Load sway control of overhead cranes with load hoisting via stability analysis

A nonlinear mathematical model representing the load sway dynamics of overhead cranes is developed in which simultaneous trolley and girder motions are allowed during hoisting or lowering of the load. The nonlinear model is linearized about the nominal operating trajectories that are obtained from the desired transport plan. The resulting linear model, however, has time-varying parameters. This complicates the design problem of a feedback controller to suppress the load sway. The stability of the load sway dynamics in the presence of feedback is investigated and a set of sufficient conditions on the feedback parameters is obtained to guarantee the asymptotic stability of the load sway in the sense that sway angle is bounded and tends to zero as time tends to infinity.