Harmonic Speed Control for Repetitive Mechanical Systems

The present paper deals with harmonic speed control in repetitive mechanical systems, in which two structures of the speed controller are proposed. One is known as harmonic speed controller where each harmonic in the spectrum of the speed error is regulated by a proportional-integral (PI) controller. The second scheme is called PI-R speed controller where the conventional PI speed controller is augmented with resonant parts to control specific harmonics of the speed error. In addition, the harmonic speed controller provides information that is used for the estimation of the load torque. The estimated load torque is then utilized in a diagnostic procedure aiming to detect single-point defects in the bearings of the machine. A slider-crank mechanism was built as an example of repetitive mechanical systems and is used to verify the operation of the proposed methods.