Output-feedback control of container cranes: a comparative analysis

Moving a suspended load is a challenging task when strict specifications on the swing-angle and on the transfer-time need to be simultaneously satisfied. Intuitively, minimizing the cycle time and counteracting the load swing are conflicting requirements whose satisfaction requires proper control actions, especially in the presence of uncertainties in the system dynamics. A control scheme presented by the authors, based on second-order sliding modes, has been compared with other existing approaches: 1. the smooth approximation of a first-order sliding-mode controller; 2. an observer/controller scheme based on Lyapunov transformations; and 3. a classical PID controller.