Redundant driving force optimization of parallel posture adjustment mechanism for ship block docking

Abstract

Block method of hull construction can significantly reduce dock occupation time and enhance the accuracy of shipbuilding through coordinated multi-axis posture adjustment mechanisms. To ensure the reliability and precision of ship block assembly docking, this paper conducts a detailed study of the mechanical properties and motion accuracy of the parallel mechanism during posture adjustment and docking. Redundant actuation allows the parallel mechanism to optimize the distribution of excess actuation forces while following a predetermined trajectory. A dynamic model of the parallel mechanism is established using the screw theory and the principle of virtual work. To address the issue of force overload in the driving mechanism that arises from the traditional minimum norm method under fully redundant actuation conditions, this paper proposes an optimal distribution method for redundant actuation force based on Red-billed Blue Magpie Optimization (RBMO). Finally, the dynamic performance and docking accuracy of the posture adjustment mechanism are analyzed through the simulation and docking experiments of the redundant actuation posture adjustment mechanism and its non-redundant counterpart. The experimental results show that compared with the non-redundant actuation, the docking accuracy of ship block is improved by 71.6% after the optimization of the redundant actuation force and the maximum position error is reduced by 65.2%.