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Operator control systems and methods for swing-free gantry-style cranes

United States Patent

*** EXPIRED ***
July 28, 1998
View the Complete Patent at the US Patent & Trademark Office
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A system and method for eliminating swing motions in gantry-style cranes while subject to operator control is presented. The present invention comprises an infinite impulse response ("IIR") filter and a proportional-integral ("PI") feedback controller (50). The IIR filter receives input signals (46) (commanded velocity or acceleration) from an operator input device (45) and transforms them into output signals (47) in such a fashion that the resulting motion is swing free (i.e., end-point swinging prevented). The parameters of the IIR filter are updated in real time using measurements from a hoist cable length encoder (25). The PI feedback controller compensates for modeling errors and external disturbances, such as wind or perturbations caused by collision with objects. The PI feedback controller operates on cable swing angle measurements provided by a cable angle sensor (27). The present invention adjusts acceleration and deceleration to eliminate oscillations. An especially important feature of the present invention is that it compensates for variable-length cable motions from multiple cables attached to a suspended payload.
Feddema; John T. (Albuquerque, NM), Petterson; Ben J. (Albuquerque, NM), Robinett, III; Rush D. (Albuquerque, NM)
Sandia Corporation (Albuquerque, NM)
08/ 651,166
May 15, 1996
I. 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.