LAUSR

Tower cranes with slender jib transporting bulky loads are commonly applied in the construction site. Human-operated commands induce vibrations of the cantilever jib, swing, and twisting of the suspended load. Coupled oscillations among jib deflection, load swing and load twisting exhibit complex dynamic behavior. Furthermore, coupled-system frequencies significantly differ from uncoupled frequencies of the jib and pendulum. Unfortunately, little attention has been directed at the coupled-oscillation dynamics and control of jib deflection, load swing, and load twisting. A dynamic model of a tower crane slewing a slender jib and moving a distributed-mass load is derived. The fully coupled effects among jib deflection, load swing, and load twisting are described in the model. Then, an equation for predicting coupled-system frequencies is presented from the analytical model. Meanwhile, a hybrid piecewise smoother is proposed to filter out coupled oscillations among jib deflection, load swing and load twisting. Many experiments validate the utility of frequency-estimation equation and verify the success of the smoother.