Gantry crane control: a novel solution explored and extended

Positioning a crane\´s swinging load, at the bottom end of a cable, by moving a gantry trolley at the top, involves resolving the apparently conflicting demands of exact load positioning and active swing damping. Proposed control strategies to date have been open-ended, involving asymptotic approach to final rest positions. By contrast, a new control strategy, assuming an idealised cable, stops the load dead, exactly at the target, in a finite time, for all but the shortest manoeuvres. Using ideas based on mechanical waves, the gantry controller "learns" from the previously unknown dynamic response in the first part of the motion exactly how to terminate the motion. In a sense, the system itself serves as the control "model". This paper uses numerical simulation to go beyond the idealised model used to develop the strategy. The strategy is found to continue to function perfectly even with many non-ideal dynamic effects. Implications are discussed.