Anti-Swing Control for Double-Pendulum Overhead Cranes: From Underactuated to FAS Configuration

The purpose of crane control is to transport the payload precisely to the desired destination while minimizing rope swing. Aiming at such an objective, this work thoroughly analyzes the dynamic system of the overhead crane with double-pendulum effects. The findings indicate that, despite being physically underactuated, the overhead crane can retain a fully actuated form mathematically. This form guides the natural transition of the controlled plant from the underactuated system to a fully actuated system (FAS). Within the FAS framework, the behaviors of both the original actuated and unactuated variables are interpreted as indirect outcomes of the control actions applied to the FAS. Consequently, the challenges of trolley positioning and swing elimination are reduced to control issues of FAS. Furthermore, a well-designed dynamical term is integrated into the system space of FAS to enhance swing suppression. The integration further leads to the control scheme for precise positioning and anti-swing, offering a fresh perspective on crane system control. Extensions to the cases with uncertainties and input saturation have also been discussed. Finally, we compare several representative methods for crane control and demonstrate that the proposed scheme outperforms them.