Nonlinear sliding mode control of a three-dimensional double pendulum crane based on load swing state estimation: Design and experiments

In this paper, a controlled study of a three-dimensional overhead crane system with a two-stage spherical pendulum effect is carried out, and a nonlinear sliding mode control method based on load swing state estimation is proposed. The method derives the coupling relationship between the hook and the load swing angle based on the crane dynamics model and designs a linear expansion state observer (LESO) to observe the two-stage swing angle. Then, the swing angle information is fed into a controller containing a nonlinear sliding mode surface, and some rigorous mathematical proofs for the stability of this controller are presented. Finally, the theoretical analysis is experimentally verified using a prototype crane, and the results of the study show the effectiveness and strong robustness of the proposed control method.