Periodic SMC Method for 4-DOF Tower Crane Systems Under Unknown Control Direction

A new periodic SMC algorithm is constructed for 4-DOF tower crane systems under unknown control direction constraints. It should be pointed out that compared with existing control direction-related control algorithms, the designed control coefficient is allowed to cross 0 continuously. The stability of the controlled system is illustrated utilizing the Lyapunov techniques. Several simulations are evaluated to prove the satisfactory control performance of the proposed periodic SMC method.