Dynamics of a Ship-Mounted Two-DoF Manipulator Case: Effect of Sea State to the Manipulator Joint Torque

In this paper, a dynamic model of a ship-mounted two-DoF manipulator subject to the motions of ship itself imparted by unidirectional long-crested random sea waves in heading sea is proposed. Equations of motions are derived using the recursive Newton-Euler (RNE) equation. All ship motions namely surge, heave, sway, roll, pitch and yaw motions are considered as the disturbances in exciting the mounted manipulator. Simulation results reveal that the torque of every joint of the manipulator increases when the sea state increases nonlinearly and the necessity for robust control methods for the suppression is absolutely required.