On the design of digital repetitive controllers using l/sub 2/ and H/sub /spl infin// optimal criteria with application to active harmonic noise cancellation in ducts

Two different optimization schemes based on l/sub 2/ and H/sub /spl infin// criteria are presented to design discrete-time repetitive controllers. These methods are designed to improve the convergence speed of the close loop system, especially when the plant possesses unstable zeros close to the unit circle. Examples are made to compare these two criteria. An experimental study on active harmonic noise cancellation in ducts is conducted to demonstrate the proposed methods.