Nonlinear Observers Applied to the Control of an Overhead Crane

This paper addresses the asymptotic output tracking problem for the model of an overhead crane. It is shown that the model is linearizable by dynamic state feedback when the full state is available for measurement. In the more realistic situation when the angle that the rope forms with respect to the vertical axis cannot be measured, two different nonlinear observers are used in order to estimate the actual value. These are: a numerical observer and a high gain observer. Numerical experiments serve to compare the performance of the proposed schemes.