Sliding mode controls of double-pendulum crane systems

This study focuses on the design of robust nonlinear controllers based on both conventional and hierarchical sliding mode techniques for double-pendulum overhead crane systems. In the first approach, a first-order sliding surface is provided and a proper control scheme is generated to stabilize the surface. In the second approach, two levels of sliding surfaces are proposed and the control scheme is designed based on the stability of the second-level surface. We also prove the stability of the first-level sliding surface. To verify the quality of the proposed controllers, simulation for a particular type of overhead crane systems is implemented. Simulation results show that all state trajectories asymptotically converged to desired values.