Position and sway control of a nonlinear tower crane system using input shaping techniques

Abstract

Crane systems are the most widely used tools in the shipping yards and construction sites to transport goods from one point to another. The emergence of high riser-building, encourages the use of modern systems particularly tower crane systems to conveniently execute various tasks within the shortest possible time. However, those systems suffered greatly from undesired swinging during the process. Conversely, this significantly posed problems to the systems, resulting to inaccurate positioning of the payload, unease of operation by the human operator and in some cases even damage to the system. This paper investigates the performance of input shaping techniques for sway control of a tower crane system. Unlike the conventional optimal controllers, input shaping is simple to design and cost effective as it does not require feedback sensors. Several input shapers were implemented and their performances were compared which are useful for future sway control designs. The nonlinear model of the system was derived using the Lagrange’s energy equation. To investigate the performance and robustness of input shaping techniques, zero vibration (ZV), zero vibration derivative (ZVD), zero vibration derivative-derivative (ZVDD) and zero vibration derivative-derivative-derivative (ZVDDD) were proposed with a constant cable dimension in an open loop configuration. Simulation and experimental results have shown that ZVDDD with the slowest response has the highest level of sway reduction and robustness to modelling errors as compared to ZV, ZVD and ZVDD. Moreover, to improve the response, a negative amplitude zero vibration derivative-derivative (NAZVDD) was designed and its performance was compared with ZVDD. It is found that NAZVDD gives a faster response with small robustness penalty as compared to ZVDD.