Eccentric-load dynamics and oscillation control of industrial cranes transporting heterogeneous loads

Industrial cranes transporting bulky loads are widely used in many engineering applications. However, heterogeneous loads give rise to eccentricity between the mass center and centroid of the load. Natural frequencies of the swing and twisting under eccentric-load mechanisms differ from those under uniform-load configurations. Therefore, load swing and twisting dynamic models that account for eccentricity are required to adequately understand and accurately control such cranes. Although significant work has been directed at the uniform-load dynamics of industrial cranes, little attention has been focused on the eccentric-load dynamics. This article presents a dynamic model of bridge cranes transporting heterogeneous loads. The frequency analyses of double-pendulum swing and twisting for eccentric loads is described. Additionally, a control method is designed using a simplified spherical pendulum with load-twisting dynamics and eccentric-load dynamics. Simulated and experimental results obtained from a small-scale bridge crane transporting a heterogeneous bar verify the utility of the analytical model and validate the effectiveness and robustness of the proposed control method.