Swing suppression control in tower cranes with time-varying rope length using real-time modified trajectory planning

To transfer heavy payloads at construction sites, tower cranes are essential. However, tower cranes are a complex underactuated system due to the strong coupling between the jib, trolley and payload. In addition, the rope length is usually time-varying in order to accomplish the transportation task in a wide three-dimensional space, which results in more complex dynamic characteristics. Hence, through combining full state anti-swing feedback damping with reference trajectories, a real-time modified trajectory planning method is presented for tower cranes with payload lowering/hoisting motion. The proposed method is simple and easy to implement. The system stability is proved strictly based on Lyapunov technique, LaSalle's invariance principle and Barbalat's lemma. In addition, various experiments are carried out and the swing suppression performance of the proposed method was found to be useful and practical, while guaranteeing precise positioning.