Enhanced-coupling nonlinear controller design for load swing suppression in three-dimensional overhead cranes with double-pendulum effect

To date, most control strategies have been designed for the two-dimensional and three-dimensional overhead crane systems with the single pendulum effect. In fact, three-dimensional overhead crane systems often exhibit the double-pendulum effect in practical applications, which is more controlled than the general single-pendulum crane, and also makes the controller design more challenging. This paper proposes a new nonlinear control strategy that enhances the coupling between the trolley speed and the swing angle components. Specifically, we devise a new energy-like function by introducing two generalized signals that can reflect the trolley speed and the hook and load swing angle components. This strategy greatly improves the effectiveness of the transient control process. Meanwhile, the asymptotic stability of the closed-loop system is not only guaranteed, but also the desired position of the trolley and swing angle suppression are achieved using the control strategy.