Crane Rig: An Experimental Setup for Developing and Verifying New Control Methods for Marine Crane Operations

This paper will present the derivation of dynamic equations describing the motion of a knuckleboom crane for marine vessels. The dynamics will be derived using Lagrange’s equation, the theory of virtual work and generalized forces. Simulations of the unforced and forced system will be carried out to verify the crane behaviour. The work is part of setting up a crane lab at the Norwegian University of Science and Technology, NTNU. The rig will be used as an experimental setup available for both students and researchers and is expected to create a solid foundation for further work regarding crane control. Examples of its application are research on heave compensation and soft landing. However, before the setup can be finished a dynamical model governing the system must be derived in order to construct simple crane controllers. As part of the modeling a step by step method for describing the crane motions will be presented. Using rotation matrices and moving reference frames the position of each point on the crane will be described in an inertial reference frame. An implementation of the model in Matlab’s Simulink will also be shown, along with some simple simulations verifying system behaviour. The main result will be a state space formulation of the crane dynamics, a Simulink model for anticipating crane behaviour and a discussion of some simple simulation scenarios.