Anti-sway control for rotating boom cranes

A process for anti-sway control of a rotating boom or other three-degree-of-freedom crane wherein the load is hoisted, at variable hoist lengths, by a cable suspended from a point that can be moved in space in three dimensions, either freely, or under known constraints. Initial acceleration of the load induces an initial sway to the load. A second lateral acceleration, equal to the first lateral acceleration, is scheduled to be applied one-half a sway period later to remove the sway induced by the first acceleration. A third acceleration is applied to correct for half the excess sway induced by hoisting, by non-linearities in the pendulum, and by crane platform motion; and a forth acceleration, of equal magnitude as the third but in the opposite direction, is scheduled for one-half a sway period later, to correct the remaining half of the excess sway energy. The first and third accelerations are constrained by the ability of the crane to execute them and to execute the delayed second and fourth accelerations. The lateral accelerations are applied additively, and repeated sequentially at a variable rate, to accelerate the load from its initial location to objective velocities and locations under controlled anti-sway conditions.