Damping Control of Suspended Load for Truck Cranes in Consideration of Second Bending Mode Oscillation

This article proposes a damping control of suspended loads for crane systems that take into consideration the second bending mode oscillation occurring at the sling hook in the middle of the suspending rope. In the proposed method, a suspended load of a crane is modeled as a double pendulum, and a state feedback control based on the model is used for damping control in consideration of the second bending mode oscillation as well as the first swinging mode oscillation. The effectiveness of the proposed method was evaluated using an actual track crane. For this purpose, firstly, parameters of the model of the actual crane were identified by experiments, and the characteristics such as the valve controller and the resonance of the crane-suspended load system has been clarified to check the validity of the double pendulum model. After the preliminary experiment, a controller designed based on the identified model was implemented in the actual crane, and the performance has been compared with a conventional controller based on a single pendulum model. As the result, it has been confirmed that for both the first swinging mode and the second bending mode oscillations, the proposed controller has achieved better damping performance than that of the conventional method and that the proposed method is effective for the second bending mode oscillation that occurs in the sling hook.