This project is aimed at developing an adaptive control structure for a mechanical slewing system. The main objective for the controller is to dampen oscillations that occurs when the system is decelerating. Three adaptive control structures will be investigated, resulting in a proposed control structure in the form of a weighted 2-DOF PD design. To accomplish the task, a nonlinear equation is derived describing the systems equations of motion. Further the 2-DOF PD design will be tested on a real mechanical slewing system and will be proven to accomplish the set task of dampening the oscillations.