Boom cranes are used for numerous material-handling and manufacturing processes in factories, shipyards, and construction sites. All cranes lift their payloads by hoisting them up using overhead suspension cables. Boom cranes move payloads by slewing their base about a vertical axis, luffing their boom in and out from the base, and changing the length of the suspension cable. 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. This paper studies the swing dynamics of such cranes. It also applies input shaping to reduce the two-mode oscillatory dynamics. Experiments confirm several of the interesting dynamic effects.