Three-Dimensional Dynamic Modeling and Control of Off-Centered Bridge Crane Lifts

Abstract

When cranes lift payloads off the ground, the payload may slide sideways or swing unexpectedly. This motion occurs when the payload is not directly beneath the overhead suspension point of the hoist cable. Given that cable suspension points can be hundreds of feet above the payload, it is difficult for crane operators to know if the hoist cable is vertical before lifting the payload off the ground. If an off-center lift creates substantial horizontal motion, then it can create significant hazards for the operators, the payload, and the surrounding environment. This paper develops a three-dimensional dynamic model that predicts motions of off-centered lifts.