Dynamics and control of dual-hoist cranes moving distributed payloads
Miller, Alexander S.
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Crane motion induces payload oscillation that makes accurate positioning of the payload a challenging task. As the payload size increases, it may be necessary to utilize multiple cranes for better control of the payload position and orientation. However, simultaneously maneuvering multiple cranes to transport a single payload increases the complexity and danger of the operation. This thesis investigates the dynamics and control of dual-hoist bridge cranes transporting distributed payloads. Insights from this dynamic analysis were used to design input shapers that reduce payload oscillation originating from various crane motions. Also, studies were conducted to investigate the effect input shaping has on the performance of human operators using a dual-hoist bridge crane to transport distributed payloads through an obstacle course. In each study, input shaping significantly improved the task completion time. Furthermore, input-shaping control greatly decreased operator effort, as measured by the number of interface button pushes needed to complete a task. These results clearly demonstrate the benefit of input-shaping control on dual-hoist bridge cranes. In addition, a new system identification method that utilizes input shaping for determining the modal frequencies and relative amplitude contributions of individual modes was developed to aid in the dynamic analysis of dual-hoist bridge cranes, as well as other multi-mode systems. This method uses a new type of input shaper to suppress all but one mode to a low level. The shaper can also be used to bring a small-amplitude mode to light by modifying one of the vibration constraints.