Modeling, Simulation and Control of Motion Compensated Gangway in Offshore Operations
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This thesis is based on the idea to develop the integrated model of offshore gangway model including multi-body dynamics model and hydraulic system model with bond-graph method in 20-sim. And based on that model, active motion compensation control approach will developed in order to compensate the ship motion during gangway operation and further more a parallel position and force control method will be proposed to make the gangway tip maintain constant contact force with windmill platform as well as compensate ship motion during transferring process. In order to get reasonable data for modeling, simulation and control of gangway operation, an offshore gangway was designed first based on the relative rules and existing products from Uptime Company. Then multi-body dynamic model is developed with IC-field based on the Lagrangian Hamiltonian equation of gangway. After that, the hydraulic system for gangway was designed and verified with simulation. Based on this developed model, the control algorithm for active motion control and parallel position and force control were proposed. The active heave compensation control is based on the kinematics solving method to mapping the gangway tip trajectory to actuator trajectory and then control the actuator by position and velocity feedback with velocity feedforward controller. And the parallel position and force control was based on the inner positon loop outer force control and the idea is to adjust the desired gangway tip trajectory by the force modulator to achieve the desired contact force.