Disturbance-Estimation-Driven Time-Varying Bandwidth Active Disturbance Rejection Control for Shipboard Boom Cranes

Shipboard boom cranes must achieve accurate positioning and suppress load oscillations under wave disturbances despite underactuation and nonlinear coupling. This study proposes a disturbance-estimation-driven time-varying bandwidth active disturbance rejection control (TVB-ADRC) framework. Differential flatness is used to formulate a flat-output tracking problem. A derivative observer reconstructs the output state chain, while an independent disturbance observer provides estimates for compensation and bandwidth scheduling. The observer and controller bandwidths adapt to estimated disturbance intensity. A Lyapunov and state-transition analysis establishes asymptotic convergence of the derivative-observer and flat-output tracking errors under bounded, sufficiently slowly varying bandwidths and an asymptotically vanishing disturbance-compensation residual. Comparative simulations examine random waves, combined wave and impulse disturbances, reference changes, load variations, and initial swing deviations. The results indicate an improved balance among positioning, swing suppression, and control effort relative to fixed-bandwidth flatness-based ADRC and active swing control. In the reported hardware experiment, TVB-ADRC limits the peak swing to 2.79 degrees and the swing settling time to 4.16 s. These results support its application to the tested positioning and anti-swing tasks, while the theoretical convergence conclusion remains conditional on the stated assumptions.