Estimating the Sway Angle of an Overhead Crane by an Observer Using Angular Velocity Sensors

A method is proposed to estimate the sway angle for an overhead crane by an unknown-input observer using data from angular velocity sensors. Characteristics of this observer are as follows. (1) It is not influenced by system elements that are difficult to identify. (2) It is designed to minimize influence of a higher frequency vibration caused by the pitching motion of the load. Furthermore, estimation of the sway angle is possible even accompanied with a torsional vibration of the rope. By means of a measument system with this observer, some experiments to control the sway angle of the load and the position of the trolley are carried out. The result is successful in keeping the sway angle in zero near the objective position. In this way the validity of the method to estimate the sway angle using angular velocity sensors is verified.