Anti-sway control of a crane under operator's command

A system is disclosed for eliminating sway of a load in a crane or crane-like system subject to operator's command. The load is suspended by a cable from a horizontally movable trolley and can be hoisted vertically. The system uses the principle of cancellation to eliminate sway even when the crane has simultaneous horizontal trolley and vertical hoisting motions. The system takes into account the full dynamical effect in computing cancellation signals. The use of a family of ordinary differential equations for the computation of the cancellation controls is a key component of the invention. In computing these controls, the differential equations are solved in real time using sensory measurement of the cable length and its time derivative.