LAUSR

In practice, vertical load motion is always involved in overhead cranes. In this case, the cable length turns from a constant to a variable, which may induce large amplitude load swing and make it more challenging to develop an appropriate controller. Most existing control methods for varying-cable-length cranes require either linearization or approximation to the original nonlinear dynamics; moreover, the case of external load disturbances is not fully considered. Inspired by these facts, we build the model and suggest an energy-based fuzzy control method for underactuated overhead cranes with load transferring, lowering, and persistent external disturbances. To estimate the persistent external disturbances, we construct a fuzzy disturbance observer. And a strict mathematical analysis of the control method without linearization approximation is presented, providing theoretical support for the superior performance of the proposed controller. Lyapunov techniques and LaSalle’s invariance theorem are used to demonstrate the stability of the closed-loop overhead crane system. Numerical simulation results are included to examine the effectiveness and robustness of the proposed method.