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Sway control method and system for rotary cranes

United States Patent

June 1, 1999
View the Complete Patent at the US Patent & Trademark Office
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Methods and apparatuses for reducing the oscillatory motion of rotary crane payloads during operator-commanded or computer-controlled maneuvers. An Input-shaping filter receives input signals from multiple operator input devices and converts them into output signals readable by the crane controller to dampen the payload tangential and radial sway associated with rotation of the jib. The input signals are characterized by a hub rotation trajectory .gamma.(t), which includes a jib angular acceleration .gamma., a trolley acceleration x, and a load-line length velocity L. The system state variables are characterized by a tangential rotation angle .theta.(t) and a radial rotation angle .phi.(t) of the load-line. The coupled equations of motion governing the filter are non-linear and configuration-dependent. In one embodiment, a filter is provided between the operator and the crane for filtering undesired frequencies from the angular .gamma. and trolley x velocities to suppress payload oscillation. In another embodiment, crane commands are computer generated and controlled to suppress vibration of the payload using a postulated asymmetrical shape for the acceleration profiles of the jib, which profiles are uniquely determined by a set of parameters (including the acceleration pulse amplitude and the duration and coast time between pulses), or a dynamic programming approach.
Robinett; Rush D. (Tijeras, NM), Parker; Gordon G. (Houghton, MI), Feddema; John T. (Albuquerque, NM), Dohrmann; Clark R. (Albuquerque, NM), Petterson; Ben J. (Albuquerque, NM)
Sandia Corporation (Albuquerque, NM)
08/ 808,821
February 28, 1997
II. GOVERNMENT RIGHTS This invention was made with United States Government support under Contract No. DE-AC04-94AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in this invention.