Modelling and control of rotary crane systems

Abstract: This thesis is devoted to the modelling and control of rotary crane systems. The goal is to design a control system that assists the operator to move a cargo without oscillations and to correctly align the cargo at the final position. The control system is divided into two independent parts, one dealing with the alignment of the load with the aid of a power swivel or a cargo rotating device, and a second that deals with the elimination of load oscillations. Both design and implementation of the control algorithms on a full scale crane are considered. In the cargo alignment system a linear cascade controller is considered that is shown to have near time-optimal performance for a system with saturation in both the angle and the angular rate of the power swivel. In the second part a weakly coupled pair of state feedback controllers with a nonlinear compensator is used to eliminate the load oscillations in two dimensions. In the third part of the thesis a software tool for simulation and real time control is presented. The development of the program started as a spin-off to the crane projects.