Comparison and extensions of control methods for narrow-band disturbance rejection

Techniques for designing and implementing algorithms for the control of periodic narrowband disturbances are discussed, and the strong similarities between the different methodologies are shown. The analysis of linear time invariant feedback systems results in a suggestion of how to extend two of the LQ-based multiple-input, multiple-output methodologies to achieve improved performance and stability robustness properties. In the analysis of the adaptive feedforward methods, it is concluded that the popular filtered-x LMS algorithm is useful for implementation, but is best analyzed from a classical linear time invariant feedback perspective. This perspective results in a suggestion of how to extend the multiple error LMS algorithm to achieve improved performance and stability robustness. Stability bounds of the adaptive feedforward approaches are derived in terms of allowable model error.>