Research On Principle And Simulation Of Offshore Knuckle Boom Crane Active Heave Compensation

The traditional offshore knuckle crane wave compensation system with the only ability to reduce the impact to crane operation caused by the ship's heaving motion,is only suitable for shallow water or low level sea state.Offshore engineering ships are of heaving motion not only,also with the larger rolling,pitching and bow motion,in the deep sea or high level sea state,thus developing the crane wave compensation control system with the ability to compensate the hull six degrees of freedom movement,not only can effectively improve the offshore knuckle crane operation performance,as well as extend the operation area of the offshore engineering ships,increase the operation window and reduce the cost.In the research of this paper,a motion model of offshore knuckle crane is established,via the kinematics theory of manipulator,because the mechanical structure of the offshore knuckle crane is similar to that of the three-degree-of-freedom series manipulator.Through the analysis of the relationships between different coordinate system,the establishment of a math relationship between the each offshore knuckle crane joint angular velocity and the hull motion velocity has been done via the homogeneous coordinate transformation matrix.Designing an algorithm for the AHCS,that could keep the jib of the offshore knuckle crane position in the fixed reference frame while the ship moving with larger roll,pitch and yaw on the sea surface.Setting such models of the ship motion in level 2,4,6 sea state,the offshore knuckle crane movement and the AHSC model,using the AMESim software.Validating the heave compensation algorithm's feasibility and dependability and that the operation of the offshore knuckle crane under the AHSC control not affected by the ship movement,after analyzing the offshore knuckle crane jib motion curve in different sea state.