A cost effective repetitive controller and its design

A structure for digital repetitive controllers is proposed along with a performance index based optimal design method. This new structure is motivated by efforts to minimize the complexity of repetitive control implementations. The addition of repetitive control to a system stabilized by observer state feedback is specifically described, but the ideas and methods should easily extend to other control systems. In a departure from existing design methods, the states of the stabilizing controller are used in addition to the plant output to drive the repetitive controller. Thus, the computation done by the stabilizing controller may be reused. An illustrative example is drawn from the area of computer disk file servosystems