Steady-State and Stochastic Performance of a Modified Discrete-Time Prototype Repetitive Controller

In this paper, the rigid stability requirement is relaxed by including an appropriately chosen filter in the repetitive signal generator. Lacking an internal model, perfect regulation is not assured in the modified system. The steady-state and stochastic performances of the resulting system are analyzed. A high repetitive gain may give good steady-state performance, but the variance propagation of stochastic disturbances is large. The converse is true when the repetitive gain is small. The performance of the modified scheme is evaluated by applying it to a simulated disk-file actuator system