Mismatched Disturbance Rejection for Overhead Cranes: A Fixed-Time Disturbance Observer-Enhanced Backstepping Approach

This paper proposes a novel motion control framework for overhead crane systems with mismatched disturbances, integrating an advanced disturbance observer with an enhanced backstepping strategy. Initially, the nonlinear crane dynamics are systematically converted into a chain structure through coordinate transformation, facilitating controller synthesis. Subsequently, a fixed-time disturbance observer is developed to estimate and compensate for mismatched perturbations. The closed-loop system's stability is rigorously proved through Lyapunov-based analysis. Finally, simulation results verify the effectiveness of the suggested method.