Variably damped swing control of the overhead crane

The author describes the results of an investigation into the application of variable damping (where the damping is varied as a function of the system states) to improve the time response of an overhead crane which uses linear feedback to control the load swing. The resulting system is unique because the overhead crane has fourth-order dynamics and variable damping is usually only applied to second-order systems. A contour map approach (based on computer simulations) is devised to shape the damping function, and it is also used to develop a general tuning strategy for the system. The advantages and limitations of the controller are discussed, based on tests performed on a laboratory crane model