Anti-sway control input for overhead traveling crane based on natural period

For safe and efficient work of handling task for heavy load by overhead traveling crane, sway of the suspended load should be avoided. Various methods have been proposed to reduce the sway, mostly by using feedback control methods. However, most material handling system uses open loop type servo controller where trapezoidal or S-shape velocity pattern is typically used for the input of the controller. Considering use of such servo controller, this paper proposes an anti-sway open loop control method based on natural period of the overhead traveling crane system and by using trapezoidal or S-shape velocity pattern for the desired input of the controller. Theoretical analysis for the conditions of no sway by the trapezoidal and S-shape velocity pattern input is presented. This method can be easily applied for an anti-sway control of the crane system when typical servo controller is used. The idea is also applied for the case of changing rope length of the overhead traveling crane system.