Active damping of tilt oscillations and trajectory control of overhead cranes

Crane systems are widely used in industrial applications for the handling of heavy loads in large workspaces. This paper presents the modeling and the control system design for a 5 t-bridge crane following a decentralized approach with independent controllers for each crane axis. The load suspension is modeled by a double pendulum to take into account the first two modes of oscillation: primary load swinging and secondary tilt oscillation of the payload relative to the rope suspension. Feedforward control, feedback control based on LQR design, and observer based disturbance rejection are used to improve tracking accuracy as well as to achieve high position accuracy at the target point. In order to maintain high control performance in spite of varying system parameters gain scheduling is employed. Experimental results taken from the bridge crane show the effectiveness of the proposed control scheme