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

Shipboard boom cranes require accurate positioning and load-swing suppression despite underactuation and disturbance coupling. This study investigates a disturbance-estimation-driven time-varying bandwidth active disturbance rejection control (TVB-ADRC) framework. A nominal differential-flatness mapping, a fourth-order derivative observer, and a leakage disturbance observer are combined with bounded, smoothed observer/controller bandwidth scheduling. Conditional convergence is established for an ideal flat-output error model, together with an ultimate error bound for a bounded, nonvanishing residual. This analysis does not constitute an unconditional stability proof for the complete nonlinear proportional-derivative-augmented implementation. Six simulation cases are compared using explicitly defined finite-window performance indices. The complete TVB-ADRC configuration achieves faster actuated-state regulation in several cases than the fixed-bandwidth ADRC and active-swing-control configurations, although it does not minimize every swing metric. A laboratory positioning experiment uses prescribed sinusoidal excitation to represent periodic wave disturbance and reports a peak swing of 2.79 degrees. This laboratory excitation is distinct from the stochastic wave signal used in simulation. The laboratory input-level interpretation uses an inferred mass-moment estimate rather than an independently measured value, and the comparisons do not isolate the independent contribution of bandwidth scheduling.