization of an offshore crane’s load.

Robust controls for ship-mounted container cranes with viscoelastic foundation and flexible hoisting cable

“…Numerous theoretical and application studies have been conducted on the dynamics and control of cranes. 1–22 However, studies that focus on ship-mounted cranes are fewer than those that focus on-shore cranes. 1–5 Many articles have also been reported on boom cranes mounted on vessels.…”

“…Resonances and sub-harmonic motions were also investigated using the technique of multiple scales. Maczynski and Wojciech 13 proposed an auxiliary mechanical system to stabilize the position of the load in ship-mounted boom cranes. Kimiaghalam et al 14 constructed a feed-forward controller for a shipboard boom crane using the gain-scheduling technique.…”

Application of the Rigid Finite Element Method for Modelling an Offshore Pedestal Crane

“…Reduction of load swinging via proper steering of crane slew and boom hoist was considered in [8,9]. A different concept of stabilizing the load position of an offshore crane was the subject of [10]. Two different algorithms of control that minimizes load waving were discussed in [11].…”

Nonlinear coordination control of offshore boom cranes with bounded control inputs

“…Specifically, compared with land-fixed cranes, much fewer results have been published for offshore cranes. [17][18][19][20][21][22] An intuitive idea to improve the performance of offshore cranes is to change their mechanical structures. For example, the well-known Maryland rigging system 23 is intensively employed to attenuate the payload swing.…”