Positioning and control of boom crane luffing with double-pendulum payloads

Boom cranes are used for numerous material-handling and manufacturing processes in factories, shipyards, and construction sites. They move payloads by hoisting up and down, slewing their base about a vertical axis, and luffing their boom in and out from the base. Many boom cranes are designed to automatically level luff, wherein the payload stays at the same height while the boom luff angle changes. All of these motions induce payload oscillation. The problem of payload oscillation becomes more challenging when the payload exhibits double-pendulum dynamics that produce two varying frequencies of oscillation. In this paper, input shaping is used to reduce the two-mode oscillatory dynamics of such systems. Furthermore, a small-step control mode is designed to allow the operator to make short and precise motions without causing oscillations.