ADAPTIVE H-INFINITY CONTROL WITH APPLICATION TO SYSTEMS WITH STRUCTURAL FLEXIBILITY

In this paper we develop a robust adaptive control algorithm using a c ombination of H-infinity design and system identification. We derive f requency dependent bounds for the tolerated unmodeled dynamics and sho w that the approach gives a closed-loop system with bounded l(infinity ) and l(2) gain when the model mismatch is small in the frequency rang e where the control gain is large. Our application focus is systems wi th structural flexibility. me present a parameter estimation algorithm that uses constrained least squares with prefiltering to overcome the problem of identifying lightly damped antiresonances (a common proble m in identification of flexible systems). The estimation and control d esign are executed at a low frequency and only when parameter updating is needed. This allows us to apply computationally expensive control design and signal processing algorithms. It also eliminates many of th e problems of earlier adaptive controllers (such as bursting, paramete r drift, etc.) by turning off the estimator. We show results from the application of adaptive H-infinity control to a high-fidelity model of the Martin Marietta flexible beam testbed.