Nonlinear antiswing control for offshore boom cranes subject to ship roll and heave disturbances

Abstract

This paper studies the automatic control problem of offshore boom cranes, which often work in harsh sea conditions. First, some novel composite signals are elaborately designed, which consist of both payload swing information and boom/rope positioning error. By utilizing the composite signals as feedback, the constructed nonlinear controller manages to react more efficiently to the uncertainties/disturbances, and hence achieves better overall control performance and stronger robustness. Particularly, the control gains are updated in real time according to the system dynamic response, so as to further improve the efficiency of the designed controller. Through rigorous mathematical deductions, it is proved that the system state variables converge to the desired values asymptotically. The conducted experiments show that the proposed method can accurately position the payload, while simultaneously suppressing its swing motion.