Command shaping boom crane control system with nonlinear inputs

Presents the application of a command shaping control method for suppressing payload swing caused by operator commanded maneuvers, in rotary, ship-based, boom cranes. The crane configuration investigated, consists of a payload mass that swings on the end of a spherical pendulum of varying lift-line length (hoisting). The lift-line is attached to a boom capable of elevation (luffing) and rotation about a vertical axis (slewing). Positioning of the payload is accomplished through luff, slew and hoist commands issued in real-time by an operator. Payload oscillation is excited by a nonlinear combination of the operator´s inputs. It is shown that linear filters are sufficient under certain conditions. The command shaping strategy, consisting of a time-varying filter, reduces payload oscillation by 18 dB in experiments using the 1/16th scale Navy Crane Testbed at Sandia National Laboratories