A New Antiswing Control Method for Underactuated Cranes With Unmodeled Uncertainties: Theoretical Design and Hardware Experiments

In practice, cranes often suffer from various unfavorable factors, such as extraneous disturbances and friction. Moreover, there are always some unmodeled uncertainties that are difficult to be described with accurate mathematical expressions. These practical problems bring much challenge for control development and may induce instability unless suitably tackled. In this paper, in terms of the aforementioned problems, we suggest a new antiswing control scheme for underactuated gantry cranes. In particular, we construct an elaborate manifold and then present a nonlinear control law that keeps the system state always staying on the manifold. Without any approximation operations to the original nonlinear model, it is rigorously proven that the state variables converge to the equilibrium point when they are on the manifold. The developed control system is robust due to the specific control structure. Hardware experiments are included, which suggest that the proposed scheme achieves superior control performance over existing methods, and it shows strong robustness to unmodeled uncertainties and external disturbances.