A new indirect adaptive algorithm for feedforward control

This paper considers the deterministic adaptive feed-forward control problem for disturbance rejection. A new indirect adaptive control algorithm is presented as an alternative to the well-known "filtered-X LMS" algorithm when the disturbance is periodic with unknown frequency. This new algorithm requires the solution of a Diophantine equation and a simple scheme to recursively solve this equation is developed. The new algorithm is shown to converge without the use of a dither signal for plant modeling. Simulations demonstrate that the proposed algorithm has improved transient response and convergence speed than the filtered-X algorithm. The applicability of the algorithm to the adaptive active noise cancelling problem is considered.