With the share of offshore wind energy in the global power mix continually rising, the operation and maintenance (O&M) demands for marine structures have become ever more stringent. To enhance both safety and efficiency of O&M operation, this paper presents the design, modelling and control of a ship-borne wave-compensation system based on a Stewart manipulator. A lumped-mass, kinematic-dynamic model of the parallel manipulator is first derived, in which the structure is decomposed into interconnected submodules whose masses are concentrated at their centroids. At each time instant, the desired extension of each actuator is computed from the inverse kinematics. Given the measured system state, a position-tracking controller was implemented to drive the electric cylinders so as to maintain the upper deck stationary in the presence of incoming waves disturbance. Time-domain simulations demonstrate that the active compensation system exhibits satisfactory wave-compensation performance, reducing residual motion error within acceptable tolerances.
Fu et al. (Sun,) studied this question.