Title page for ETD etd-5134151959631701

Type of Document

Master's Thesis

Author

Fowler, Leslie Paige

URN

etd-5134151959631701

Title

Application of the Filtered-X LMS Algorithm for Disturbance Rejection in Time-Periodic Systems

Degree

Master of Science

Department

Mechanical Engineering

Advisory Committee

Advisor Name	Title
Harry H. Robertshaw	Committee Chair
Harley H. Cudney	none
William R. Saunders	none

Keywords

adaptive control
filtered-x LMS
time-periodic
disturbance rejection
helicopter rotor blade

Date of Defense

1996-05-03

Availability

unrestricted

Abstract

Extensive disturbance rejection methods have

been established for time-invariant systems.

However, the development of these

techniques has not focused on application to

time-periodic systems in particular until

recently. The filtered-X LMS algorithm is

regarded as the best disturbance rejection

technique for aperiodic systems by many, as

has been proven in the acoustics industry for

rejecting unwanted noise. Since this is

essentially a feedforward approach, we might

expect its performance to be good with

respect to time-periodic systems in which the

disturbance frequency is already known. The

work presented in this thesis is an

investigation of the performance of the

filtered-X LMS algorithm for disturbance

rejection in time-periodic systems. Two cases

are examined: a generalized linear,

time-periodic system and the helicopter rotor

blade in forward flight. Results for the

generalized system show that the filtered-X

LMS algorithm does converge for

time-periodic disturbance inputs and can

produce very small errors. For the helicopter

rotor blade system the algorithm is shown to

produce very small errors, with a 96%, or 14

dB, reduction in error from the open-loop

system. The filtered-X LMS disturbance

rejection technique is shown to provide a

successful means of rejecting time-periodic

disturbances for time-periodic systems.

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