Vibration control of an overhead crane by elimination of the natural frequency component

Abstract

Overhead traveling cranes are widely used at ports and factories, and they play an important role in mass transportation systems. The main problem with such cranes is that residual vibration of the cargo often occurs at the end of transportation. At present, prevention of residual vibration depends on the skills of the crane operator. Therefore, an automatic operation system for overhead traveling cranes is strongly desired for efficient and safe transportation. In this paper, a new type of open-loop control method is proposed for suppressing the residual vibration. This method is based on the fact that residual vibration is completely suppressed in a linear undamped system excited by an external force that does not contain the natural frequency component of the system. We apply this to a nonlinear damped system and develop an efficient method for determining a trolley trajectory that prevents residual vibration. Numerical simulations confirm that this method can prevent residual vibration. Furthermore, we employ a trigonometric series as well as a power series created by modifying Legendre polynomials in order to construct the trolley trajectory, then examine which is more advantageous for transportation. The results demonstrate that the power series exhibits a better performance in terms of the maximum swing angle of the cargo during transportation and limit of transportation time.