A Combined Feedback and Command Shaping Controller for Improving Positioning and Reducing Cable Sway in Cranes
Sorensen, Khalid Lief
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Bridge and gantry cranes are crucially important elements in the industrial complex; they are used in many areas such as shipping, building construction, steel mills, and nuclear facilities, just to name a few. These types of systems tend to be highly flexible in nature, generally responding to commanded motion with oscillations of the payload and hook. The response of these systems to external disturbances, such as wind, is also oscillatory in nature. Often, the oscillations of the hook and payload have undesirable consequences. For instance, precise manipulation of payloads is difficult when cable sway is present. Oscillation of the hook can also present a safety hazard. For these reasons, the ability to successfully negate these detrimental dynamics can result in improved positioning, quicker settling time, and improved safety. This thesis addresses the dynamic properties of bridge and gantry cranes in an effort to develop a control scheme that enables strides to be made in these areas of positioning, efficiency, and safety. The fundamental advancement arising from this thesis is the development of a control scheme that enables precise positioning of the payload while motion and disturbance-induced oscillations are eliminated. A command generation technique uniquely suited for reducing oscillation in low-frequency flexible systems is examined and utilized in the control. The control scheme is implemented on a 10-ton bridge crane for validation purposes.