A method of positioning a movable structure of an overhead crane, the movable structure being either a trolley or a bridge of the overhead crane, the method comprising providing a position reference for the movable structure, controlling with a state-feedback controller the position of the movable structure, the position of the movable structure and a sway angle of the load being state variables of the system used in the state-feedback controller. Further the method comprises determining the position or speed of the movable structure and the sway angle of the load or angular velocity of the load, providing the determined position or speed of the movable structure, the determined sway angle of the load or angular velocity of the load and the output of the state-feedback controller to an observer, producing with the observer at least two estimated state variables, forming a feedback vector from the estimated state variables or from the estimated state variables together with determined state variables, using the formed feedback vector as a feedback for the state-feedback controller, and providing the output of the controller to a frequency converter.