Discrepancy-based control for positioning of large gantry crane

This paper is concerned with nonlinear control for positioning of large gantry cranes. An important structural dynamics problem of this type of cranes are flexible structural vibrations in the direction of trolley travel. They lead to faster wear of the crane construction and worsen the performance of the crane operation. Since they are mainly caused by movement of the trolley, they can be taken in consideration by redesign of the trolley motion control system. To design an appropriate control law, a generalized error measure, known as the discrepancy, is applied. Utilizing the associated stability with respect to two discrepancies, a nonlinear stabilizing control for large gantry cranes is obtained. The proposed control has been evaluated on a mathematical model and an experimental laboratory crane.