Modeling and nonlinear coordination control for an underactuated dual overhead crane system

The past decades have seen increasing demands for the transportation capability of overhead cranes. In practice, as the cargoes grow larger and heavier, they often need to be cooperatively delivered by two cranes. However, even with wide application, the study of such dual overhead crane system (DOCS) still fails to receive enough attention from researchers. Until now, few results have been published for DOCS, and most of them present no rigorous analysis for the overall system dynamics. Motivated to solve these issues, a precise model is first set up for DOCS by utilizing the Lagrangian modeling method. Based on that, a nonlinear control strategy is further proposed, which elaborately considers the coordination between cranes. By utilizing Lyapunov techniques and LaSalle's invariance theorem, the desired equilibrium point of the closed-loop system is proved to be asymptotically stable, without tuning to linearization or approximations. Finally, feasibility and efficiency of the proposed method are further validated by convincing hardware experimental results.