Bounded tracking and anti-swing control of underactuated cranes for payload transportation and lowering

For crane systems, anti-swing control for the payload horizontal transferring and vertical lowering processes is of significant importance to safety and efficiency. On the other hand, existing crane control methods can only achieve asymptotic stabilization/tracking results, while the varying ranges of error signals during the control process cannot be ensured. To address the control problem, we present a novel swing elimination control scheme that can effectively minimize the payload swing angle while achieving precise horizontal and vertical tracking control. In addition, different from all existing crane control methods reported in the literature, the proposed method admits us to preset the allowable tracking error bounds in advance; it can theoretically guarantee the tracking errors, both horizontally and vertically, to be always within the preset bounds and then converge to zero. Lyapunov techniques are utilized to analyze the boundedness and convergence of all closed-loop signals. Both numerical simulation and experimental results confirm the superior performance of the proposed method and show that it is robust with respect to external disturbances.