When crane payloads are lifted off the ground, the payload may unexpectedly swing sideways. This occurs when the hoist cables are at an angle relative to vertical and the payload is not directly beneath the hoist. Because the hoist point is far above the payload, it is difficult for crane operators to know if the hoist cable is perfectly vertical before they start to lift the payload. Some amount of horizontal motion of the payload will always occur at lift off. If an off-centered lift results in significant horizontal motion, then it creates a hazard for the human operators, the payload, and the surrounding environment. This paper develops dynamic models of off-centered lifts and presents experimental verification of the theoretical predictions. To mitigate the detrimental effects of off-centered lifts, autonomous-centering solutions are proposed.
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