G.G. Parker and J.D. Bird, III (USA)
Crane, Swing, Pendulation, Control, Knuckle Boom.
Shipboard cranes can be used to move cargo between ships in open seas. Forcing the crane to track a target can induce swing when the target ship is moving. Additional sources of swing include external disturbances and the operator’s commands. Previous active damping studies have focused on using the crane’s slew and luff axes to damp swing. This means that the commands to the crane’s primary drive systems are modified to include both the operator’s inputs and those computed by the swing damping control system. Thus, the crane’s boom, which is often massive, is used to damp swing in addition to its normal objective of gross positioning of the load. This paper describes the use of a modified knuckle boom crane with a lightweight, addi tional member whose sole purpose is to damp swing. The swing dynamics are derived, in addition to the control strat egy. It was found that a decoupled control approach could be employed that separates the target tracking and active damping objectives. Simulation results indicate that target tracking can be improved by 80% compared to the uncon trolled case.
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