Energy-shaping-based nonlinear controller design for rotary cranes with double-pendulum effect considering actuator saturation

Dynamic performance analysis and controller design become more difficult when the load sway in rotary cranes exhibits double-pendulum characteristics. Furthermore, uncertain parameters and external disturbances in the crane system make it difficult for traditional methods to obtain satisfactory control performance. In addition, in an actual crane system, because of physical constraints, the output torque of the motors cannot be infinite. Therefore, the motor torque calculated by existing methods may exceed the maximum value, and actuator saturation will occur, which will affect the control performance. For this purpose, an energy-shaping-based nonlinear controller is presented after simplifying the original crane model. Stability analysis is carried out using the Lyapunov technique and LaSalle's invariance theorem. Numerical simulations validate that the proposed method can provide a robust control performance superior to that of traditional controllers.